From ab39ce7d97da873d53278399bc82f42a3e158a79 Mon Sep 17 00:00:00 2001
From: Christian Brauner <brauner@kernel.org>
Date: Tue, 11 Feb 2025 18:16:00 +0100
Subject: [PATCH] acct: block access to kernel internal filesystems
commit 890ed45bde808c422c3c27d3285fc45affa0f930 upstream.
There's no point in allowing anything kernel internal nor procfs or
sysfs.
Link: https://lore.kernel.org/r/20250127091811.3183623-1-quzicheng@huawei.com
Link: https://lore.kernel.org/r/20250211-work-acct-v1-2-1c16aecab8b3@kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reported-by: Zicheng Qu <quzicheng@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/acct.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/kernel/acct.c b/kernel/acct.c
index 5bab78747ed37..d9d55fa4d01a7 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -243,6 +243,20 @@ static int acct_on(struct filename *pathname)
return -EACCES;
}
+ /* Exclude kernel kernel internal filesystems. */
+ if (file_inode(file)->i_sb->s_flags & (SB_NOUSER | SB_KERNMOUNT)) {
+ kfree(acct);
+ filp_close(file, NULL);
+ return -EINVAL;
+ }
+
+ /* Exclude procfs and sysfs. */
+ if (file_inode(file)->i_sb->s_iflags & SB_I_USERNS_VISIBLE) {
+ kfree(acct);
+ filp_close(file, NULL);
+ return -EINVAL;
+ }
+
if (!(file->f_mode & FMODE_CAN_WRITE)) {
kfree(acct);
filp_close(file, NULL);
--
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