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Message-Id: <1267041846-10469-5-git-send-email-arnd@arndb.de>
Date: Wed, 24 Feb 2010 21:04:00 +0100
From: Arnd Bergmann <arnd@...db.de>
To: paulmck@...ux.vnet.ibm.com
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
linux-kernel@...r.kernel.org, mingo@...e.hu, laijs@...fujitsu.com,
dipankar@...ibm.com, akpm@...ux-foundation.org,
josh@...htriplett.org, dvhltc@...ibm.com, niv@...ibm.com,
tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
Valdis.Kletnieks@...edu, dhowells@...hat.com
Subject: [PATCH 04/10] credentials: rcu annotation
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
include/linux/cred.h | 4 +-
include/linux/sched.h | 4 +-
kernel/cred.c | 50 +++++++++++++++++++++++++-----------------------
kernel/fork.c | 4 +-
4 files changed, 32 insertions(+), 30 deletions(-)
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 4e3387a..944fdfc 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -267,7 +267,7 @@ static inline void put_cred(const struct cred *_cred)
* Access the subjective credentials of the current task.
*/
#define current_cred() \
- (current->cred)
+ __rcu_dereference(current->cred)
/**
* __task_cred - Access a task's objective credentials
@@ -356,7 +356,7 @@ static inline void put_cred(const struct cred *_cred)
#define current_cred_xxx(xxx) \
({ \
- current->cred->xxx; \
+ __rcu_dereference(current->cred)->xxx; \
})
#define current_uid() (current_cred_xxx(uid))
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 038e16f..52a33eb 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1361,9 +1361,9 @@ struct task_struct {
struct list_head cpu_timers[3];
/* process credentials */
- const struct cred *real_cred; /* objective and real subjective task
+ const struct cred __rcu *real_cred; /* objective and real subjective task
* credentials (COW) */
- const struct cred *cred; /* effective (overridable) subjective task
+ const struct cred __rcu *cred; /* effective (overridable) subjective task
* credentials (COW) */
struct mutex cred_guard_mutex; /* guard against foreign influences on
* credential calculations
diff --git a/kernel/cred.c b/kernel/cred.c
index 1ed8ca1..eed586d 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -171,8 +171,8 @@ void __put_cred(struct cred *cred)
cred->magic = CRED_MAGIC_DEAD;
cred->put_addr = __builtin_return_address(0);
#endif
- BUG_ON(cred == current->cred);
- BUG_ON(cred == current->real_cred);
+ BUG_ON(cred == __rcu_dereference(current->cred));
+ BUG_ON(cred == __rcu_dereference(current->real_cred));
call_rcu(&cred->rcu, put_cred_rcu);
}
@@ -183,23 +183,22 @@ EXPORT_SYMBOL(__put_cred);
*/
void exit_creds(struct task_struct *tsk)
{
- struct cred *cred;
+ struct cred *cred = (struct cred *)rcu_dereference(tsk->cred);
+ struct cred *real_cred = (struct cred *)rcu_dereference(tsk->real_cred);
- kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
- atomic_read(&tsk->cred->usage),
- read_cred_subscribers(tsk->cred));
+ kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid,
+ real_cred, cred, atomic_read(&cred->usage),
+ read_cred_subscribers(cred));
- cred = (struct cred *) tsk->real_cred;
tsk->real_cred = NULL;
validate_creds(cred);
alter_cred_subscribers(cred, -1);
put_cred(cred);
- cred = (struct cred *) tsk->cred;
tsk->cred = NULL;
- validate_creds(cred);
- alter_cred_subscribers(cred, -1);
- put_cred(cred);
+ validate_creds(real_cred);
+ alter_cred_subscribers(real_cred, -1);
+ put_cred(real_cred);
cred = (struct cred *) tsk->replacement_session_keyring;
if (cred) {
@@ -273,7 +272,7 @@ struct cred *prepare_creds(void)
kdebug("prepare_creds() alloc %p", new);
- old = task->cred;
+ old = rcu_dereference(task->cred);
memcpy(new, old, sizeof(struct cred));
atomic_set(&new->usage, 1);
@@ -415,23 +414,25 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
struct thread_group_cred *tgcred;
#endif
struct cred *new;
+ const struct cred *cred;
int ret;
mutex_init(&p->cred_guard_mutex);
+ cred = rcu_dereference(p->cred);
if (
#ifdef CONFIG_KEYS
- !p->cred->thread_keyring &&
+ !cred->thread_keyring &&
#endif
clone_flags & CLONE_THREAD
) {
- p->real_cred = get_cred(p->cred);
- get_cred(p->cred);
- alter_cred_subscribers(p->cred, 2);
+ rcu_assign_pointer(p->real_cred, get_cred(cred));
+ get_cred(cred);
+ alter_cred_subscribers(cred, 2);
kdebug("share_creds(%p{%d,%d})",
- p->cred, atomic_read(&p->cred->usage),
- read_cred_subscribers(p->cred));
- atomic_inc(&p->cred->user->processes);
+ cred, atomic_read(&cred->usage),
+ read_cred_subscribers(cred));
+ atomic_inc(&cred->user->processes);
return 0;
}
@@ -475,7 +476,8 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
#endif
atomic_inc(&new->user->processes);
- p->cred = p->real_cred = get_cred(new);
+ rcu_assign_pointer(p->cred, get_cred(new));
+ rcu_assign_pointer(p->real_cred, new);
alter_cred_subscribers(new, 2);
validate_creds(new);
return 0;
@@ -502,13 +504,13 @@ error_put:
int commit_creds(struct cred *new)
{
struct task_struct *task = current;
- const struct cred *old = task->real_cred;
+ const struct cred *old = __rcu_dereference(task->real_cred);
kdebug("commit_creds(%p{%d,%d})", new,
atomic_read(&new->usage),
read_cred_subscribers(new));
- BUG_ON(task->cred != old);
+ BUG_ON(__rcu_dereference(task->cred) != old);
#ifdef CONFIG_DEBUG_CREDENTIALS
BUG_ON(read_cred_subscribers(old) < 2);
validate_creds(old);
@@ -605,7 +607,7 @@ EXPORT_SYMBOL(abort_creds);
*/
const struct cred *override_creds(const struct cred *new)
{
- const struct cred *old = current->cred;
+ const struct cred *old = rcu_dereference(current->cred);
kdebug("override_creds(%p{%d,%d})", new,
atomic_read(&new->usage),
@@ -634,7 +636,7 @@ EXPORT_SYMBOL(override_creds);
*/
void revert_creds(const struct cred *old)
{
- const struct cred *override = current->cred;
+ const struct cred *override = rcu_dereference(current->cred);
kdebug("revert_creds(%p{%d,%d})", old,
atomic_read(&old->usage),
diff --git a/kernel/fork.c b/kernel/fork.c
index f88bd98..ba7489b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1032,10 +1032,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
#endif
retval = -EAGAIN;
- if (atomic_read(&p->real_cred->user->processes) >=
+ if (atomic_read(&rcu_dereference(p->real_cred)->user->processes) >=
p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
- p->real_cred->user != INIT_USER)
+ rcu_dereference(p->real_cred)->user != INIT_USER)
goto bad_fork_free;
}
--
1.6.3.3
--
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