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authorMaxim Patlasov <mpatlasov@virtuozzo.com>2016-07-21 18:24:26 -0700
committerMiklos Szeredi <mszeredi@redhat.com>2016-07-22 10:54:20 +0200
commitcfc9fde0b07c3b44b570057c5f93dda59dca1c94 (patch)
tree7f36d4f2a49719673c436767707d25ef5f5e9041
parent07a2daab49c549a37b5b744cbebb6e3f445f12bc (diff)
downloadlinux-cfc9fde0b07c3b44b570057c5f93dda59dca1c94.tar.gz
linux-cfc9fde0b07c3b44b570057c5f93dda59dca1c94.tar.xz
ovl: verify upper dentry in ovl_remove_and_whiteout()
The upper dentry may become stale before we call ovl_lock_rename_workdir. For example, someone could (mistakenly or maliciously) manually unlink(2) it directly from upperdir. To ensure it is not stale, let's lookup it after ovl_lock_rename_workdir and and check if it matches the upper dentry. Essentially, it is the same problem and similar solution as in commit 11f3710417d0 ("ovl: verify upper dentry before unlink and rename"). Signed-off-by: Maxim Patlasov <mpatlasov@virtuozzo.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Cc: <stable@vger.kernel.org>
-rw-r--r--fs/overlayfs/dir.c54
1 files changed, 24 insertions, 30 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index c2a6b08..5c9d2d8 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -505,6 +505,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
struct dentry *upper;
struct dentry *opaquedir = NULL;
int err;
+ int flags = 0;
if (WARN_ON(!workdir))
return -EROFS;
@@ -534,46 +535,39 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
if (err)
goto out_dput;
- whiteout = ovl_whiteout(workdir, dentry);
- err = PTR_ERR(whiteout);
- if (IS_ERR(whiteout))
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
goto out_unlock;
- upper = ovl_dentry_upper(dentry);
- if (!upper) {
- upper = lookup_one_len(dentry->d_name.name, upperdir,
- dentry->d_name.len);
- err = PTR_ERR(upper);
- if (IS_ERR(upper))
- goto kill_whiteout;
-
- err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
- dput(upper);
- if (err)
- goto kill_whiteout;
- } else {
- int flags = 0;
+ err = -ESTALE;
+ if ((opaquedir && upper != opaquedir) ||
+ (!opaquedir && ovl_dentry_upper(dentry) &&
+ upper != ovl_dentry_upper(dentry))) {
+ goto out_dput_upper;
+ }
- if (opaquedir)
- upper = opaquedir;
- err = -ESTALE;
- if (upper->d_parent != upperdir)
- goto kill_whiteout;
+ whiteout = ovl_whiteout(workdir, dentry);
+ err = PTR_ERR(whiteout);
+ if (IS_ERR(whiteout))
+ goto out_dput_upper;
- if (is_dir)
- flags |= RENAME_EXCHANGE;
+ if (d_is_dir(upper))
+ flags = RENAME_EXCHANGE;
- err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
- if (err)
- goto kill_whiteout;
+ err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
+ if (err)
+ goto kill_whiteout;
+ if (flags)
+ ovl_cleanup(wdir, upper);
- if (is_dir)
- ovl_cleanup(wdir, upper);
- }
ovl_dentry_version_inc(dentry->d_parent);
out_d_drop:
d_drop(dentry);
dput(whiteout);
+out_dput_upper:
+ dput(upper);
out_unlock:
unlock_rename(workdir, upperdir);
out_dput: