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| author | Al Viro <viro@zeniv.linux.org.uk> | 2021-01-04 21:25:34 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2021-01-04 21:31:58 +0100 |
| commit | a0a6df9afcaf439a6b4c88a3b522e3d05fdef46f (patch) | |
| tree | 7ef2ed36a935d9643b6e6b50988054a603187755 /fs | |
| parent | Linux 5.11-rc1 (diff) | |
| download | linux-a0a6df9afcaf439a6b4c88a3b522e3d05fdef46f.tar.xz linux-a0a6df9afcaf439a6b4c88a3b522e3d05fdef46f.zip | |
umount(2): move the flag validity checks first
Unfortunately, there's userland code that used to rely upon these
checks being done before anything else to check for UMOUNT_NOFOLLOW
support. That broke in 41525f56e256 ("fs: refactor ksys_umount").
Separate those from the rest of checks and move them to ksys_umount();
unlike everything else in there, this can be sanely done there.
Reported-by: Sargun Dhillon <sargun@sargun.me>
Fixes: 41525f56e256 ("fs: refactor ksys_umount")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namespace.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index d2db7dfe232b..9d33909d0f9e 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1713,8 +1713,6 @@ static int can_umount(const struct path *path, int flags) { struct mount *mnt = real_mount(path->mnt); - if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) - return -EINVAL; if (!may_mount()) return -EPERM; if (path->dentry != path->mnt->mnt_root) @@ -1728,6 +1726,7 @@ static int can_umount(const struct path *path, int flags) return 0; } +// caller is responsible for flags being sane int path_umount(struct path *path, int flags) { struct mount *mnt = real_mount(path->mnt); @@ -1749,6 +1748,10 @@ static int ksys_umount(char __user *name, int flags) struct path path; int ret; + // basic validity checks done first + if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) + return -EINVAL; + if (!(flags & UMOUNT_NOFOLLOW)) lookup_flags |= LOOKUP_FOLLOW; ret = user_path_at(AT_FDCWD, name, lookup_flags, &path); |