From: "Eric W. Biederman" <ebiederm@xmission.com>
To: linux-kernel@vger.kernel.org
Cc: "Alexey Gladkov" <legion@kernel.org>,
"Kees Cook" <keescook@chromium.org>,
"Shuah Khan" <shuah@kernel.org>,
"Christian Brauner" <brauner@kernel.org>,
"Solar Designer" <solar@openwall.com>,
"Ran Xiaokai" <ran.xiaokai@zte.com.cn>,
containers@lists.linux-foundation.org,
"Michal Koutný" <mkoutny@suse.com>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 8/8] ucounts: Use the same code to enforce RLIMIT_NPROC in fork and exec
Date: Thu, 10 Feb 2022 20:13:24 -0600 [thread overview]
Message-ID: <20220211021324.4116773-8-ebiederm@xmission.com> (raw)
In-Reply-To: <87o83e2mbu.fsf@email.froward.int.ebiederm.org>
Historically these pieces of code have slightly diverged and caused
problems. To avoid that in the future create a common function to see
if RLIMIT_NPROC is over a limit and the limit should be enforced.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/exec.c | 7 ++-----
include/linux/sched/signal.h | 2 ++
kernel/fork.c | 25 +++++++++++++++++++------
3 files changed, 23 insertions(+), 11 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 01c8c7bae9b4..8913dbb9a479 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1875,14 +1875,11 @@ static int do_execveat_common(int fd, struct filename *filename,
return PTR_ERR(filename);
/*
- * After calling set*uid() is RLIMT_NPROC exceeded?
+ * After calling set*uid() is RLIMIT_NPROC exceeded?
* This can not be checked in set*uid() because too many programs don't
* check the setuid() return code.
*/
- if ((current->flags & PF_NPROC_CHECK) &&
- is_ucounts_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)) &&
- (current_ucounts() != &init_ucounts) &&
- !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
+ if ((current->flags & PF_NPROC_CHECK) && is_nproc_overlimit()) {
retval = -EAGAIN;
goto out_ret;
}
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index b6ecb9fc4cd2..b682131c52fa 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -742,4 +742,6 @@ static inline unsigned long rlimit_max(unsigned int limit)
return task_rlimit_max(current, limit);
}
+extern bool is_nproc_overlimit(void);
+
#endif /* _LINUX_SCHED_SIGNAL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index 79661678a5bf..a18f15053e22 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1891,6 +1891,23 @@ static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
mutex_unlock(&oom_adj_mutex);
}
+static bool is_task_nproc_overlimit(struct task_struct *task)
+{
+ struct ucounts *ucounts = task_ucounts(task);
+ /* clone does not change RLIMIT_NPROC. The parents value is safe. */
+ unsigned long limit = rlimit(RLIMIT_NPROC);
+
+ return is_ucounts_overlimit(ucounts, UCOUNT_RLIMIT_NPROC, limit) &&
+ (ucounts != &init_ucounts) &&
+ !has_capability(task, CAP_SYS_RESOURCE) &&
+ !has_capability(task, CAP_SYS_ADMIN);
+}
+
+bool is_nproc_overlimit(void)
+{
+ return is_task_nproc_overlimit(current);
+}
+
/*
* This creates a new process as a copy of the old one,
* but does not actually start it yet.
@@ -2028,12 +2045,8 @@ static __latent_entropy struct task_struct *copy_process(
retval = -EAGAIN;
if (inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1) == LONG_MAX)
goto bad_fork_cleanup_count;
- if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
- if ((task_ucounts(p) != &init_ucounts) &&
- !has_capability(p, CAP_SYS_RESOURCE) &&
- !has_capability(p, CAP_SYS_ADMIN))
- goto bad_fork_cleanup_count;
- }
+ if (is_task_nproc_overlimit(p))
+ goto bad_fork_cleanup_count;
current->flags &= ~PF_NPROC_CHECK;
/*
--
2.29.2
next prev parent reply other threads:[~2022-02-11 2:14 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 12:17 [RFC PATCH 0/6] RLIMIT_NPROC in ucounts fixups Michal Koutný
2022-02-07 12:17 ` [RFC PATCH 1/6] set_user: Perform RLIMIT_NPROC capability check against new user credentials Michal Koutný
2022-02-10 1:14 ` Solar Designer
2022-02-10 1:57 ` Eric W. Biederman
2022-02-11 20:32 ` Eric W. Biederman
2022-02-12 22:14 ` Solar Designer
2022-02-15 11:55 ` Michal Koutný
2022-02-07 12:17 ` [RFC PATCH 2/6] set*uid: Check RLIMIT_PROC against new credentials Michal Koutný
2022-02-07 12:17 ` [RFC PATCH 3/6] cred: Count tasks by their real uid into RLIMIT_NPROC Michal Koutný
2022-02-07 12:17 ` [RFC PATCH 4/6] ucounts: Allow root to override RLIMIT_NPROC Michal Koutný
2022-02-10 0:21 ` Eric W. Biederman
2022-02-07 12:17 ` [RFC PATCH 5/6] selftests: Challenge RLIMIT_NPROC in user namespaces Michal Koutný
2022-02-10 1:22 ` Shuah Khan
2022-02-15 9:45 ` Michal Koutný
2022-02-07 12:18 ` [RFC PATCH 6/6] selftests: Test RLIMIT_NPROC in clone-created " Michal Koutný
2022-02-10 1:25 ` Shuah Khan
2022-02-15 9:34 ` Michal Koutný
2022-02-08 13:54 ` [RFC PATCH 0/6] RLIMIT_NPROC in ucounts fixups Eric W. Biederman
2022-02-11 2:01 ` [PATCH 0/8] ucounts: RLIMIT_NPROC fixes Eric W. Biederman
2022-02-11 2:13 ` [PATCH 1/8] ucounts: Fix RLIMIT_NPROC regression Eric W. Biederman
2022-02-14 18:37 ` Michal Koutný
2022-02-16 15:22 ` Eric W. Biederman
2022-02-11 2:13 ` [PATCH 2/8] ucounts: Fix set_cred_ucounts Eric W. Biederman
2022-02-15 11:10 ` Michal Koutný
2022-02-11 2:13 ` [PATCH 3/8] ucounts: Fix and simplify RLIMIT_NPROC handling during setuid()+execve Eric W. Biederman
2022-02-12 23:17 ` Solar Designer
2022-02-14 15:10 ` Eric W. Biederman
2022-02-14 17:43 ` Eric W. Biederman
2022-02-15 10:25 ` Michal Koutný
2022-02-16 15:35 ` Eric W. Biederman
2022-02-11 2:13 ` [PATCH 4/8] ucounts: Only except the root user in init_user_ns from RLIMIT_NPROC Eric W. Biederman
2022-02-15 10:54 ` Michal Koutný
2022-02-16 15:41 ` Eric W. Biederman
2022-02-11 2:13 ` [PATCH 5/8] ucounts: Handle wrapping in is_ucounts_overlimit Eric W. Biederman
2022-02-12 22:36 ` Solar Designer
2022-02-14 15:23 ` Eric W. Biederman
2022-02-14 15:23 ` Eric W. Biederman
2022-02-15 11:25 ` Michal Koutný
2022-02-14 17:16 ` David Laight
2022-02-11 2:13 ` [PATCH 6/8] ucounts: Handle inc_rlimit_ucounts wrapping in fork Eric W. Biederman
2022-02-11 11:34 ` Alexey Gladkov
2022-02-11 17:50 ` Eric W. Biederman
2022-02-11 18:32 ` Shuah Khan
2022-02-11 18:40 ` Alexey Gladkov
2022-02-11 19:56 ` Eric W. Biederman
2022-02-11 2:13 ` [PATCH 7/8] rlimit: For RLIMIT_NPROC test the child not the parent for capabilites Eric W. Biederman
2022-02-11 2:13 ` Eric W. Biederman [this message]
2022-02-11 18:22 ` [PATCH 0/8] ucounts: RLIMIT_NPROC fixes Shuah Khan
2022-02-11 19:23 ` Eric W. Biederman
2022-02-15 11:37 ` Michal Koutný
2022-02-16 15:56 ` [PATCH v2 0/5] " Eric W. Biederman
2022-02-16 15:58 ` [PATCH v2 1/5] rlimit: Fix RLIMIT_NPROC enforcement failure caused by capability calls in set_user Eric W. Biederman
2022-02-16 17:42 ` Solar Designer
2022-02-16 15:58 ` [PATCH v2 2/5] ucounts: Enforce RLIMIT_NPROC not RLIMIT_NPROC+1 Eric W. Biederman
2022-02-16 15:58 ` [PATCH v2 3/5] ucounts: Base set_cred_ucounts changes on the real user Eric W. Biederman
2022-02-16 15:58 ` [PATCH v2 4/5] ucounts: Move RLIMIT_NPROC handling after set_user Eric W. Biederman
2022-02-16 15:58 ` [PATCH v2 5/5] ucounts: Handle wrapping in is_ucounts_overlimit Eric W. Biederman
2022-02-16 17:28 ` Shuah Khan
2022-02-18 15:34 ` [GIT PULL] ucounts: RLIMIT_NPROC fixes for v5.17 Eric W. Biederman
2022-02-20 19:05 ` pr-tracker-bot
2022-03-03 0:12 ` [GIT PULL] ucounts: Regression fix " Eric W. Biederman
2022-03-03 0:30 ` pr-tracker-bot
2022-02-12 15:32 ` [RFC PATCH 0/6] RLIMIT_NPROC in ucounts fixups Etienne Dechamps
2022-02-15 10:11 ` Michal Koutný
2022-02-23 0:57 ` Eric W. Biederman
2022-02-23 18:00 ` How should rlimits, suid exec, and capabilities interact? Eric W. Biederman
2022-02-23 19:44 ` Andy Lutomirski
2022-02-23 21:28 ` Willy Tarreau
2022-02-23 19:50 ` Linus Torvalds
2022-02-24 1:24 ` Eric W. Biederman
2022-02-24 1:41 ` Linus Torvalds
2022-02-24 2:12 ` Eric W. Biederman
2022-02-24 15:41 ` [PATCH] ucounts: Fix systemd LimigtNPROC with private users regression Eric W. Biederman
2022-02-24 16:28 ` Kees Cook
2022-02-24 18:53 ` Michal Koutný
2022-02-25 0:29 ` Eric W. Biederman
2022-02-24 3:00 ` How should rlimits, suid exec, and capabilities interact? David Laight
2022-02-24 1:32 ` Eric W. Biederman
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