diff options
| author | Alexey Gladkov <legion@kernel.org> | 2021-04-22 14:27:13 +0200 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2021-04-30 14:14:02 -0500 |
| commit | d64696905554e919321e31afc210606653b8f6a4 (patch) | |
| tree | 7c153f685f7e89823fc6c0b3e420d8fff12037df /kernel | |
| parent | 6e52a9f0532f912af37bab4caf18b57d1b9845f4 (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')
| -rw-r--r-- | kernel/fork.c | 1 | ||||
| -rw-r--r-- | kernel/signal.c | 25 | ||||
| -rw-r--r-- | kernel/ucount.c | 1 | ||||
| -rw-r--r-- | kernel/user.c | 1 | ||||
| -rw-r--r-- | kernel/user_namespace.c | 1 |
5 files changed, 16 insertions, 13 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index a9c5097dfc86..03119926b27d 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -824,6 +824,7 @@ void __init fork_init(void) init_user_ns.ucount_max[UCOUNT_RLIMIT_NPROC] = task_rlimit(&init_task, RLIMIT_NPROC); init_user_ns.ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = task_rlimit(&init_task, RLIMIT_MSGQUEUE); + init_user_ns.ucount_max[UCOUNT_RLIMIT_SIGPENDING] = task_rlimit(&init_task, RLIMIT_SIGPENDING); #ifdef CONFIG_VMAP_STACK cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", 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); } diff --git a/kernel/ucount.c b/kernel/ucount.c index 6e6f936a5963..8ce62da6a62c 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -82,6 +82,7 @@ static struct ctl_table user_table[] = { #endif { }, { }, + { }, { } }; #endif /* CONFIG_SYSCTL */ diff --git a/kernel/user.c b/kernel/user.c index 7f5ff498207a..6737327f83be 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -98,7 +98,6 @@ static DEFINE_SPINLOCK(uidhash_lock); /* root_user.__count is 1, for init task cred */ struct user_struct root_user = { .__count = REFCOUNT_INIT(1), - .sigpending = ATOMIC_INIT(0), .locked_shm = 0, .uid = GLOBAL_ROOT_UID, .ratelimit = RATELIMIT_STATE_INIT(root_user.ratelimit, 0, 0), diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 7eccc4f84549..822eacee4588 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -124,6 +124,7 @@ int create_user_ns(struct cred *new) } ns->ucount_max[UCOUNT_RLIMIT_NPROC] = rlimit(RLIMIT_NPROC); ns->ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = rlimit(RLIMIT_MSGQUEUE); + ns->ucount_max[UCOUNT_RLIMIT_SIGPENDING] = rlimit(RLIMIT_SIGPENDING); ns->ucounts = ucounts; /* Inherit USERNS_SETGROUPS_ALLOWED from our parent */ |