From ccf61486fe1e1a48e18c638d1813cda77b3c0737 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Fri, 14 Jul 2023 00:09:58 +1000 Subject: 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// files") Fixes: 1b3044e39a89 ("procfs: fix pthread cross-thread naming if !PR_DUMPABLE") Cc: stable@vger.kernel.org # v4.7+ Signed-off-by: Aleksa Sarai Message-Id: <20230713141001.27046-1-cyphar@cyphar.com> Signed-off-by: Christian Brauner --- fs/proc/base.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/proc') 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, }; /* -- cgit