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-rw-r--r--ipc/sem.c161
-rw-r--r--ipc/util.h5
2 files changed, 118 insertions, 48 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index 5b167d00efa6..cd1093cf7e8f 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -204,13 +204,34 @@ static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
return container_of(ipcp, struct sem_array, sem_perm);
}
+static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id)
+{
+ struct kern_ipc_perm *ipcp = ipc_obtain_object(&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_lock_check(struct ipc_namespace *ns,
int id)
{
struct kern_ipc_perm *ipcp = ipc_lock_check(&sem_ids(ns), id);
if (IS_ERR(ipcp))
- return (struct sem_array *)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);
}
@@ -234,6 +255,16 @@ static inline void sem_putref(struct sem_array *sma)
ipc_unlock(&(sma)->sem_perm);
}
+/*
+ * Call inside the rcu read section.
+ */
+static inline void sem_getref(struct sem_array *sma)
+{
+ spin_lock(&(sma)->sem_perm.lock);
+ ipc_rcu_getref(sma);
+ ipc_unlock(&(sma)->sem_perm);
+}
+
static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
{
ipc_rmid(&sem_ids(ns), &s->sem_perm);
@@ -842,18 +873,25 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
case SEM_STAT:
{
struct semid64_ds tbuf;
- int id;
+ int id = 0;
+
+ memset(&tbuf, 0, sizeof(tbuf));
if (cmd == SEM_STAT) {
- sma = sem_lock(ns, semid);
- if (IS_ERR(sma))
- return PTR_ERR(sma);
+ rcu_read_lock();
+ sma = sem_obtain_object(ns, semid);
+ if (IS_ERR(sma)) {
+ err = PTR_ERR(sma);
+ goto out_unlock;
+ }
id = sma->sem_perm.id;
} else {
- sma = sem_lock_check(ns, semid);
- if (IS_ERR(sma))
- return PTR_ERR(sma);
- id = 0;
+ rcu_read_lock();
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ err = PTR_ERR(sma);
+ goto out_unlock;
+ }
}
err = -EACCES;
@@ -864,13 +902,11 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
if (err)
goto out_unlock;
- memset(&tbuf, 0, sizeof(tbuf));
-
kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
tbuf.sem_otime = sma->sem_otime;
tbuf.sem_ctime = sma->sem_ctime;
tbuf.sem_nsems = sma->sem_nsems;
- sem_unlock(sma);
+ rcu_read_unlock();
if (copy_semid_to_user(p, &tbuf, version))
return -EFAULT;
return id;
@@ -879,7 +915,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
return -EINVAL;
}
out_unlock:
- sem_unlock(sma);
+ rcu_read_unlock();
return err;
}
@@ -947,27 +983,34 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
{
struct sem_array *sma;
struct sem* curr;
- int err;
+ int err, nsems;
ushort fast_sem_io[SEMMSL_FAST];
ushort* sem_io = fast_sem_io;
- int nsems;
struct list_head tasks;
- sma = sem_lock_check(ns, semid);
- if (IS_ERR(sma))
+ INIT_LIST_HEAD(&tasks);
+
+ rcu_read_lock();
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
return PTR_ERR(sma);
+ }
- INIT_LIST_HEAD(&tasks);
nsems = sma->sem_nsems;
err = -EACCES;
if (ipcperms(ns, &sma->sem_perm,
- cmd == SETALL ? S_IWUGO : S_IRUGO))
- goto out_unlock;
+ cmd == SETALL ? S_IWUGO : S_IRUGO)) {
+ rcu_read_unlock();
+ goto out_wakeup;
+ }
err = security_sem_semctl(sma, cmd);
- if (err)
- goto out_unlock;
+ if (err) {
+ rcu_read_unlock();
+ goto out_wakeup;
+ }
err = -EACCES;
switch (cmd) {
@@ -977,7 +1020,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
int i;
if(nsems > SEMMSL_FAST) {
- sem_getref_and_unlock(sma);
+ sem_getref(sma);
sem_io = ipc_alloc(sizeof(ushort)*nsems);
if(sem_io == NULL) {
@@ -993,6 +1036,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
}
}
+ spin_lock(&sma->sem_perm.lock);
for (i = 0; i < sma->sem_nsems; i++)
sem_io[i] = sma->sem_base[i].semval;
sem_unlock(sma);
@@ -1006,7 +1050,8 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
int i;
struct sem_undo *un;
- sem_getref_and_unlock(sma);
+ ipc_rcu_getref(sma);
+ rcu_read_unlock();
if(nsems > SEMMSL_FAST) {
sem_io = ipc_alloc(sizeof(ushort)*nsems);
@@ -1053,9 +1098,12 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
/* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */
}
err = -EINVAL;
- if(semnum < 0 || semnum >= nsems)
- goto out_unlock;
+ if (semnum < 0 || semnum >= nsems) {
+ rcu_read_unlock();
+ goto out_wakeup;
+ }
+ spin_lock(&sma->sem_perm.lock);
curr = &sma->sem_base[semnum];
switch (cmd) {
@@ -1072,10 +1120,11 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
err = count_semzcnt(sma,semnum);
goto out_unlock;
}
+
out_unlock:
sem_unlock(sma);
+out_wakeup:
wake_up_sem_queue_do(&tasks);
-
out_free:
if(sem_io != fast_sem_io)
ipc_free(sem_io, sizeof(ushort)*nsems);
@@ -1126,29 +1175,35 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
return -EFAULT;
}
- ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid, cmd,
- &semid64.sem_perm, 0);
+ ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd,
+ &semid64.sem_perm, 0);
if (IS_ERR(ipcp))
return PTR_ERR(ipcp);
sma = container_of(ipcp, struct sem_array, sem_perm);
err = security_sem_semctl(sma, cmd);
- if (err)
+ if (err) {
+ rcu_read_unlock();
goto out_unlock;
+ }
switch(cmd){
case IPC_RMID:
+ ipc_lock_object(&sma->sem_perm);
freeary(ns, ipcp);
goto out_up;
case IPC_SET:
+ ipc_lock_object(&sma->sem_perm);
err = ipc_update_perm(&semid64.sem_perm, ipcp);
if (err)
goto out_unlock;
sma->sem_ctime = get_seconds();
break;
default:
+ rcu_read_unlock();
err = -EINVAL;
+ goto out_up;
}
out_unlock:
@@ -1277,16 +1332,18 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
spin_unlock(&ulp->lock);
if (likely(un!=NULL))
goto out;
- rcu_read_unlock();
/* no undo structure around - allocate one. */
/* step 1: figure out the size of the semaphore array */
- sma = sem_lock_check(ns, semid);
- if (IS_ERR(sma))
+ sma = sem_obtain_object_check(ns, semid);
+ if (IS_ERR(sma)) {
+ rcu_read_unlock();
return ERR_CAST(sma);
+ }
nsems = sma->sem_nsems;
- sem_getref_and_unlock(sma);
+ ipc_rcu_getref(sma);
+ rcu_read_unlock();
/* step 2: allocate new undo structure */
new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
@@ -1421,7 +1478,8 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
INIT_LIST_HEAD(&tasks);
- sma = sem_lock_check(ns, semid);
+ rcu_read_lock();
+ sma = sem_obtain_object_check(ns, semid);
if (IS_ERR(sma)) {
if (un)
rcu_read_unlock();
@@ -1429,6 +1487,24 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
goto out_free;
}
+ error = -EFBIG;
+ if (max >= sma->sem_nsems) {
+ rcu_read_unlock();
+ goto out_wakeup;
+ }
+
+ error = -EACCES;
+ if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
+ rcu_read_unlock();
+ goto out_wakeup;
+ }
+
+ error = security_sem_semop(sma, sops, nsops, alter);
+ if (error) {
+ rcu_read_unlock();
+ goto out_wakeup;
+ }
+
/*
* semid identifiers are not unique - find_alloc_undo may have
* allocated an undo structure, it was invalidated by an RMID
@@ -1437,6 +1513,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
* "un" itself is guaranteed by rcu.
*/
error = -EIDRM;
+ ipc_lock_object(&sma->sem_perm);
if (un) {
if (un->semid == -1) {
rcu_read_unlock();
@@ -1454,18 +1531,6 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
}
}
- error = -EFBIG;
- if (max >= sma->sem_nsems)
- goto out_unlock_free;
-
- error = -EACCES;
- if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
- goto out_unlock_free;
-
- error = security_sem_semop(sma, sops, nsops, alter);
- if (error)
- goto out_unlock_free;
-
error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
if (error <= 0) {
if (alter && error == 0)
@@ -1568,7 +1633,7 @@ sleep_again:
out_unlock_free:
sem_unlock(sma);
-
+out_wakeup:
wake_up_sem_queue_do(&tasks);
out_free:
if(sops != fast_sops)
diff --git a/ipc/util.h b/ipc/util.h
index 13d92fea15a3..c36b9977c957 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -171,6 +171,11 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
rcu_read_unlock();
}
+static inline void ipc_lock_object(struct kern_ipc_perm *perm)
+{
+ spin_lock(&perm->lock);
+}
+
struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,

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