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 // SPDX-License-Identifier: GPL-2.0
 /*
  * linux/kernel/seccomp.c
  *
  * Copyright 2004-2005  Andrea Arcangeli <andrea@cpushare.com>
  *
  * Copyright (C) 2012 Google, Inc.
  * Will Drewry <wad@chromium.org>
  *
  * This defines a simple but solid secure-computing facility.
  *
  * Mode 1 uses a fixed list of allowed system calls.
  * Mode 2 allows user-defined system call filters in the form
  *        of Berkeley Packet Filters/Linux Socket Filters.
  */
 #define pr_fmt(fmt) "seccomp: " fmt
 
 #include <linux/refcount.h>
 #include <linux/audit.h>
 #include <linux/compat.h>
 #include <linux/coredump.h>
 #include <linux/kmemleak.h>
 #include <linux/nospec.h>
 #include <linux/prctl.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/seccomp.h>
 #include <linux/slab.h>
 #include <linux/syscalls.h>
 #include <linux/sysctl.h>
 
 /* Not exposed in headers: strictly internal use only. */
 #define SECCOMP_MODE_DEAD   (SECCOMP_MODE_FILTER + 1)
 
 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
 #include <asm/syscall.h>
 #endif
 
 #ifdef CONFIG_SECCOMP_FILTER
 #include <linux/file.h>
 #include <linux/filter.h>
 #include <linux/pid.h>
 #include <linux/ptrace.h>
 #include <linux/capability.h>
 #include <linux/uaccess.h>
 #include <linux/anon_inodes.h>
 #include <linux/lockdep.h>
 
 /*
  * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
  * wrong direction flag in the ioctl number. This is the broken one,
  * which the kernel needs to keep supporting until all userspaces stop
  * using the wrong command number.
  */
 #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR  SECCOMP_IOR(2, __u64)
 
 enum notify_state {
     SECCOMP_NOTIFY_INIT,
     SECCOMP_NOTIFY_SENT,
     SECCOMP_NOTIFY_REPLIED,
 };
 
 struct seccomp_knotif {
     /* The struct pid of the task whose filter triggered the notification */
     struct task_struct *task;
 
     /* The "cookie" for this request; this is unique for this filter. */
     u64 id;
 
     /*
      * The seccomp data. This pointer is valid the entire time this
      * notification is active, since it comes from __seccomp_filter which
      * eclipses the entire lifecycle here.
      */
     const struct seccomp_data *data;
 
     /*
      * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
      * struct seccomp_knotif is created and starts out in INIT. Once the
      * handler reads the notification off of an FD, it transitions to SENT.
      * If a signal is received the state transitions back to INIT and
      * another message is sent. When the userspace handler replies, state
      * transitions to REPLIED.
      */
     enum notify_state state;
 
     /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
     int error;
     long val;
     u32 flags;
 
     /*
      * Signals when this has changed states, such as the listener
      * dying, a new seccomp addfd message, or changing to REPLIED
      */
     struct completion ready;
 
     struct list_head list;
 
     /* outstanding addfd requests */
     struct list_head addfd;
 };
 
 /**
  * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
  *
  * @file: A reference to the file to install in the other task
  * @fd: The fd number to install it at. If the fd number is -1, it means the
  *      installing process should allocate the fd as normal.
  * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
  *         is allowed.
  * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
  * @ret: The return value of the installing process. It is set to the fd num
  *       upon success (>= 0).
  * @completion: Indicates that the installing process has completed fd
  *              installation, or gone away (either due to successful
  *              reply, or signal)
  *
  */
 struct seccomp_kaddfd {
     struct file *file;
     int fd;
     unsigned int flags;
     __u32 ioctl_flags;
 
     union {
         bool setfd;
         /* To only be set on reply */
         int ret;
     };
     struct completion completion;
     struct list_head list;
 };
 
 /**
  * struct notification - container for seccomp userspace notifications. Since
  * most seccomp filters will not have notification listeners attached and this
  * structure is fairly large, we store the notification-specific stuff in a
  * separate structure.
  *
  * @request: A semaphore that users of this notification can wait on for
  *           changes. Actual reads and writes are still controlled with
  *           filter->notify_lock.
  * @next_id: The id of the next request.
  * @notifications: A list of struct seccomp_knotif elements.
  */
 struct notification {
     struct semaphore request;
     u64 next_id;
     struct list_head notifications;
 };
 
 #ifdef SECCOMP_ARCH_NATIVE
 /**
  * struct action_cache - per-filter cache of seccomp actions per
  * arch/syscall pair
  *
  * @allow_native: A bitmap where each bit represents whether the
  *        filter will always allow the syscall, for the
  *        native architecture.
  * @allow_compat: A bitmap where each bit represents whether the
  *        filter will always allow the syscall, for the
  *        compat architecture.
  */
 struct action_cache {
     DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
 #ifdef SECCOMP_ARCH_COMPAT
     DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
 #endif
 };
 #else
 struct action_cache { };
 
 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
                          const struct seccomp_data *sd)
 {
     return false;
 }
 
 static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
 {
 }
 #endif /* SECCOMP_ARCH_NATIVE */
 
 /**
  * struct seccomp_filter - container for seccomp BPF programs
  *
  * @refs: Reference count to manage the object lifetime.
  *    A filter's reference count is incremented for each directly
  *    attached task, once for the dependent filter, and if
  *    requested for the user notifier. When @refs reaches zero,
  *    the filter can be freed.
  * @users: A filter's @users count is incremented for each directly
  *         attached task (filter installation, fork(), thread_sync),
  *     and once for the dependent filter (tracked in filter->prev).
  *     When it reaches zero it indicates that no direct or indirect
  *     users of that filter exist. No new tasks can get associated with
  *     this filter after reaching 0. The @users count is always smaller
  *     or equal to @refs. Hence, reaching 0 for @users does not mean
  *     the filter can be freed.
  * @cache: cache of arch/syscall mappings to actions
  * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
  * @wait_killable_recv: Put notifying process in killable state once the
  *          notification is received by the userspace listener.
  * @prev: points to a previously installed, or inherited, filter
  * @prog: the BPF program to evaluate
  * @notif: the struct that holds all notification related information
  * @notify_lock: A lock for all notification-related accesses.
  * @wqh: A wait queue for poll if a notifier is in use.
  *
  * seccomp_filter objects are organized in a tree linked via the @prev
  * pointer.  For any task, it appears to be a singly-linked list starting
  * with current->seccomp.filter, the most recently attached or inherited filter.
  * However, multiple filters may share a @prev node, by way of fork(), which
  * results in a unidirectional tree existing in memory.  This is similar to
  * how namespaces work.
  *
  * seccomp_filter objects should never be modified after being attached
  * to a task_struct (other than @refs).
  */
 struct seccomp_filter {
     refcount_t refs;
     refcount_t users;
     bool log;
     bool wait_killable_recv;
     struct action_cache cache;
     struct seccomp_filter *prev;
     struct bpf_prog *prog;
     struct notification *notif;
     struct mutex notify_lock;
     wait_queue_head_t wqh;
 };
 
 /* Limit any path through the tree to 256KB worth of instructions. */
 #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
 
 /*
  * Endianness is explicitly ignored and left for BPF program authors to manage
  * as per the specific architecture.
  */
 static void populate_seccomp_data(struct seccomp_data *sd)
 {
     /*
      * Instead of using current_pt_reg(), we're already doing the work
      * to safely fetch "current", so just use "task" everywhere below.
      */
     struct task_struct *task = current;
     struct pt_regs *regs = task_pt_regs(task);
     unsigned long args[6];
 
     sd->nr = syscall_get_nr(task, regs);
     sd->arch = syscall_get_arch(task);
     syscall_get_arguments(task, regs, args);
     sd->args[0] = args[0];
     sd->args[1] = args[1];
     sd->args[2] = args[2];
     sd->args[3] = args[3];
     sd->args[4] = args[4];
     sd->args[5] = args[5];
     sd->instruction_pointer = KSTK_EIP(task);
 }
 
 /**
  *  seccomp_check_filter - verify seccomp filter code
  *  @filter: filter to verify
  *  @flen: length of filter
  *
  * Takes a previously checked filter (by bpf_check_classic) and
  * redirects all filter code that loads struct sk_buff data
  * and related data through seccomp_bpf_load.  It also
  * enforces length and alignment checking of those loads.
  *
  * Returns 0 if the rule set is legal or -EINVAL if not.
  */
 static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
 {
     int pc;
     for (pc = 0; pc < flen; pc++) {
         struct sock_filter *ftest = &filter[pc];
         u16 code = ftest->code;
         u32 k = ftest->k;
 
         switch (code) {
         case BPF_LD | BPF_W | BPF_ABS:
             ftest->code = BPF_LDX | BPF_W | BPF_ABS;
             /* 32-bit aligned and not out of bounds. */
             if (k >= sizeof(struct seccomp_data) || k & 3)
                 return -EINVAL;
             continue;
         case BPF_LD | BPF_W | BPF_LEN:
             ftest->code = BPF_LD | BPF_IMM;
             ftest->k = sizeof(struct seccomp_data);
             continue;
         case BPF_LDX | BPF_W | BPF_LEN:
             ftest->code = BPF_LDX | BPF_IMM;
             ftest->k = sizeof(struct seccomp_data);
             continue;
         /* Explicitly include allowed calls. */
         case BPF_RET | BPF_K:
         case BPF_RET | BPF_A:
         case BPF_ALU | BPF_ADD | BPF_K:
         case BPF_ALU | BPF_ADD | BPF_X:
         case BPF_ALU | BPF_SUB | BPF_K:
         case BPF_ALU | BPF_SUB | BPF_X:
         case BPF_ALU | BPF_MUL | BPF_K:
         case BPF_ALU | BPF_MUL | BPF_X:
         case BPF_ALU | BPF_DIV | BPF_K:
         case BPF_ALU | BPF_DIV | BPF_X:
         case BPF_ALU | BPF_AND | BPF_K:
         case BPF_ALU | BPF_AND | BPF_X:
         case BPF_ALU | BPF_OR | BPF_K:
         case BPF_ALU | BPF_OR | BPF_X:
         case BPF_ALU | BPF_XOR | BPF_K:
         case BPF_ALU | BPF_XOR | BPF_X:
         case BPF_ALU | BPF_LSH | BPF_K:
         case BPF_ALU | BPF_LSH | BPF_X:
         case BPF_ALU | BPF_RSH | BPF_K:
         case BPF_ALU | BPF_RSH | BPF_X:
         case BPF_ALU | BPF_NEG:
         case BPF_LD | BPF_IMM:
         case BPF_LDX | BPF_IMM:
         case BPF_MISC | BPF_TAX:
         case BPF_MISC | BPF_TXA:
         case BPF_LD | BPF_MEM:
         case BPF_LDX | BPF_MEM:
         case BPF_ST:
         case BPF_STX:
         case BPF_JMP | BPF_JA:
         case BPF_JMP | BPF_JEQ | BPF_K:
         case BPF_JMP | BPF_JEQ | BPF_X:
         case BPF_JMP | BPF_JGE | BPF_K:
         case BPF_JMP | BPF_JGE | BPF_X:
         case BPF_JMP | BPF_JGT | BPF_K:
         case BPF_JMP | BPF_JGT | BPF_X:
         case BPF_JMP | BPF_JSET | BPF_K:
         case BPF_JMP | BPF_JSET | BPF_X:
             continue;
         default:
             return -EINVAL;
         }
     }
     return 0;
 }
 
 #ifdef SECCOMP_ARCH_NATIVE
 static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
                             size_t bitmap_size,
                             int syscall_nr)
 {
     if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
         return false;
     syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
 
     return test_bit(syscall_nr, bitmap);
 }
 
 /**
  * seccomp_cache_check_allow - lookup seccomp cache
  * @sfilter: The seccomp filter
  * @sd: The seccomp data to lookup the cache with
  *
  * Returns true if the seccomp_data is cached and allowed.
  */
 static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
                          const struct seccomp_data *sd)
 {
     int syscall_nr = sd->nr;
     const struct action_cache *cache = &sfilter->cache;
 
 #ifndef SECCOMP_ARCH_COMPAT
     /* A native-only architecture doesn't need to check sd->arch. */
     return seccomp_cache_check_allow_bitmap(cache->allow_native,
                         SECCOMP_ARCH_NATIVE_NR,
                         syscall_nr);
 #else
     if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
         return seccomp_cache_check_allow_bitmap(cache->allow_native,
                             SECCOMP_ARCH_NATIVE_NR,
                             syscall_nr);
     if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
         return seccomp_cache_check_allow_bitmap(cache->allow_compat,
                             SECCOMP_ARCH_COMPAT_NR,
                             syscall_nr);
 #endif /* SECCOMP_ARCH_COMPAT */
 
     WARN_ON_ONCE(true);
     return false;
 }
 #endif /* SECCOMP_ARCH_NATIVE */
 
 /**
  * seccomp_run_filters - evaluates all seccomp filters against @sd
  * @sd: optional seccomp data to be passed to filters
  * @match: stores struct seccomp_filter that resulted in the return value,
  *         unless filter returned SECCOMP_RET_ALLOW, in which case it will
  *         be unchanged.
  *
  * Returns valid seccomp BPF response codes.
  */
 #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
 static u32 seccomp_run_filters(const struct seccomp_data *sd,
                    struct seccomp_filter **match)
 {
     u32 ret = SECCOMP_RET_ALLOW;
     /* Make sure cross-thread synced filter points somewhere sane. */
     struct seccomp_filter *f =
             READ_ONCE(current->seccomp.filter);
 
     /* Ensure unexpected behavior doesn't result in failing open. */
     if (WARN_ON(f == NULL))
         return SECCOMP_RET_KILL_PROCESS;
 
     if (seccomp_cache_check_allow(f, sd))
         return SECCOMP_RET_ALLOW;
 
     /*
      * All filters in the list are evaluated and the lowest BPF return
      * value always takes priority (ignoring the DATA).
      */
     for (; f; f = f->prev) {
         u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
 
         if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
             ret = cur_ret;
             *match = f;
         }
     }
     return ret;
 }
 #endif /* CONFIG_SECCOMP_FILTER */
 
 static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
 {
     assert_spin_locked(&current->sighand->siglock);
 
     if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
         return false;
 
     return true;
 }
 
 void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
 
 static inline void seccomp_assign_mode(struct task_struct *task,
                        unsigned long seccomp_mode,
                        unsigned long flags)
 {
     assert_spin_locked(&task->sighand->siglock);
 
     task->seccomp.mode = seccomp_mode;
     /*
      * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
      * filter) is set.
      */
     smp_mb__before_atomic();
     /* Assume default seccomp processes want spec flaw mitigation. */
     if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
         arch_seccomp_spec_mitigate(task);
     set_task_syscall_work(task, SECCOMP);
 }
 
 #ifdef CONFIG_SECCOMP_FILTER
 /* Returns 1 if the parent is an ancestor of the child. */
 static int is_ancestor(struct seccomp_filter *parent,
                struct seccomp_filter *child)
 {
     /* NULL is the root ancestor. */
     if (parent == NULL)
         return 1;
     for (; child; child = child->prev)
         if (child == parent)
             return 1;
     return 0;
 }
 
 /**
  * seccomp_can_sync_threads: checks if all threads can be synchronized
  *
  * Expects sighand and cred_guard_mutex locks to be held.
  *
  * Returns 0 on success, -ve on error, or the pid of a thread which was
  * either not in the correct seccomp mode or did not have an ancestral
  * seccomp filter.
  */
 static inline pid_t seccomp_can_sync_threads(void)
 {
     struct task_struct *thread, *caller;
 
     BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
     assert_spin_locked(&current->sighand->siglock);
 
     /* Validate all threads being eligible for synchronization. */
     caller = current;
     for_each_thread(caller, thread) {
         pid_t failed;
 
         /* Skip current, since it is initiating the sync. */
         if (thread == caller)
             continue;
 
         if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
             (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
              is_ancestor(thread->seccomp.filter,
                  caller->seccomp.filter)))
             continue;
 
         /* Return the first thread that cannot be synchronized. */
         failed = task_pid_vnr(thread);
         /* If the pid cannot be resolved, then return -ESRCH */
         if (WARN_ON(failed == 0))
             failed = -ESRCH;
         return failed;
     }
 
     return 0;
 }
 
 static inline void seccomp_filter_free(struct seccomp_filter *filter)
 {
     if (filter) {
         bpf_prog_destroy(filter->prog);
         kfree(filter);
     }
 }
 
 static void __seccomp_filter_orphan(struct seccomp_filter *orig)
 {
     while (orig && refcount_dec_and_test(&orig->users)) {
         if (waitqueue_active(&orig->wqh))
             wake_up_poll(&orig->wqh, EPOLLHUP);
         orig = orig->prev;
     }
 }
 
 static void __put_seccomp_filter(struct seccomp_filter *orig)
 {
     /* Clean up single-reference branches iteratively. */
     while (orig && refcount_dec_and_test(&orig->refs)) {
         struct seccomp_filter *freeme = orig;
         orig = orig->prev;
         seccomp_filter_free(freeme);
     }
 }
 
 static void __seccomp_filter_release(struct seccomp_filter *orig)
 {
     /* Notify about any unused filters in the task's former filter tree. */
     __seccomp_filter_orphan(orig);
     /* Finally drop all references to the task's former tree. */
     __put_seccomp_filter(orig);
 }
 
 /**
  * seccomp_filter_release - Detach the task from its filter tree,
  *              drop its reference count, and notify
  *              about unused filters
  *
  * This function should only be called when the task is exiting as
  * it detaches it from its filter tree. As such, READ_ONCE() and
  * barriers are not needed here, as would normally be needed.
  */
 void seccomp_filter_release(struct task_struct *tsk)
 {
     struct seccomp_filter *orig = tsk->seccomp.filter;
 
     /* We are effectively holding the siglock by not having any sighand. */
     WARN_ON(tsk->sighand != NULL);
 
     /* Detach task from its filter tree. */
     tsk->seccomp.filter = NULL;
     __seccomp_filter_release(orig);
 }
 
 /**
  * seccomp_sync_threads: sets all threads to use current's filter
  *
  * Expects sighand and cred_guard_mutex locks to be held, and for
  * seccomp_can_sync_threads() to have returned success already
  * without dropping the locks.
  *
  */
 static inline void seccomp_sync_threads(unsigned long flags)
 {
     struct task_struct *thread, *caller;
 
     BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
     assert_spin_locked(&current->sighand->siglock);
 
     /* Synchronize all threads. */
     caller = current;
     for_each_thread(caller, thread) {
         /* Skip current, since it needs no changes. */
         if (thread == caller)
             continue;
 
         /* Get a task reference for the new leaf node. */
         get_seccomp_filter(caller);
 
         /*
          * Drop the task reference to the shared ancestor since
          * current's path will hold a reference.  (This also
          * allows a put before the assignment.)
          */
         __seccomp_filter_release(thread->seccomp.filter);
 
         /* Make our new filter tree visible. */
         smp_store_release(&thread->seccomp.filter,
                   caller->seccomp.filter);
         atomic_set(&thread->seccomp.filter_count,
                atomic_read(&caller->seccomp.filter_count));
 
         /*
          * Don't let an unprivileged task work around
          * the no_new_privs restriction by creating
          * a thread that sets it up, enters seccomp,
          * then dies.
          */
         if (task_no_new_privs(caller))
             task_set_no_new_privs(thread);
 
         /*
          * Opt the other thread into seccomp if needed.
          * As threads are considered to be trust-realm
          * equivalent (see ptrace_may_access), it is safe to
          * allow one thread to transition the other.
          */
         if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
             seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
                         flags);
     }
 }
 
 /**
  * seccomp_prepare_filter: Prepares a seccomp filter for use.
  * @fprog: BPF program to install
  *
  * Returns filter on success or an ERR_PTR on failure.
  */
 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
 {
     struct seccomp_filter *sfilter;
     int ret;
     const bool save_orig =
 #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
         true;
 #else
         false;
 #endif
 
     if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
         return ERR_PTR(-EINVAL);
 
     BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
 
     /*
      * Installing a seccomp filter requires that the task has
      * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
      * This avoids scenarios where unprivileged tasks can affect the
      * behavior of privileged children.
      */
     if (!task_no_new_privs(current) &&
             !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
         return ERR_PTR(-EACCES);
 
     /* Allocate a new seccomp_filter */
     sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
     if (!sfilter)
         return ERR_PTR(-ENOMEM);
 
     mutex_init(&sfilter->notify_lock);
     ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
                     seccomp_check_filter, save_orig);
     if (ret < 0) {
         kfree(sfilter);
         return ERR_PTR(ret);
     }
 
     refcount_set(&sfilter->refs, 1);
     refcount_set(&sfilter->users, 1);
     init_waitqueue_head(&sfilter->wqh);
 
     return sfilter;
 }
 
 /**
  * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
  * @user_filter: pointer to the user data containing a sock_fprog.
  *
  * Returns 0 on success and non-zero otherwise.
  */
 static struct seccomp_filter *
 seccomp_prepare_user_filter(const char __user *user_filter)
 {
     struct sock_fprog fprog;
     struct seccomp_filter *filter = ERR_PTR(-EFAULT);
 
 #ifdef CONFIG_COMPAT
     if (in_compat_syscall()) {
         struct compat_sock_fprog fprog32;
         if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
             goto out;
         fprog.len = fprog32.len;
         fprog.filter = compat_ptr(fprog32.filter);
     } else /* falls through to the if below. */
 #endif
     if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
         goto out;
     filter = seccomp_prepare_filter(&fprog);
 out:
     return filter;
 }
 
 #ifdef SECCOMP_ARCH_NATIVE
 /**
  * seccomp_is_const_allow - check if filter is constant allow with given data
  * @fprog: The BPF programs
  * @sd: The seccomp data to check against, only syscall number and arch
  *      number are considered constant.
  */
 static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
                    struct seccomp_data *sd)
 {
     unsigned int reg_value = 0;
     unsigned int pc;
     bool op_res;
 
     if (WARN_ON_ONCE(!fprog))
         return false;
 
     for (pc = 0; pc < fprog->len; pc++) {
         struct sock_filter *insn = &fprog->filter[pc];
         u16 code = insn->code;
         u32 k = insn->k;
 
         switch (code) {
         case BPF_LD | BPF_W | BPF_ABS:
             switch (k) {
             case offsetof(struct seccomp_data, nr):
                 reg_value = sd->nr;
                 break;
             case offsetof(struct seccomp_data, arch):
                 reg_value = sd->arch;
                 break;
             default:
                 /* can't optimize (non-constant value load) */
                 return false;
             }
             break;
         case BPF_RET | BPF_K:
             /* reached return with constant values only, check allow */
             return k == SECCOMP_RET_ALLOW;
         case BPF_JMP | BPF_JA:
             pc += insn->k;
             break;
         case BPF_JMP | BPF_JEQ | BPF_K:
         case BPF_JMP | BPF_JGE | BPF_K:
         case BPF_JMP | BPF_JGT | BPF_K:
         case BPF_JMP | BPF_JSET | BPF_K:
             switch (BPF_OP(code)) {
             case BPF_JEQ:
                 op_res = reg_value == k;
                 break;
             case BPF_JGE:
                 op_res = reg_value >= k;
                 break;
             case BPF_JGT:
                 op_res = reg_value > k;
                 break;
             case BPF_JSET:
                 op_res = !!(reg_value & k);
                 break;
             default:
                 /* can't optimize (unknown jump) */
                 return false;
             }
 
             pc += op_res ? insn->jt : insn->jf;
             break;
         case BPF_ALU | BPF_AND | BPF_K:
             reg_value &= k;
             break;
         default:
             /* can't optimize (unknown insn) */
             return false;
         }
     }
 
     /* ran off the end of the filter?! */
     WARN_ON(1);
     return false;
 }
 
 static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
                      void *bitmap, const void *bitmap_prev,
                      size_t bitmap_size, int arch)
 {
     struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
     struct seccomp_data sd;
     int nr;
 
     if (bitmap_prev) {
         /* The new filter must be as restrictive as the last. */
         bitmap_copy(bitmap, bitmap_prev, bitmap_size);
     } else {
         /* Before any filters, all syscalls are always allowed. */
         bitmap_fill(bitmap, bitmap_size);
     }
 
     for (nr = 0; nr < bitmap_size; nr++) {
         /* No bitmap change: not a cacheable action. */
         if (!test_bit(nr, bitmap))
             continue;
 
         sd.nr = nr;
         sd.arch = arch;
 
         /* No bitmap change: continue to always allow. */
         if (seccomp_is_const_allow(fprog, &sd))
             continue;
 
         /*
          * Not a cacheable action: always run filters.
          * atomic clear_bit() not needed, filter not visible yet.
          */
         __clear_bit(nr, bitmap);
     }
 }
 
 /**
  * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
  * @sfilter: The seccomp filter
  *
  * Returns 0 if successful or -errno if error occurred.
  */
 static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
 {
     struct action_cache *cache = &sfilter->cache;
     const struct action_cache *cache_prev =
         sfilter->prev ? &sfilter->prev->cache : NULL;
 
     seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
                      cache_prev ? cache_prev->allow_native : NULL,
                      SECCOMP_ARCH_NATIVE_NR,
                      SECCOMP_ARCH_NATIVE);
 
 #ifdef SECCOMP_ARCH_COMPAT
     seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
                      cache_prev ? cache_prev->allow_compat : NULL,
                      SECCOMP_ARCH_COMPAT_NR,
                      SECCOMP_ARCH_COMPAT);
 #endif /* SECCOMP_ARCH_COMPAT */
 }
 #endif /* SECCOMP_ARCH_NATIVE */
 
 /**
  * seccomp_attach_filter: validate and attach filter
  * @flags:  flags to change filter behavior
  * @filter: seccomp filter to add to the current process
  *
  * Caller must be holding current->sighand->siglock lock.
  *
  * Returns 0 on success, -ve on error, or
  *   - in TSYNC mode: the pid of a thread which was either not in the correct
  *     seccomp mode or did not have an ancestral seccomp filter
  *   - in NEW_LISTENER mode: the fd of the new listener
  */
 static long seccomp_attach_filter(unsigned int flags,
                   struct seccomp_filter *filter)
 {
     unsigned long total_insns;
     struct seccomp_filter *walker;
 
     assert_spin_locked(&current->sighand->siglock);
 
     /* Validate resulting filter length. */
     total_insns = filter->prog->len;
     for (walker = current->seccomp.filter; walker; walker = walker->prev)
         total_insns += walker->prog->len + 4;  /* 4 instr penalty */
     if (total_insns > MAX_INSNS_PER_PATH)
         return -ENOMEM;
 
     /* If thread sync has been requested, check that it is possible. */
     if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
         int ret;
 
         ret = seccomp_can_sync_threads();
         if (ret) {
             if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
                 return -ESRCH;
             else
                 return ret;
         }
     }
 
     /* Set log flag, if present. */
     if (flags & SECCOMP_FILTER_FLAG_LOG)
         filter->log = true;
 
     /* Set wait killable flag, if present. */
     if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
         filter->wait_killable_recv = true;
 
     /*
      * If there is an existing filter, make it the prev and don't drop its
      * task reference.
      */
     filter->prev = current->seccomp.filter;
     seccomp_cache_prepare(filter);
     current->seccomp.filter = filter;
     atomic_inc(&current->seccomp.filter_count);
 
     /* Now that the new filter is in place, synchronize to all threads. */
     if (flags & SECCOMP_FILTER_FLAG_TSYNC)
         seccomp_sync_threads(flags);
 
     return 0;
 }
 
 static void __get_seccomp_filter(struct seccomp_filter *filter)
 {
     refcount_inc(&filter->refs);
 }
 
 /* get_seccomp_filter - increments the reference count of the filter on @tsk */
 void get_seccomp_filter(struct task_struct *tsk)
 {
     struct seccomp_filter *orig = tsk->seccomp.filter;
     if (!orig)
         return;
     __get_seccomp_filter(orig);
     refcount_inc(&orig->users);
 }
 
 #endif  /* CONFIG_SECCOMP_FILTER */
 
 /* For use with seccomp_actions_logged */
 #define SECCOMP_LOG_KILL_PROCESS    (1 << 0)
 #define SECCOMP_LOG_KILL_THREAD     (1 << 1)
 #define SECCOMP_LOG_TRAP        (1 << 2)
 #define SECCOMP_LOG_ERRNO       (1 << 3)
 #define SECCOMP_LOG_TRACE       (1 << 4)
 #define SECCOMP_LOG_LOG         (1 << 5)
 #define SECCOMP_LOG_ALLOW       (1 << 6)
 #define SECCOMP_LOG_USER_NOTIF      (1 << 7)
 
 static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
                     SECCOMP_LOG_KILL_THREAD  |
                     SECCOMP_LOG_TRAP  |
                     SECCOMP_LOG_ERRNO |
                     SECCOMP_LOG_USER_NOTIF |
                     SECCOMP_LOG_TRACE |
                     SECCOMP_LOG_LOG;
 
 static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
                    bool requested)
 {
     bool log = false;
 
     switch (action) {
     case SECCOMP_RET_ALLOW:
         break;
     case SECCOMP_RET_TRAP:
         log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
         break;
     case SECCOMP_RET_ERRNO:
         log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
         break;
     case SECCOMP_RET_TRACE:
         log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
         break;
     case SECCOMP_RET_USER_NOTIF:
         log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
         break;
     case SECCOMP_RET_LOG:
         log = seccomp_actions_logged & SECCOMP_LOG_LOG;
         break;
     case SECCOMP_RET_KILL_THREAD:
         log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
         break;
     case SECCOMP_RET_KILL_PROCESS:
     default:
         log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
     }
 
     /*
      * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
      * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
      * any action from being logged by removing the action name from the
      * seccomp_actions_logged sysctl.
      */
     if (!log)
         return;
 
     audit_seccomp(syscall, signr, action);
 }
 
 /*
  * Secure computing mode 1 allows only read/write/exit/sigreturn.
  * To be fully secure this must be combined with rlimit
  * to limit the stack allocations too.
  */
 static const int mode1_syscalls[] = {
     __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
     -1, /* negative terminated */
 };
 
 static void __secure_computing_strict(int this_syscall)
 {
     const int *allowed_syscalls = mode1_syscalls;
 #ifdef CONFIG_COMPAT
     if (in_compat_syscall())
         allowed_syscalls = get_compat_mode1_syscalls();
 #endif
     do {
         if (*allowed_syscalls == this_syscall)
             return;
     } while (*++allowed_syscalls != -1);
 
 #ifdef SECCOMP_DEBUG
     dump_stack();
 #endif
     current->seccomp.mode = SECCOMP_MODE_DEAD;
     seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
     do_exit(SIGKILL);
 }
 
 #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
 void secure_computing_strict(int this_syscall)
 {
     int mode = current->seccomp.mode;
 
     if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
         unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
         return;
 
     if (mode == SECCOMP_MODE_DISABLED)
         return;
     else if (mode == SECCOMP_MODE_STRICT)
         __secure_computing_strict(this_syscall);
     else
         BUG();
 }
 #else
 
 #ifdef CONFIG_SECCOMP_FILTER
 static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
 {
     /*
      * Note: overflow is ok here, the id just needs to be unique per
      * filter.
      */
     lockdep_assert_held(&filter->notify_lock);
     return filter->notif->next_id++;
 }
 
 static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
 {
     int fd;
 
     /*
      * Remove the notification, and reset the list pointers, indicating
      * that it has been handled.
      */
     list_del_init(&addfd->list);
     if (!addfd->setfd)
         fd = receive_fd(addfd->file, addfd->flags);
     else
         fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
     addfd->ret = fd;
 
     if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
         /* If we fail reset and return an error to the notifier */
         if (fd < 0) {
             n->state = SECCOMP_NOTIFY_SENT;
         } else {
             /* Return the FD we just added */
             n->flags = 0;
             n->error = 0;
             n->val = fd;
         }
     }
 
     /*
      * Mark the notification as completed. From this point, addfd mem
      * might be invalidated and we can't safely read it anymore.
      */
     complete(&addfd->completion);
 }
 
 static bool should_sleep_killable(struct seccomp_filter *match,
                   struct seccomp_knotif *n)
 {
     return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
 }
 
 static int seccomp_do_user_notification(int this_syscall,
                     struct seccomp_filter *match,
                     const struct seccomp_data *sd)
 {
     int err;
     u32 flags = 0;
     long ret = 0;
     struct seccomp_knotif n = {};
     struct seccomp_kaddfd *addfd, *tmp;
 
     mutex_lock(&match->notify_lock);
     err = -ENOSYS;
     if (!match->notif)
         goto out;
 
     n.task = current;
     n.state = SECCOMP_NOTIFY_INIT;
     n.data = sd;
     n.id = seccomp_next_notify_id(match);
     init_completion(&n.ready);
     list_add_tail(&n.list, &match->notif->notifications);
     INIT_LIST_HEAD(&n.addfd);
 
     up(&match->notif->request);
     wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
 
     /*
      * This is where we wait for a reply from userspace.
      */
     do {
         bool wait_killable = should_sleep_killable(match, &n);
 
         mutex_unlock(&match->notify_lock);
         if (wait_killable)
             err = wait_for_completion_killable(&n.ready);
         else
             err = wait_for_completion_interruptible(&n.ready);
         mutex_lock(&match->notify_lock);
 
         if (err != 0) {
             /*
              * Check to see if the notifcation got picked up and
              * whether we should switch to wait killable.
              */
             if (!wait_killable && should_sleep_killable(match, &n))
                 continue;
 
             goto interrupted;
         }
 
         addfd = list_first_entry_or_null(&n.addfd,
                          struct seccomp_kaddfd, list);
         /* Check if we were woken up by a addfd message */
         if (addfd)
             seccomp_handle_addfd(addfd, &n);
 
     }  while (n.state != SECCOMP_NOTIFY_REPLIED);
 
     ret = n.val;
     err = n.error;
     flags = n.flags;
 
 interrupted:
     /* If there were any pending addfd calls, clear them out */
     list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
         /* The process went away before we got a chance to handle it */
         addfd->ret = -ESRCH;
         list_del_init(&addfd->list);
         complete(&addfd->completion);
     }
 
     /*
      * Note that it's possible the listener died in between the time when
      * we were notified of a response (or a signal) and when we were able to
      * re-acquire the lock, so only delete from the list if the
      * notification actually exists.
      *
      * Also note that this test is only valid because there's no way to
      * *reattach* to a notifier right now. If one is added, we'll need to
      * keep track of the notif itself and make sure they match here.
      */
     if (match->notif)
         list_del(&n.list);
 out:
     mutex_unlock(&match->notify_lock);
 
     /* Userspace requests to continue the syscall. */
     if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
         return 0;
 
     syscall_set_return_value(current, current_pt_regs(),
                  err, ret);
     return -1;
 }
 
 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
                 const bool recheck_after_trace)
 {
     u32 filter_ret, action;
     struct seccomp_filter *match = NULL;
     int data;
     struct seccomp_data sd_local;
 
     /*
      * Make sure that any changes to mode from another thread have
      * been seen after SYSCALL_WORK_SECCOMP was seen.
      */
     smp_rmb();
 
     if (!sd) {
         populate_seccomp_data(&sd_local);
         sd = &sd_local;
     }
 
     filter_ret = seccomp_run_filters(sd, &match);
     data = filter_ret & SECCOMP_RET_DATA;
     action = filter_ret & SECCOMP_RET_ACTION_FULL;
 
     switch (action) {
     case SECCOMP_RET_ERRNO:
         /* Set low-order bits as an errno, capped at MAX_ERRNO. */
         if (data > MAX_ERRNO)
             data = MAX_ERRNO;
         syscall_set_return_value(current, current_pt_regs(),
                      -data, 0);
         goto skip;
 
     case SECCOMP_RET_TRAP:
         /* Show the handler the original registers. */
         syscall_rollback(current, current_pt_regs());
         /* Let the filter pass back 16 bits of data. */
         force_sig_seccomp(this_syscall, data, false);
         goto skip;
 
     case SECCOMP_RET_TRACE:
         /* We've been put in this state by the ptracer already. */
         if (recheck_after_trace)
             return 0;
 
         /* ENOSYS these calls if there is no tracer attached. */
         if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
             syscall_set_return_value(current,
                          current_pt_regs(),
                          -ENOSYS, 0);
             goto skip;
         }
 
         /* Allow the BPF to provide the event message */
         ptrace_event(PTRACE_EVENT_SECCOMP, data);
         /*
          * The delivery of a fatal signal during event
          * notification may silently skip tracer notification,
          * which could leave us with a potentially unmodified
          * syscall that the tracer would have liked to have
          * changed. Since the process is about to die, we just
          * force the syscall to be skipped and let the signal
          * kill the process and correctly handle any tracer exit
          * notifications.
          */
         if (fatal_signal_pending(current))
             goto skip;
         /* Check if the tracer forced the syscall to be skipped. */
         this_syscall = syscall_get_nr(current, current_pt_regs());
         if (this_syscall < 0)
             goto skip;
 
         /*
          * Recheck the syscall, since it may have changed. This
          * intentionally uses a NULL struct seccomp_data to force
          * a reload of all registers. This does not goto skip since
          * a skip would have already been reported.
          */
         if (__seccomp_filter(this_syscall, NULL, true))
             return -1;
 
         return 0;
 
     case SECCOMP_RET_USER_NOTIF:
         if (seccomp_do_user_notification(this_syscall, match, sd))
             goto skip;
 
         return 0;
 
     case SECCOMP_RET_LOG:
         seccomp_log(this_syscall, 0, action, true);
         return 0;
 
     case SECCOMP_RET_ALLOW:
         /*
          * Note that the "match" filter will always be NULL for
          * this action since SECCOMP_RET_ALLOW is the starting
          * state in seccomp_run_filters().
          */
         return 0;
 
     case SECCOMP_RET_KILL_THREAD:
     case SECCOMP_RET_KILL_PROCESS:
     default:
         current->seccomp.mode = SECCOMP_MODE_DEAD;
         seccomp_log(this_syscall, SIGSYS, action, true);
         /* Dump core only if this is the last remaining thread. */
         if (action != SECCOMP_RET_KILL_THREAD ||
             (atomic_read(&current->signal->live) == 1)) {
             /* Show the original registers in the dump. */
             syscall_rollback(current, current_pt_regs());
             /* Trigger a coredump with SIGSYS */
             force_sig_seccomp(this_syscall, data, true);
         } else {
             do_exit(SIGSYS);
         }
         return -1; /* skip the syscall go directly to signal handling */
     }
 
     unreachable();
 
 skip:
     seccomp_log(this_syscall, 0, action, match ? match->log : false);
     return -1;
 }
 #else
 static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
                 const bool recheck_after_trace)
 {
     BUG();
 
     return -1;
 }
 #endif
 
 int __secure_computing(const struct seccomp_data *sd)
 {
     int mode = current->seccomp.mode;
     int this_syscall;
 
     if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
         unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
         return 0;
 
     this_syscall = sd ? sd->nr :
         syscall_get_nr(current, current_pt_regs());
 
     switch (mode) {
     case SECCOMP_MODE_STRICT:
         __secure_computing_strict(this_syscall);  /* may call do_exit */
         return 0;
     case SECCOMP_MODE_FILTER:
         return __seccomp_filter(this_syscall, sd, false);
     /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
     case SECCOMP_MODE_DEAD:
         WARN_ON_ONCE(1);
         do_exit(SIGKILL);
         return -1;
     default:
         BUG();
     }
 }
 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
 
 long prctl_get_seccomp(void)
 {
     return current->seccomp.mode;
 }
 
 /**
  * seccomp_set_mode_strict: internal function for setting strict seccomp
  *
  * Once current->seccomp.mode is non-zero, it may not be changed.
  *
  * Returns 0 on success or -EINVAL on failure.
  */
 static long seccomp_set_mode_strict(void)
 {
     const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
     long ret = -EINVAL;
 
     spin_lock_irq(&current->sighand->siglock);
 
     if (!seccomp_may_assign_mode(seccomp_mode))
         goto out;
 
 #ifdef TIF_NOTSC
     disable_TSC();
 #endif
     seccomp_assign_mode(current, seccomp_mode, 0);
     ret = 0;
 
 out:
     spin_unlock_irq(&current->sighand->siglock);
 
     return ret;
 }
 
 #ifdef CONFIG_SECCOMP_FILTER
 static void seccomp_notify_free(struct seccomp_filter *filter)
 {
     kfree(filter->notif);
     filter->notif = NULL;
 }
 
 static void seccomp_notify_detach(struct seccomp_filter *filter)
 {
     struct seccomp_knotif *knotif;
 
     if (!filter)
         return;
 
     mutex_lock(&filter->notify_lock);
 
     /*
      * If this file is being closed because e.g. the task who owned it
      * died, let's wake everyone up who was waiting on us.
      */
     list_for_each_entry(knotif, &filter->notif->notifications, list) {
         if (knotif->state == SECCOMP_NOTIFY_REPLIED)
             continue;
 
         knotif->state = SECCOMP_NOTIFY_REPLIED;
         knotif->error = -ENOSYS;
         knotif->val = 0;
 
         /*
          * We do not need to wake up any pending addfd messages, as
          * the notifier will do that for us, as this just looks
          * like a standard reply.
          */
         complete(&knotif->ready);
     }
 
     seccomp_notify_free(filter);
     mutex_unlock(&filter->notify_lock);
 }
 
 static int seccomp_notify_release(struct inode *inode, struct file *file)
 {
     struct seccomp_filter *filter = file->private_data;
 
     seccomp_notify_detach(filter);
     __put_seccomp_filter(filter);
     return 0;
 }
 
 /* must be called with notif_lock held */
 static inline struct seccomp_knotif *
 find_notification(struct seccomp_filter *filter, u64 id)
 {
     struct seccomp_knotif *cur;
 
     lockdep_assert_held(&filter->notify_lock);
 
     list_for_each_entry(cur, &filter->notif->notifications, list) {
         if (cur->id == id)
             return cur;
     }
 
     return NULL;
 }
 
 
 static long seccomp_notify_recv(struct seccomp_filter *filter,
                 void __user *buf)
 {
     struct seccomp_knotif *knotif = NULL, *cur;
     struct seccomp_notif unotif;
     ssize_t ret;
 
     /* Verify that we're not given garbage to keep struct extensible. */
     ret = check_zeroed_user(buf, sizeof(unotif));
     if (ret < 0)
         return ret;
     if (!ret)
         return -EINVAL;
 
     memset(&unotif, 0, sizeof(unotif));
 
     ret = down_interruptible(&filter->notif->request);
     if (ret < 0)
         return ret;
 
     mutex_lock(&filter->notify_lock);
     list_for_each_entry(cur, &filter->notif->notifications, list) {
         if (cur->state == SECCOMP_NOTIFY_INIT) {
             knotif = cur;
             break;
         }
     }
 
     /*
      * If we didn't find a notification, it could be that the task was
      * interrupted by a fatal signal between the time we were woken and
      * when we were able to acquire the rw lock.
      */
     if (!knotif) {
         ret = -ENOENT;
         goto out;
     }
 
     unotif.id = knotif->id;
     unotif.pid = task_pid_vnr(knotif->task);
     unotif.data = *(knotif->data);
 
     knotif->state = SECCOMP_NOTIFY_SENT;
     wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
     ret = 0;
 out:
     mutex_unlock(&filter->notify_lock);
 
     if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
         ret = -EFAULT;
 
         /*
          * Userspace screwed up. To make sure that we keep this
          * notification alive, let's reset it back to INIT. It
          * may have died when we released the lock, so we need to make
          * sure it's still around.
          */
         mutex_lock(&filter->notify_lock);
         knotif = find_notification(filter, unotif.id);
         if (knotif) {
             /* Reset the process to make sure it's not stuck */
             if (should_sleep_killable(filter, knotif))
                 complete(&knotif->ready);
             knotif->state = SECCOMP_NOTIFY_INIT;
             up(&filter->notif->request);
         }
         mutex_unlock(&filter->notify_lock);
     }
 
     return ret;
 }
 
 static long seccomp_notify_send(struct seccomp_filter *filter,
                 void __user *buf)
 {
     struct seccomp_notif_resp resp = {};
     struct seccomp_knotif *knotif;
     long ret;
 
     if (copy_from_user(&resp, buf, sizeof(resp)))
         return -EFAULT;
 
     if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
         return -EINVAL;
 
     if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
         (resp.error || resp.val))
         return -EINVAL;
 
     ret = mutex_lock_interruptible(&filter->notify_lock);
     if (ret < 0)
         return ret;
 
     knotif = find_notification(filter, resp.id);
     if (!knotif) {
         ret = -ENOENT;
         goto out;
     }
 
     /* Allow exactly one reply. */
     if (knotif->state != SECCOMP_NOTIFY_SENT) {
         ret = -EINPROGRESS;
         goto out;
     }
 
     ret = 0;
     knotif->state = SECCOMP_NOTIFY_REPLIED;
     knotif->error = resp.error;
     knotif->val = resp.val;
     knotif->flags = resp.flags;
     complete(&knotif->ready);
 out:
     mutex_unlock(&filter->notify_lock);
     return ret;
 }
 
 static long seccomp_notify_id_valid(struct seccomp_filter *filter,
                     void __user *buf)
 {
     struct seccomp_knotif *knotif;
     u64 id;
     long ret;
 
     if (copy_from_user(&id, buf, sizeof(id)))
         return -EFAULT;
 
     ret = mutex_lock_interruptible(&filter->notify_lock);
     if (ret < 0)
         return ret;
 
     knotif = find_notification(filter, id);
     if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
         ret = 0;
     else
         ret = -ENOENT;
 
     mutex_unlock(&filter->notify_lock);
     return ret;
 }
 
 static long seccomp_notify_addfd(struct seccomp_filter *filter,
                  struct seccomp_notif_addfd __user *uaddfd,
                  unsigned int size)
 {
     struct seccomp_notif_addfd addfd;
     struct seccomp_knotif *knotif;
     struct seccomp_kaddfd kaddfd;
     int ret;
 
     BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
     BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
 
     if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
         return -EINVAL;
 
     ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
     if (ret)
         return ret;
 
     if (addfd.newfd_flags & ~O_CLOEXEC)
         return -EINVAL;
 
     if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
         return -EINVAL;
 
     if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
         return -EINVAL;
 
     kaddfd.file = fget(addfd.srcfd);
     if (!kaddfd.file)
         return -EBADF;
 
     kaddfd.ioctl_flags = addfd.flags;
     kaddfd.flags = addfd.newfd_flags;
     kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
     kaddfd.fd = addfd.newfd;
     init_completion(&kaddfd.completion);
 
     ret = mutex_lock_interruptible(&filter->notify_lock);
     if (ret < 0)
         goto out;
 
     knotif = find_notification(filter, addfd.id);
     if (!knotif) {
         ret = -ENOENT;
         goto out_unlock;
     }
 
     /*
      * We do not want to allow for FD injection to occur before the
      * notification has been picked up by a userspace handler, or after
      * the notification has been replied to.
      */
     if (knotif->state != SECCOMP_NOTIFY_SENT) {
         ret = -EINPROGRESS;
         goto out_unlock;
     }
 
     if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
         /*
          * Disallow queuing an atomic addfd + send reply while there are
          * some addfd requests still to process.
          *
          * There is no clear reason to support it and allows us to keep
          * the loop on the other side straight-forward.
          */
         if (!list_empty(&knotif->addfd)) {
             ret = -EBUSY;
             goto out_unlock;
         }
 
         /* Allow exactly only one reply */
         knotif->state = SECCOMP_NOTIFY_REPLIED;
     }
 
     list_add(&kaddfd.list, &knotif->addfd);
     complete(&knotif->ready);
     mutex_unlock(&filter->notify_lock);
 
     /* Now we wait for it to be processed or be interrupted */
     ret = wait_for_completion_interruptible(&kaddfd.completion);
     if (ret == 0) {
         /*
          * We had a successful completion. The other side has already
          * removed us from the addfd queue, and
          * wait_for_completion_interruptible has a memory barrier upon
          * success that lets us read this value directly without
          * locking.
          */
         ret = kaddfd.ret;
         goto out;
     }
 
     mutex_lock(&filter->notify_lock);
     /*
      * Even though we were woken up by a signal and not a successful
      * completion, a completion may have happened in the mean time.
      *
      * We need to check again if the addfd request has been handled,
      * and if not, we will remove it from the queue.
      */
     if (list_empty(&kaddfd.list))
         ret = kaddfd.ret;
     else
         list_del(&kaddfd.list);
 
 out_unlock:
     mutex_unlock(&filter->notify_lock);
 out:
     fput(kaddfd.file);
 
     return ret;
 }
 
 static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
                  unsigned long arg)
 {
     struct seccomp_filter *filter = file->private_data;
     void __user *buf = (void __user *)arg;
 
     /* Fixed-size ioctls */
     switch (cmd) {
     case SECCOMP_IOCTL_NOTIF_RECV:
         return seccomp_notify_recv(filter, buf);
     case SECCOMP_IOCTL_NOTIF_SEND:
         return seccomp_notify_send(filter, buf);
     case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
     case SECCOMP_IOCTL_NOTIF_ID_VALID:
         return seccomp_notify_id_valid(filter, buf);
     }
 
     /* Extensible Argument ioctls */
 #define EA_IOCTL(cmd)   ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
     switch (EA_IOCTL(cmd)) {
     case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
         return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
     default:
         return -EINVAL;
     }
 }
 
 static __poll_t seccomp_notify_poll(struct file *file,
                     struct poll_table_struct *poll_tab)
 {
     struct seccomp_filter *filter = file->private_data;
     __poll_t ret = 0;
     struct seccomp_knotif *cur;
 
     poll_wait(file, &filter->wqh, poll_tab);
 
     if (mutex_lock_interruptible(&filter->notify_lock) < 0)
         return EPOLLERR;
 
     list_for_each_entry(cur, &filter->notif->notifications, list) {
         if (cur->state == SECCOMP_NOTIFY_INIT)
             ret |= EPOLLIN | EPOLLRDNORM;
         if (cur->state == SECCOMP_NOTIFY_SENT)
             ret |= EPOLLOUT | EPOLLWRNORM;
         if ((ret & EPOLLIN) && (ret & EPOLLOUT))
             break;
     }
 
     mutex_unlock(&filter->notify_lock);
 
     if (refcount_read(&filter->users) == 0)
         ret |= EPOLLHUP;
 
     return ret;
 }
 
 static const struct file_operations seccomp_notify_ops = {
     .poll = seccomp_notify_poll,
     .release = seccomp_notify_release,
     .unlocked_ioctl = seccomp_notify_ioctl,
     .compat_ioctl = seccomp_notify_ioctl,
 };
 
 static struct file *init_listener(struct seccomp_filter *filter)
 {
     struct file *ret;
 
     ret = ERR_PTR(-ENOMEM);
     filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
     if (!filter->notif)
         goto out;
 
     sema_init(&filter->notif->request, 0);
     filter->notif->next_id = get_random_u64();
     INIT_LIST_HEAD(&filter->notif->notifications);
 
     ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
                  filter, O_RDWR);
     if (IS_ERR(ret))
         goto out_notif;
 
     /* The file has a reference to it now */
     __get_seccomp_filter(filter);
 
 out_notif:
     if (IS_ERR(ret))
         seccomp_notify_free(filter);
 out:
     return ret;
 }
 
 /*
  * Does @new_child have a listener while an ancestor also has a listener?
  * If so, we'll want to reject this filter.
  * This only has to be tested for the current process, even in the TSYNC case,
  * because TSYNC installs @child with the same parent on all threads.
  * Note that @new_child is not hooked up to its parent at this point yet, so
  * we use current->seccomp.filter.
  */
 static bool has_duplicate_listener(struct seccomp_filter *new_child)
 {
     struct seccomp_filter *cur;
 
     /* must be protected against concurrent TSYNC */
     lockdep_assert_held(&current->sighand->siglock);
 
     if (!new_child->notif)
         return false;
     for (cur = current->seccomp.filter; cur; cur = cur->prev) {
         if (cur->notif)
             return true;
     }
 
     return false;
 }
 
 /**
  * seccomp_set_mode_filter: internal function for setting seccomp filter
  * @flags:  flags to change filter behavior
  * @filter: struct sock_fprog containing filter
  *
  * This function may be called repeatedly to install additional filters.
  * Every filter successfully installed will be evaluated (in reverse order)
  * for each system call the task makes.
  *
  * Once current->seccomp.mode is non-zero, it may not be changed.
  *
  * Returns 0 on success or -EINVAL on failure.
  */
 static long seccomp_set_mode_filter(unsigned int flags,
                     const char __user *filter)
 {
     const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
     struct seccomp_filter *prepared = NULL;
     long ret = -EINVAL;
     int listener = -1;
     struct file *listener_f = NULL;
 
     /* Validate flags. */
     if (flags & ~SECCOMP_FILTER_FLAG_MASK)
         return -EINVAL;
 
     /*
      * In the successful case, NEW_LISTENER returns the new listener fd.
      * But in the failure case, TSYNC returns the thread that died. If you
      * combine these two flags, there's no way to tell whether something
      * succeeded or failed. So, let's disallow this combination if the user
      * has not explicitly requested no errors from TSYNC.
      */
     if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
         (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
         ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
         return -EINVAL;
 
     /*
      * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
      * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
      */
     if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
         ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
         return -EINVAL;
 
     /* Prepare the new filter before holding any locks. */
     prepared = seccomp_prepare_user_filter(filter);
     if (IS_ERR(prepared))
         return PTR_ERR(prepared);
 
     if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
         listener = get_unused_fd_flags(O_CLOEXEC);
         if (listener < 0) {
             ret = listener;
             goto out_free;
         }
 
         listener_f = init_listener(prepared);
         if (IS_ERR(listener_f)) {
             put_unused_fd(listener);
             ret = PTR_ERR(listener_f);
             goto out_free;
         }
     }
 
     /*
      * Make sure we cannot change seccomp or nnp state via TSYNC
      * while another thread is in the middle of calling exec.
      */
     if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
         mutex_lock_killable(&current->signal->cred_guard_mutex))
         goto out_put_fd;
 
     spin_lock_irq(&current->sighand->siglock);
 
     if (!seccomp_may_assign_mode(seccomp_mode))
         goto out;
 
     if (has_duplicate_listener(prepared)) {
         ret = -EBUSY;
         goto out;
     }
 
     ret = seccomp_attach_filter(flags, prepared);
     if (ret)
         goto out;
     /* Do not free the successfully attached filter. */
     prepared = NULL;
 
     seccomp_assign_mode(current, seccomp_mode, flags);
 out:
     spin_unlock_irq(&current->sighand->siglock);
     if (flags & SECCOMP_FILTER_FLAG_TSYNC)
         mutex_unlock(&current->signal->cred_guard_mutex);
 out_put_fd:
     if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
         if (ret) {
             listener_f->private_data = NULL;
             fput(listener_f);
             put_unused_fd(listener);
             seccomp_notify_detach(prepared);
         } else {
             fd_install(listener, listener_f);
             ret = listener;
         }
     }
 out_free:
     seccomp_filter_free(prepared);
     return ret;
 }
 #else
 static inline long seccomp_set_mode_filter(unsigned int flags,
                        const char __user *filter)
 {
     return -EINVAL;
 }
 #endif
 
 static long seccomp_get_action_avail(const char __user *uaction)
 {
     u32 action;
 
     if (copy_from_user(&action, uaction, sizeof(action)))
         return -EFAULT;
 
     switch (action) {
     case SECCOMP_RET_KILL_PROCESS:
     case SECCOMP_RET_KILL_THREAD:
     case SECCOMP_RET_TRAP:
     case SECCOMP_RET_ERRNO:
     case SECCOMP_RET_USER_NOTIF:
     case SECCOMP_RET_TRACE:
     case SECCOMP_RET_LOG:
     case SECCOMP_RET_ALLOW:
         break;
     default:
         return -EOPNOTSUPP;
     }
 
     return 0;
 }
 
 static long seccomp_get_notif_sizes(void __user *usizes)
 {
     struct seccomp_notif_sizes sizes = {
         .seccomp_notif = sizeof(struct seccomp_notif),
         .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
         .seccomp_data = sizeof(struct seccomp_data),
     };
 
     if (copy_to_user(usizes, &sizes, sizeof(sizes)))
         return -EFAULT;
 
     return 0;
 }
 
 /* Common entry point for both prctl and syscall. */
 static long do_seccomp(unsigned int op, unsigned int flags,
                void __user *uargs)
 {
     switch (op) {
     case SECCOMP_SET_MODE_STRICT:
         if (flags != 0 || uargs != NULL)
             return -EINVAL;
         return seccomp_set_mode_strict();
     case SECCOMP_SET_MODE_FILTER:
         return seccomp_set_mode_filter(flags, uargs);
     case SECCOMP_GET_ACTION_AVAIL:
         if (flags != 0)
             return -EINVAL;
 
         return seccomp_get_action_avail(uargs);
     case SECCOMP_GET_NOTIF_SIZES:
         if (flags != 0)
             return -EINVAL;
 
         return seccomp_get_notif_sizes(uargs);
     default:
         return -EINVAL;
     }
 }
 
 SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
              void __user *, uargs)
 {
     return do_seccomp(op, flags, uargs);
 }
 
 /**
  * prctl_set_seccomp: configures current->seccomp.mode
  * @seccomp_mode: requested mode to use
  * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
  *
  * Returns 0 on success or -EINVAL on failure.
  */
 long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
 {
     unsigned int op;
     void __user *uargs;
 
     switch (seccomp_mode) {
     case SECCOMP_MODE_STRICT:
         op = SECCOMP_SET_MODE_STRICT;
         /*
          * Setting strict mode through prctl always ignored filter,
          * so make sure it is always NULL here to pass the internal
          * check in do_seccomp().
          */
         uargs = NULL;
         break;
     case SECCOMP_MODE_FILTER:
         op = SECCOMP_SET_MODE_FILTER;
         uargs = filter;
         break;
     default:
         return -EINVAL;
     }
 
     /* prctl interface doesn't have flags, so they are always zero. */
     return do_seccomp(op, 0, uargs);
 }
 
 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
 static struct seccomp_filter *get_nth_filter(struct task_struct *task,
                          unsigned long filter_off)
 {
     struct seccomp_filter *orig, *filter;
     unsigned long count;
 
     /*
      * Note: this is only correct because the caller should be the (ptrace)
      * tracer of the task, otherwise lock_task_sighand is needed.
      */
     spin_lock_irq(&task->sighand->siglock);
 
     if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
         spin_unlock_irq(&task->sighand->siglock);
         return ERR_PTR(-EINVAL);
     }
 
     orig = task->seccomp.filter;
     __get_seccomp_filter(orig);
     spin_unlock_irq(&task->sighand->siglock);
 
     count = 0;
     for (filter = orig; filter; filter = filter->prev)
         count++;
 
     if (filter_off >= count) {
         filter = ERR_PTR(-ENOENT);
         goto out;
     }
 
     count -= filter_off;
     for (filter = orig; filter && count > 1; filter = filter->prev)
         count--;
 
     if (WARN_ON(count != 1 || !filter)) {
         filter = ERR_PTR(-ENOENT);
         goto out;
     }
 
     __get_seccomp_filter(filter);
 
 out:
     __put_seccomp_filter(orig);
     return filter;
 }
 
 long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
             void __user *data)
 {
     struct seccomp_filter *filter;
     struct sock_fprog_kern *fprog;
     long ret;
 
     if (!capable(CAP_SYS_ADMIN) ||
         current->seccomp.mode != SECCOMP_MODE_DISABLED) {
         return -EACCES;
     }
 
     filter = get_nth_filter(task, filter_off);
     if (IS_ERR(filter))
         return PTR_ERR(filter);
 
     fprog = filter->prog->orig_prog;
     if (!fprog) {
         /* This must be a new non-cBPF filter, since we save
          * every cBPF filter's orig_prog above when
          * CONFIG_CHECKPOINT_RESTORE is enabled.
          */
         ret = -EMEDIUMTYPE;
         goto out;
     }
 
     ret = fprog->len;
     if (!data)
         goto out;
 
     if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
         ret = -EFAULT;
 
 out:
     __put_seccomp_filter(filter);
     return ret;
 }
 
 long seccomp_get_metadata(struct task_struct *task,
               unsigned long size, void __user *data)
 {
     long ret;
     struct seccomp_filter *filter;
     struct seccomp_metadata kmd = {};
 
     if (!capable(CAP_SYS_ADMIN) ||
         current->seccomp.mode != SECCOMP_MODE_DISABLED) {
         return -EACCES;
     }
 
     size = min_t(unsigned long, size, sizeof(kmd));
 
     if (size < sizeof(kmd.filter_off))
         return -EINVAL;
 
     if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
         return -EFAULT;
 
     filter = get_nth_filter(task, kmd.filter_off);
     if (IS_ERR(filter))
         return PTR_ERR(filter);
 
     if (filter->log)
         kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
 
     ret = size;
     if (copy_to_user(data, &kmd, size))
         ret = -EFAULT;
 
     __put_seccomp_filter(filter);
     return ret;
 }
 #endif
 
 #ifdef CONFIG_SYSCTL
 
 /* Human readable action names for friendly sysctl interaction */
 #define SECCOMP_RET_KILL_PROCESS_NAME   "kill_process"
 #define SECCOMP_RET_KILL_THREAD_NAME    "kill_thread"
 #define SECCOMP_RET_TRAP_NAME       "trap"
 #define SECCOMP_RET_ERRNO_NAME      "errno"
 #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
 #define SECCOMP_RET_TRACE_NAME      "trace"
 #define SECCOMP_RET_LOG_NAME        "log"
 #define SECCOMP_RET_ALLOW_NAME      "allow"
 
 static const char seccomp_actions_avail[] =
                 SECCOMP_RET_KILL_PROCESS_NAME   " "
                 SECCOMP_RET_KILL_THREAD_NAME    " "
                 SECCOMP_RET_TRAP_NAME       " "
                 SECCOMP_RET_ERRNO_NAME      " "
                 SECCOMP_RET_USER_NOTIF_NAME     " "
                 SECCOMP_RET_TRACE_NAME      " "
                 SECCOMP_RET_LOG_NAME        " "
                 SECCOMP_RET_ALLOW_NAME;
 
 struct seccomp_log_name {
     u32     log;
     const char  *name;
 };
 
 static const struct seccomp_log_name seccomp_log_names[] = {
     { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
     { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
     { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
     { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
     { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
     { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
     { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
     { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
     { }
 };
 
 static bool seccomp_names_from_actions_logged(char *names, size_t size,
                           u32 actions_logged,
                           const char *sep)
 {
     const struct seccomp_log_name *cur;
     bool append_sep = false;
 
     for (cur = seccomp_log_names; cur->name && size; cur++) {
         ssize_t ret;
 
         if (!(actions_logged & cur->log))
             continue;
 
         if (append_sep) {
             ret = strscpy(names, sep, size);
             if (ret < 0)
                 return false;
 
             names += ret;
             size -= ret;
         } else
             append_sep = true;
 
         ret = strscpy(names, cur->name, size);
         if (ret < 0)
             return false;
 
         names += ret;
         size -= ret;
     }
 
     return true;
 }
 
 static bool seccomp_action_logged_from_name(u32 *action_logged,
                         const char *name)
 {
     const struct seccomp_log_name *cur;
 
     for (cur = seccomp_log_names; cur->name; cur++) {
         if (!strcmp(cur->name, name)) {
             *action_logged = cur->log;
             return true;
         }
     }
 
     return false;
 }
 
 static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
 {
     char *name;
 
     *actions_logged = 0;
     while ((name = strsep(&names, " ")) && *name) {
         u32 action_logged = 0;
 
         if (!seccomp_action_logged_from_name(&action_logged, name))
             return false;
 
         *actions_logged |= action_logged;
     }
 
     return true;
 }
 
 static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
                    size_t *lenp, loff_t *ppos)
 {
     char names[sizeof(seccomp_actions_avail)];
     struct ctl_table table;
 
     memset(names, 0, sizeof(names));
 
     if (!seccomp_names_from_actions_logged(names, sizeof(names),
                            seccomp_actions_logged, " "))
         return -EINVAL;
 
     table = *ro_table;
     table.data = names;
     table.maxlen = sizeof(names);
     return proc_dostring(&table, 0, buffer, lenp, ppos);
 }
 
 static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
                 size_t *lenp, loff_t *ppos, u32 *actions_logged)
 {
     char names[sizeof(seccomp_actions_avail)];
     struct ctl_table table;
     int ret;
 
     if (!capable(CAP_SYS_ADMIN))
         return -EPERM;
 
     memset(names, 0, sizeof(names));
 
     table = *ro_table;
     table.data = names;
     table.maxlen = sizeof(names);
     ret = proc_dostring(&table, 1, buffer, lenp, ppos);
     if (ret)
         return ret;
 
     if (!seccomp_actions_logged_from_names(actions_logged, table.data))
         return -EINVAL;
 
     if (*actions_logged & SECCOMP_LOG_ALLOW)
         return -EINVAL;
 
     seccomp_actions_logged = *actions_logged;
     return 0;
 }
 
 static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
                  int ret)
 {
     char names[sizeof(seccomp_actions_avail)];
     char old_names[sizeof(seccomp_actions_avail)];
     const char *new = names;
     const char *old = old_names;
 
     if (!audit_enabled)
         return;
 
     memset(names, 0, sizeof(names));
     memset(old_names, 0, sizeof(old_names));
 
     if (ret)
         new = "?";
     else if (!actions_logged)
         new = "(none)";
     else if (!seccomp_names_from_actions_logged(names, sizeof(names),
                             actions_logged, ","))
         new = "?";
 
     if (!old_actions_logged)
         old = "(none)";
     else if (!seccomp_names_from_actions_logged(old_names,
                             sizeof(old_names),
                             old_actions_logged, ","))
         old = "?";
 
     return audit_seccomp_actions_logged(new, old, !ret);
 }
 
 static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
                       void *buffer, size_t *lenp,
                       loff_t *ppos)
 {
     int ret;
 
     if (write) {
         u32 actions_logged = 0;
         u32 old_actions_logged = seccomp_actions_logged;
 
         ret = write_actions_logged(ro_table, buffer, lenp, ppos,
                        &actions_logged);
         audit_actions_logged(actions_logged, old_actions_logged, ret);
     } else
         ret = read_actions_logged(ro_table, buffer, lenp, ppos);
 
     return ret;
 }
 
 static struct ctl_path seccomp_sysctl_path[] = {
     { .procname = "kernel", },
     { .procname = "seccomp", },
     { }
 };
 
 static struct ctl_table seccomp_sysctl_table[] = {
     {
         .procname   = "actions_avail",
         .data       = (void *) &seccomp_actions_avail,
         .maxlen     = sizeof(seccomp_actions_avail),
         .mode       = 0444,
         .proc_handler   = proc_dostring,
     },
     {
         .procname   = "actions_logged",
         .mode       = 0644,
         .proc_handler   = seccomp_actions_logged_handler,
     },
     { }
 };
 
 static int __init seccomp_sysctl_init(void)
 {
     struct ctl_table_header *hdr;
 
     hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
     if (!hdr)
         pr_warn("sysctl registration failed\n");
     else
         kmemleak_not_leak(hdr);
 
     return 0;
 }
 
 device_initcall(seccomp_sysctl_init)
 
 #endif /* CONFIG_SYSCTL */
 
 #ifdef CONFIG_SECCOMP_CACHE_DEBUG
 /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
 static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
                     const void *bitmap, size_t bitmap_size)
 {
     int nr;
 
     for (nr = 0; nr < bitmap_size; nr++) {
         bool cached = test_bit(nr, bitmap);
         char *status = cached ? "ALLOW" : "FILTER";
 
         seq_printf(m, "%s %d %s\n", name, nr, status);
     }
 }
 
 int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
                struct pid *pid, struct task_struct *task)
 {
     struct seccomp_filter *f;
     unsigned long flags;
 
     /*
      * We don't want some sandboxed process to know what their seccomp
      * filters consist of.
      */
     if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
         return -EACCES;
 
     if (!lock_task_sighand(task, &flags))
         return -ESRCH;
 
     f = READ_ONCE(task->seccomp.filter);
     if (!f) {
         unlock_task_sighand(task, &flags);
         return 0;
     }
 
     /* prevent filter from being freed while we are printing it */
     __get_seccomp_filter(f);
     unlock_task_sighand(task, &flags);
 
     proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
                     f->cache.allow_native,
                     SECCOMP_ARCH_NATIVE_NR);
 
 #ifdef SECCOMP_ARCH_COMPAT
     proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
                     f->cache.allow_compat,
                     SECCOMP_ARCH_COMPAT_NR);
 #endif /* SECCOMP_ARCH_COMPAT */
 
     __put_seccomp_filter(f);
     return 0;
 }
 #endif /* CONFIG_SECCOMP_CACHE_DEBUG */

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