linux-kernel - [PATCH] set_user: add capability check when rlimit(RLIMIT

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Date:   Wed, 28 Jul 2021 00:26:29 -0700
From:   cgel.zte@...il.com
To:     christian.brauner@...ntu.com, peterz@...radead.org,
        tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org, Ran Xiaokai <ran.xiaokai@....com.cn>
Subject: [PATCH] set_user: add capability check when rlimit(RLIMIT_NPROC) exceeds

From: Ran Xiaokai <ran.xiaokai@....com.cn>

in copy_process(): non root users but with capability CAP_SYS_RESOURCE
or CAP_SYS_ADMIN will clean PF_NPROC_EXCEEDED flag even
rlimit(RLIMIT_NPROC) exceeds. Add the same capability check logic here.

Signed-off-by: Ran Xiaokai <ran.xiaokai@....com.cn>
---
 kernel/sys.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index ef1a78f5d71c..72c7639e3c98 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -480,7 +480,8 @@ static int set_user(struct cred *new)
 	 * failure to the execve() stage.
 	 */
 	if (is_ucounts_overlimit(new->ucounts, UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)) &&
-			new_user != INIT_USER)
+			new_user != INIT_USER &&
+			!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
 		current->flags |= PF_NPROC_EXCEEDED;
 	else
 		current->flags &= ~PF_NPROC_EXCEEDED;
-- 
2.25.1