security/keys/proc.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /* procfs files for key database enumeration
0003  *
0004  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
0005  * Written by David Howells (dhowells@redhat.com)
0006  */
0007
0008 #include <linux/init.h>
0009 #include <linux/sched.h>
0010 #include <linux/fs.h>
0011 #include <linux/proc_fs.h>
0012 #include <linux/seq_file.h>
0013 #include <asm/errno.h>
0014 #include "internal.h"
0015
0016 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
0017 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
0018 static void proc_keys_stop(struct seq_file *p, void *v);
0019 static int proc_keys_show(struct seq_file *m, void *v);
0020
0021 static const struct seq_operations proc_keys_ops = {
0022     .start  = proc_keys_start,
0023     .next   = proc_keys_next,
0024     .stop   = proc_keys_stop,
0025     .show   = proc_keys_show,
0026 };
0027
0028 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
0029 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
0030 static void proc_key_users_stop(struct seq_file *p, void *v);
0031 static int proc_key_users_show(struct seq_file *m, void *v);
0032
0033 static const struct seq_operations proc_key_users_ops = {
0034     .start  = proc_key_users_start,
0035     .next   = proc_key_users_next,
0036     .stop   = proc_key_users_stop,
0037     .show   = proc_key_users_show,
0038 };
0039
0040 /*
0041  * Declare the /proc files.
0042  */
0043 static int __init key_proc_init(void)
0044 {
0045     struct proc_dir_entry *p;
0046
0047     p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
0048     if (!p)
0049         panic("Cannot create /proc/keys\n");
0050
0051     p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
0052     if (!p)
0053         panic("Cannot create /proc/key-users\n");
0054
0055     return 0;
0056 }
0057
0058 __initcall(key_proc_init);
0059
0060 /*
0061  * Implement "/proc/keys" to provide a list of the keys on the system that
0062  * grant View permission to the caller.
0063  */
0064 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
0065 {
0066     struct user_namespace *user_ns = seq_user_ns(p);
0067
0068     n = rb_next(n);
0069     while (n) {
0070         struct key *key = rb_entry(n, struct key, serial_node);
0071         if (kuid_has_mapping(user_ns, key->user->uid))
0072             break;
0073         n = rb_next(n);
0074     }
0075     return n;
0076 }
0077
0078 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
0079 {
0080     struct user_namespace *user_ns = seq_user_ns(p);
0081     struct rb_node *n = key_serial_tree.rb_node;
0082     struct key *minkey = NULL;
0083
0084     while (n) {
0085         struct key *key = rb_entry(n, struct key, serial_node);
0086         if (id < key->serial) {
0087             if (!minkey || minkey->serial > key->serial)
0088                 minkey = key;
0089             n = n->rb_left;
0090         } else if (id > key->serial) {
0091             n = n->rb_right;
0092         } else {
0093             minkey = key;
0094             break;
0095         }
0096         key = NULL;
0097     }
0098
0099     if (!minkey)
0100         return NULL;
0101
0102     for (;;) {
0103         if (kuid_has_mapping(user_ns, minkey->user->uid))
0104             return minkey;
0105         n = rb_next(&minkey->serial_node);
0106         if (!n)
0107             return NULL;
0108         minkey = rb_entry(n, struct key, serial_node);
0109     }
0110 }
0111
0112 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
0113     __acquires(key_serial_lock)
0114 {
0115     key_serial_t pos = *_pos;
0116     struct key *key;
0117
0118     spin_lock(&key_serial_lock);
0119
0120     if (*_pos > INT_MAX)
0121         return NULL;
0122     key = find_ge_key(p, pos);
0123     if (!key)
0124         return NULL;
0125     *_pos = key->serial;
0126     return &key->serial_node;
0127 }
0128
0129 static inline key_serial_t key_node_serial(struct rb_node *n)
0130 {
0131     struct key *key = rb_entry(n, struct key, serial_node);
0132     return key->serial;
0133 }
0134
0135 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
0136 {
0137     struct rb_node *n;
0138
0139     n = key_serial_next(p, v);
0140     if (n)
0141         *_pos = key_node_serial(n);
0142     else
0143         (*_pos)++;
0144     return n;
0145 }
0146
0147 static void proc_keys_stop(struct seq_file *p, void *v)
0148     __releases(key_serial_lock)
0149 {
0150     spin_unlock(&key_serial_lock);
0151 }
0152
0153 static int proc_keys_show(struct seq_file *m, void *v)
0154 {
0155     struct rb_node *_p = v;
0156     struct key *key = rb_entry(_p, struct key, serial_node);
0157     unsigned long flags;
0158     key_ref_t key_ref, skey_ref;
0159     time64_t now, expiry;
0160     char xbuf[16];
0161     short state;
0162     u64 timo;
0163     int rc;
0164
0165     struct keyring_search_context ctx = {
0166         .index_key      = key->index_key,
0167         .cred           = m->file->f_cred,
0168         .match_data.cmp     = lookup_user_key_possessed,
0169         .match_data.raw_data    = key,
0170         .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
0171         .flags          = (KEYRING_SEARCH_NO_STATE_CHECK |
0172                        KEYRING_SEARCH_RECURSE),
0173     };
0174
0175     key_ref = make_key_ref(key, 0);
0176
0177     /* determine if the key is possessed by this process (a test we can
0178      * skip if the key does not indicate the possessor can view it
0179      */
0180     if (key->perm & KEY_POS_VIEW) {
0181         rcu_read_lock();
0182         skey_ref = search_cred_keyrings_rcu(&ctx);
0183         rcu_read_unlock();
0184         if (!IS_ERR(skey_ref)) {
0185             key_ref_put(skey_ref);
0186             key_ref = make_key_ref(key, 1);
0187         }
0188     }
0189
0190     /* check whether the current task is allowed to view the key */
0191     rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
0192     if (rc < 0)
0193         return 0;
0194
0195     now = ktime_get_real_seconds();
0196
0197     rcu_read_lock();
0198
0199     /* come up with a suitable timeout value */
0200     expiry = READ_ONCE(key->expiry);
0201     if (expiry == 0) {
0202         memcpy(xbuf, "perm", 5);
0203     } else if (now >= expiry) {
0204         memcpy(xbuf, "expd", 5);
0205     } else {
0206         timo = expiry - now;
0207
0208         if (timo < 60)
0209             sprintf(xbuf, "%llus", timo);
0210         else if (timo < 60*60)
0211             sprintf(xbuf, "%llum", div_u64(timo, 60));
0212         else if (timo < 60*60*24)
0213             sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
0214         else if (timo < 60*60*24*7)
0215             sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
0216         else
0217             sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
0218     }
0219
0220     state = key_read_state(key);
0221
0222 #define showflag(FLAGS, LETTER, FLAG) \
0223     ((FLAGS & (1 << FLAG)) ? LETTER : '-')
0224
0225     flags = READ_ONCE(key->flags);
0226     seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
0227            key->serial,
0228            state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
0229            showflag(flags, 'R', KEY_FLAG_REVOKED),
0230            showflag(flags, 'D', KEY_FLAG_DEAD),
0231            showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
0232            showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
0233            state < 0 ? 'N' : '-',
0234            showflag(flags, 'i', KEY_FLAG_INVALIDATED),
0235            refcount_read(&key->usage),
0236            xbuf,
0237            key->perm,
0238            from_kuid_munged(seq_user_ns(m), key->uid),
0239            from_kgid_munged(seq_user_ns(m), key->gid),
0240            key->type->name);
0241
0242 #undef showflag
0243
0244     if (key->type->describe)
0245         key->type->describe(key, m);
0246     seq_putc(m, '\n');
0247
0248     rcu_read_unlock();
0249     return 0;
0250 }
0251
0252 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
0253 {
0254     while (n) {
0255         struct key_user *user = rb_entry(n, struct key_user, node);
0256         if (kuid_has_mapping(user_ns, user->uid))
0257             break;
0258         n = rb_next(n);
0259     }
0260     return n;
0261 }
0262
0263 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
0264 {
0265     return __key_user_next(user_ns, rb_next(n));
0266 }
0267
0268 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
0269 {
0270     struct rb_node *n = rb_first(r);
0271     return __key_user_next(user_ns, n);
0272 }
0273
0274 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
0275     __acquires(key_user_lock)
0276 {
0277     struct rb_node *_p;
0278     loff_t pos = *_pos;
0279
0280     spin_lock(&key_user_lock);
0281
0282     _p = key_user_first(seq_user_ns(p), &key_user_tree);
0283     while (pos > 0 && _p) {
0284         pos--;
0285         _p = key_user_next(seq_user_ns(p), _p);
0286     }
0287
0288     return _p;
0289 }
0290
0291 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
0292 {
0293     (*_pos)++;
0294     return key_user_next(seq_user_ns(p), (struct rb_node *)v);
0295 }
0296
0297 static void proc_key_users_stop(struct seq_file *p, void *v)
0298     __releases(key_user_lock)
0299 {
0300     spin_unlock(&key_user_lock);
0301 }
0302
0303 static int proc_key_users_show(struct seq_file *m, void *v)
0304 {
0305     struct rb_node *_p = v;
0306     struct key_user *user = rb_entry(_p, struct key_user, node);
0307     unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
0308         key_quota_root_maxkeys : key_quota_maxkeys;
0309     unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
0310         key_quota_root_maxbytes : key_quota_maxbytes;
0311
0312     seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
0313            from_kuid_munged(seq_user_ns(m), user->uid),
0314            refcount_read(&user->usage),
0315            atomic_read(&user->nkeys),
0316            atomic_read(&user->nikeys),
0317            user->qnkeys,
0318            maxkeys,
0319            user->qnbytes,
0320            maxbytes);
0321
0322     return 0;
0323 }