v4.19.13 snapshot.
diff --git a/ipc/sem.c b/ipc/sem.c
new file mode 100644
index 0000000..26f8e37
--- /dev/null
+++ b/ipc/sem.c
@@ -0,0 +1,2425 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/ipc/sem.c
+ * Copyright (C) 1992 Krishna Balasubramanian
+ * Copyright (C) 1995 Eric Schenk, Bruno Haible
+ *
+ * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
+ *
+ * SMP-threaded, sysctl's added
+ * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
+ * Enforced range limit on SEM_UNDO
+ * (c) 2001 Red Hat Inc
+ * Lockless wakeup
+ * (c) 2003 Manfred Spraul <manfred@colorfullife.com>
+ * (c) 2016 Davidlohr Bueso <dave@stgolabs.net>
+ * Further wakeup optimizations, documentation
+ * (c) 2010 Manfred Spraul <manfred@colorfullife.com>
+ *
+ * support for audit of ipc object properties and permission changes
+ * Dustin Kirkland <dustin.kirkland@us.ibm.com>
+ *
+ * namespaces support
+ * OpenVZ, SWsoft Inc.
+ * Pavel Emelianov <xemul@openvz.org>
+ *
+ * Implementation notes: (May 2010)
+ * This file implements System V semaphores.
+ *
+ * User space visible behavior:
+ * - FIFO ordering for semop() operations (just FIFO, not starvation
+ * protection)
+ * - multiple semaphore operations that alter the same semaphore in
+ * one semop() are handled.
+ * - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and
+ * SETALL calls.
+ * - two Linux specific semctl() commands: SEM_STAT, SEM_INFO.
+ * - undo adjustments at process exit are limited to 0..SEMVMX.
+ * - namespace are supported.
+ * - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtine by writing
+ * to /proc/sys/kernel/sem.
+ * - statistics about the usage are reported in /proc/sysvipc/sem.
+ *
+ * Internals:
+ * - scalability:
+ * - all global variables are read-mostly.
+ * - semop() calls and semctl(RMID) are synchronized by RCU.
+ * - most operations do write operations (actually: spin_lock calls) to
+ * the per-semaphore array structure.
+ * Thus: Perfect SMP scaling between independent semaphore arrays.
+ * If multiple semaphores in one array are used, then cache line
+ * trashing on the semaphore array spinlock will limit the scaling.
+ * - semncnt and semzcnt are calculated on demand in count_semcnt()
+ * - the task that performs a successful semop() scans the list of all
+ * sleeping tasks and completes any pending operations that can be fulfilled.
+ * Semaphores are actively given to waiting tasks (necessary for FIFO).
+ * (see update_queue())
+ * - To improve the scalability, the actual wake-up calls are performed after
+ * dropping all locks. (see wake_up_sem_queue_prepare())
+ * - All work is done by the waker, the woken up task does not have to do
+ * anything - not even acquiring a lock or dropping a refcount.
+ * - A woken up task may not even touch the semaphore array anymore, it may
+ * have been destroyed already by a semctl(RMID).
+ * - UNDO values are stored in an array (one per process and per
+ * semaphore array, lazily allocated). For backwards compatibility, multiple
+ * modes for the UNDO variables are supported (per process, per thread)
+ * (see copy_semundo, CLONE_SYSVSEM)
+ * - There are two lists of the pending operations: a per-array list
+ * and per-semaphore list (stored in the array). This allows to achieve FIFO
+ * ordering without always scanning all pending operations.
+ * The worst-case behavior is nevertheless O(N^2) for N wakeups.
+ */
+
+#include <linux/compat.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/time.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <linux/capability.h>
+#include <linux/seq_file.h>
+#include <linux/rwsem.h>
+#include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
+#include <linux/sched/wake_q.h>
+#include <linux/nospec.h>
+#include <linux/rhashtable.h>
+
+#include <linux/uaccess.h>
+#include "util.h"
+
+/* One semaphore structure for each semaphore in the system. */
+struct sem {
+ int semval; /* current value */
+ /*
+ * PID of the process that last modified the semaphore. For
+ * Linux, specifically these are:
+ * - semop
+ * - semctl, via SETVAL and SETALL.
+ * - at task exit when performing undo adjustments (see exit_sem).
+ */
+ struct pid *sempid;
+ spinlock_t lock; /* spinlock for fine-grained semtimedop */
+ struct list_head pending_alter; /* pending single-sop operations */
+ /* that alter the semaphore */
+ struct list_head pending_const; /* pending single-sop operations */
+ /* that do not alter the semaphore*/
+ time64_t sem_otime; /* candidate for sem_otime */
+} ____cacheline_aligned_in_smp;
+
+/* One sem_array data structure for each set of semaphores in the system. */
+struct sem_array {
+ struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */
+ time64_t sem_ctime; /* create/last semctl() time */
+ struct list_head pending_alter; /* pending operations */
+ /* that alter the array */
+ struct list_head pending_const; /* pending complex operations */
+ /* that do not alter semvals */
+ struct list_head list_id; /* undo requests on this array */
+ int sem_nsems; /* no. of semaphores in array */
+ int complex_count; /* pending complex operations */
+ unsigned int use_global_lock;/* >0: global lock required */
+
+ struct sem sems[];
+} __randomize_layout;
+
+/* One queue for each sleeping process in the system. */
+struct sem_queue {
+ struct list_head list; /* queue of pending operations */
+ struct task_struct *sleeper; /* this process */
+ struct sem_undo *undo; /* undo structure */
+ struct pid *pid; /* process id of requesting process */
+ int status; /* completion status of operation */
+ struct sembuf *sops; /* array of pending operations */
+ struct sembuf *blocking; /* the operation that blocked */
+ int nsops; /* number of operations */
+ bool alter; /* does *sops alter the array? */
+ bool dupsop; /* sops on more than one sem_num */
+};
+
+/* Each task has a list of undo requests. They are executed automatically
+ * when the process exits.
+ */
+struct sem_undo {
+ struct list_head list_proc; /* per-process list: *
+ * all undos from one process
+ * rcu protected */
+ struct rcu_head rcu; /* rcu struct for sem_undo */
+ struct sem_undo_list *ulp; /* back ptr to sem_undo_list */
+ struct list_head list_id; /* per semaphore array list:
+ * all undos for one array */
+ int semid; /* semaphore set identifier */
+ short *semadj; /* array of adjustments */
+ /* one per semaphore */
+};
+
+/* sem_undo_list controls shared access to the list of sem_undo structures
+ * that may be shared among all a CLONE_SYSVSEM task group.
+ */
+struct sem_undo_list {
+ refcount_t refcnt;
+ spinlock_t lock;
+ struct list_head list_proc;
+};
+
+
+#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS])
+
+static int newary(struct ipc_namespace *, struct ipc_params *);
+static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
+#ifdef CONFIG_PROC_FS
+static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
+#endif
+
+#define SEMMSL_FAST 256 /* 512 bytes on stack */
+#define SEMOPM_FAST 64 /* ~ 372 bytes on stack */
+
+/*
+ * Switching from the mode suitable for simple ops
+ * to the mode for complex ops is costly. Therefore:
+ * use some hysteresis
+ */
+#define USE_GLOBAL_LOCK_HYSTERESIS 10
+
+/*
+ * Locking:
+ * a) global sem_lock() for read/write
+ * sem_undo.id_next,
+ * sem_array.complex_count,
+ * sem_array.pending{_alter,_const},
+ * sem_array.sem_undo
+ *
+ * b) global or semaphore sem_lock() for read/write:
+ * sem_array.sems[i].pending_{const,alter}:
+ *
+ * c) special:
+ * sem_undo_list.list_proc:
+ * * undo_list->lock for write
+ * * rcu for read
+ * use_global_lock:
+ * * global sem_lock() for write
+ * * either local or global sem_lock() for read.
+ *
+ * Memory ordering:
+ * Most ordering is enforced by using spin_lock() and spin_unlock().
+ * The special case is use_global_lock:
+ * Setting it from non-zero to 0 is a RELEASE, this is ensured by
+ * using smp_store_release().
+ * Testing if it is non-zero is an ACQUIRE, this is ensured by using
+ * smp_load_acquire().
+ * Setting it from 0 to non-zero must be ordered with regards to
+ * this smp_load_acquire(), this is guaranteed because the smp_load_acquire()
+ * is inside a spin_lock() and after a write from 0 to non-zero a
+ * spin_lock()+spin_unlock() is done.
+ */
+
+#define sc_semmsl sem_ctls[0]
+#define sc_semmns sem_ctls[1]
+#define sc_semopm sem_ctls[2]
+#define sc_semmni sem_ctls[3]
+
+void sem_init_ns(struct ipc_namespace *ns)
+{
+ ns->sc_semmsl = SEMMSL;
+ ns->sc_semmns = SEMMNS;
+ ns->sc_semopm = SEMOPM;
+ ns->sc_semmni = SEMMNI;
+ ns->used_sems = 0;
+ ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
+}
+
+#ifdef CONFIG_IPC_NS
+void sem_exit_ns(struct ipc_namespace *ns)
+{
+ free_ipcs(ns, &sem_ids(ns), freeary);
+ idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
+ rhashtable_destroy(&ns->ids[IPC_SEM_IDS].key_ht);
+}
+#endif
+
+void __init sem_init(void)
+{
+ sem_init_ns(&init_ipc_ns);
+ ipc_init_proc_interface("sysvipc/sem",
+ " key semid perms nsems uid gid cuid cgid otime ctime\n",
+ IPC_SEM_IDS, sysvipc_sem_proc_show);
+}
+
+/**
+ * unmerge_queues - unmerge queues, if possible.
+ * @sma: semaphore array
+ *
+ * The function unmerges the wait queues if complex_count is 0.
+ * It must be called prior to dropping the global semaphore array lock.
+ */
+static void unmerge_queues(struct sem_array *sma)
+{
+ struct sem_queue *q, *tq;
+
+ /* complex operations still around? */
+ if (sma->complex_count)
+ return;
+ /*
+ * We will switch back to simple mode.
+ * Move all pending operation back into the per-semaphore
+ * queues.
+ */
+ list_for_each_entry_safe(q, tq, &sma->pending_alter, list) {
+ struct sem *curr;
+ curr = &sma->sems[q->sops[0].sem_num];
+
+ list_add_tail(&q->list, &curr->pending_alter);
+ }
+ INIT_LIST_HEAD(&sma->pending_alter);
+}
+
+/**
+ * merge_queues - merge single semop queues into global queue
+ * @sma: semaphore array
+ *
+ * This function merges all per-semaphore queues into the global queue.
+ * It is necessary to achieve FIFO ordering for the pending single-sop
+ * operations when a multi-semop operation must sleep.
+ * Only the alter operations must be moved, the const operations can stay.
+ */
+static void merge_queues(struct sem_array *sma)
+{
+ int i;
+ for (i = 0; i < sma->sem_nsems; i++) {
+ struct sem *sem = &sma->sems[i];
+
+ list_splice_init(&sem->pending_alter, &sma->pending_alter);
+ }
+}
+
+static void sem_rcu_free(struct rcu_head *head)
+{
+ struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
+ struct sem_array *sma = container_of(p, struct sem_array, sem_perm);
+
+ security_sem_free(&sma->sem_perm);
+ kvfree(sma);
+}
+
+/*
+ * Enter the mode suitable for non-simple operations:
+ * Caller must own sem_perm.lock.
+ */
+static void complexmode_enter(struct sem_array *sma)
+{
+ int i;
+ struct sem *sem;
+
+ if (sma->use_global_lock > 0) {
+ /*
+ * We are already in global lock mode.
+ * Nothing to do, just reset the
+ * counter until we return to simple mode.
+ */
+ sma->use_global_lock = USE_GLOBAL_LOCK_HYSTERESIS;
+ return;
+ }
+ sma->use_global_lock = USE_GLOBAL_LOCK_HYSTERESIS;
+
+ for (i = 0; i < sma->sem_nsems; i++) {
+ sem = &sma->sems[i];
+ spin_lock(&sem->lock);
+ spin_unlock(&sem->lock);
+ }
+}
+
+/*
+ * Try to leave the mode that disallows simple operations:
+ * Caller must own sem_perm.lock.
+ */
+static void complexmode_tryleave(struct sem_array *sma)
+{
+ if (sma->complex_count) {
+ /* Complex ops are sleeping.
+ * We must stay in complex mode
+ */
+ return;
+ }
+ if (sma->use_global_lock == 1) {
+ /*
+ * Immediately after setting use_global_lock to 0,
+ * a simple op can start. Thus: all memory writes
+ * performed by the current operation must be visible
+ * before we set use_global_lock to 0.
+ */
+ smp_store_release(&sma->use_global_lock, 0);
+ } else {
+ sma->use_global_lock--;
+ }
+}
+
+#define SEM_GLOBAL_LOCK (-1)
+/*
+ * If the request contains only one semaphore operation, and there are
+ * no complex transactions pending, lock only the semaphore involved.
+ * Otherwise, lock the entire semaphore array, since we either have
+ * multiple semaphores in our own semops, or we need to look at
+ * semaphores from other pending complex operations.
+ */
+static inline int sem_lock(struct sem_array *sma, struct sembuf *sops,
+ int nsops)
+{
+ struct sem *sem;
+ int idx;
+
+ if (nsops != 1) {
+ /* Complex operation - acquire a full lock */
+ ipc_lock_object(&sma->sem_perm);
+
+ /* Prevent parallel simple ops */
+ complexmode_enter(sma);
+ return SEM_GLOBAL_LOCK;
+ }
+
+ /*
+ * Only one semaphore affected - try to optimize locking.
+ * Optimized locking is possible if no complex operation
+ * is either enqueued or processed right now.
+ *
+ * Both facts are tracked by use_global_mode.
+ */
+ idx = array_index_nospec(sops->sem_num, sma->sem_nsems);
+ sem = &sma->sems[idx];
+
+ /*
+ * Initial check for use_global_lock. Just an optimization,
+ * no locking, no memory barrier.
+ */
+ if (!sma->use_global_lock) {
+ /*
+ * It appears that no complex operation is around.
+ * Acquire the per-semaphore lock.
+ */
+ spin_lock(&sem->lock);
+
+ /* pairs with smp_store_release() */
+ if (!smp_load_acquire(&sma->use_global_lock)) {
+ /* fast path successful! */
+ return sops->sem_num;
+ }
+ spin_unlock(&sem->lock);
+ }
+
+ /* slow path: acquire the full lock */
+ ipc_lock_object(&sma->sem_perm);
+
+ if (sma->use_global_lock == 0) {
+ /*
+ * The use_global_lock mode ended while we waited for
+ * sma->sem_perm.lock. Thus we must switch to locking
+ * with sem->lock.
+ * Unlike in the fast path, there is no need to recheck
+ * sma->use_global_lock after we have acquired sem->lock:
+ * We own sma->sem_perm.lock, thus use_global_lock cannot
+ * change.
+ */
+ spin_lock(&sem->lock);
+
+ ipc_unlock_object(&sma->sem_perm);
+ return sops->sem_num;
+ } else {
+ /*
+ * Not a false alarm, thus continue to use the global lock
+ * mode. No need for complexmode_enter(), this was done by
+ * the caller that has set use_global_mode to non-zero.
+ */
+ return SEM_GLOBAL_LOCK;
+ }
+}
+
+static inline void sem_unlock(struct sem_array *sma, int locknum)
+{
+ if (locknum == SEM_GLOBAL_LOCK) {
+ unmerge_queues(sma);
+ complexmode_tryleave(sma);
+ ipc_unlock_object(&sma->sem_perm);
+ } else {
+ struct sem *sem = &sma->sems[locknum];
+ spin_unlock(&sem->lock);
+ }
+}
+
+/*
+ * sem_lock_(check_) routines are called in the paths where the rwsem
+ * is not held.
+ *
+ * The caller holds the RCU read lock.
+ */
+static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id)
+{
+ struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&sem_ids(ns), id);
+
+ if (IS_ERR(ipcp))
+ return ERR_CAST(ipcp);
+
+ return container_of(ipcp, struct sem_array, sem_perm);
+}
+
+static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns,
+ int id)
+{
+ struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id);
+
+ if (IS_ERR(ipcp))
+ return ERR_CAST(ipcp);
+
+ return container_of(ipcp, struct sem_array, sem_perm);
+}
+
+static inline void sem_lock_and_putref(struct sem_array *sma)
+{
+ sem_lock(sma, NULL, -1);
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+}
+
+static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
+{
+ ipc_rmid(&sem_ids(ns), &s->sem_perm);
+}
+
+static struct sem_array *sem_alloc(size_t nsems)
+{
+ struct sem_array *sma;
+ size_t size;
+
+ if (nsems > (INT_MAX - sizeof(*sma)) / sizeof(sma->sems[0]))
+ return NULL;
+
+ size = sizeof(*sma) + nsems * sizeof(sma->sems[0]);
+ sma = kvmalloc(size, GFP_KERNEL);
+ if (unlikely(!sma))
+ return NULL;
+
+ memset(sma, 0, size);
+
+ return sma;
+}
+
+/**
+ * newary - Create a new semaphore set
+ * @ns: namespace
+ * @params: ptr to the structure that contains key, semflg and nsems
+ *
+ * Called with sem_ids.rwsem held (as a writer)
+ */
+static int newary(struct ipc_namespace *ns, struct ipc_params *params)
+{
+ int retval;
+ struct sem_array *sma;
+ key_t key = params->key;
+ int nsems = params->u.nsems;
+ int semflg = params->flg;
+ int i;
+
+ if (!nsems)
+ return -EINVAL;
+ if (ns->used_sems + nsems > ns->sc_semmns)
+ return -ENOSPC;
+
+ sma = sem_alloc(nsems);
+ if (!sma)
+ return -ENOMEM;
+
+ sma->sem_perm.mode = (semflg & S_IRWXUGO);
+ sma->sem_perm.key = key;
+
+ sma->sem_perm.security = NULL;
+ retval = security_sem_alloc(&sma->sem_perm);
+ if (retval) {
+ kvfree(sma);
+ return retval;
+ }
+
+ for (i = 0; i < nsems; i++) {
+ INIT_LIST_HEAD(&sma->sems[i].pending_alter);
+ INIT_LIST_HEAD(&sma->sems[i].pending_const);
+ spin_lock_init(&sma->sems[i].lock);
+ }
+
+ sma->complex_count = 0;
+ sma->use_global_lock = USE_GLOBAL_LOCK_HYSTERESIS;
+ INIT_LIST_HEAD(&sma->pending_alter);
+ INIT_LIST_HEAD(&sma->pending_const);
+ INIT_LIST_HEAD(&sma->list_id);
+ sma->sem_nsems = nsems;
+ sma->sem_ctime = ktime_get_real_seconds();
+
+ /* ipc_addid() locks sma upon success. */
+ retval = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
+ if (retval < 0) {
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+ return retval;
+ }
+ ns->used_sems += nsems;
+
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+
+ return sma->sem_perm.id;
+}
+
+
+/*
+ * Called with sem_ids.rwsem and ipcp locked.
+ */
+static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
+ struct ipc_params *params)
+{
+ struct sem_array *sma;
+
+ sma = container_of(ipcp, struct sem_array, sem_perm);
+ if (params->u.nsems > sma->sem_nsems)
+ return -EINVAL;
+
+ return 0;
+}
+
+long ksys_semget(key_t key, int nsems, int semflg)
+{
+ struct ipc_namespace *ns;
+ static const struct ipc_ops sem_ops = {
+ .getnew = newary,
+ .associate = security_sem_associate,
+ .more_checks = sem_more_checks,
+ };
+ struct ipc_params sem_params;
+
+ ns = current->nsproxy->ipc_ns;
+
+ if (nsems < 0 || nsems > ns->sc_semmsl)
+ return -EINVAL;
+
+ sem_params.key = key;
+ sem_params.flg = semflg;
+ sem_params.u.nsems = nsems;
+
+ return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
+}
+
+SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
+{
+ return ksys_semget(key, nsems, semflg);
+}
+
+/**
+ * perform_atomic_semop[_slow] - Attempt to perform semaphore
+ * operations on a given array.
+ * @sma: semaphore array
+ * @q: struct sem_queue that describes the operation
+ *
+ * Caller blocking are as follows, based the value
+ * indicated by the semaphore operation (sem_op):
+ *
+ * (1) >0 never blocks.
+ * (2) 0 (wait-for-zero operation): semval is non-zero.
+ * (3) <0 attempting to decrement semval to a value smaller than zero.
+ *
+ * Returns 0 if the operation was possible.
+ * Returns 1 if the operation is impossible, the caller must sleep.
+ * Returns <0 for error codes.
+ */
+static int perform_atomic_semop_slow(struct sem_array *sma, struct sem_queue *q)
+{
+ int result, sem_op, nsops;
+ struct pid *pid;
+ struct sembuf *sop;
+ struct sem *curr;
+ struct sembuf *sops;
+ struct sem_undo *un;
+
+ sops = q->sops;
+ nsops = q->nsops;
+ un = q->undo;
+
+ for (sop = sops; sop < sops + nsops; sop++) {
+ int idx = array_index_nospec(sop->sem_num, sma->sem_nsems);
+ curr = &sma->sems[idx];
+ sem_op = sop->sem_op;
+ result = curr->semval;
+
+ if (!sem_op && result)
+ goto would_block;
+
+ result += sem_op;
+ if (result < 0)
+ goto would_block;
+ if (result > SEMVMX)
+ goto out_of_range;
+
+ if (sop->sem_flg & SEM_UNDO) {
+ int undo = un->semadj[sop->sem_num] - sem_op;
+ /* Exceeding the undo range is an error. */
+ if (undo < (-SEMAEM - 1) || undo > SEMAEM)
+ goto out_of_range;
+ un->semadj[sop->sem_num] = undo;
+ }
+
+ curr->semval = result;
+ }
+
+ sop--;
+ pid = q->pid;
+ while (sop >= sops) {
+ ipc_update_pid(&sma->sems[sop->sem_num].sempid, pid);
+ sop--;
+ }
+
+ return 0;
+
+out_of_range:
+ result = -ERANGE;
+ goto undo;
+
+would_block:
+ q->blocking = sop;
+
+ if (sop->sem_flg & IPC_NOWAIT)
+ result = -EAGAIN;
+ else
+ result = 1;
+
+undo:
+ sop--;
+ while (sop >= sops) {
+ sem_op = sop->sem_op;
+ sma->sems[sop->sem_num].semval -= sem_op;
+ if (sop->sem_flg & SEM_UNDO)
+ un->semadj[sop->sem_num] += sem_op;
+ sop--;
+ }
+
+ return result;
+}
+
+static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q)
+{
+ int result, sem_op, nsops;
+ struct sembuf *sop;
+ struct sem *curr;
+ struct sembuf *sops;
+ struct sem_undo *un;
+
+ sops = q->sops;
+ nsops = q->nsops;
+ un = q->undo;
+
+ if (unlikely(q->dupsop))
+ return perform_atomic_semop_slow(sma, q);
+
+ /*
+ * We scan the semaphore set twice, first to ensure that the entire
+ * operation can succeed, therefore avoiding any pointless writes
+ * to shared memory and having to undo such changes in order to block
+ * until the operations can go through.
+ */
+ for (sop = sops; sop < sops + nsops; sop++) {
+ int idx = array_index_nospec(sop->sem_num, sma->sem_nsems);
+
+ curr = &sma->sems[idx];
+ sem_op = sop->sem_op;
+ result = curr->semval;
+
+ if (!sem_op && result)
+ goto would_block; /* wait-for-zero */
+
+ result += sem_op;
+ if (result < 0)
+ goto would_block;
+
+ if (result > SEMVMX)
+ return -ERANGE;
+
+ if (sop->sem_flg & SEM_UNDO) {
+ int undo = un->semadj[sop->sem_num] - sem_op;
+
+ /* Exceeding the undo range is an error. */
+ if (undo < (-SEMAEM - 1) || undo > SEMAEM)
+ return -ERANGE;
+ }
+ }
+
+ for (sop = sops; sop < sops + nsops; sop++) {
+ curr = &sma->sems[sop->sem_num];
+ sem_op = sop->sem_op;
+ result = curr->semval;
+
+ if (sop->sem_flg & SEM_UNDO) {
+ int undo = un->semadj[sop->sem_num] - sem_op;
+
+ un->semadj[sop->sem_num] = undo;
+ }
+ curr->semval += sem_op;
+ ipc_update_pid(&curr->sempid, q->pid);
+ }
+
+ return 0;
+
+would_block:
+ q->blocking = sop;
+ return sop->sem_flg & IPC_NOWAIT ? -EAGAIN : 1;
+}
+
+static inline void wake_up_sem_queue_prepare(struct sem_queue *q, int error,
+ struct wake_q_head *wake_q)
+{
+ wake_q_add(wake_q, q->sleeper);
+ /*
+ * Rely on the above implicit barrier, such that we can
+ * ensure that we hold reference to the task before setting
+ * q->status. Otherwise we could race with do_exit if the
+ * task is awoken by an external event before calling
+ * wake_up_process().
+ */
+ WRITE_ONCE(q->status, error);
+}
+
+static void unlink_queue(struct sem_array *sma, struct sem_queue *q)
+{
+ list_del(&q->list);
+ if (q->nsops > 1)
+ sma->complex_count--;
+}
+
+/** check_restart(sma, q)
+ * @sma: semaphore array
+ * @q: the operation that just completed
+ *
+ * update_queue is O(N^2) when it restarts scanning the whole queue of
+ * waiting operations. Therefore this function checks if the restart is
+ * really necessary. It is called after a previously waiting operation
+ * modified the array.
+ * Note that wait-for-zero operations are handled without restart.
+ */
+static inline int check_restart(struct sem_array *sma, struct sem_queue *q)
+{
+ /* pending complex alter operations are too difficult to analyse */
+ if (!list_empty(&sma->pending_alter))
+ return 1;
+
+ /* we were a sleeping complex operation. Too difficult */
+ if (q->nsops > 1)
+ return 1;
+
+ /* It is impossible that someone waits for the new value:
+ * - complex operations always restart.
+ * - wait-for-zero are handled seperately.
+ * - q is a previously sleeping simple operation that
+ * altered the array. It must be a decrement, because
+ * simple increments never sleep.
+ * - If there are older (higher priority) decrements
+ * in the queue, then they have observed the original
+ * semval value and couldn't proceed. The operation
+ * decremented to value - thus they won't proceed either.
+ */
+ return 0;
+}
+
+/**
+ * wake_const_ops - wake up non-alter tasks
+ * @sma: semaphore array.
+ * @semnum: semaphore that was modified.
+ * @wake_q: lockless wake-queue head.
+ *
+ * wake_const_ops must be called after a semaphore in a semaphore array
+ * was set to 0. If complex const operations are pending, wake_const_ops must
+ * be called with semnum = -1, as well as with the number of each modified
+ * semaphore.
+ * The tasks that must be woken up are added to @wake_q. The return code
+ * is stored in q->pid.
+ * The function returns 1 if at least one operation was completed successfully.
+ */
+static int wake_const_ops(struct sem_array *sma, int semnum,
+ struct wake_q_head *wake_q)
+{
+ struct sem_queue *q, *tmp;
+ struct list_head *pending_list;
+ int semop_completed = 0;
+
+ if (semnum == -1)
+ pending_list = &sma->pending_const;
+ else
+ pending_list = &sma->sems[semnum].pending_const;
+
+ list_for_each_entry_safe(q, tmp, pending_list, list) {
+ int error = perform_atomic_semop(sma, q);
+
+ if (error > 0)
+ continue;
+ /* operation completed, remove from queue & wakeup */
+ unlink_queue(sma, q);
+
+ wake_up_sem_queue_prepare(q, error, wake_q);
+ if (error == 0)
+ semop_completed = 1;
+ }
+
+ return semop_completed;
+}
+
+/**
+ * do_smart_wakeup_zero - wakeup all wait for zero tasks
+ * @sma: semaphore array
+ * @sops: operations that were performed
+ * @nsops: number of operations
+ * @wake_q: lockless wake-queue head
+ *
+ * Checks all required queue for wait-for-zero operations, based
+ * on the actual changes that were performed on the semaphore array.
+ * The function returns 1 if at least one operation was completed successfully.
+ */
+static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops,
+ int nsops, struct wake_q_head *wake_q)
+{
+ int i;
+ int semop_completed = 0;
+ int got_zero = 0;
+
+ /* first: the per-semaphore queues, if known */
+ if (sops) {
+ for (i = 0; i < nsops; i++) {
+ int num = sops[i].sem_num;
+
+ if (sma->sems[num].semval == 0) {
+ got_zero = 1;
+ semop_completed |= wake_const_ops(sma, num, wake_q);
+ }
+ }
+ } else {
+ /*
+ * No sops means modified semaphores not known.
+ * Assume all were changed.
+ */
+ for (i = 0; i < sma->sem_nsems; i++) {
+ if (sma->sems[i].semval == 0) {
+ got_zero = 1;
+ semop_completed |= wake_const_ops(sma, i, wake_q);
+ }
+ }
+ }
+ /*
+ * If one of the modified semaphores got 0,
+ * then check the global queue, too.
+ */
+ if (got_zero)
+ semop_completed |= wake_const_ops(sma, -1, wake_q);
+
+ return semop_completed;
+}
+
+
+/**
+ * update_queue - look for tasks that can be completed.
+ * @sma: semaphore array.
+ * @semnum: semaphore that was modified.
+ * @wake_q: lockless wake-queue head.
+ *
+ * update_queue must be called after a semaphore in a semaphore array
+ * was modified. If multiple semaphores were modified, update_queue must
+ * be called with semnum = -1, as well as with the number of each modified
+ * semaphore.
+ * The tasks that must be woken up are added to @wake_q. The return code
+ * is stored in q->pid.
+ * The function internally checks if const operations can now succeed.
+ *
+ * The function return 1 if at least one semop was completed successfully.
+ */
+static int update_queue(struct sem_array *sma, int semnum, struct wake_q_head *wake_q)
+{
+ struct sem_queue *q, *tmp;
+ struct list_head *pending_list;
+ int semop_completed = 0;
+
+ if (semnum == -1)
+ pending_list = &sma->pending_alter;
+ else
+ pending_list = &sma->sems[semnum].pending_alter;
+
+again:
+ list_for_each_entry_safe(q, tmp, pending_list, list) {
+ int error, restart;
+
+ /* If we are scanning the single sop, per-semaphore list of
+ * one semaphore and that semaphore is 0, then it is not
+ * necessary to scan further: simple increments
+ * that affect only one entry succeed immediately and cannot
+ * be in the per semaphore pending queue, and decrements
+ * cannot be successful if the value is already 0.
+ */
+ if (semnum != -1 && sma->sems[semnum].semval == 0)
+ break;
+
+ error = perform_atomic_semop(sma, q);
+
+ /* Does q->sleeper still need to sleep? */
+ if (error > 0)
+ continue;
+
+ unlink_queue(sma, q);
+
+ if (error) {
+ restart = 0;
+ } else {
+ semop_completed = 1;
+ do_smart_wakeup_zero(sma, q->sops, q->nsops, wake_q);
+ restart = check_restart(sma, q);
+ }
+
+ wake_up_sem_queue_prepare(q, error, wake_q);
+ if (restart)
+ goto again;
+ }
+ return semop_completed;
+}
+
+/**
+ * set_semotime - set sem_otime
+ * @sma: semaphore array
+ * @sops: operations that modified the array, may be NULL
+ *
+ * sem_otime is replicated to avoid cache line trashing.
+ * This function sets one instance to the current time.
+ */
+static void set_semotime(struct sem_array *sma, struct sembuf *sops)
+{
+ if (sops == NULL) {
+ sma->sems[0].sem_otime = ktime_get_real_seconds();
+ } else {
+ sma->sems[sops[0].sem_num].sem_otime =
+ ktime_get_real_seconds();
+ }
+}
+
+/**
+ * do_smart_update - optimized update_queue
+ * @sma: semaphore array
+ * @sops: operations that were performed
+ * @nsops: number of operations
+ * @otime: force setting otime
+ * @wake_q: lockless wake-queue head
+ *
+ * do_smart_update() does the required calls to update_queue and wakeup_zero,
+ * based on the actual changes that were performed on the semaphore array.
+ * Note that the function does not do the actual wake-up: the caller is
+ * responsible for calling wake_up_q().
+ * It is safe to perform this call after dropping all locks.
+ */
+static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops,
+ int otime, struct wake_q_head *wake_q)
+{
+ int i;
+
+ otime |= do_smart_wakeup_zero(sma, sops, nsops, wake_q);
+
+ if (!list_empty(&sma->pending_alter)) {
+ /* semaphore array uses the global queue - just process it. */
+ otime |= update_queue(sma, -1, wake_q);
+ } else {
+ if (!sops) {
+ /*
+ * No sops, thus the modified semaphores are not
+ * known. Check all.
+ */
+ for (i = 0; i < sma->sem_nsems; i++)
+ otime |= update_queue(sma, i, wake_q);
+ } else {
+ /*
+ * Check the semaphores that were increased:
+ * - No complex ops, thus all sleeping ops are
+ * decrease.
+ * - if we decreased the value, then any sleeping
+ * semaphore ops wont be able to run: If the
+ * previous value was too small, then the new
+ * value will be too small, too.
+ */
+ for (i = 0; i < nsops; i++) {
+ if (sops[i].sem_op > 0) {
+ otime |= update_queue(sma,
+ sops[i].sem_num, wake_q);
+ }
+ }
+ }
+ }
+ if (otime)
+ set_semotime(sma, sops);
+}
+
+/*
+ * check_qop: Test if a queued operation sleeps on the semaphore semnum
+ */
+static int check_qop(struct sem_array *sma, int semnum, struct sem_queue *q,
+ bool count_zero)
+{
+ struct sembuf *sop = q->blocking;
+
+ /*
+ * Linux always (since 0.99.10) reported a task as sleeping on all
+ * semaphores. This violates SUS, therefore it was changed to the
+ * standard compliant behavior.
+ * Give the administrators a chance to notice that an application
+ * might misbehave because it relies on the Linux behavior.
+ */
+ pr_info_once("semctl(GETNCNT/GETZCNT) is since 3.16 Single Unix Specification compliant.\n"
+ "The task %s (%d) triggered the difference, watch for misbehavior.\n",
+ current->comm, task_pid_nr(current));
+
+ if (sop->sem_num != semnum)
+ return 0;
+
+ if (count_zero && sop->sem_op == 0)
+ return 1;
+ if (!count_zero && sop->sem_op < 0)
+ return 1;
+
+ return 0;
+}
+
+/* The following counts are associated to each semaphore:
+ * semncnt number of tasks waiting on semval being nonzero
+ * semzcnt number of tasks waiting on semval being zero
+ *
+ * Per definition, a task waits only on the semaphore of the first semop
+ * that cannot proceed, even if additional operation would block, too.
+ */
+static int count_semcnt(struct sem_array *sma, ushort semnum,
+ bool count_zero)
+{
+ struct list_head *l;
+ struct sem_queue *q;
+ int semcnt;
+
+ semcnt = 0;
+ /* First: check the simple operations. They are easy to evaluate */
+ if (count_zero)
+ l = &sma->sems[semnum].pending_const;
+ else
+ l = &sma->sems[semnum].pending_alter;
+
+ list_for_each_entry(q, l, list) {
+ /* all task on a per-semaphore list sleep on exactly
+ * that semaphore
+ */
+ semcnt++;
+ }
+
+ /* Then: check the complex operations. */
+ list_for_each_entry(q, &sma->pending_alter, list) {
+ semcnt += check_qop(sma, semnum, q, count_zero);
+ }
+ if (count_zero) {
+ list_for_each_entry(q, &sma->pending_const, list) {
+ semcnt += check_qop(sma, semnum, q, count_zero);
+ }
+ }
+ return semcnt;
+}
+
+/* Free a semaphore set. freeary() is called with sem_ids.rwsem locked
+ * as a writer and the spinlock for this semaphore set hold. sem_ids.rwsem
+ * remains locked on exit.
+ */
+static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
+{
+ struct sem_undo *un, *tu;
+ struct sem_queue *q, *tq;
+ struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
+ int i;
+ DEFINE_WAKE_Q(wake_q);
+
+ /* Free the existing undo structures for this semaphore set. */
+ ipc_assert_locked_object(&sma->sem_perm);
+ list_for_each_entry_safe(un, tu, &sma->list_id, list_id) {
+ list_del(&un->list_id);
+ spin_lock(&un->ulp->lock);
+ un->semid = -1;
+ list_del_rcu(&un->list_proc);
+ spin_unlock(&un->ulp->lock);
+ kfree_rcu(un, rcu);
+ }
+
+ /* Wake up all pending processes and let them fail with EIDRM. */
+ list_for_each_entry_safe(q, tq, &sma->pending_const, list) {
+ unlink_queue(sma, q);
+ wake_up_sem_queue_prepare(q, -EIDRM, &wake_q);
+ }
+
+ list_for_each_entry_safe(q, tq, &sma->pending_alter, list) {
+ unlink_queue(sma, q);
+ wake_up_sem_queue_prepare(q, -EIDRM, &wake_q);
+ }
+ for (i = 0; i < sma->sem_nsems; i++) {
+ struct sem *sem = &sma->sems[i];
+ list_for_each_entry_safe(q, tq, &sem->pending_const, list) {
+ unlink_queue(sma, q);
+ wake_up_sem_queue_prepare(q, -EIDRM, &wake_q);
+ }
+ list_for_each_entry_safe(q, tq, &sem->pending_alter, list) {
+ unlink_queue(sma, q);
+ wake_up_sem_queue_prepare(q, -EIDRM, &wake_q);
+ }
+ ipc_update_pid(&sem->sempid, NULL);
+ }
+
+ /* Remove the semaphore set from the IDR */
+ sem_rmid(ns, sma);
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+
+ wake_up_q(&wake_q);
+ ns->used_sems -= sma->sem_nsems;
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+}
+
+static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
+{
+ switch (version) {
+ case IPC_64:
+ return copy_to_user(buf, in, sizeof(*in));
+ case IPC_OLD:
+ {
+ struct semid_ds out;
+
+ memset(&out, 0, sizeof(out));
+
+ ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
+
+ out.sem_otime = in->sem_otime;
+ out.sem_ctime = in->sem_ctime;
+ out.sem_nsems = in->sem_nsems;
+
+ return copy_to_user(buf, &out, sizeof(out));
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static time64_t get_semotime(struct sem_array *sma)
+{
+ int i;
+ time64_t res;
+
+ res = sma->sems[0].sem_otime;
+ for (i = 1; i < sma->sem_nsems; i++) {
+ time64_t to = sma->sems[i].sem_otime;
+
+ if (to > res)
+ res = to;
+ }
+ return res;
+}
+
+static int semctl_stat(struct ipc_namespace *ns, int semid,
+ int cmd, struct semid64_ds *semid64)
+{
+ struct sem_array *sma;
+ time64_t semotime;
+ int err;
+
+ memset(semid64, 0, sizeof(*semid64));
+
+ rcu_read_lock();
+ if (cmd == SEM_STAT || cmd == SEM_STAT_ANY) {
+ sma = sem_obtain_object(ns, semid);
+ if (IS_ERR(sma)) {
+ err = PTR_ERR(sma);
+ goto out_unlock;
+ }
+ } else { /* IPC_STAT */
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ err = PTR_ERR(sma);
+ goto out_unlock;
+ }
+ }
+
+ /* see comment for SHM_STAT_ANY */
+ if (cmd == SEM_STAT_ANY)
+ audit_ipc_obj(&sma->sem_perm);
+ else {
+ err = -EACCES;
+ if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
+ goto out_unlock;
+ }
+
+ err = security_sem_semctl(&sma->sem_perm, cmd);
+ if (err)
+ goto out_unlock;
+
+ ipc_lock_object(&sma->sem_perm);
+
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ ipc_unlock_object(&sma->sem_perm);
+ err = -EIDRM;
+ goto out_unlock;
+ }
+
+ kernel_to_ipc64_perm(&sma->sem_perm, &semid64->sem_perm);
+ semotime = get_semotime(sma);
+ semid64->sem_otime = semotime;
+ semid64->sem_ctime = sma->sem_ctime;
+#ifndef CONFIG_64BIT
+ semid64->sem_otime_high = semotime >> 32;
+ semid64->sem_ctime_high = sma->sem_ctime >> 32;
+#endif
+ semid64->sem_nsems = sma->sem_nsems;
+
+ if (cmd == IPC_STAT) {
+ /*
+ * As defined in SUS:
+ * Return 0 on success
+ */
+ err = 0;
+ } else {
+ /*
+ * SEM_STAT and SEM_STAT_ANY (both Linux specific)
+ * Return the full id, including the sequence number
+ */
+ err = sma->sem_perm.id;
+ }
+ ipc_unlock_object(&sma->sem_perm);
+out_unlock:
+ rcu_read_unlock();
+ return err;
+}
+
+static int semctl_info(struct ipc_namespace *ns, int semid,
+ int cmd, void __user *p)
+{
+ struct seminfo seminfo;
+ int max_idx;
+ int err;
+
+ err = security_sem_semctl(NULL, cmd);
+ if (err)
+ return err;
+
+ memset(&seminfo, 0, sizeof(seminfo));
+ seminfo.semmni = ns->sc_semmni;
+ seminfo.semmns = ns->sc_semmns;
+ seminfo.semmsl = ns->sc_semmsl;
+ seminfo.semopm = ns->sc_semopm;
+ seminfo.semvmx = SEMVMX;
+ seminfo.semmnu = SEMMNU;
+ seminfo.semmap = SEMMAP;
+ seminfo.semume = SEMUME;
+ down_read(&sem_ids(ns).rwsem);
+ if (cmd == SEM_INFO) {
+ seminfo.semusz = sem_ids(ns).in_use;
+ seminfo.semaem = ns->used_sems;
+ } else {
+ seminfo.semusz = SEMUSZ;
+ seminfo.semaem = SEMAEM;
+ }
+ max_idx = ipc_get_maxidx(&sem_ids(ns));
+ up_read(&sem_ids(ns).rwsem);
+ if (copy_to_user(p, &seminfo, sizeof(struct seminfo)))
+ return -EFAULT;
+ return (max_idx < 0) ? 0 : max_idx;
+}
+
+static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum,
+ int val)
+{
+ struct sem_undo *un;
+ struct sem_array *sma;
+ struct sem *curr;
+ int err;
+ DEFINE_WAKE_Q(wake_q);
+
+ if (val > SEMVMX || val < 0)
+ return -ERANGE;
+
+ rcu_read_lock();
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
+ return PTR_ERR(sma);
+ }
+
+ if (semnum < 0 || semnum >= sma->sem_nsems) {
+ rcu_read_unlock();
+ return -EINVAL;
+ }
+
+
+ if (ipcperms(ns, &sma->sem_perm, S_IWUGO)) {
+ rcu_read_unlock();
+ return -EACCES;
+ }
+
+ err = security_sem_semctl(&sma->sem_perm, SETVAL);
+ if (err) {
+ rcu_read_unlock();
+ return -EACCES;
+ }
+
+ sem_lock(sma, NULL, -1);
+
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ return -EIDRM;
+ }
+
+ semnum = array_index_nospec(semnum, sma->sem_nsems);
+ curr = &sma->sems[semnum];
+
+ ipc_assert_locked_object(&sma->sem_perm);
+ list_for_each_entry(un, &sma->list_id, list_id)
+ un->semadj[semnum] = 0;
+
+ curr->semval = val;
+ ipc_update_pid(&curr->sempid, task_tgid(current));
+ sma->sem_ctime = ktime_get_real_seconds();
+ /* maybe some queued-up processes were waiting for this */
+ do_smart_update(sma, NULL, 0, 0, &wake_q);
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ wake_up_q(&wake_q);
+ return 0;
+}
+
+static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
+ int cmd, void __user *p)
+{
+ struct sem_array *sma;
+ struct sem *curr;
+ int err, nsems;
+ ushort fast_sem_io[SEMMSL_FAST];
+ ushort *sem_io = fast_sem_io;
+ DEFINE_WAKE_Q(wake_q);
+
+ rcu_read_lock();
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
+ return PTR_ERR(sma);
+ }
+
+ nsems = sma->sem_nsems;
+
+ err = -EACCES;
+ if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO))
+ goto out_rcu_wakeup;
+
+ err = security_sem_semctl(&sma->sem_perm, cmd);
+ if (err)
+ goto out_rcu_wakeup;
+
+ err = -EACCES;
+ switch (cmd) {
+ case GETALL:
+ {
+ ushort __user *array = p;
+ int i;
+
+ sem_lock(sma, NULL, -1);
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ err = -EIDRM;
+ goto out_unlock;
+ }
+ if (nsems > SEMMSL_FAST) {
+ if (!ipc_rcu_getref(&sma->sem_perm)) {
+ err = -EIDRM;
+ goto out_unlock;
+ }
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ sem_io = kvmalloc_array(nsems, sizeof(ushort),
+ GFP_KERNEL);
+ if (sem_io == NULL) {
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+ return -ENOMEM;
+ }
+
+ rcu_read_lock();
+ sem_lock_and_putref(sma);
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ err = -EIDRM;
+ goto out_unlock;
+ }
+ }
+ for (i = 0; i < sma->sem_nsems; i++)
+ sem_io[i] = sma->sems[i].semval;
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ err = 0;
+ if (copy_to_user(array, sem_io, nsems*sizeof(ushort)))
+ err = -EFAULT;
+ goto out_free;
+ }
+ case SETALL:
+ {
+ int i;
+ struct sem_undo *un;
+
+ if (!ipc_rcu_getref(&sma->sem_perm)) {
+ err = -EIDRM;
+ goto out_rcu_wakeup;
+ }
+ rcu_read_unlock();
+
+ if (nsems > SEMMSL_FAST) {
+ sem_io = kvmalloc_array(nsems, sizeof(ushort),
+ GFP_KERNEL);
+ if (sem_io == NULL) {
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+ return -ENOMEM;
+ }
+ }
+
+ if (copy_from_user(sem_io, p, nsems*sizeof(ushort))) {
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+ err = -EFAULT;
+ goto out_free;
+ }
+
+ for (i = 0; i < nsems; i++) {
+ if (sem_io[i] > SEMVMX) {
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+ err = -ERANGE;
+ goto out_free;
+ }
+ }
+ rcu_read_lock();
+ sem_lock_and_putref(sma);
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ err = -EIDRM;
+ goto out_unlock;
+ }
+
+ for (i = 0; i < nsems; i++) {
+ sma->sems[i].semval = sem_io[i];
+ ipc_update_pid(&sma->sems[i].sempid, task_tgid(current));
+ }
+
+ ipc_assert_locked_object(&sma->sem_perm);
+ list_for_each_entry(un, &sma->list_id, list_id) {
+ for (i = 0; i < nsems; i++)
+ un->semadj[i] = 0;
+ }
+ sma->sem_ctime = ktime_get_real_seconds();
+ /* maybe some queued-up processes were waiting for this */
+ do_smart_update(sma, NULL, 0, 0, &wake_q);
+ err = 0;
+ goto out_unlock;
+ }
+ /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */
+ }
+ err = -EINVAL;
+ if (semnum < 0 || semnum >= nsems)
+ goto out_rcu_wakeup;
+
+ sem_lock(sma, NULL, -1);
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ err = -EIDRM;
+ goto out_unlock;
+ }
+
+ semnum = array_index_nospec(semnum, nsems);
+ curr = &sma->sems[semnum];
+
+ switch (cmd) {
+ case GETVAL:
+ err = curr->semval;
+ goto out_unlock;
+ case GETPID:
+ err = pid_vnr(curr->sempid);
+ goto out_unlock;
+ case GETNCNT:
+ err = count_semcnt(sma, semnum, 0);
+ goto out_unlock;
+ case GETZCNT:
+ err = count_semcnt(sma, semnum, 1);
+ goto out_unlock;
+ }
+
+out_unlock:
+ sem_unlock(sma, -1);
+out_rcu_wakeup:
+ rcu_read_unlock();
+ wake_up_q(&wake_q);
+out_free:
+ if (sem_io != fast_sem_io)
+ kvfree(sem_io);
+ return err;
+}
+
+static inline unsigned long
+copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
+{
+ switch (version) {
+ case IPC_64:
+ if (copy_from_user(out, buf, sizeof(*out)))
+ return -EFAULT;
+ return 0;
+ case IPC_OLD:
+ {
+ struct semid_ds tbuf_old;
+
+ if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
+ return -EFAULT;
+
+ out->sem_perm.uid = tbuf_old.sem_perm.uid;
+ out->sem_perm.gid = tbuf_old.sem_perm.gid;
+ out->sem_perm.mode = tbuf_old.sem_perm.mode;
+
+ return 0;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+/*
+ * This function handles some semctl commands which require the rwsem
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rwsem is taken inside this function.
+ */
+static int semctl_down(struct ipc_namespace *ns, int semid,
+ int cmd, struct semid64_ds *semid64)
+{
+ struct sem_array *sma;
+ int err;
+ struct kern_ipc_perm *ipcp;
+
+ down_write(&sem_ids(ns).rwsem);
+ rcu_read_lock();
+
+ ipcp = ipcctl_obtain_check(ns, &sem_ids(ns), semid, cmd,
+ &semid64->sem_perm, 0);
+ if (IS_ERR(ipcp)) {
+ err = PTR_ERR(ipcp);
+ goto out_unlock1;
+ }
+
+ sma = container_of(ipcp, struct sem_array, sem_perm);
+
+ err = security_sem_semctl(&sma->sem_perm, cmd);
+ if (err)
+ goto out_unlock1;
+
+ switch (cmd) {
+ case IPC_RMID:
+ sem_lock(sma, NULL, -1);
+ /* freeary unlocks the ipc object and rcu */
+ freeary(ns, ipcp);
+ goto out_up;
+ case IPC_SET:
+ sem_lock(sma, NULL, -1);
+ err = ipc_update_perm(&semid64->sem_perm, ipcp);
+ if (err)
+ goto out_unlock0;
+ sma->sem_ctime = ktime_get_real_seconds();
+ break;
+ default:
+ err = -EINVAL;
+ goto out_unlock1;
+ }
+
+out_unlock0:
+ sem_unlock(sma, -1);
+out_unlock1:
+ rcu_read_unlock();
+out_up:
+ up_write(&sem_ids(ns).rwsem);
+ return err;
+}
+
+long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg)
+{
+ int version;
+ struct ipc_namespace *ns;
+ void __user *p = (void __user *)arg;
+ struct semid64_ds semid64;
+ int err;
+
+ if (semid < 0)
+ return -EINVAL;
+
+ version = ipc_parse_version(&cmd);
+ ns = current->nsproxy->ipc_ns;
+
+ switch (cmd) {
+ case IPC_INFO:
+ case SEM_INFO:
+ return semctl_info(ns, semid, cmd, p);
+ case IPC_STAT:
+ case SEM_STAT:
+ case SEM_STAT_ANY:
+ err = semctl_stat(ns, semid, cmd, &semid64);
+ if (err < 0)
+ return err;
+ if (copy_semid_to_user(p, &semid64, version))
+ err = -EFAULT;
+ return err;
+ case GETALL:
+ case GETVAL:
+ case GETPID:
+ case GETNCNT:
+ case GETZCNT:
+ case SETALL:
+ return semctl_main(ns, semid, semnum, cmd, p);
+ case SETVAL: {
+ int val;
+#if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN)
+ /* big-endian 64bit */
+ val = arg >> 32;
+#else
+ /* 32bit or little-endian 64bit */
+ val = arg;
+#endif
+ return semctl_setval(ns, semid, semnum, val);
+ }
+ case IPC_SET:
+ if (copy_semid_from_user(&semid64, p, version))
+ return -EFAULT;
+ case IPC_RMID:
+ return semctl_down(ns, semid, cmd, &semid64);
+ default:
+ return -EINVAL;
+ }
+}
+
+SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg)
+{
+ return ksys_semctl(semid, semnum, cmd, arg);
+}
+
+#ifdef CONFIG_COMPAT
+
+struct compat_semid_ds {
+ struct compat_ipc_perm sem_perm;
+ compat_time_t sem_otime;
+ compat_time_t sem_ctime;
+ compat_uptr_t sem_base;
+ compat_uptr_t sem_pending;
+ compat_uptr_t sem_pending_last;
+ compat_uptr_t undo;
+ unsigned short sem_nsems;
+};
+
+static int copy_compat_semid_from_user(struct semid64_ds *out, void __user *buf,
+ int version)
+{
+ memset(out, 0, sizeof(*out));
+ if (version == IPC_64) {
+ struct compat_semid64_ds __user *p = buf;
+ return get_compat_ipc64_perm(&out->sem_perm, &p->sem_perm);
+ } else {
+ struct compat_semid_ds __user *p = buf;
+ return get_compat_ipc_perm(&out->sem_perm, &p->sem_perm);
+ }
+}
+
+static int copy_compat_semid_to_user(void __user *buf, struct semid64_ds *in,
+ int version)
+{
+ if (version == IPC_64) {
+ struct compat_semid64_ds v;
+ memset(&v, 0, sizeof(v));
+ to_compat_ipc64_perm(&v.sem_perm, &in->sem_perm);
+ v.sem_otime = lower_32_bits(in->sem_otime);
+ v.sem_otime_high = upper_32_bits(in->sem_otime);
+ v.sem_ctime = lower_32_bits(in->sem_ctime);
+ v.sem_ctime_high = upper_32_bits(in->sem_ctime);
+ v.sem_nsems = in->sem_nsems;
+ return copy_to_user(buf, &v, sizeof(v));
+ } else {
+ struct compat_semid_ds v;
+ memset(&v, 0, sizeof(v));
+ to_compat_ipc_perm(&v.sem_perm, &in->sem_perm);
+ v.sem_otime = in->sem_otime;
+ v.sem_ctime = in->sem_ctime;
+ v.sem_nsems = in->sem_nsems;
+ return copy_to_user(buf, &v, sizeof(v));
+ }
+}
+
+long compat_ksys_semctl(int semid, int semnum, int cmd, int arg)
+{
+ void __user *p = compat_ptr(arg);
+ struct ipc_namespace *ns;
+ struct semid64_ds semid64;
+ int version = compat_ipc_parse_version(&cmd);
+ int err;
+
+ ns = current->nsproxy->ipc_ns;
+
+ if (semid < 0)
+ return -EINVAL;
+
+ switch (cmd & (~IPC_64)) {
+ case IPC_INFO:
+ case SEM_INFO:
+ return semctl_info(ns, semid, cmd, p);
+ case IPC_STAT:
+ case SEM_STAT:
+ case SEM_STAT_ANY:
+ err = semctl_stat(ns, semid, cmd, &semid64);
+ if (err < 0)
+ return err;
+ if (copy_compat_semid_to_user(p, &semid64, version))
+ err = -EFAULT;
+ return err;
+ case GETVAL:
+ case GETPID:
+ case GETNCNT:
+ case GETZCNT:
+ case GETALL:
+ case SETALL:
+ return semctl_main(ns, semid, semnum, cmd, p);
+ case SETVAL:
+ return semctl_setval(ns, semid, semnum, arg);
+ case IPC_SET:
+ if (copy_compat_semid_from_user(&semid64, p, version))
+ return -EFAULT;
+ /* fallthru */
+ case IPC_RMID:
+ return semctl_down(ns, semid, cmd, &semid64);
+ default:
+ return -EINVAL;
+ }
+}
+
+COMPAT_SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, int, arg)
+{
+ return compat_ksys_semctl(semid, semnum, cmd, arg);
+}
+#endif
+
+/* If the task doesn't already have a undo_list, then allocate one
+ * here. We guarantee there is only one thread using this undo list,
+ * and current is THE ONE
+ *
+ * If this allocation and assignment succeeds, but later
+ * portions of this code fail, there is no need to free the sem_undo_list.
+ * Just let it stay associated with the task, and it'll be freed later
+ * at exit time.
+ *
+ * This can block, so callers must hold no locks.
+ */
+static inline int get_undo_list(struct sem_undo_list **undo_listp)
+{
+ struct sem_undo_list *undo_list;
+
+ undo_list = current->sysvsem.undo_list;
+ if (!undo_list) {
+ undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
+ if (undo_list == NULL)
+ return -ENOMEM;
+ spin_lock_init(&undo_list->lock);
+ refcount_set(&undo_list->refcnt, 1);
+ INIT_LIST_HEAD(&undo_list->list_proc);
+
+ current->sysvsem.undo_list = undo_list;
+ }
+ *undo_listp = undo_list;
+ return 0;
+}
+
+static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
+{
+ struct sem_undo *un;
+
+ list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) {
+ if (un->semid == semid)
+ return un;
+ }
+ return NULL;
+}
+
+static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
+{
+ struct sem_undo *un;
+
+ assert_spin_locked(&ulp->lock);
+
+ un = __lookup_undo(ulp, semid);
+ if (un) {
+ list_del_rcu(&un->list_proc);
+ list_add_rcu(&un->list_proc, &ulp->list_proc);
+ }
+ return un;
+}
+
+/**
+ * find_alloc_undo - lookup (and if not present create) undo array
+ * @ns: namespace
+ * @semid: semaphore array id
+ *
+ * The function looks up (and if not present creates) the undo structure.
+ * The size of the undo structure depends on the size of the semaphore
+ * array, thus the alloc path is not that straightforward.
+ * Lifetime-rules: sem_undo is rcu-protected, on success, the function
+ * performs a rcu_read_lock().
+ */
+static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
+{
+ struct sem_array *sma;
+ struct sem_undo_list *ulp;
+ struct sem_undo *un, *new;
+ int nsems, error;
+
+ error = get_undo_list(&ulp);
+ if (error)
+ return ERR_PTR(error);
+
+ rcu_read_lock();
+ spin_lock(&ulp->lock);
+ un = lookup_undo(ulp, semid);
+ spin_unlock(&ulp->lock);
+ if (likely(un != NULL))
+ goto out;
+
+ /* no undo structure around - allocate one. */
+ /* step 1: figure out the size of the semaphore array */
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
+ return ERR_CAST(sma);
+ }
+
+ nsems = sma->sem_nsems;
+ if (!ipc_rcu_getref(&sma->sem_perm)) {
+ rcu_read_unlock();
+ un = ERR_PTR(-EIDRM);
+ goto out;
+ }
+ rcu_read_unlock();
+
+ /* step 2: allocate new undo structure */
+ new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
+ if (!new) {
+ ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* step 3: Acquire the lock on semaphore array */
+ rcu_read_lock();
+ sem_lock_and_putref(sma);
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ kfree(new);
+ un = ERR_PTR(-EIDRM);
+ goto out;
+ }
+ spin_lock(&ulp->lock);
+
+ /*
+ * step 4: check for races: did someone else allocate the undo struct?
+ */
+ un = lookup_undo(ulp, semid);
+ if (un) {
+ kfree(new);
+ goto success;
+ }
+ /* step 5: initialize & link new undo structure */
+ new->semadj = (short *) &new[1];
+ new->ulp = ulp;
+ new->semid = semid;
+ assert_spin_locked(&ulp->lock);
+ list_add_rcu(&new->list_proc, &ulp->list_proc);
+ ipc_assert_locked_object(&sma->sem_perm);
+ list_add(&new->list_id, &sma->list_id);
+ un = new;
+
+success:
+ spin_unlock(&ulp->lock);
+ sem_unlock(sma, -1);
+out:
+ return un;
+}
+
+static long do_semtimedop(int semid, struct sembuf __user *tsops,
+ unsigned nsops, const struct timespec64 *timeout)
+{
+ int error = -EINVAL;
+ struct sem_array *sma;
+ struct sembuf fast_sops[SEMOPM_FAST];
+ struct sembuf *sops = fast_sops, *sop;
+ struct sem_undo *un;
+ int max, locknum;
+ bool undos = false, alter = false, dupsop = false;
+ struct sem_queue queue;
+ unsigned long dup = 0, jiffies_left = 0;
+ struct ipc_namespace *ns;
+
+ ns = current->nsproxy->ipc_ns;
+
+ if (nsops < 1 || semid < 0)
+ return -EINVAL;
+ if (nsops > ns->sc_semopm)
+ return -E2BIG;
+ if (nsops > SEMOPM_FAST) {
+ sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
+ if (sops == NULL)
+ return -ENOMEM;
+ }
+
+ if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) {
+ error = -EFAULT;
+ goto out_free;
+ }
+
+ if (timeout) {
+ if (timeout->tv_sec < 0 || timeout->tv_nsec < 0 ||
+ timeout->tv_nsec >= 1000000000L) {
+ error = -EINVAL;
+ goto out_free;
+ }
+ jiffies_left = timespec64_to_jiffies(timeout);
+ }
+
+ max = 0;
+ for (sop = sops; sop < sops + nsops; sop++) {
+ unsigned long mask = 1ULL << ((sop->sem_num) % BITS_PER_LONG);
+
+ if (sop->sem_num >= max)
+ max = sop->sem_num;
+ if (sop->sem_flg & SEM_UNDO)
+ undos = true;
+ if (dup & mask) {
+ /*
+ * There was a previous alter access that appears
+ * to have accessed the same semaphore, thus use
+ * the dupsop logic. "appears", because the detection
+ * can only check % BITS_PER_LONG.
+ */
+ dupsop = true;
+ }
+ if (sop->sem_op != 0) {
+ alter = true;
+ dup |= mask;
+ }
+ }
+
+ if (undos) {
+ /* On success, find_alloc_undo takes the rcu_read_lock */
+ un = find_alloc_undo(ns, semid);
+ if (IS_ERR(un)) {
+ error = PTR_ERR(un);
+ goto out_free;
+ }
+ } else {
+ un = NULL;
+ rcu_read_lock();
+ }
+
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
+ error = PTR_ERR(sma);
+ goto out_free;
+ }
+
+ error = -EFBIG;
+ if (max >= sma->sem_nsems) {
+ rcu_read_unlock();
+ goto out_free;
+ }
+
+ error = -EACCES;
+ if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
+ rcu_read_unlock();
+ goto out_free;
+ }
+
+ error = security_sem_semop(&sma->sem_perm, sops, nsops, alter);
+ if (error) {
+ rcu_read_unlock();
+ goto out_free;
+ }
+
+ error = -EIDRM;
+ locknum = sem_lock(sma, sops, nsops);
+ /*
+ * We eventually might perform the following check in a lockless
+ * fashion, considering ipc_valid_object() locking constraints.
+ * If nsops == 1 and there is no contention for sem_perm.lock, then
+ * only a per-semaphore lock is held and it's OK to proceed with the
+ * check below. More details on the fine grained locking scheme
+ * entangled here and why it's RMID race safe on comments at sem_lock()
+ */
+ if (!ipc_valid_object(&sma->sem_perm))
+ goto out_unlock_free;
+ /*
+ * semid identifiers are not unique - find_alloc_undo may have
+ * allocated an undo structure, it was invalidated by an RMID
+ * and now a new array with received the same id. Check and fail.
+ * This case can be detected checking un->semid. The existence of
+ * "un" itself is guaranteed by rcu.
+ */
+ if (un && un->semid == -1)
+ goto out_unlock_free;
+
+ queue.sops = sops;
+ queue.nsops = nsops;
+ queue.undo = un;
+ queue.pid = task_tgid(current);
+ queue.alter = alter;
+ queue.dupsop = dupsop;
+
+ error = perform_atomic_semop(sma, &queue);
+ if (error == 0) { /* non-blocking succesfull path */
+ DEFINE_WAKE_Q(wake_q);
+
+ /*
+ * If the operation was successful, then do
+ * the required updates.
+ */
+ if (alter)
+ do_smart_update(sma, sops, nsops, 1, &wake_q);
+ else
+ set_semotime(sma, sops);
+
+ sem_unlock(sma, locknum);
+ rcu_read_unlock();
+ wake_up_q(&wake_q);
+
+ goto out_free;
+ }
+ if (error < 0) /* non-blocking error path */
+ goto out_unlock_free;
+
+ /*
+ * We need to sleep on this operation, so we put the current
+ * task into the pending queue and go to sleep.
+ */
+ if (nsops == 1) {
+ struct sem *curr;
+ int idx = array_index_nospec(sops->sem_num, sma->sem_nsems);
+ curr = &sma->sems[idx];
+
+ if (alter) {
+ if (sma->complex_count) {
+ list_add_tail(&queue.list,
+ &sma->pending_alter);
+ } else {
+
+ list_add_tail(&queue.list,
+ &curr->pending_alter);
+ }
+ } else {
+ list_add_tail(&queue.list, &curr->pending_const);
+ }
+ } else {
+ if (!sma->complex_count)
+ merge_queues(sma);
+
+ if (alter)
+ list_add_tail(&queue.list, &sma->pending_alter);
+ else
+ list_add_tail(&queue.list, &sma->pending_const);
+
+ sma->complex_count++;
+ }
+
+ do {
+ WRITE_ONCE(queue.status, -EINTR);
+ queue.sleeper = current;
+
+ __set_current_state(TASK_INTERRUPTIBLE);
+ sem_unlock(sma, locknum);
+ rcu_read_unlock();
+
+ if (timeout)
+ jiffies_left = schedule_timeout(jiffies_left);
+ else
+ schedule();
+
+ /*
+ * fastpath: the semop has completed, either successfully or
+ * not, from the syscall pov, is quite irrelevant to us at this
+ * point; we're done.
+ *
+ * We _do_ care, nonetheless, about being awoken by a signal or
+ * spuriously. The queue.status is checked again in the
+ * slowpath (aka after taking sem_lock), such that we can detect
+ * scenarios where we were awakened externally, during the
+ * window between wake_q_add() and wake_up_q().
+ */
+ error = READ_ONCE(queue.status);
+ if (error != -EINTR) {
+ /*
+ * User space could assume that semop() is a memory
+ * barrier: Without the mb(), the cpu could
+ * speculatively read in userspace stale data that was
+ * overwritten by the previous owner of the semaphore.
+ */
+ smp_mb();
+ goto out_free;
+ }
+
+ rcu_read_lock();
+ locknum = sem_lock(sma, sops, nsops);
+
+ if (!ipc_valid_object(&sma->sem_perm))
+ goto out_unlock_free;
+
+ error = READ_ONCE(queue.status);
+
+ /*
+ * If queue.status != -EINTR we are woken up by another process.
+ * Leave without unlink_queue(), but with sem_unlock().
+ */
+ if (error != -EINTR)
+ goto out_unlock_free;
+
+ /*
+ * If an interrupt occurred we have to clean up the queue.
+ */
+ if (timeout && jiffies_left == 0)
+ error = -EAGAIN;
+ } while (error == -EINTR && !signal_pending(current)); /* spurious */
+
+ unlink_queue(sma, &queue);
+
+out_unlock_free:
+ sem_unlock(sma, locknum);
+ rcu_read_unlock();
+out_free:
+ if (sops != fast_sops)
+ kvfree(sops);
+ return error;
+}
+
+long ksys_semtimedop(int semid, struct sembuf __user *tsops,
+ unsigned int nsops, const struct __kernel_timespec __user *timeout)
+{
+ if (timeout) {
+ struct timespec64 ts;
+ if (get_timespec64(&ts, timeout))
+ return -EFAULT;
+ return do_semtimedop(semid, tsops, nsops, &ts);
+ }
+ return do_semtimedop(semid, tsops, nsops, NULL);
+}
+
+SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
+ unsigned int, nsops, const struct __kernel_timespec __user *, timeout)
+{
+ return ksys_semtimedop(semid, tsops, nsops, timeout);
+}
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
+ unsigned int nsops,
+ const struct compat_timespec __user *timeout)
+{
+ if (timeout) {
+ struct timespec64 ts;
+ if (compat_get_timespec64(&ts, timeout))
+ return -EFAULT;
+ return do_semtimedop(semid, tsems, nsops, &ts);
+ }
+ return do_semtimedop(semid, tsems, nsops, NULL);
+}
+
+COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
+ unsigned int, nsops,
+ const struct compat_timespec __user *, timeout)
+{
+ return compat_ksys_semtimedop(semid, tsems, nsops, timeout);
+}
+#endif
+
+SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,
+ unsigned, nsops)
+{
+ return do_semtimedop(semid, tsops, nsops, NULL);
+}
+
+/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
+ * parent and child tasks.
+ */
+
+int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
+{
+ struct sem_undo_list *undo_list;
+ int error;
+
+ if (clone_flags & CLONE_SYSVSEM) {
+ error = get_undo_list(&undo_list);
+ if (error)
+ return error;
+ refcount_inc(&undo_list->refcnt);
+ tsk->sysvsem.undo_list = undo_list;
+ } else
+ tsk->sysvsem.undo_list = NULL;
+
+ return 0;
+}
+
+/*
+ * add semadj values to semaphores, free undo structures.
+ * undo structures are not freed when semaphore arrays are destroyed
+ * so some of them may be out of date.
+ * IMPLEMENTATION NOTE: There is some confusion over whether the
+ * set of adjustments that needs to be done should be done in an atomic
+ * manner or not. That is, if we are attempting to decrement the semval
+ * should we queue up and wait until we can do so legally?
+ * The original implementation attempted to do this (queue and wait).
+ * The current implementation does not do so. The POSIX standard
+ * and SVID should be consulted to determine what behavior is mandated.
+ */
+void exit_sem(struct task_struct *tsk)
+{
+ struct sem_undo_list *ulp;
+
+ ulp = tsk->sysvsem.undo_list;
+ if (!ulp)
+ return;
+ tsk->sysvsem.undo_list = NULL;
+
+ if (!refcount_dec_and_test(&ulp->refcnt))
+ return;
+
+ for (;;) {
+ struct sem_array *sma;
+ struct sem_undo *un;
+ int semid, i;
+ DEFINE_WAKE_Q(wake_q);
+
+ cond_resched();
+
+ rcu_read_lock();
+ un = list_entry_rcu(ulp->list_proc.next,
+ struct sem_undo, list_proc);
+ if (&un->list_proc == &ulp->list_proc) {
+ /*
+ * We must wait for freeary() before freeing this ulp,
+ * in case we raced with last sem_undo. There is a small
+ * possibility where we exit while freeary() didn't
+ * finish unlocking sem_undo_list.
+ */
+ spin_lock(&ulp->lock);
+ spin_unlock(&ulp->lock);
+ rcu_read_unlock();
+ break;
+ }
+ spin_lock(&ulp->lock);
+ semid = un->semid;
+ spin_unlock(&ulp->lock);
+
+ /* exit_sem raced with IPC_RMID, nothing to do */
+ if (semid == -1) {
+ rcu_read_unlock();
+ continue;
+ }
+
+ sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, semid);
+ /* exit_sem raced with IPC_RMID, nothing to do */
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
+ continue;
+ }
+
+ sem_lock(sma, NULL, -1);
+ /* exit_sem raced with IPC_RMID, nothing to do */
+ if (!ipc_valid_object(&sma->sem_perm)) {
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ continue;
+ }
+ un = __lookup_undo(ulp, semid);
+ if (un == NULL) {
+ /* exit_sem raced with IPC_RMID+semget() that created
+ * exactly the same semid. Nothing to do.
+ */
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ continue;
+ }
+
+ /* remove un from the linked lists */
+ ipc_assert_locked_object(&sma->sem_perm);
+ list_del(&un->list_id);
+
+ /* we are the last process using this ulp, acquiring ulp->lock
+ * isn't required. Besides that, we are also protected against
+ * IPC_RMID as we hold sma->sem_perm lock now
+ */
+ list_del_rcu(&un->list_proc);
+
+ /* perform adjustments registered in un */
+ for (i = 0; i < sma->sem_nsems; i++) {
+ struct sem *semaphore = &sma->sems[i];
+ if (un->semadj[i]) {
+ semaphore->semval += un->semadj[i];
+ /*
+ * Range checks of the new semaphore value,
+ * not defined by sus:
+ * - Some unices ignore the undo entirely
+ * (e.g. HP UX 11i 11.22, Tru64 V5.1)
+ * - some cap the value (e.g. FreeBSD caps
+ * at 0, but doesn't enforce SEMVMX)
+ *
+ * Linux caps the semaphore value, both at 0
+ * and at SEMVMX.
+ *
+ * Manfred <manfred@colorfullife.com>
+ */
+ if (semaphore->semval < 0)
+ semaphore->semval = 0;
+ if (semaphore->semval > SEMVMX)
+ semaphore->semval = SEMVMX;
+ ipc_update_pid(&semaphore->sempid, task_tgid(current));
+ }
+ }
+ /* maybe some queued-up processes were waiting for this */
+ do_smart_update(sma, NULL, 0, 1, &wake_q);
+ sem_unlock(sma, -1);
+ rcu_read_unlock();
+ wake_up_q(&wake_q);
+
+ kfree_rcu(un, rcu);
+ }
+ kfree(ulp);
+}
+
+#ifdef CONFIG_PROC_FS
+static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
+{
+ struct user_namespace *user_ns = seq_user_ns(s);
+ struct kern_ipc_perm *ipcp = it;
+ struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
+ time64_t sem_otime;
+
+ /*
+ * The proc interface isn't aware of sem_lock(), it calls
+ * ipc_lock_object() directly (in sysvipc_find_ipc).
+ * In order to stay compatible with sem_lock(), we must
+ * enter / leave complex_mode.
+ */
+ complexmode_enter(sma);
+
+ sem_otime = get_semotime(sma);
+
+ seq_printf(s,
+ "%10d %10d %4o %10u %5u %5u %5u %5u %10llu %10llu\n",
+ sma->sem_perm.key,
+ sma->sem_perm.id,
+ sma->sem_perm.mode,
+ sma->sem_nsems,
+ from_kuid_munged(user_ns, sma->sem_perm.uid),
+ from_kgid_munged(user_ns, sma->sem_perm.gid),
+ from_kuid_munged(user_ns, sma->sem_perm.cuid),
+ from_kgid_munged(user_ns, sma->sem_perm.cgid),
+ sem_otime,
+ sma->sem_ctime);
+
+ complexmode_tryleave(sma);
+
+ return 0;
+}
+#endif