netdev - [PATCH 08/16] binfmt_misc: use credential guards

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251103-work-creds-guards-simple-v1-8-a3e156839e7f@kernel.org>
Date: Mon, 03 Nov 2025 12:26:56 +0100
From: Christian Brauner <brauner@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-aio@...ck.org, linux-unionfs@...r.kernel.org, 
 linux-erofs@...ts.ozlabs.org, linux-nfs@...r.kernel.org, 
 linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org, 
 cgroups@...r.kernel.org, netdev@...r.kernel.org, 
 Christian Brauner <brauner@...nel.org>
Subject: [PATCH 08/16] binfmt_misc: use credential guards

Use credential guards for scoped credential override with automatic
restoration on scope exit.

Signed-off-by: Christian Brauner <brauner@...nel.org>
---
 fs/binfmt_misc.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index a839f960cd4a..558db4bd6c2a 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -782,8 +782,6 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
 		return PTR_ERR(e);
 
 	if (e->flags & MISC_FMT_OPEN_FILE) {
-		const struct cred *old_cred;
-
 		/*
 		 * Now that we support unprivileged binfmt_misc mounts make
 		 * sure we use the credentials that the register @file was
@@ -791,9 +789,8 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
 		 * didn't matter much as only a privileged process could open
 		 * the register file.
 		 */
-		old_cred = override_creds(file->f_cred);
-		f = open_exec(e->interpreter);
-		revert_creds(old_cred);
+		scoped_with_creds(file->f_cred)
+			f = open_exec(e->interpreter);
 		if (IS_ERR(f)) {
 			pr_notice("register: failed to install interpreter file %s\n",
 				 e->interpreter);

-- 
2.47.3