kernel/bpf/hashtab.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
0003  * Copyright (c) 2016 Facebook
0004  */
0005 #include <linux/bpf.h>
0006 #include <linux/btf.h>
0007 #include <linux/jhash.h>
0008 #include <linux/filter.h>
0009 #include <linux/rculist_nulls.h>
0010 #include <linux/random.h>
0011 #include <uapi/linux/btf.h>
0012 #include <linux/rcupdate_trace.h>
0013 #include <linux/btf_ids.h>
0014 #include "percpu_freelist.h"
0015 #include "bpf_lru_list.h"
0016 #include "map_in_map.h"
0017
0018 #define HTAB_CREATE_FLAG_MASK                       \
0019     (BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |    \
0020      BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED)
0021
0022 #define BATCH_OPS(_name)            \
0023     .map_lookup_batch =         \
0024     _name##_map_lookup_batch,       \
0025     .map_lookup_and_delete_batch =      \
0026     _name##_map_lookup_and_delete_batch,    \
0027     .map_update_batch =         \
0028     generic_map_update_batch,       \
0029     .map_delete_batch =         \
0030     generic_map_delete_batch
0031
0032 /*
0033  * The bucket lock has two protection scopes:
0034  *
0035  * 1) Serializing concurrent operations from BPF programs on different
0036  *    CPUs
0037  *
0038  * 2) Serializing concurrent operations from BPF programs and sys_bpf()
0039  *
0040  * BPF programs can execute in any context including perf, kprobes and
0041  * tracing. As there are almost no limits where perf, kprobes and tracing
0042  * can be invoked from the lock operations need to be protected against
0043  * deadlocks. Deadlocks can be caused by recursion and by an invocation in
0044  * the lock held section when functions which acquire this lock are invoked
0045  * from sys_bpf(). BPF recursion is prevented by incrementing the per CPU
0046  * variable bpf_prog_active, which prevents BPF programs attached to perf
0047  * events, kprobes and tracing to be invoked before the prior invocation
0048  * from one of these contexts completed. sys_bpf() uses the same mechanism
0049  * by pinning the task to the current CPU and incrementing the recursion
0050  * protection across the map operation.
0051  *
0052  * This has subtle implications on PREEMPT_RT. PREEMPT_RT forbids certain
0053  * operations like memory allocations (even with GFP_ATOMIC) from atomic
0054  * contexts. This is required because even with GFP_ATOMIC the memory
0055  * allocator calls into code paths which acquire locks with long held lock
0056  * sections. To ensure the deterministic behaviour these locks are regular
0057  * spinlocks, which are converted to 'sleepable' spinlocks on RT. The only
0058  * true atomic contexts on an RT kernel are the low level hardware
0059  * handling, scheduling, low level interrupt handling, NMIs etc. None of
0060  * these contexts should ever do memory allocations.
0061  *
0062  * As regular device interrupt handlers and soft interrupts are forced into
0063  * thread context, the existing code which does
0064  *   spin_lock*(); alloc(GFP_ATOMIC); spin_unlock*();
0065  * just works.
0066  *
0067  * In theory the BPF locks could be converted to regular spinlocks as well,
0068  * but the bucket locks and percpu_freelist locks can be taken from
0069  * arbitrary contexts (perf, kprobes, tracepoints) which are required to be
0070  * atomic contexts even on RT. These mechanisms require preallocated maps,
0071  * so there is no need to invoke memory allocations within the lock held
0072  * sections.
0073  *
0074  * BPF maps which need dynamic allocation are only used from (forced)
0075  * thread context on RT and can therefore use regular spinlocks which in
0076  * turn allows to invoke memory allocations from the lock held section.
0077  *
0078  * On a non RT kernel this distinction is neither possible nor required.
0079  * spinlock maps to raw_spinlock and the extra code is optimized out by the
0080  * compiler.
0081  */
0082 struct bucket {
0083     struct hlist_nulls_head head;
0084     union {
0085         raw_spinlock_t raw_lock;
0086         spinlock_t     lock;
0087     };
0088 };
0089
0090 #define HASHTAB_MAP_LOCK_COUNT 8
0091 #define HASHTAB_MAP_LOCK_MASK (HASHTAB_MAP_LOCK_COUNT - 1)
0092
0093 struct bpf_htab {
0094     struct bpf_map map;
0095     struct bucket *buckets;
0096     void *elems;
0097     union {
0098         struct pcpu_freelist freelist;
0099         struct bpf_lru lru;
0100     };
0101     struct htab_elem *__percpu *extra_elems;
0102     atomic_t count; /* number of elements in this hashtable */
0103     u32 n_buckets;  /* number of hash buckets */
0104     u32 elem_size;  /* size of each element in bytes */
0105     u32 hashrnd;
0106     struct lock_class_key lockdep_key;
0107     int __percpu *map_locked[HASHTAB_MAP_LOCK_COUNT];
0108 };
0109
0110 /* each htab element is struct htab_elem + key + value */
0111 struct htab_elem {
0112     union {
0113         struct hlist_nulls_node hash_node;
0114         struct {
0115             void *padding;
0116             union {
0117                 struct bpf_htab *htab;
0118                 struct pcpu_freelist_node fnode;
0119                 struct htab_elem *batch_flink;
0120             };
0121         };
0122     };
0123     union {
0124         struct rcu_head rcu;
0125         struct bpf_lru_node lru_node;
0126     };
0127     u32 hash;
0128     char key[] __aligned(8);
0129 };
0130
0131 static inline bool htab_is_prealloc(const struct bpf_htab *htab)
0132 {
0133     return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
0134 }
0135
0136 static inline bool htab_use_raw_lock(const struct bpf_htab *htab)
0137 {
0138     return (!IS_ENABLED(CONFIG_PREEMPT_RT) || htab_is_prealloc(htab));
0139 }
0140
0141 static void htab_init_buckets(struct bpf_htab *htab)
0142 {
0143     unsigned int i;
0144
0145     for (i = 0; i < htab->n_buckets; i++) {
0146         INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
0147         if (htab_use_raw_lock(htab)) {
0148             raw_spin_lock_init(&htab->buckets[i].raw_lock);
0149             lockdep_set_class(&htab->buckets[i].raw_lock,
0150                       &htab->lockdep_key);
0151         } else {
0152             spin_lock_init(&htab->buckets[i].lock);
0153             lockdep_set_class(&htab->buckets[i].lock,
0154                       &htab->lockdep_key);
0155         }
0156         cond_resched();
0157     }
0158 }
0159
0160 static inline int htab_lock_bucket(const struct bpf_htab *htab,
0161                    struct bucket *b, u32 hash,
0162                    unsigned long *pflags)
0163 {
0164     unsigned long flags;
0165
0166     hash = hash & HASHTAB_MAP_LOCK_MASK;
0167
0168     migrate_disable();
0169     if (unlikely(__this_cpu_inc_return(*(htab->map_locked[hash])) != 1)) {
0170         __this_cpu_dec(*(htab->map_locked[hash]));
0171         migrate_enable();
0172         return -EBUSY;
0173     }
0174
0175     if (htab_use_raw_lock(htab))
0176         raw_spin_lock_irqsave(&b->raw_lock, flags);
0177     else
0178         spin_lock_irqsave(&b->lock, flags);
0179     *pflags = flags;
0180
0181     return 0;
0182 }
0183
0184 static inline void htab_unlock_bucket(const struct bpf_htab *htab,
0185                       struct bucket *b, u32 hash,
0186                       unsigned long flags)
0187 {
0188     hash = hash & HASHTAB_MAP_LOCK_MASK;
0189     if (htab_use_raw_lock(htab))
0190         raw_spin_unlock_irqrestore(&b->raw_lock, flags);
0191     else
0192         spin_unlock_irqrestore(&b->lock, flags);
0193     __this_cpu_dec(*(htab->map_locked[hash]));
0194     migrate_enable();
0195 }
0196
0197 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node);
0198
0199 static bool htab_is_lru(const struct bpf_htab *htab)
0200 {
0201     return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
0202         htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
0203 }
0204
0205 static bool htab_is_percpu(const struct bpf_htab *htab)
0206 {
0207     return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
0208         htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
0209 }
0210
0211 static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
0212                      void __percpu *pptr)
0213 {
0214     *(void __percpu **)(l->key + key_size) = pptr;
0215 }
0216
0217 static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
0218 {
0219     return *(void __percpu **)(l->key + key_size);
0220 }
0221
0222 static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
0223 {
0224     return *(void **)(l->key + roundup(map->key_size, 8));
0225 }
0226
0227 static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
0228 {
0229     return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size);
0230 }
0231
0232 static bool htab_has_extra_elems(struct bpf_htab *htab)
0233 {
0234     return !htab_is_percpu(htab) && !htab_is_lru(htab);
0235 }
0236
0237 static void htab_free_prealloced_timers(struct bpf_htab *htab)
0238 {
0239     u32 num_entries = htab->map.max_entries;
0240     int i;
0241
0242     if (!map_value_has_timer(&htab->map))
0243         return;
0244     if (htab_has_extra_elems(htab))
0245         num_entries += num_possible_cpus();
0246
0247     for (i = 0; i < num_entries; i++) {
0248         struct htab_elem *elem;
0249
0250         elem = get_htab_elem(htab, i);
0251         bpf_timer_cancel_and_free(elem->key +
0252                       round_up(htab->map.key_size, 8) +
0253                       htab->map.timer_off);
0254         cond_resched();
0255     }
0256 }
0257
0258 static void htab_free_prealloced_kptrs(struct bpf_htab *htab)
0259 {
0260     u32 num_entries = htab->map.max_entries;
0261     int i;
0262
0263     if (!map_value_has_kptrs(&htab->map))
0264         return;
0265     if (htab_has_extra_elems(htab))
0266         num_entries += num_possible_cpus();
0267
0268     for (i = 0; i < num_entries; i++) {
0269         struct htab_elem *elem;
0270
0271         elem = get_htab_elem(htab, i);
0272         bpf_map_free_kptrs(&htab->map, elem->key + round_up(htab->map.key_size, 8));
0273         cond_resched();
0274     }
0275 }
0276
0277 static void htab_free_elems(struct bpf_htab *htab)
0278 {
0279     int i;
0280
0281     if (!htab_is_percpu(htab))
0282         goto free_elems;
0283
0284     for (i = 0; i < htab->map.max_entries; i++) {
0285         void __percpu *pptr;
0286
0287         pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
0288                      htab->map.key_size);
0289         free_percpu(pptr);
0290         cond_resched();
0291     }
0292 free_elems:
0293     bpf_map_area_free(htab->elems);
0294 }
0295
0296 /* The LRU list has a lock (lru_lock). Each htab bucket has a lock
0297  * (bucket_lock). If both locks need to be acquired together, the lock
0298  * order is always lru_lock -> bucket_lock and this only happens in
0299  * bpf_lru_list.c logic. For example, certain code path of
0300  * bpf_lru_pop_free(), which is called by function prealloc_lru_pop(),
0301  * will acquire lru_lock first followed by acquiring bucket_lock.
0302  *
0303  * In hashtab.c, to avoid deadlock, lock acquisition of
0304  * bucket_lock followed by lru_lock is not allowed. In such cases,
0305  * bucket_lock needs to be released first before acquiring lru_lock.
0306  */
0307 static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
0308                       u32 hash)
0309 {
0310     struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
0311     struct htab_elem *l;
0312
0313     if (node) {
0314         l = container_of(node, struct htab_elem, lru_node);
0315         memcpy(l->key, key, htab->map.key_size);
0316         return l;
0317     }
0318
0319     return NULL;
0320 }
0321
0322 static int prealloc_init(struct bpf_htab *htab)
0323 {
0324     u32 num_entries = htab->map.max_entries;
0325     int err = -ENOMEM, i;
0326
0327     if (htab_has_extra_elems(htab))
0328         num_entries += num_possible_cpus();
0329
0330     htab->elems = bpf_map_area_alloc((u64)htab->elem_size * num_entries,
0331                      htab->map.numa_node);
0332     if (!htab->elems)
0333         return -ENOMEM;
0334
0335     if (!htab_is_percpu(htab))
0336         goto skip_percpu_elems;
0337
0338     for (i = 0; i < num_entries; i++) {
0339         u32 size = round_up(htab->map.value_size, 8);
0340         void __percpu *pptr;
0341
0342         pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
0343                         GFP_USER | __GFP_NOWARN);
0344         if (!pptr)
0345             goto free_elems;
0346         htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
0347                   pptr);
0348         cond_resched();
0349     }
0350
0351 skip_percpu_elems:
0352     if (htab_is_lru(htab))
0353         err = bpf_lru_init(&htab->lru,
0354                    htab->map.map_flags & BPF_F_NO_COMMON_LRU,
0355                    offsetof(struct htab_elem, hash) -
0356                    offsetof(struct htab_elem, lru_node),
0357                    htab_lru_map_delete_node,
0358                    htab);
0359     else
0360         err = pcpu_freelist_init(&htab->freelist);
0361
0362     if (err)
0363         goto free_elems;
0364
0365     if (htab_is_lru(htab))
0366         bpf_lru_populate(&htab->lru, htab->elems,
0367                  offsetof(struct htab_elem, lru_node),
0368                  htab->elem_size, num_entries);
0369     else
0370         pcpu_freelist_populate(&htab->freelist,
0371                        htab->elems + offsetof(struct htab_elem, fnode),
0372                        htab->elem_size, num_entries);
0373
0374     return 0;
0375
0376 free_elems:
0377     htab_free_elems(htab);
0378     return err;
0379 }
0380
0381 static void prealloc_destroy(struct bpf_htab *htab)
0382 {
0383     htab_free_elems(htab);
0384
0385     if (htab_is_lru(htab))
0386         bpf_lru_destroy(&htab->lru);
0387     else
0388         pcpu_freelist_destroy(&htab->freelist);
0389 }
0390
0391 static int alloc_extra_elems(struct bpf_htab *htab)
0392 {
0393     struct htab_elem *__percpu *pptr, *l_new;
0394     struct pcpu_freelist_node *l;
0395     int cpu;
0396
0397     pptr = bpf_map_alloc_percpu(&htab->map, sizeof(struct htab_elem *), 8,
0398                     GFP_USER | __GFP_NOWARN);
0399     if (!pptr)
0400         return -ENOMEM;
0401
0402     for_each_possible_cpu(cpu) {
0403         l = pcpu_freelist_pop(&htab->freelist);
0404         /* pop will succeed, since prealloc_init()
0405          * preallocated extra num_possible_cpus elements
0406          */
0407         l_new = container_of(l, struct htab_elem, fnode);
0408         *per_cpu_ptr(pptr, cpu) = l_new;
0409     }
0410     htab->extra_elems = pptr;
0411     return 0;
0412 }
0413
0414 /* Called from syscall */
0415 static int htab_map_alloc_check(union bpf_attr *attr)
0416 {
0417     bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
0418                attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
0419     bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
0420             attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
0421     /* percpu_lru means each cpu has its own LRU list.
0422      * it is different from BPF_MAP_TYPE_PERCPU_HASH where
0423      * the map's value itself is percpu.  percpu_lru has
0424      * nothing to do with the map's value.
0425      */
0426     bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
0427     bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
0428     bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED);
0429     int numa_node = bpf_map_attr_numa_node(attr);
0430
0431     BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
0432              offsetof(struct htab_elem, hash_node.pprev));
0433     BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
0434              offsetof(struct htab_elem, hash_node.pprev));
0435
0436     if (lru && !bpf_capable())
0437         /* LRU implementation is much complicated than other
0438          * maps.  Hence, limit to CAP_BPF.
0439          */
0440         return -EPERM;
0441
0442     if (zero_seed && !capable(CAP_SYS_ADMIN))
0443         /* Guard against local DoS, and discourage production use. */
0444         return -EPERM;
0445
0446     if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK ||
0447         !bpf_map_flags_access_ok(attr->map_flags))
0448         return -EINVAL;
0449
0450     if (!lru && percpu_lru)
0451         return -EINVAL;
0452
0453     if (lru && !prealloc)
0454         return -ENOTSUPP;
0455
0456     if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
0457         return -EINVAL;
0458
0459     /* check sanity of attributes.
0460      * value_size == 0 may be allowed in the future to use map as a set
0461      */
0462     if (attr->max_entries == 0 || attr->key_size == 0 ||
0463         attr->value_size == 0)
0464         return -EINVAL;
0465
0466     if ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE -
0467        sizeof(struct htab_elem))
0468         /* if key_size + value_size is bigger, the user space won't be
0469          * able to access the elements via bpf syscall. This check
0470          * also makes sure that the elem_size doesn't overflow and it's
0471          * kmalloc-able later in htab_map_update_elem()
0472          */
0473         return -E2BIG;
0474
0475     return 0;
0476 }
0477
0478 static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
0479 {
0480     bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
0481                attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
0482     bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
0483             attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
0484     /* percpu_lru means each cpu has its own LRU list.
0485      * it is different from BPF_MAP_TYPE_PERCPU_HASH where
0486      * the map's value itself is percpu.  percpu_lru has
0487      * nothing to do with the map's value.
0488      */
0489     bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
0490     bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
0491     struct bpf_htab *htab;
0492     int err, i;
0493
0494     htab = kzalloc(sizeof(*htab), GFP_USER | __GFP_ACCOUNT);
0495     if (!htab)
0496         return ERR_PTR(-ENOMEM);
0497
0498     lockdep_register_key(&htab->lockdep_key);
0499
0500     bpf_map_init_from_attr(&htab->map, attr);
0501
0502     if (percpu_lru) {
0503         /* ensure each CPU's lru list has >=1 elements.
0504          * since we are at it, make each lru list has the same
0505          * number of elements.
0506          */
0507         htab->map.max_entries = roundup(attr->max_entries,
0508                         num_possible_cpus());
0509         if (htab->map.max_entries < attr->max_entries)
0510             htab->map.max_entries = rounddown(attr->max_entries,
0511                               num_possible_cpus());
0512     }
0513
0514     /* hash table size must be power of 2 */
0515     htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
0516
0517     htab->elem_size = sizeof(struct htab_elem) +
0518               round_up(htab->map.key_size, 8);
0519     if (percpu)
0520         htab->elem_size += sizeof(void *);
0521     else
0522         htab->elem_size += round_up(htab->map.value_size, 8);
0523
0524     err = -E2BIG;
0525     /* prevent zero size kmalloc and check for u32 overflow */
0526     if (htab->n_buckets == 0 ||
0527         htab->n_buckets > U32_MAX / sizeof(struct bucket))
0528         goto free_htab;
0529
0530     err = -ENOMEM;
0531     htab->buckets = bpf_map_area_alloc(htab->n_buckets *
0532                        sizeof(struct bucket),
0533                        htab->map.numa_node);
0534     if (!htab->buckets)
0535         goto free_htab;
0536
0537     for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++) {
0538         htab->map_locked[i] = bpf_map_alloc_percpu(&htab->map,
0539                                sizeof(int),
0540                                sizeof(int),
0541                                GFP_USER);
0542         if (!htab->map_locked[i])
0543             goto free_map_locked;
0544     }
0545
0546     if (htab->map.map_flags & BPF_F_ZERO_SEED)
0547         htab->hashrnd = 0;
0548     else
0549         htab->hashrnd = get_random_int();
0550
0551     htab_init_buckets(htab);
0552
0553     if (prealloc) {
0554         err = prealloc_init(htab);
0555         if (err)
0556             goto free_map_locked;
0557
0558         if (!percpu && !lru) {
0559             /* lru itself can remove the least used element, so
0560              * there is no need for an extra elem during map_update.
0561              */
0562             err = alloc_extra_elems(htab);
0563             if (err)
0564                 goto free_prealloc;
0565         }
0566     }
0567
0568     return &htab->map;
0569
0570 free_prealloc:
0571     prealloc_destroy(htab);
0572 free_map_locked:
0573     for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
0574         free_percpu(htab->map_locked[i]);
0575     bpf_map_area_free(htab->buckets);
0576 free_htab:
0577     lockdep_unregister_key(&htab->lockdep_key);
0578     kfree(htab);
0579     return ERR_PTR(err);
0580 }
0581
0582 static inline u32 htab_map_hash(const void *key, u32 key_len, u32 hashrnd)
0583 {
0584     return jhash(key, key_len, hashrnd);
0585 }
0586
0587 static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
0588 {
0589     return &htab->buckets[hash & (htab->n_buckets - 1)];
0590 }
0591
0592 static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
0593 {
0594     return &__select_bucket(htab, hash)->head;
0595 }
0596
0597 /* this lookup function can only be called with bucket lock taken */
0598 static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
0599                      void *key, u32 key_size)
0600 {
0601     struct hlist_nulls_node *n;
0602     struct htab_elem *l;
0603
0604     hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
0605         if (l->hash == hash && !memcmp(&l->key, key, key_size))
0606             return l;
0607
0608     return NULL;
0609 }
0610
0611 /* can be called without bucket lock. it will repeat the loop in
0612  * the unlikely event when elements moved from one bucket into another
0613  * while link list is being walked
0614  */
0615 static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
0616                            u32 hash, void *key,
0617                            u32 key_size, u32 n_buckets)
0618 {
0619     struct hlist_nulls_node *n;
0620     struct htab_elem *l;
0621
0622 again:
0623     hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
0624         if (l->hash == hash && !memcmp(&l->key, key, key_size))
0625             return l;
0626
0627     if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
0628         goto again;
0629
0630     return NULL;
0631 }
0632
0633 /* Called from syscall or from eBPF program directly, so
0634  * arguments have to match bpf_map_lookup_elem() exactly.
0635  * The return value is adjusted by BPF instructions
0636  * in htab_map_gen_lookup().
0637  */
0638 static void *__htab_map_lookup_elem(struct bpf_map *map, void *key)
0639 {
0640     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
0641     struct hlist_nulls_head *head;
0642     struct htab_elem *l;
0643     u32 hash, key_size;
0644
0645     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
0646              !rcu_read_lock_bh_held());
0647
0648     key_size = map->key_size;
0649
0650     hash = htab_map_hash(key, key_size, htab->hashrnd);
0651
0652     head = select_bucket(htab, hash);
0653
0654     l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
0655
0656     return l;
0657 }
0658
0659 static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
0660 {
0661     struct htab_elem *l = __htab_map_lookup_elem(map, key);
0662
0663     if (l)
0664         return l->key + round_up(map->key_size, 8);
0665
0666     return NULL;
0667 }
0668
0669 /* inline bpf_map_lookup_elem() call.
0670  * Instead of:
0671  * bpf_prog
0672  *   bpf_map_lookup_elem
0673  *     map->ops->map_lookup_elem
0674  *       htab_map_lookup_elem
0675  *         __htab_map_lookup_elem
0676  * do:
0677  * bpf_prog
0678  *   __htab_map_lookup_elem
0679  */
0680 static int htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
0681 {
0682     struct bpf_insn *insn = insn_buf;
0683     const int ret = BPF_REG_0;
0684
0685     BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
0686              (void *(*)(struct bpf_map *map, void *key))NULL));
0687     *insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
0688     *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
0689     *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
0690                 offsetof(struct htab_elem, key) +
0691                 round_up(map->key_size, 8));
0692     return insn - insn_buf;
0693 }
0694
0695 static __always_inline void *__htab_lru_map_lookup_elem(struct bpf_map *map,
0696                             void *key, const bool mark)
0697 {
0698     struct htab_elem *l = __htab_map_lookup_elem(map, key);
0699
0700     if (l) {
0701         if (mark)
0702             bpf_lru_node_set_ref(&l->lru_node);
0703         return l->key + round_up(map->key_size, 8);
0704     }
0705
0706     return NULL;
0707 }
0708
0709 static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
0710 {
0711     return __htab_lru_map_lookup_elem(map, key, true);
0712 }
0713
0714 static void *htab_lru_map_lookup_elem_sys(struct bpf_map *map, void *key)
0715 {
0716     return __htab_lru_map_lookup_elem(map, key, false);
0717 }
0718
0719 static int htab_lru_map_gen_lookup(struct bpf_map *map,
0720                    struct bpf_insn *insn_buf)
0721 {
0722     struct bpf_insn *insn = insn_buf;
0723     const int ret = BPF_REG_0;
0724     const int ref_reg = BPF_REG_1;
0725
0726     BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
0727              (void *(*)(struct bpf_map *map, void *key))NULL));
0728     *insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
0729     *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
0730     *insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
0731                   offsetof(struct htab_elem, lru_node) +
0732                   offsetof(struct bpf_lru_node, ref));
0733     *insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
0734     *insn++ = BPF_ST_MEM(BPF_B, ret,
0735                  offsetof(struct htab_elem, lru_node) +
0736                  offsetof(struct bpf_lru_node, ref),
0737                  1);
0738     *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
0739                 offsetof(struct htab_elem, key) +
0740                 round_up(map->key_size, 8));
0741     return insn - insn_buf;
0742 }
0743
0744 static void check_and_free_fields(struct bpf_htab *htab,
0745                   struct htab_elem *elem)
0746 {
0747     void *map_value = elem->key + round_up(htab->map.key_size, 8);
0748
0749     if (map_value_has_timer(&htab->map))
0750         bpf_timer_cancel_and_free(map_value + htab->map.timer_off);
0751     if (map_value_has_kptrs(&htab->map))
0752         bpf_map_free_kptrs(&htab->map, map_value);
0753 }
0754
0755 /* It is called from the bpf_lru_list when the LRU needs to delete
0756  * older elements from the htab.
0757  */
0758 static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
0759 {
0760     struct bpf_htab *htab = arg;
0761     struct htab_elem *l = NULL, *tgt_l;
0762     struct hlist_nulls_head *head;
0763     struct hlist_nulls_node *n;
0764     unsigned long flags;
0765     struct bucket *b;
0766     int ret;
0767
0768     tgt_l = container_of(node, struct htab_elem, lru_node);
0769     b = __select_bucket(htab, tgt_l->hash);
0770     head = &b->head;
0771
0772     ret = htab_lock_bucket(htab, b, tgt_l->hash, &flags);
0773     if (ret)
0774         return false;
0775
0776     hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
0777         if (l == tgt_l) {
0778             hlist_nulls_del_rcu(&l->hash_node);
0779             check_and_free_fields(htab, l);
0780             break;
0781         }
0782
0783     htab_unlock_bucket(htab, b, tgt_l->hash, flags);
0784
0785     return l == tgt_l;
0786 }
0787
0788 /* Called from syscall */
0789 static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
0790 {
0791     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
0792     struct hlist_nulls_head *head;
0793     struct htab_elem *l, *next_l;
0794     u32 hash, key_size;
0795     int i = 0;
0796
0797     WARN_ON_ONCE(!rcu_read_lock_held());
0798
0799     key_size = map->key_size;
0800
0801     if (!key)
0802         goto find_first_elem;
0803
0804     hash = htab_map_hash(key, key_size, htab->hashrnd);
0805
0806     head = select_bucket(htab, hash);
0807
0808     /* lookup the key */
0809     l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
0810
0811     if (!l)
0812         goto find_first_elem;
0813
0814     /* key was found, get next key in the same bucket */
0815     next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
0816                   struct htab_elem, hash_node);
0817
0818     if (next_l) {
0819         /* if next elem in this hash list is non-zero, just return it */
0820         memcpy(next_key, next_l->key, key_size);
0821         return 0;
0822     }
0823
0824     /* no more elements in this hash list, go to the next bucket */
0825     i = hash & (htab->n_buckets - 1);
0826     i++;
0827
0828 find_first_elem:
0829     /* iterate over buckets */
0830     for (; i < htab->n_buckets; i++) {
0831         head = select_bucket(htab, i);
0832
0833         /* pick first element in the bucket */
0834         next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_first_rcu(head)),
0835                       struct htab_elem, hash_node);
0836         if (next_l) {
0837             /* if it's not empty, just return it */
0838             memcpy(next_key, next_l->key, key_size);
0839             return 0;
0840         }
0841     }
0842
0843     /* iterated over all buckets and all elements */
0844     return -ENOENT;
0845 }
0846
0847 static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
0848 {
0849     if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
0850         free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
0851     check_and_free_fields(htab, l);
0852     kfree(l);
0853 }
0854
0855 static void htab_elem_free_rcu(struct rcu_head *head)
0856 {
0857     struct htab_elem *l = container_of(head, struct htab_elem, rcu);
0858     struct bpf_htab *htab = l->htab;
0859
0860     htab_elem_free(htab, l);
0861 }
0862
0863 static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l)
0864 {
0865     struct bpf_map *map = &htab->map;
0866     void *ptr;
0867
0868     if (map->ops->map_fd_put_ptr) {
0869         ptr = fd_htab_map_get_ptr(map, l);
0870         map->ops->map_fd_put_ptr(ptr);
0871     }
0872 }
0873
0874 static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
0875 {
0876     htab_put_fd_value(htab, l);
0877
0878     if (htab_is_prealloc(htab)) {
0879         check_and_free_fields(htab, l);
0880         __pcpu_freelist_push(&htab->freelist, &l->fnode);
0881     } else {
0882         atomic_dec(&htab->count);
0883         l->htab = htab;
0884         call_rcu(&l->rcu, htab_elem_free_rcu);
0885     }
0886 }
0887
0888 static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
0889                 void *value, bool onallcpus)
0890 {
0891     if (!onallcpus) {
0892         /* copy true value_size bytes */
0893         memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
0894     } else {
0895         u32 size = round_up(htab->map.value_size, 8);
0896         int off = 0, cpu;
0897
0898         for_each_possible_cpu(cpu) {
0899             bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
0900                     value + off, size);
0901             off += size;
0902         }
0903     }
0904 }
0905
0906 static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr,
0907                 void *value, bool onallcpus)
0908 {
0909     /* When using prealloc and not setting the initial value on all cpus,
0910      * zero-fill element values for other cpus (just as what happens when
0911      * not using prealloc). Otherwise, bpf program has no way to ensure
0912      * known initial values for cpus other than current one
0913      * (onallcpus=false always when coming from bpf prog).
0914      */
0915     if (htab_is_prealloc(htab) && !onallcpus) {
0916         u32 size = round_up(htab->map.value_size, 8);
0917         int current_cpu = raw_smp_processor_id();
0918         int cpu;
0919
0920         for_each_possible_cpu(cpu) {
0921             if (cpu == current_cpu)
0922                 bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value,
0923                         size);
0924             else
0925                 memset(per_cpu_ptr(pptr, cpu), 0, size);
0926         }
0927     } else {
0928         pcpu_copy_value(htab, pptr, value, onallcpus);
0929     }
0930 }
0931
0932 static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
0933 {
0934     return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
0935            BITS_PER_LONG == 64;
0936 }
0937
0938 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
0939                      void *value, u32 key_size, u32 hash,
0940                      bool percpu, bool onallcpus,
0941                      struct htab_elem *old_elem)
0942 {
0943     u32 size = htab->map.value_size;
0944     bool prealloc = htab_is_prealloc(htab);
0945     struct htab_elem *l_new, **pl_new;
0946     void __percpu *pptr;
0947
0948     if (prealloc) {
0949         if (old_elem) {
0950             /* if we're updating the existing element,
0951              * use per-cpu extra elems to avoid freelist_pop/push
0952              */
0953             pl_new = this_cpu_ptr(htab->extra_elems);
0954             l_new = *pl_new;
0955             htab_put_fd_value(htab, old_elem);
0956             *pl_new = old_elem;
0957         } else {
0958             struct pcpu_freelist_node *l;
0959
0960             l = __pcpu_freelist_pop(&htab->freelist);
0961             if (!l)
0962                 return ERR_PTR(-E2BIG);
0963             l_new = container_of(l, struct htab_elem, fnode);
0964         }
0965     } else {
0966         if (atomic_inc_return(&htab->count) > htab->map.max_entries)
0967             if (!old_elem) {
0968                 /* when map is full and update() is replacing
0969                  * old element, it's ok to allocate, since
0970                  * old element will be freed immediately.
0971                  * Otherwise return an error
0972                  */
0973                 l_new = ERR_PTR(-E2BIG);
0974                 goto dec_count;
0975             }
0976         l_new = bpf_map_kmalloc_node(&htab->map, htab->elem_size,
0977                          GFP_NOWAIT | __GFP_NOWARN,
0978                          htab->map.numa_node);
0979         if (!l_new) {
0980             l_new = ERR_PTR(-ENOMEM);
0981             goto dec_count;
0982         }
0983         check_and_init_map_value(&htab->map,
0984                      l_new->key + round_up(key_size, 8));
0985     }
0986
0987     memcpy(l_new->key, key, key_size);
0988     if (percpu) {
0989         size = round_up(size, 8);
0990         if (prealloc) {
0991             pptr = htab_elem_get_ptr(l_new, key_size);
0992         } else {
0993             /* alloc_percpu zero-fills */
0994             pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
0995                             GFP_NOWAIT | __GFP_NOWARN);
0996             if (!pptr) {
0997                 kfree(l_new);
0998                 l_new = ERR_PTR(-ENOMEM);
0999                 goto dec_count;
1000             }
1001         }
1002
1003         pcpu_init_value(htab, pptr, value, onallcpus);
1004
1005         if (!prealloc)
1006             htab_elem_set_ptr(l_new, key_size, pptr);
1007     } else if (fd_htab_map_needs_adjust(htab)) {
1008         size = round_up(size, 8);
1009         memcpy(l_new->key + round_up(key_size, 8), value, size);
1010     } else {
1011         copy_map_value(&htab->map,
1012                    l_new->key + round_up(key_size, 8),
1013                    value);
1014     }
1015
1016     l_new->hash = hash;
1017     return l_new;
1018 dec_count:
1019     atomic_dec(&htab->count);
1020     return l_new;
1021 }
1022
1023 static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
1024                u64 map_flags)
1025 {
1026     if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
1027         /* elem already exists */
1028         return -EEXIST;
1029
1030     if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
1031         /* elem doesn't exist, cannot update it */
1032         return -ENOENT;
1033
1034     return 0;
1035 }
1036
1037 /* Called from syscall or from eBPF program */
1038 static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
1039                 u64 map_flags)
1040 {
1041     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1042     struct htab_elem *l_new = NULL, *l_old;
1043     struct hlist_nulls_head *head;
1044     unsigned long flags;
1045     struct bucket *b;
1046     u32 key_size, hash;
1047     int ret;
1048
1049     if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
1050         /* unknown flags */
1051         return -EINVAL;
1052
1053     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
1054              !rcu_read_lock_bh_held());
1055
1056     key_size = map->key_size;
1057
1058     hash = htab_map_hash(key, key_size, htab->hashrnd);
1059
1060     b = __select_bucket(htab, hash);
1061     head = &b->head;
1062
1063     if (unlikely(map_flags & BPF_F_LOCK)) {
1064         if (unlikely(!map_value_has_spin_lock(map)))
1065             return -EINVAL;
1066         /* find an element without taking the bucket lock */
1067         l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
1068                           htab->n_buckets);
1069         ret = check_flags(htab, l_old, map_flags);
1070         if (ret)
1071             return ret;
1072         if (l_old) {
1073             /* grab the element lock and update value in place */
1074             copy_map_value_locked(map,
1075                           l_old->key + round_up(key_size, 8),
1076                           value, false);
1077             return 0;
1078         }
1079         /* fall through, grab the bucket lock and lookup again.
1080          * 99.9% chance that the element won't be found,
1081          * but second lookup under lock has to be done.
1082          */
1083     }
1084
1085     ret = htab_lock_bucket(htab, b, hash, &flags);
1086     if (ret)
1087         return ret;
1088
1089     l_old = lookup_elem_raw(head, hash, key, key_size);
1090
1091     ret = check_flags(htab, l_old, map_flags);
1092     if (ret)
1093         goto err;
1094
1095     if (unlikely(l_old && (map_flags & BPF_F_LOCK))) {
1096         /* first lookup without the bucket lock didn't find the element,
1097          * but second lookup with the bucket lock found it.
1098          * This case is highly unlikely, but has to be dealt with:
1099          * grab the element lock in addition to the bucket lock
1100          * and update element in place
1101          */
1102         copy_map_value_locked(map,
1103                       l_old->key + round_up(key_size, 8),
1104                       value, false);
1105         ret = 0;
1106         goto err;
1107     }
1108
1109     l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
1110                 l_old);
1111     if (IS_ERR(l_new)) {
1112         /* all pre-allocated elements are in use or memory exhausted */
1113         ret = PTR_ERR(l_new);
1114         goto err;
1115     }
1116
1117     /* add new element to the head of the list, so that
1118      * concurrent search will find it before old elem
1119      */
1120     hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1121     if (l_old) {
1122         hlist_nulls_del_rcu(&l_old->hash_node);
1123         if (!htab_is_prealloc(htab))
1124             free_htab_elem(htab, l_old);
1125         else
1126             check_and_free_fields(htab, l_old);
1127     }
1128     ret = 0;
1129 err:
1130     htab_unlock_bucket(htab, b, hash, flags);
1131     return ret;
1132 }
1133
1134 static void htab_lru_push_free(struct bpf_htab *htab, struct htab_elem *elem)
1135 {
1136     check_and_free_fields(htab, elem);
1137     bpf_lru_push_free(&htab->lru, &elem->lru_node);
1138 }
1139
1140 static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value,
1141                     u64 map_flags)
1142 {
1143     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1144     struct htab_elem *l_new, *l_old = NULL;
1145     struct hlist_nulls_head *head;
1146     unsigned long flags;
1147     struct bucket *b;
1148     u32 key_size, hash;
1149     int ret;
1150
1151     if (unlikely(map_flags > BPF_EXIST))
1152         /* unknown flags */
1153         return -EINVAL;
1154
1155     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
1156              !rcu_read_lock_bh_held());
1157
1158     key_size = map->key_size;
1159
1160     hash = htab_map_hash(key, key_size, htab->hashrnd);
1161
1162     b = __select_bucket(htab, hash);
1163     head = &b->head;
1164
1165     /* For LRU, we need to alloc before taking bucket's
1166      * spinlock because getting free nodes from LRU may need
1167      * to remove older elements from htab and this removal
1168      * operation will need a bucket lock.
1169      */
1170     l_new = prealloc_lru_pop(htab, key, hash);
1171     if (!l_new)
1172         return -ENOMEM;
1173     copy_map_value(&htab->map,
1174                l_new->key + round_up(map->key_size, 8), value);
1175
1176     ret = htab_lock_bucket(htab, b, hash, &flags);
1177     if (ret)
1178         return ret;
1179
1180     l_old = lookup_elem_raw(head, hash, key, key_size);
1181
1182     ret = check_flags(htab, l_old, map_flags);
1183     if (ret)
1184         goto err;
1185
1186     /* add new element to the head of the list, so that
1187      * concurrent search will find it before old elem
1188      */
1189     hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1190     if (l_old) {
1191         bpf_lru_node_set_ref(&l_new->lru_node);
1192         hlist_nulls_del_rcu(&l_old->hash_node);
1193     }
1194     ret = 0;
1195
1196 err:
1197     htab_unlock_bucket(htab, b, hash, flags);
1198
1199     if (ret)
1200         htab_lru_push_free(htab, l_new);
1201     else if (l_old)
1202         htab_lru_push_free(htab, l_old);
1203
1204     return ret;
1205 }
1206
1207 static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
1208                      void *value, u64 map_flags,
1209                      bool onallcpus)
1210 {
1211     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1212     struct htab_elem *l_new = NULL, *l_old;
1213     struct hlist_nulls_head *head;
1214     unsigned long flags;
1215     struct bucket *b;
1216     u32 key_size, hash;
1217     int ret;
1218
1219     if (unlikely(map_flags > BPF_EXIST))
1220         /* unknown flags */
1221         return -EINVAL;
1222
1223     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
1224              !rcu_read_lock_bh_held());
1225
1226     key_size = map->key_size;
1227
1228     hash = htab_map_hash(key, key_size, htab->hashrnd);
1229
1230     b = __select_bucket(htab, hash);
1231     head = &b->head;
1232
1233     ret = htab_lock_bucket(htab, b, hash, &flags);
1234     if (ret)
1235         return ret;
1236
1237     l_old = lookup_elem_raw(head, hash, key, key_size);
1238
1239     ret = check_flags(htab, l_old, map_flags);
1240     if (ret)
1241         goto err;
1242
1243     if (l_old) {
1244         /* per-cpu hash map can update value in-place */
1245         pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1246                 value, onallcpus);
1247     } else {
1248         l_new = alloc_htab_elem(htab, key, value, key_size,
1249                     hash, true, onallcpus, NULL);
1250         if (IS_ERR(l_new)) {
1251             ret = PTR_ERR(l_new);
1252             goto err;
1253         }
1254         hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1255     }
1256     ret = 0;
1257 err:
1258     htab_unlock_bucket(htab, b, hash, flags);
1259     return ret;
1260 }
1261
1262 static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1263                          void *value, u64 map_flags,
1264                          bool onallcpus)
1265 {
1266     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1267     struct htab_elem *l_new = NULL, *l_old;
1268     struct hlist_nulls_head *head;
1269     unsigned long flags;
1270     struct bucket *b;
1271     u32 key_size, hash;
1272     int ret;
1273
1274     if (unlikely(map_flags > BPF_EXIST))
1275         /* unknown flags */
1276         return -EINVAL;
1277
1278     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
1279              !rcu_read_lock_bh_held());
1280
1281     key_size = map->key_size;
1282
1283     hash = htab_map_hash(key, key_size, htab->hashrnd);
1284
1285     b = __select_bucket(htab, hash);
1286     head = &b->head;
1287
1288     /* For LRU, we need to alloc before taking bucket's
1289      * spinlock because LRU's elem alloc may need
1290      * to remove older elem from htab and this removal
1291      * operation will need a bucket lock.
1292      */
1293     if (map_flags != BPF_EXIST) {
1294         l_new = prealloc_lru_pop(htab, key, hash);
1295         if (!l_new)
1296             return -ENOMEM;
1297     }
1298
1299     ret = htab_lock_bucket(htab, b, hash, &flags);
1300     if (ret)
1301         return ret;
1302
1303     l_old = lookup_elem_raw(head, hash, key, key_size);
1304
1305     ret = check_flags(htab, l_old, map_flags);
1306     if (ret)
1307         goto err;
1308
1309     if (l_old) {
1310         bpf_lru_node_set_ref(&l_old->lru_node);
1311
1312         /* per-cpu hash map can update value in-place */
1313         pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
1314                 value, onallcpus);
1315     } else {
1316         pcpu_init_value(htab, htab_elem_get_ptr(l_new, key_size),
1317                 value, onallcpus);
1318         hlist_nulls_add_head_rcu(&l_new->hash_node, head);
1319         l_new = NULL;
1320     }
1321     ret = 0;
1322 err:
1323     htab_unlock_bucket(htab, b, hash, flags);
1324     if (l_new)
1325         bpf_lru_push_free(&htab->lru, &l_new->lru_node);
1326     return ret;
1327 }
1328
1329 static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
1330                        void *value, u64 map_flags)
1331 {
1332     return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
1333 }
1334
1335 static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
1336                        void *value, u64 map_flags)
1337 {
1338     return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
1339                          false);
1340 }
1341
1342 /* Called from syscall or from eBPF program */
1343 static int htab_map_delete_elem(struct bpf_map *map, void *key)
1344 {
1345     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1346     struct hlist_nulls_head *head;
1347     struct bucket *b;
1348     struct htab_elem *l;
1349     unsigned long flags;
1350     u32 hash, key_size;
1351     int ret;
1352
1353     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
1354              !rcu_read_lock_bh_held());
1355
1356     key_size = map->key_size;
1357
1358     hash = htab_map_hash(key, key_size, htab->hashrnd);
1359     b = __select_bucket(htab, hash);
1360     head = &b->head;
1361
1362     ret = htab_lock_bucket(htab, b, hash, &flags);
1363     if (ret)
1364         return ret;
1365
1366     l = lookup_elem_raw(head, hash, key, key_size);
1367
1368     if (l) {
1369         hlist_nulls_del_rcu(&l->hash_node);
1370         free_htab_elem(htab, l);
1371     } else {
1372         ret = -ENOENT;
1373     }
1374
1375     htab_unlock_bucket(htab, b, hash, flags);
1376     return ret;
1377 }
1378
1379 static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
1380 {
1381     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1382     struct hlist_nulls_head *head;
1383     struct bucket *b;
1384     struct htab_elem *l;
1385     unsigned long flags;
1386     u32 hash, key_size;
1387     int ret;
1388
1389     WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
1390              !rcu_read_lock_bh_held());
1391
1392     key_size = map->key_size;
1393
1394     hash = htab_map_hash(key, key_size, htab->hashrnd);
1395     b = __select_bucket(htab, hash);
1396     head = &b->head;
1397
1398     ret = htab_lock_bucket(htab, b, hash, &flags);
1399     if (ret)
1400         return ret;
1401
1402     l = lookup_elem_raw(head, hash, key, key_size);
1403
1404     if (l)
1405         hlist_nulls_del_rcu(&l->hash_node);
1406     else
1407         ret = -ENOENT;
1408
1409     htab_unlock_bucket(htab, b, hash, flags);
1410     if (l)
1411         htab_lru_push_free(htab, l);
1412     return ret;
1413 }
1414
1415 static void delete_all_elements(struct bpf_htab *htab)
1416 {
1417     int i;
1418
1419     for (i = 0; i < htab->n_buckets; i++) {
1420         struct hlist_nulls_head *head = select_bucket(htab, i);
1421         struct hlist_nulls_node *n;
1422         struct htab_elem *l;
1423
1424         hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1425             hlist_nulls_del_rcu(&l->hash_node);
1426             htab_elem_free(htab, l);
1427         }
1428     }
1429 }
1430
1431 static void htab_free_malloced_timers(struct bpf_htab *htab)
1432 {
1433     int i;
1434
1435     rcu_read_lock();
1436     for (i = 0; i < htab->n_buckets; i++) {
1437         struct hlist_nulls_head *head = select_bucket(htab, i);
1438         struct hlist_nulls_node *n;
1439         struct htab_elem *l;
1440
1441         hlist_nulls_for_each_entry(l, n, head, hash_node) {
1442             /* We don't reset or free kptr on uref dropping to zero,
1443              * hence just free timer.
1444              */
1445             bpf_timer_cancel_and_free(l->key +
1446                           round_up(htab->map.key_size, 8) +
1447                           htab->map.timer_off);
1448         }
1449         cond_resched_rcu();
1450     }
1451     rcu_read_unlock();
1452 }
1453
1454 static void htab_map_free_timers(struct bpf_map *map)
1455 {
1456     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1457
1458     /* We don't reset or free kptr on uref dropping to zero. */
1459     if (!map_value_has_timer(&htab->map))
1460         return;
1461     if (!htab_is_prealloc(htab))
1462         htab_free_malloced_timers(htab);
1463     else
1464         htab_free_prealloced_timers(htab);
1465 }
1466
1467 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
1468 static void htab_map_free(struct bpf_map *map)
1469 {
1470     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1471     int i;
1472
1473     /* bpf_free_used_maps() or close(map_fd) will trigger this map_free callback.
1474      * bpf_free_used_maps() is called after bpf prog is no longer executing.
1475      * There is no need to synchronize_rcu() here to protect map elements.
1476      */
1477
1478     /* some of free_htab_elem() callbacks for elements of this map may
1479      * not have executed. Wait for them.
1480      */
1481     rcu_barrier();
1482     if (!htab_is_prealloc(htab)) {
1483         delete_all_elements(htab);
1484     } else {
1485         htab_free_prealloced_kptrs(htab);
1486         prealloc_destroy(htab);
1487     }
1488
1489     bpf_map_free_kptr_off_tab(map);
1490     free_percpu(htab->extra_elems);
1491     bpf_map_area_free(htab->buckets);
1492     for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
1493         free_percpu(htab->map_locked[i]);
1494     lockdep_unregister_key(&htab->lockdep_key);
1495     kfree(htab);
1496 }
1497
1498 static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
1499                    struct seq_file *m)
1500 {
1501     void *value;
1502
1503     rcu_read_lock();
1504
1505     value = htab_map_lookup_elem(map, key);
1506     if (!value) {
1507         rcu_read_unlock();
1508         return;
1509     }
1510
1511     btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
1512     seq_puts(m, ": ");
1513     btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
1514     seq_puts(m, "\n");
1515
1516     rcu_read_unlock();
1517 }
1518
1519 static int __htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
1520                          void *value, bool is_lru_map,
1521                          bool is_percpu, u64 flags)
1522 {
1523     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1524     struct hlist_nulls_head *head;
1525     unsigned long bflags;
1526     struct htab_elem *l;
1527     u32 hash, key_size;
1528     struct bucket *b;
1529     int ret;
1530
1531     key_size = map->key_size;
1532
1533     hash = htab_map_hash(key, key_size, htab->hashrnd);
1534     b = __select_bucket(htab, hash);
1535     head = &b->head;
1536
1537     ret = htab_lock_bucket(htab, b, hash, &bflags);
1538     if (ret)
1539         return ret;
1540
1541     l = lookup_elem_raw(head, hash, key, key_size);
1542     if (!l) {
1543         ret = -ENOENT;
1544     } else {
1545         if (is_percpu) {
1546             u32 roundup_value_size = round_up(map->value_size, 8);
1547             void __percpu *pptr;
1548             int off = 0, cpu;
1549
1550             pptr = htab_elem_get_ptr(l, key_size);
1551             for_each_possible_cpu(cpu) {
1552                 bpf_long_memcpy(value + off,
1553                         per_cpu_ptr(pptr, cpu),
1554                         roundup_value_size);
1555                 off += roundup_value_size;
1556             }
1557         } else {
1558             u32 roundup_key_size = round_up(map->key_size, 8);
1559
1560             if (flags & BPF_F_LOCK)
1561                 copy_map_value_locked(map, value, l->key +
1562                               roundup_key_size,
1563                               true);
1564             else
1565                 copy_map_value(map, value, l->key +
1566                            roundup_key_size);
1567             check_and_init_map_value(map, value);
1568         }
1569
1570         hlist_nulls_del_rcu(&l->hash_node);
1571         if (!is_lru_map)
1572             free_htab_elem(htab, l);
1573     }
1574
1575     htab_unlock_bucket(htab, b, hash, bflags);
1576
1577     if (is_lru_map && l)
1578         htab_lru_push_free(htab, l);
1579
1580     return ret;
1581 }
1582
1583 static int htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
1584                        void *value, u64 flags)
1585 {
1586     return __htab_map_lookup_and_delete_elem(map, key, value, false, false,
1587                          flags);
1588 }
1589
1590 static int htab_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
1591                           void *key, void *value,
1592                           u64 flags)
1593 {
1594     return __htab_map_lookup_and_delete_elem(map, key, value, false, true,
1595                          flags);
1596 }
1597
1598 static int htab_lru_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
1599                            void *value, u64 flags)
1600 {
1601     return __htab_map_lookup_and_delete_elem(map, key, value, true, false,
1602                          flags);
1603 }
1604
1605 static int htab_lru_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
1606                               void *key, void *value,
1607                               u64 flags)
1608 {
1609     return __htab_map_lookup_and_delete_elem(map, key, value, true, true,
1610                          flags);
1611 }
1612
1613 static int
1614 __htab_map_lookup_and_delete_batch(struct bpf_map *map,
1615                    const union bpf_attr *attr,
1616                    union bpf_attr __user *uattr,
1617                    bool do_delete, bool is_lru_map,
1618                    bool is_percpu)
1619 {
1620     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
1621     u32 bucket_cnt, total, key_size, value_size, roundup_key_size;
1622     void *keys = NULL, *values = NULL, *value, *dst_key, *dst_val;
1623     void __user *uvalues = u64_to_user_ptr(attr->batch.values);
1624     void __user *ukeys = u64_to_user_ptr(attr->batch.keys);
1625     void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch);
1626     u32 batch, max_count, size, bucket_size, map_id;
1627     struct htab_elem *node_to_free = NULL;
1628     u64 elem_map_flags, map_flags;
1629     struct hlist_nulls_head *head;
1630     struct hlist_nulls_node *n;
1631     unsigned long flags = 0;
1632     bool locked = false;
1633     struct htab_elem *l;
1634     struct bucket *b;
1635     int ret = 0;
1636
1637     elem_map_flags = attr->batch.elem_flags;
1638     if ((elem_map_flags & ~BPF_F_LOCK) ||
1639         ((elem_map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map)))
1640         return -EINVAL;
1641
1642     map_flags = attr->batch.flags;
1643     if (map_flags)
1644         return -EINVAL;
1645
1646     max_count = attr->batch.count;
1647     if (!max_count)
1648         return 0;
1649
1650     if (put_user(0, &uattr->batch.count))
1651         return -EFAULT;
1652
1653     batch = 0;
1654     if (ubatch && copy_from_user(&batch, ubatch, sizeof(batch)))
1655         return -EFAULT;
1656
1657     if (batch >= htab->n_buckets)
1658         return -ENOENT;
1659
1660     key_size = htab->map.key_size;
1661     roundup_key_size = round_up(htab->map.key_size, 8);
1662     value_size = htab->map.value_size;
1663     size = round_up(value_size, 8);
1664     if (is_percpu)
1665         value_size = size * num_possible_cpus();
1666     total = 0;
1667     /* while experimenting with hash tables with sizes ranging from 10 to
1668      * 1000, it was observed that a bucket can have up to 5 entries.
1669      */
1670     bucket_size = 5;
1671
1672 alloc:
1673     /* We cannot do copy_from_user or copy_to_user inside
1674      * the rcu_read_lock. Allocate enough space here.
1675      */
1676     keys = kvmalloc_array(key_size, bucket_size, GFP_USER | __GFP_NOWARN);
1677     values = kvmalloc_array(value_size, bucket_size, GFP_USER | __GFP_NOWARN);
1678     if (!keys || !values) {
1679         ret = -ENOMEM;
1680         goto after_loop;
1681     }
1682
1683 again:
1684     bpf_disable_instrumentation();
1685     rcu_read_lock();
1686 again_nocopy:
1687     dst_key = keys;
1688     dst_val = values;
1689     b = &htab->buckets[batch];
1690     head = &b->head;
1691     /* do not grab the lock unless need it (bucket_cnt > 0). */
1692     if (locked) {
1693         ret = htab_lock_bucket(htab, b, batch, &flags);
1694         if (ret)
1695             goto next_batch;
1696     }
1697
1698     bucket_cnt = 0;
1699     hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
1700         bucket_cnt++;
1701
1702     if (bucket_cnt && !locked) {
1703         locked = true;
1704         goto again_nocopy;
1705     }
1706
1707     if (bucket_cnt > (max_count - total)) {
1708         if (total == 0)
1709             ret = -ENOSPC;
1710         /* Note that since bucket_cnt > 0 here, it is implicit
1711          * that the locked was grabbed, so release it.
1712          */
1713         htab_unlock_bucket(htab, b, batch, flags);
1714         rcu_read_unlock();
1715         bpf_enable_instrumentation();
1716         goto after_loop;
1717     }
1718
1719     if (bucket_cnt > bucket_size) {
1720         bucket_size = bucket_cnt;
1721         /* Note that since bucket_cnt > 0 here, it is implicit
1722          * that the locked was grabbed, so release it.
1723          */
1724         htab_unlock_bucket(htab, b, batch, flags);
1725         rcu_read_unlock();
1726         bpf_enable_instrumentation();
1727         kvfree(keys);
1728         kvfree(values);
1729         goto alloc;
1730     }
1731
1732     /* Next block is only safe to run if you have grabbed the lock */
1733     if (!locked)
1734         goto next_batch;
1735
1736     hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
1737         memcpy(dst_key, l->key, key_size);
1738
1739         if (is_percpu) {
1740             int off = 0, cpu;
1741             void __percpu *pptr;
1742
1743             pptr = htab_elem_get_ptr(l, map->key_size);
1744             for_each_possible_cpu(cpu) {
1745                 bpf_long_memcpy(dst_val + off,
1746                         per_cpu_ptr(pptr, cpu), size);
1747                 off += size;
1748             }
1749         } else {
1750             value = l->key + roundup_key_size;
1751             if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
1752                 struct bpf_map **inner_map = value;
1753
1754                  /* Actual value is the id of the inner map */
1755                 map_id = map->ops->map_fd_sys_lookup_elem(*inner_map);
1756                 value = &map_id;
1757             }
1758
1759             if (elem_map_flags & BPF_F_LOCK)
1760                 copy_map_value_locked(map, dst_val, value,
1761                               true);
1762             else
1763                 copy_map_value(map, dst_val, value);
1764             check_and_init_map_value(map, dst_val);
1765         }
1766         if (do_delete) {
1767             hlist_nulls_del_rcu(&l->hash_node);
1768
1769             /* bpf_lru_push_free() will acquire lru_lock, which
1770              * may cause deadlock. See comments in function
1771              * prealloc_lru_pop(). Let us do bpf_lru_push_free()
1772              * after releasing the bucket lock.
1773              */
1774             if (is_lru_map) {
1775                 l->batch_flink = node_to_free;
1776                 node_to_free = l;
1777             } else {
1778                 free_htab_elem(htab, l);
1779             }
1780         }
1781         dst_key += key_size;
1782         dst_val += value_size;
1783     }
1784
1785     htab_unlock_bucket(htab, b, batch, flags);
1786     locked = false;
1787
1788     while (node_to_free) {
1789         l = node_to_free;
1790         node_to_free = node_to_free->batch_flink;
1791         htab_lru_push_free(htab, l);
1792     }
1793
1794 next_batch:
1795     /* If we are not copying data, we can go to next bucket and avoid
1796      * unlocking the rcu.
1797      */
1798     if (!bucket_cnt && (batch + 1 < htab->n_buckets)) {
1799         batch++;
1800         goto again_nocopy;
1801     }
1802
1803     rcu_read_unlock();
1804     bpf_enable_instrumentation();
1805     if (bucket_cnt && (copy_to_user(ukeys + total * key_size, keys,
1806         key_size * bucket_cnt) ||
1807         copy_to_user(uvalues + total * value_size, values,
1808         value_size * bucket_cnt))) {
1809         ret = -EFAULT;
1810         goto after_loop;
1811     }
1812
1813     total += bucket_cnt;
1814     batch++;
1815     if (batch >= htab->n_buckets) {
1816         ret = -ENOENT;
1817         goto after_loop;
1818     }
1819     goto again;
1820
1821 after_loop:
1822     if (ret == -EFAULT)
1823         goto out;
1824
1825     /* copy # of entries and next batch */
1826     ubatch = u64_to_user_ptr(attr->batch.out_batch);
1827     if (copy_to_user(ubatch, &batch, sizeof(batch)) ||
1828         put_user(total, &uattr->batch.count))
1829         ret = -EFAULT;
1830
1831 out:
1832     kvfree(keys);
1833     kvfree(values);
1834     return ret;
1835 }
1836
1837 static int
1838 htab_percpu_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
1839                  union bpf_attr __user *uattr)
1840 {
1841     return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
1842                           false, true);
1843 }
1844
1845 static int
1846 htab_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
1847                     const union bpf_attr *attr,
1848                     union bpf_attr __user *uattr)
1849 {
1850     return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
1851                           false, true);
1852 }
1853
1854 static int
1855 htab_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
1856               union bpf_attr __user *uattr)
1857 {
1858     return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
1859                           false, false);
1860 }
1861
1862 static int
1863 htab_map_lookup_and_delete_batch(struct bpf_map *map,
1864                  const union bpf_attr *attr,
1865                  union bpf_attr __user *uattr)
1866 {
1867     return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
1868                           false, false);
1869 }
1870
1871 static int
1872 htab_lru_percpu_map_lookup_batch(struct bpf_map *map,
1873                  const union bpf_attr *attr,
1874                  union bpf_attr __user *uattr)
1875 {
1876     return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
1877                           true, true);
1878 }
1879
1880 static int
1881 htab_lru_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
1882                         const union bpf_attr *attr,
1883                         union bpf_attr __user *uattr)
1884 {
1885     return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
1886                           true, true);
1887 }
1888
1889 static int
1890 htab_lru_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
1891               union bpf_attr __user *uattr)
1892 {
1893     return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
1894                           true, false);
1895 }
1896
1897 static int
1898 htab_lru_map_lookup_and_delete_batch(struct bpf_map *map,
1899                      const union bpf_attr *attr,
1900                      union bpf_attr __user *uattr)
1901 {
1902     return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
1903                           true, false);
1904 }
1905
1906 struct bpf_iter_seq_hash_map_info {
1907     struct bpf_map *map;
1908     struct bpf_htab *htab;
1909     void *percpu_value_buf; // non-zero means percpu hash
1910     u32 bucket_id;
1911     u32 skip_elems;
1912 };
1913
1914 static struct htab_elem *
1915 bpf_hash_map_seq_find_next(struct bpf_iter_seq_hash_map_info *info,
1916                struct htab_elem *prev_elem)
1917 {
1918     const struct bpf_htab *htab = info->htab;
1919     u32 skip_elems = info->skip_elems;
1920     u32 bucket_id = info->bucket_id;
1921     struct hlist_nulls_head *head;
1922     struct hlist_nulls_node *n;
1923     struct htab_elem *elem;
1924     struct bucket *b;
1925     u32 i, count;
1926
1927     if (bucket_id >= htab->n_buckets)
1928         return NULL;
1929
1930     /* try to find next elem in the same bucket */
1931     if (prev_elem) {
1932         /* no update/deletion on this bucket, prev_elem should be still valid
1933          * and we won't skip elements.
1934          */
1935         n = rcu_dereference_raw(hlist_nulls_next_rcu(&prev_elem->hash_node));
1936         elem = hlist_nulls_entry_safe(n, struct htab_elem, hash_node);
1937         if (elem)
1938             return elem;
1939
1940         /* not found, unlock and go to the next bucket */
1941         b = &htab->buckets[bucket_id++];
1942         rcu_read_unlock();
1943         skip_elems = 0;
1944     }
1945
1946     for (i = bucket_id; i < htab->n_buckets; i++) {
1947         b = &htab->buckets[i];
1948         rcu_read_lock();
1949
1950         count = 0;
1951         head = &b->head;
1952         hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
1953             if (count >= skip_elems) {
1954                 info->bucket_id = i;
1955                 info->skip_elems = count;
1956                 return elem;
1957             }
1958             count++;
1959         }
1960
1961         rcu_read_unlock();
1962         skip_elems = 0;
1963     }
1964
1965     info->bucket_id = i;
1966     info->skip_elems = 0;
1967     return NULL;
1968 }
1969
1970 static void *bpf_hash_map_seq_start(struct seq_file *seq, loff_t *pos)
1971 {
1972     struct bpf_iter_seq_hash_map_info *info = seq->private;
1973     struct htab_elem *elem;
1974
1975     elem = bpf_hash_map_seq_find_next(info, NULL);
1976     if (!elem)
1977         return NULL;
1978
1979     if (*pos == 0)
1980         ++*pos;
1981     return elem;
1982 }
1983
1984 static void *bpf_hash_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1985 {
1986     struct bpf_iter_seq_hash_map_info *info = seq->private;
1987
1988     ++*pos;
1989     ++info->skip_elems;
1990     return bpf_hash_map_seq_find_next(info, v);
1991 }
1992
1993 static int __bpf_hash_map_seq_show(struct seq_file *seq, struct htab_elem *elem)
1994 {
1995     struct bpf_iter_seq_hash_map_info *info = seq->private;
1996     u32 roundup_key_size, roundup_value_size;
1997     struct bpf_iter__bpf_map_elem ctx = {};
1998     struct bpf_map *map = info->map;
1999     struct bpf_iter_meta meta;
2000     int ret = 0, off = 0, cpu;
2001     struct bpf_prog *prog;
2002     void __percpu *pptr;
2003
2004     meta.seq = seq;
2005     prog = bpf_iter_get_info(&meta, elem == NULL);
2006     if (prog) {
2007         ctx.meta = &meta;
2008         ctx.map = info->map;
2009         if (elem) {
2010             roundup_key_size = round_up(map->key_size, 8);
2011             ctx.key = elem->key;
2012             if (!info->percpu_value_buf) {
2013                 ctx.value = elem->key + roundup_key_size;
2014             } else {
2015                 roundup_value_size = round_up(map->value_size, 8);
2016                 pptr = htab_elem_get_ptr(elem, map->key_size);
2017                 for_each_possible_cpu(cpu) {
2018                     bpf_long_memcpy(info->percpu_value_buf + off,
2019                             per_cpu_ptr(pptr, cpu),
2020                             roundup_value_size);
2021                     off += roundup_value_size;
2022                 }
2023                 ctx.value = info->percpu_value_buf;
2024             }
2025         }
2026         ret = bpf_iter_run_prog(prog, &ctx);
2027     }
2028
2029     return ret;
2030 }
2031
2032 static int bpf_hash_map_seq_show(struct seq_file *seq, void *v)
2033 {
2034     return __bpf_hash_map_seq_show(seq, v);
2035 }
2036
2037 static void bpf_hash_map_seq_stop(struct seq_file *seq, void *v)
2038 {
2039     if (!v)
2040         (void)__bpf_hash_map_seq_show(seq, NULL);
2041     else
2042         rcu_read_unlock();
2043 }
2044
2045 static int bpf_iter_init_hash_map(void *priv_data,
2046                   struct bpf_iter_aux_info *aux)
2047 {
2048     struct bpf_iter_seq_hash_map_info *seq_info = priv_data;
2049     struct bpf_map *map = aux->map;
2050     void *value_buf;
2051     u32 buf_size;
2052
2053     if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
2054         map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
2055         buf_size = round_up(map->value_size, 8) * num_possible_cpus();
2056         value_buf = kmalloc(buf_size, GFP_USER | __GFP_NOWARN);
2057         if (!value_buf)
2058             return -ENOMEM;
2059
2060         seq_info->percpu_value_buf = value_buf;
2061     }
2062
2063     bpf_map_inc_with_uref(map);
2064     seq_info->map = map;
2065     seq_info->htab = container_of(map, struct bpf_htab, map);
2066     return 0;
2067 }
2068
2069 static void bpf_iter_fini_hash_map(void *priv_data)
2070 {
2071     struct bpf_iter_seq_hash_map_info *seq_info = priv_data;
2072
2073     bpf_map_put_with_uref(seq_info->map);
2074     kfree(seq_info->percpu_value_buf);
2075 }
2076
2077 static const struct seq_operations bpf_hash_map_seq_ops = {
2078     .start  = bpf_hash_map_seq_start,
2079     .next   = bpf_hash_map_seq_next,
2080     .stop   = bpf_hash_map_seq_stop,
2081     .show   = bpf_hash_map_seq_show,
2082 };
2083
2084 static const struct bpf_iter_seq_info iter_seq_info = {
2085     .seq_ops        = &bpf_hash_map_seq_ops,
2086     .init_seq_private   = bpf_iter_init_hash_map,
2087     .fini_seq_private   = bpf_iter_fini_hash_map,
2088     .seq_priv_size      = sizeof(struct bpf_iter_seq_hash_map_info),
2089 };
2090
2091 static int bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_fn,
2092                   void *callback_ctx, u64 flags)
2093 {
2094     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
2095     struct hlist_nulls_head *head;
2096     struct hlist_nulls_node *n;
2097     struct htab_elem *elem;
2098     u32 roundup_key_size;
2099     int i, num_elems = 0;
2100     void __percpu *pptr;
2101     struct bucket *b;
2102     void *key, *val;
2103     bool is_percpu;
2104     u64 ret = 0;
2105
2106     if (flags != 0)
2107         return -EINVAL;
2108
2109     is_percpu = htab_is_percpu(htab);
2110
2111     roundup_key_size = round_up(map->key_size, 8);
2112     /* disable migration so percpu value prepared here will be the
2113      * same as the one seen by the bpf program with bpf_map_lookup_elem().
2114      */
2115     if (is_percpu)
2116         migrate_disable();
2117     for (i = 0; i < htab->n_buckets; i++) {
2118         b = &htab->buckets[i];
2119         rcu_read_lock();
2120         head = &b->head;
2121         hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
2122             key = elem->key;
2123             if (is_percpu) {
2124                 /* current cpu value for percpu map */
2125                 pptr = htab_elem_get_ptr(elem, map->key_size);
2126                 val = this_cpu_ptr(pptr);
2127             } else {
2128                 val = elem->key + roundup_key_size;
2129             }
2130             num_elems++;
2131             ret = callback_fn((u64)(long)map, (u64)(long)key,
2132                       (u64)(long)val, (u64)(long)callback_ctx, 0);
2133             /* return value: 0 - continue, 1 - stop and return */
2134             if (ret) {
2135                 rcu_read_unlock();
2136                 goto out;
2137             }
2138         }
2139         rcu_read_unlock();
2140     }
2141 out:
2142     if (is_percpu)
2143         migrate_enable();
2144     return num_elems;
2145 }
2146
2147 BTF_ID_LIST_SINGLE(htab_map_btf_ids, struct, bpf_htab)
2148 const struct bpf_map_ops htab_map_ops = {
2149     .map_meta_equal = bpf_map_meta_equal,
2150     .map_alloc_check = htab_map_alloc_check,
2151     .map_alloc = htab_map_alloc,
2152     .map_free = htab_map_free,
2153     .map_get_next_key = htab_map_get_next_key,
2154     .map_release_uref = htab_map_free_timers,
2155     .map_lookup_elem = htab_map_lookup_elem,
2156     .map_lookup_and_delete_elem = htab_map_lookup_and_delete_elem,
2157     .map_update_elem = htab_map_update_elem,
2158     .map_delete_elem = htab_map_delete_elem,
2159     .map_gen_lookup = htab_map_gen_lookup,
2160     .map_seq_show_elem = htab_map_seq_show_elem,
2161     .map_set_for_each_callback_args = map_set_for_each_callback_args,
2162     .map_for_each_callback = bpf_for_each_hash_elem,
2163     BATCH_OPS(htab),
2164     .map_btf_id = &htab_map_btf_ids[0],
2165     .iter_seq_info = &iter_seq_info,
2166 };
2167
2168 const struct bpf_map_ops htab_lru_map_ops = {
2169     .map_meta_equal = bpf_map_meta_equal,
2170     .map_alloc_check = htab_map_alloc_check,
2171     .map_alloc = htab_map_alloc,
2172     .map_free = htab_map_free,
2173     .map_get_next_key = htab_map_get_next_key,
2174     .map_release_uref = htab_map_free_timers,
2175     .map_lookup_elem = htab_lru_map_lookup_elem,
2176     .map_lookup_and_delete_elem = htab_lru_map_lookup_and_delete_elem,
2177     .map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,
2178     .map_update_elem = htab_lru_map_update_elem,
2179     .map_delete_elem = htab_lru_map_delete_elem,
2180     .map_gen_lookup = htab_lru_map_gen_lookup,
2181     .map_seq_show_elem = htab_map_seq_show_elem,
2182     .map_set_for_each_callback_args = map_set_for_each_callback_args,
2183     .map_for_each_callback = bpf_for_each_hash_elem,
2184     BATCH_OPS(htab_lru),
2185     .map_btf_id = &htab_map_btf_ids[0],
2186     .iter_seq_info = &iter_seq_info,
2187 };
2188
2189 /* Called from eBPF program */
2190 static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
2191 {
2192     struct htab_elem *l = __htab_map_lookup_elem(map, key);
2193
2194     if (l)
2195         return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
2196     else
2197         return NULL;
2198 }
2199
2200 static void *htab_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
2201 {
2202     struct htab_elem *l;
2203
2204     if (cpu >= nr_cpu_ids)
2205         return NULL;
2206
2207     l = __htab_map_lookup_elem(map, key);
2208     if (l)
2209         return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
2210     else
2211         return NULL;
2212 }
2213
2214 static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
2215 {
2216     struct htab_elem *l = __htab_map_lookup_elem(map, key);
2217
2218     if (l) {
2219         bpf_lru_node_set_ref(&l->lru_node);
2220         return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
2221     }
2222
2223     return NULL;
2224 }
2225
2226 static void *htab_lru_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
2227 {
2228     struct htab_elem *l;
2229
2230     if (cpu >= nr_cpu_ids)
2231         return NULL;
2232
2233     l = __htab_map_lookup_elem(map, key);
2234     if (l) {
2235         bpf_lru_node_set_ref(&l->lru_node);
2236         return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
2237     }
2238
2239     return NULL;
2240 }
2241
2242 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
2243 {
2244     struct htab_elem *l;
2245     void __percpu *pptr;
2246     int ret = -ENOENT;
2247     int cpu, off = 0;
2248     u32 size;
2249
2250     /* per_cpu areas are zero-filled and bpf programs can only
2251      * access 'value_size' of them, so copying rounded areas
2252      * will not leak any kernel data
2253      */
2254     size = round_up(map->value_size, 8);
2255     rcu_read_lock();
2256     l = __htab_map_lookup_elem(map, key);
2257     if (!l)
2258         goto out;
2259     /* We do not mark LRU map element here in order to not mess up
2260      * eviction heuristics when user space does a map walk.
2261      */
2262     pptr = htab_elem_get_ptr(l, map->key_size);
2263     for_each_possible_cpu(cpu) {
2264         bpf_long_memcpy(value + off,
2265                 per_cpu_ptr(pptr, cpu), size);
2266         off += size;
2267     }
2268     ret = 0;
2269 out:
2270     rcu_read_unlock();
2271     return ret;
2272 }
2273
2274 int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
2275                u64 map_flags)
2276 {
2277     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
2278     int ret;
2279
2280     rcu_read_lock();
2281     if (htab_is_lru(htab))
2282         ret = __htab_lru_percpu_map_update_elem(map, key, value,
2283                             map_flags, true);
2284     else
2285         ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
2286                             true);
2287     rcu_read_unlock();
2288
2289     return ret;
2290 }
2291
2292 static void htab_percpu_map_seq_show_elem(struct bpf_map *map, void *key,
2293                       struct seq_file *m)
2294 {
2295     struct htab_elem *l;
2296     void __percpu *pptr;
2297     int cpu;
2298
2299     rcu_read_lock();
2300
2301     l = __htab_map_lookup_elem(map, key);
2302     if (!l) {
2303         rcu_read_unlock();
2304         return;
2305     }
2306
2307     btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
2308     seq_puts(m, ": {\n");
2309     pptr = htab_elem_get_ptr(l, map->key_size);
2310     for_each_possible_cpu(cpu) {
2311         seq_printf(m, "\tcpu%d: ", cpu);
2312         btf_type_seq_show(map->btf, map->btf_value_type_id,
2313                   per_cpu_ptr(pptr, cpu), m);
2314         seq_puts(m, "\n");
2315     }
2316     seq_puts(m, "}\n");
2317
2318     rcu_read_unlock();
2319 }
2320
2321 const struct bpf_map_ops htab_percpu_map_ops = {
2322     .map_meta_equal = bpf_map_meta_equal,
2323     .map_alloc_check = htab_map_alloc_check,
2324     .map_alloc = htab_map_alloc,
2325     .map_free = htab_map_free,
2326     .map_get_next_key = htab_map_get_next_key,
2327     .map_lookup_elem = htab_percpu_map_lookup_elem,
2328     .map_lookup_and_delete_elem = htab_percpu_map_lookup_and_delete_elem,
2329     .map_update_elem = htab_percpu_map_update_elem,
2330     .map_delete_elem = htab_map_delete_elem,
2331     .map_lookup_percpu_elem = htab_percpu_map_lookup_percpu_elem,
2332     .map_seq_show_elem = htab_percpu_map_seq_show_elem,
2333     .map_set_for_each_callback_args = map_set_for_each_callback_args,
2334     .map_for_each_callback = bpf_for_each_hash_elem,
2335     BATCH_OPS(htab_percpu),
2336     .map_btf_id = &htab_map_btf_ids[0],
2337     .iter_seq_info = &iter_seq_info,
2338 };
2339
2340 const struct bpf_map_ops htab_lru_percpu_map_ops = {
2341     .map_meta_equal = bpf_map_meta_equal,
2342     .map_alloc_check = htab_map_alloc_check,
2343     .map_alloc = htab_map_alloc,
2344     .map_free = htab_map_free,
2345     .map_get_next_key = htab_map_get_next_key,
2346     .map_lookup_elem = htab_lru_percpu_map_lookup_elem,
2347     .map_lookup_and_delete_elem = htab_lru_percpu_map_lookup_and_delete_elem,
2348     .map_update_elem = htab_lru_percpu_map_update_elem,
2349     .map_delete_elem = htab_lru_map_delete_elem,
2350     .map_lookup_percpu_elem = htab_lru_percpu_map_lookup_percpu_elem,
2351     .map_seq_show_elem = htab_percpu_map_seq_show_elem,
2352     .map_set_for_each_callback_args = map_set_for_each_callback_args,
2353     .map_for_each_callback = bpf_for_each_hash_elem,
2354     BATCH_OPS(htab_lru_percpu),
2355     .map_btf_id = &htab_map_btf_ids[0],
2356     .iter_seq_info = &iter_seq_info,
2357 };
2358
2359 static int fd_htab_map_alloc_check(union bpf_attr *attr)
2360 {
2361     if (attr->value_size != sizeof(u32))
2362         return -EINVAL;
2363     return htab_map_alloc_check(attr);
2364 }
2365
2366 static void fd_htab_map_free(struct bpf_map *map)
2367 {
2368     struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
2369     struct hlist_nulls_node *n;
2370     struct hlist_nulls_head *head;
2371     struct htab_elem *l;
2372     int i;
2373
2374     for (i = 0; i < htab->n_buckets; i++) {
2375         head = select_bucket(htab, i);
2376
2377         hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
2378             void *ptr = fd_htab_map_get_ptr(map, l);
2379
2380             map->ops->map_fd_put_ptr(ptr);
2381         }
2382     }
2383
2384     htab_map_free(map);
2385 }
2386
2387 /* only called from syscall */
2388 int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
2389 {
2390     void **ptr;
2391     int ret = 0;
2392
2393     if (!map->ops->map_fd_sys_lookup_elem)
2394         return -ENOTSUPP;
2395
2396     rcu_read_lock();
2397     ptr = htab_map_lookup_elem(map, key);
2398     if (ptr)
2399         *value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
2400     else
2401         ret = -ENOENT;
2402     rcu_read_unlock();
2403
2404     return ret;
2405 }
2406
2407 /* only called from syscall */
2408 int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
2409                 void *key, void *value, u64 map_flags)
2410 {
2411     void *ptr;
2412     int ret;
2413     u32 ufd = *(u32 *)value;
2414
2415     ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
2416     if (IS_ERR(ptr))
2417         return PTR_ERR(ptr);
2418
2419     ret = htab_map_update_elem(map, key, &ptr, map_flags);
2420     if (ret)
2421         map->ops->map_fd_put_ptr(ptr);
2422
2423     return ret;
2424 }
2425
2426 static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
2427 {
2428     struct bpf_map *map, *inner_map_meta;
2429
2430     inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
2431     if (IS_ERR(inner_map_meta))
2432         return inner_map_meta;
2433
2434     map = htab_map_alloc(attr);
2435     if (IS_ERR(map)) {
2436         bpf_map_meta_free(inner_map_meta);
2437         return map;
2438     }
2439
2440     map->inner_map_meta = inner_map_meta;
2441
2442     return map;
2443 }
2444
2445 static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
2446 {
2447     struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);
2448
2449     if (!inner_map)
2450         return NULL;
2451
2452     return READ_ONCE(*inner_map);
2453 }
2454
2455 static int htab_of_map_gen_lookup(struct bpf_map *map,
2456                   struct bpf_insn *insn_buf)
2457 {
2458     struct bpf_insn *insn = insn_buf;
2459     const int ret = BPF_REG_0;
2460
2461     BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
2462              (void *(*)(struct bpf_map *map, void *key))NULL));
2463     *insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
2464     *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
2465     *insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
2466                 offsetof(struct htab_elem, key) +
2467                 round_up(map->key_size, 8));
2468     *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
2469
2470     return insn - insn_buf;
2471 }
2472
2473 static void htab_of_map_free(struct bpf_map *map)
2474 {
2475     bpf_map_meta_free(map->inner_map_meta);
2476     fd_htab_map_free(map);
2477 }
2478
2479 const struct bpf_map_ops htab_of_maps_map_ops = {
2480     .map_alloc_check = fd_htab_map_alloc_check,
2481     .map_alloc = htab_of_map_alloc,
2482     .map_free = htab_of_map_free,
2483     .map_get_next_key = htab_map_get_next_key,
2484     .map_lookup_elem = htab_of_map_lookup_elem,
2485     .map_delete_elem = htab_map_delete_elem,
2486     .map_fd_get_ptr = bpf_map_fd_get_ptr,
2487     .map_fd_put_ptr = bpf_map_fd_put_ptr,
2488     .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
2489     .map_gen_lookup = htab_of_map_gen_lookup,
2490     .map_check_btf = map_check_no_btf,
2491     BATCH_OPS(htab),
2492     .map_btf_id = &htab_map_btf_ids[0],
2493 };