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authorLinus Torvalds <torvalds@linux-foundation.org>2017-05-12 11:39:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-12 11:39:59 -0700
commit050453295f808dd683b9a88f58a1b29540097394 (patch)
tree1d43b39b72779d9133de345a96a6ea92cf96582c /fs/namespace.c
parente0c4a5fc750e22c6f8d5c1ab7cc18592b88852ab (diff)
parent4f757f3cbf54edef7b75c68d6d6d2f1a0ca08d2e (diff)
Merge branch 'work.sane_pwd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc vfs updates from Al Viro: "Making sure that something like a referral point won't end up as pwd or root. The main part is the last commit (fixing mntns_install()); that one fixes a hard-to-hit race. The fchdir() commit is making fchdir(2) a bit more robust - it should be impossible to get opened files (even O_PATH ones) for referral points in the first place, so the existing checks are OK, but checking the same thing as in chdir(2) is just as cheap. The path_init() commit removes a redundant check that shouldn't have been there in the first place" * 'work.sane_pwd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: make sure that mntns_install() doesn't end up with referral for root path_init(): don't bother with checking MAY_EXEC for LOOKUP_ROOT make sure that fchdir() won't accept referral points, etc.
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index b3b115bd4e1e..8bd3e4d448b9 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3462,8 +3462,9 @@ static void mntns_put(struct ns_common *ns)
static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns)
{
struct fs_struct *fs = current->fs;
- struct mnt_namespace *mnt_ns = to_mnt_ns(ns);
+ struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns;
struct path root;
+ int err;
if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
!ns_capable(current_user_ns(), CAP_SYS_CHROOT) ||
@@ -3474,15 +3475,18 @@ static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns)
return -EINVAL;
get_mnt_ns(mnt_ns);
- put_mnt_ns(nsproxy->mnt_ns);
+ old_mnt_ns = nsproxy->mnt_ns;
nsproxy->mnt_ns = mnt_ns;
/* Find the root */
- root.mnt = &mnt_ns->root->mnt;
- root.dentry = mnt_ns->root->mnt.mnt_root;
- path_get(&root);
- while(d_mountpoint(root.dentry) && follow_down_one(&root))
- ;
+ err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt,
+ "/", LOOKUP_DOWN, &root);
+ if (err) {
+ /* revert to old namespace */
+ nsproxy->mnt_ns = old_mnt_ns;
+ put_mnt_ns(mnt_ns);
+ return err;
+ }
/* Update the pwd and root */
set_fs_pwd(fs, &root);