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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-03 19:15:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-03 19:15:32 -0700
commit17dec0a949153d9ac00760ba2f5b78cb583e995f (patch)
treeaaf44fee3aca81a86ecfa46f3f409d5cf5675f1f /ipc/sem.c
parentMerge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq (diff)
parentipc/shm: Fix pid freeing. (diff)
downloadlinux-dev-17dec0a949153d9ac00760ba2f5b78cb583e995f.tar.xz
linux-dev-17dec0a949153d9ac00760ba2f5b78cb583e995f.zip
Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull namespace updates from Eric Biederman: "There was a lot of work this cycle fixing bugs that were discovered after the merge window and getting everything ready where we can reasonably support fully unprivileged fuse. The bug fixes you already have and much of the unprivileged fuse work is coming in via other trees. Still left for fully unprivileged fuse is figuring out how to cleanly handle .set_acl and .get_acl in the legacy case, and properly handling of evm xattrs on unprivileged mounts. Included in the tree is a cleanup from Alexely that replaced a linked list with a statically allocated fix sized array for the pid caches, which simplifies and speeds things up. Then there is are some cleanups and fixes for the ipc namespace. The motivation was that in reviewing other code it was discovered that access ipc objects from different pid namespaces recorded pids in such a way that when asked the wrong pids were returned. In the worst case there has been a measured 30% performance impact for sysvipc semaphores. Other test cases showed no measurable performance impact. Manfred Spraul and Davidlohr Bueso who tend to work on sysvipc performance both gave the nod that this is good enough. Casey Schaufler and James Morris have given their approval to the LSM side of the changes. I simplified the types and the code dealing with sysvipc to pass just kern_ipc_perm for all three types of ipc. Which reduced the header dependencies throughout the kernel and simplified the lsm code. Which let me work on the pid fixes without having to worry about trivial changes causing complete kernel recompiles" * 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: ipc/shm: Fix pid freeing. ipc/shm: fix up for struct file no longer being available in shm.h ipc/smack: Tidy up from the change in type of the ipc security hooks ipc: Directly call the security hook in ipc_ops.associate ipc/sem: Fix semctl(..., GETPID, ...) between pid namespaces ipc/msg: Fix msgctl(..., IPC_STAT, ...) between pid namespaces ipc/shm: Fix shmctl(..., IPC_STAT, ...) between pid namespaces. ipc/util: Helpers for making the sysvipc operations pid namespace aware ipc: Move IPCMNI from include/ipc.h into ipc/util.h msg: Move struct msg_queue into ipc/msg.c shm: Move struct shmid_kernel into ipc/shm.c sem: Move struct sem and struct sem_array into ipc/sem.c msg/security: Pass kern_ipc_perm not msg_queue into the msg_queue security hooks shm/security: Pass kern_ipc_perm not shmid_kernel into the shm security hooks sem/security: Pass kern_ipc_perm not sem_array into the sem security hooks pidns: simpler allocation of pid_* caches
Diffstat (limited to 'ipc/sem.c')
-rw-r--r--ipc/sem.c81
1 files changed, 53 insertions, 28 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index 1cf56279a84c..2994da8ccc7f 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -88,13 +88,47 @@
#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*/
+ time_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 */
- int pid; /* process id of requesting process */
+ 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 */
@@ -265,7 +299,7 @@ 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);
+ security_sem_free(&sma->sem_perm);
kvfree(sma);
}
@@ -495,7 +529,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
sma->sem_perm.key = key;
sma->sem_perm.security = NULL;
- retval = security_sem_alloc(sma);
+ retval = security_sem_alloc(&sma->sem_perm);
if (retval) {
kvfree(sma);
return retval;
@@ -533,17 +567,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
/*
* Called with sem_ids.rwsem and ipcp locked.
*/
-static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
-{
- struct sem_array *sma;
-
- sma = container_of(ipcp, struct sem_array, sem_perm);
- return security_sem_associate(sma, semflg);
-}
-
-/*
- * Called with sem_ids.rwsem and ipcp locked.
- */
static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
struct ipc_params *params)
{
@@ -561,7 +584,7 @@ long ksys_semget(key_t key, int nsems, int semflg)
struct ipc_namespace *ns;
static const struct ipc_ops sem_ops = {
.getnew = newary,
- .associate = sem_security,
+ .associate = security_sem_associate,
.more_checks = sem_more_checks,
};
struct ipc_params sem_params;
@@ -602,7 +625,8 @@ SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
*/
static int perform_atomic_semop_slow(struct sem_array *sma, struct sem_queue *q)
{
- int result, sem_op, nsops, pid;
+ int result, sem_op, nsops;
+ struct pid *pid;
struct sembuf *sop;
struct sem *curr;
struct sembuf *sops;
@@ -640,7 +664,7 @@ static int perform_atomic_semop_slow(struct sem_array *sma, struct sem_queue *q)
sop--;
pid = q->pid;
while (sop >= sops) {
- sma->sems[sop->sem_num].sempid = pid;
+ ipc_update_pid(&sma->sems[sop->sem_num].sempid, pid);
sop--;
}
@@ -727,7 +751,7 @@ static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q)
un->semadj[sop->sem_num] = undo;
}
curr->semval += sem_op;
- curr->sempid = q->pid;
+ ipc_update_pid(&curr->sempid, q->pid);
}
return 0;
@@ -1134,6 +1158,7 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
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 */
@@ -1214,7 +1239,7 @@ static int semctl_stat(struct ipc_namespace *ns, int semid,
if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
goto out_unlock;
- err = security_sem_semctl(sma, cmd);
+ err = security_sem_semctl(&sma->sem_perm, cmd);
if (err)
goto out_unlock;
@@ -1305,7 +1330,7 @@ static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum,
return -EACCES;
}
- err = security_sem_semctl(sma, SETVAL);
+ err = security_sem_semctl(&sma->sem_perm, SETVAL);
if (err) {
rcu_read_unlock();
return -EACCES;
@@ -1326,7 +1351,7 @@ static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum,
un->semadj[semnum] = 0;
curr->semval = val;
- curr->sempid = task_tgid_vnr(current);
+ 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);
@@ -1359,7 +1384,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO))
goto out_rcu_wakeup;
- err = security_sem_semctl(sma, cmd);
+ err = security_sem_semctl(&sma->sem_perm, cmd);
if (err)
goto out_rcu_wakeup;
@@ -1447,7 +1472,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
for (i = 0; i < nsems; i++) {
sma->sems[i].semval = sem_io[i];
- sma->sems[i].sempid = task_tgid_vnr(current);
+ ipc_update_pid(&sma->sems[i].sempid, task_tgid(current));
}
ipc_assert_locked_object(&sma->sem_perm);
@@ -1479,7 +1504,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
err = curr->semval;
goto out_unlock;
case GETPID:
- err = curr->sempid;
+ err = pid_vnr(curr->sempid);
goto out_unlock;
case GETNCNT:
err = count_semcnt(sma, semnum, 0);
@@ -1550,7 +1575,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
sma = container_of(ipcp, struct sem_array, sem_perm);
- err = security_sem_semctl(sma, cmd);
+ err = security_sem_semctl(&sma->sem_perm, cmd);
if (err)
goto out_unlock1;
@@ -1977,7 +2002,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
goto out_free;
}
- error = security_sem_semop(sma, sops, nsops, alter);
+ error = security_sem_semop(&sma->sem_perm, sops, nsops, alter);
if (error) {
rcu_read_unlock();
goto out_free;
@@ -2008,7 +2033,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
queue.sops = sops;
queue.nsops = nsops;
queue.undo = un;
- queue.pid = task_tgid_vnr(current);
+ queue.pid = task_tgid(current);
queue.alter = alter;
queue.dupsop = dupsop;
@@ -2315,7 +2340,7 @@ void exit_sem(struct task_struct *tsk)
semaphore->semval = 0;
if (semaphore->semval > SEMVMX)
semaphore->semval = SEMVMX;
- semaphore->sempid = task_tgid_vnr(current);
+ ipc_update_pid(&semaphore->sempid, task_tgid(current));
}
}
/* maybe some queued-up processes were waiting for this */