[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20230713141001.27046-1-cyphar@cyphar.com>
Date: Fri, 14 Jul 2023 00:09:58 +1000
From: Aleksa Sarai <cyphar@...har.com>
To: Christian Brauner <brauner@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Dave Chinner <dchinner@...hat.com>,
xu xin <cgel.zte@...il.com>, Al Viro <viro@...iv.linux.org.uk>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Zhihao Cheng <chengzhihao1@...wei.com>,
Stefan Roesch <shr@...kernel.io>,
Janis Danisevskis <jdanis@...gle.com>,
Kees Cook <keescook@...omium.org>
Cc: Thomas Weißschuh <thomas@...ch.de>,
Aleksa Sarai <cyphar@...har.com>, stable@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH v2] procfs: block chmod on /proc/thread-self/comm
Due to an oversight in commit 1b3044e39a89 ("procfs: fix pthread
cross-thread naming if !PR_DUMPABLE") in switching from REG to NOD,
chmod operations on /proc/thread-self/comm were no longer blocked as
they are on almost all other procfs files.
A very similar situation with /proc/self/environ was used to as a root
exploit a long time ago, but procfs has SB_I_NOEXEC so this is simply a
correctness issue.
Ref: https://lwn.net/Articles/191954/
Ref: 6d76fa58b050 ("Don't allow chmod() on the /proc/<pid>/ files")
Fixes: 1b3044e39a89 ("procfs: fix pthread cross-thread naming if !PR_DUMPABLE")
Cc: stable@...r.kernel.org # v4.7+
Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
v2: removed nolibc selftests as per review
v1: <https://lore.kernel.org/linux-fsdevel/20230713121907.9693-1-cyphar@cyphar.com/>
---
fs/proc/base.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 05452c3b9872..7394229816f3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3583,7 +3583,8 @@ static int proc_tid_comm_permission(struct mnt_idmap *idmap,
}
static const struct inode_operations proc_tid_comm_inode_operations = {
- .permission = proc_tid_comm_permission,
+ .setattr = proc_setattr,
+ .permission = proc_tid_comm_permission,
};
/*
--
2.41.0
Powered by blists - more mailing lists