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authorAlexey Gladkov <legion@kernel.org>2021-04-22 14:27:13 +0200
committerEric W. Biederman <ebiederm@xmission.com>2021-04-30 14:14:02 -0500
commitd64696905554e919321e31afc210606653b8f6a4 (patch)
tree7c153f685f7e89823fc6c0b3e420d8fff12037df /kernel/signal.c
parent6e52a9f0532f912af37bab4caf18b57d1b9845f4 (diff)
Reimplement RLIMIT_SIGPENDING on top of ucounts
The rlimit counter is tied to uid in the user_namespace. This allows rlimit values to be specified in userns even if they are already globally exceeded by the user. However, the value of the previous user_namespaces cannot be exceeded. Changelog v11: * Revert most of changes to fix performance issues. v10: * Fix memory leak on get_ucounts failure. Signed-off-by: Alexey Gladkov <legion@kernel.org> Link: https://lkml.kernel.org/r/df9d7764dddd50f28616b7840de74ec0f81711a8.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c25
1 files changed, 13 insertions, 12 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index f2718350bf4b..9a6dab712123 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -413,8 +413,8 @@ static struct sigqueue *
__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
{
struct sigqueue *q = NULL;
- struct user_struct *user;
- int sigpending;
+ struct ucounts *ucounts = NULL;
+ long sigpending;
/*
* Protect access to @t credentials. This can go away when all
@@ -425,27 +425,26 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
* changes from/to zero.
*/
rcu_read_lock();
- user = __task_cred(t)->user;
- sigpending = atomic_inc_return(&user->sigpending);
+ ucounts = task_ucounts(t);
+ sigpending = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1);
if (sigpending == 1)
- get_uid(user);
+ ucounts = get_ucounts(ucounts);
rcu_read_unlock();
- if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
+ if (override_rlimit || (sigpending < LONG_MAX && sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
q = kmem_cache_alloc(sigqueue_cachep, flags);
} else {
print_dropped_signal(sig);
}
if (unlikely(q == NULL)) {
- if (atomic_dec_and_test(&user->sigpending))
- free_uid(user);
+ if (ucounts && dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1))
+ put_ucounts(ucounts);
} else {
INIT_LIST_HEAD(&q->list);
q->flags = 0;
- q->user = user;
+ q->ucounts = ucounts;
}
-
return q;
}
@@ -453,8 +452,10 @@ static void __sigqueue_free(struct sigqueue *q)
{
if (q->flags & SIGQUEUE_PREALLOC)
return;
- if (atomic_dec_and_test(&q->user->sigpending))
- free_uid(q->user);
+ if (q->ucounts && dec_rlimit_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING, 1)) {
+ put_ucounts(q->ucounts);
+ q->ucounts = NULL;
+ }
kmem_cache_free(sigqueue_cachep, q);
}

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