Re: [PATCH 2/2] acct: block access to kernel internal filesystems

On Tue, Feb 11, 2025 at 6:17 PM Christian Brauner brauner@kernel.org wrote:

There's no point in allowing anything kernel internal nor procfs or sysfs.

Reported-by: Zicheng Qu quzicheng@huawei.com Link: https://lore.kernel.org/r/20250127091811.3183623-1-quzicheng@huawei.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner brauner@kernel.org

Reviewed-by: Amir Goldstein amir73il@gmail.com

---

kernel/acct.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)

diff --git a/kernel/acct.c b/kernel/acct.c index 48283efe8a12..6520baa13669 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);
  
  

-- 2.47.2