* Missing check for CAP_SYS_ADMIN before calling reconfigure_super()
@ 2021-05-31 15:17 tianyu zhou
0 siblings, 0 replies; only message in thread
From: tianyu zhou @ 2021-05-31 15:17 UTC (permalink / raw)
To: Alexander Viro, linux-fsdevel
Hi, there exists a check for CAP_SYS_ADMIN in do_remount(),
do_umount() and vfs_fsconfig_locked() before they finally call
reconfigure_super().
---------------------
// fs/namespace.c
static int do_umount(struct mount *mnt, int flags)
{
...
if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
return -EPERM;
return do_umount_root(sb);
...
}
static int do_umount_root(struct super_block *sb)
{
...
ret = reconfigure_super(fc);
...
}
---------------------
However, for function do_emergency_remount_callback(), vfs_get_super()
and reconfigure_single() in fs/super.c, there is no such check for
CAP_SYS_ADMIN before calling reconfigure_super(), neither do their
callers.
Is this a missing check bug which may break the protection for superblock?
Thanks!
Best regards,
Tianyu
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2021-05-31 15:17 Missing check for CAP_SYS_ADMIN before calling reconfigure_super() tianyu zhou
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