diff options
| -rw-r--r-- | include/linux/user_namespace.h | 2 | ||||
| -rw-r--r-- | kernel/cred.c | 9 | ||||
| -rw-r--r-- | kernel/signal.c | 25 | ||||
| -rw-r--r-- | kernel/ucount.c | 49 | ||||
| -rw-r--r-- | security/keys/process_keys.c | 8 |
5 files changed, 69 insertions, 24 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index eb70cabe6e7f..33a4240e6a6f 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -127,6 +127,8 @@ static inline long get_ucounts_value(struct ucounts *ucounts, enum ucount_type t long inc_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v); bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v); +long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum ucount_type type); +void dec_rlimit_put_ucounts(struct ucounts *ucounts, enum ucount_type type); bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsigned long max); static inline void set_rlimit_ucount_max(struct user_namespace *ns, diff --git a/kernel/cred.c b/kernel/cred.c index f784e08c2fbd..1ae0b4948a5a 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -225,8 +225,6 @@ struct cred *cred_alloc_blank(void) #ifdef CONFIG_DEBUG_CREDENTIALS new->magic = CRED_MAGIC; #endif - new->ucounts = get_ucounts(&init_ucounts); - if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0) goto error; @@ -501,7 +499,7 @@ int commit_creds(struct cred *new) inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1); rcu_assign_pointer(task->real_cred, new); rcu_assign_pointer(task->cred, new); - if (new->user != old->user) + if (new->user != old->user || new->user_ns != old->user_ns) dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1); alter_cred_subscribers(old, -2); @@ -669,7 +667,7 @@ int set_cred_ucounts(struct cred *new) { struct task_struct *task = current; const struct cred *old = task->real_cred; - struct ucounts *old_ucounts = new->ucounts; + struct ucounts *new_ucounts, *old_ucounts = new->ucounts; if (new->user == old->user && new->user_ns == old->user_ns) return 0; @@ -681,9 +679,10 @@ int set_cred_ucounts(struct cred *new) if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid)) return 0; - if (!(new->ucounts = alloc_ucounts(new->user_ns, new->euid))) + if (!(new_ucounts = alloc_ucounts(new->user_ns, new->euid))) return -EAGAIN; + new->ucounts = new_ucounts; if (old_ucounts) put_ucounts(old_ucounts); diff --git a/kernel/signal.c b/kernel/signal.c index 952741f6d0f9..487bf4f5dadf 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -426,22 +426,10 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags, */ rcu_read_lock(); ucounts = task_ucounts(t); - sigpending = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1); - switch (sigpending) { - case 1: - if (likely(get_ucounts(ucounts))) - break; - fallthrough; - case LONG_MAX: - /* - * we need to decrease the ucount in the userns tree on any - * failure to avoid counts leaking. - */ - dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1); - rcu_read_unlock(); - return NULL; - } + sigpending = inc_rlimit_get_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING); rcu_read_unlock(); + if (!sigpending) + return NULL; if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) { q = kmem_cache_alloc(sigqueue_cachep, gfp_flags); @@ -450,8 +438,7 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t gfp_flags, } if (unlikely(q == NULL)) { - if (dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING, 1)) - put_ucounts(ucounts); + dec_rlimit_put_ucounts(ucounts, UCOUNT_RLIMIT_SIGPENDING); } else { INIT_LIST_HEAD(&q->list); q->flags = sigqueue_flags; @@ -464,8 +451,8 @@ static void __sigqueue_free(struct sigqueue *q) { if (q->flags & SIGQUEUE_PREALLOC) return; - if (q->ucounts && dec_rlimit_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING, 1)) { - put_ucounts(q->ucounts); + if (q->ucounts) { + dec_rlimit_put_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING); q->ucounts = NULL; } kmem_cache_free(sigqueue_cachep, q); diff --git a/kernel/ucount.c b/kernel/ucount.c index bb51849e6375..eb03f3c68375 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -284,6 +284,55 @@ bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v) return (new == 0); } +static void do_dec_rlimit_put_ucounts(struct ucounts *ucounts, + struct ucounts *last, enum ucount_type type) +{ + struct ucounts *iter, *next; + for (iter = ucounts; iter != last; iter = next) { + long dec = atomic_long_add_return(-1, &iter->ucount[type]); + WARN_ON_ONCE(dec < 0); + next = iter->ns->ucounts; + if (dec == 0) + put_ucounts(iter); + } +} + +void dec_rlimit_put_ucounts(struct ucounts *ucounts, enum ucount_type type) +{ + do_dec_rlimit_put_ucounts(ucounts, NULL, type); +} + +long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum ucount_type type) +{ + /* Caller must hold a reference to ucounts */ + struct ucounts *iter; + long dec, ret = 0; + + for (iter = ucounts; iter; iter = iter->ns->ucounts) { + long max = READ_ONCE(iter->ns->ucount_max[type]); + long new = atomic_long_add_return(1, &iter->ucount[type]); + if (new < 0 || new > max) + goto unwind; + if (iter == ucounts) + ret = new; + /* + * Grab an extra ucount reference for the caller when + * the rlimit count was previously 0. + */ + if (new != 1) + continue; + if (!get_ucounts(iter)) + goto dec_unwind; + } + return ret; +dec_unwind: + dec = atomic_long_add_return(-1, &iter->ucount[type]); + WARN_ON_ONCE(dec < 0); +unwind: + do_dec_rlimit_put_ucounts(ucounts, iter, type); + return 0; +} + bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsigned long max) { struct ucounts *iter; diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index e3d79a7b6db6..b5d5333ab330 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -918,6 +918,13 @@ void key_change_session_keyring(struct callback_head *twork) return; } + /* If get_ucounts fails more bits are needed in the refcount */ + if (unlikely(!get_ucounts(old->ucounts))) { + WARN_ONCE(1, "In %s get_ucounts failed\n", __func__); + put_cred(new); + return; + } + new-> uid = old-> uid; new-> euid = old-> euid; new-> suid = old-> suid; @@ -927,6 +934,7 @@ void key_change_session_keyring(struct callback_head *twork) new-> sgid = old-> sgid; new->fsgid = old->fsgid; new->user = get_uid(old->user); + new->ucounts = old->ucounts; new->user_ns = get_user_ns(old->user_ns); new->group_info = get_group_info(old->group_info); |