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authorAmir Goldstein <amir73il@gmail.com>2018-11-14 16:01:34 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2018-11-19 16:21:29 +0100
commit91ff20f34e94424e586f57f4f593beae16504f86 (patch)
tree0ced724127ec90e38c993af075847ea37b00f52e
parent9ff01193a20d391e8dbce4403dd5ef87c7eaaca6 (diff)
downloadlinux-91ff20f34e94424e586f57f4f593beae16504f86.tar.bz2
ovl: fix missing override creds in link of a metacopy upper
Theodore Ts'o reported a v4.19 regression with docker-dropbox: https://marc.info/?l=linux-fsdevel&m=154070089431116&w=2 "I was rebuilding my dropbox Docker container, and it failed in 4.19 with the following error: ... dpkg: error: error creating new backup file \ '/var/lib/dpkg/status-old': Invalid cross-device link" The problem did not reproduce with metacopy feature disabled. The error was caused by insufficient credentials to set "trusted.overlay.redirect" xattr on link of a metacopy file. Reproducer: echo Y > /sys/module/overlay/parameters/redirect_dir echo Y > /sys/module/overlay/parameters/metacopy cd /tmp mkdir l u w m chmod 777 l u touch l/foo ln l/foo l/link chmod 666 l/foo mount -t overlay none -olowerdir=l,upperdir=u,workdir=w m su fsgqa ln m/foo m/bar [ 21.455823] overlayfs: failed to set redirect (-1) ln: failed to create hard link 'm/bar' => 'm/foo':\ Invalid cross-device link Reported-by: Theodore Y. Ts'o <tytso@mit.edu> Reported-by: Maciej Zięba <maciekz82@gmail.com> Fixes: 4120fe64dce4 ("ovl: Set redirect on upper inode when it is linked") Cc: <stable@vger.kernel.org> # v4.19 Signed-off-by: Amir Goldstein <amir73il@gmail.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-rw-r--r--fs/overlayfs/dir.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index c6289147c787..82c129bfe58d 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -651,6 +651,18 @@ static int ovl_symlink(struct inode *dir, struct dentry *dentry,
return ovl_create_object(dentry, S_IFLNK, 0, link);
}
+static int ovl_set_link_redirect(struct dentry *dentry)
+{
+ const struct cred *old_cred;
+ int err;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_set_redirect(dentry, false);
+ revert_creds(old_cred);
+
+ return err;
+}
+
static int ovl_link(struct dentry *old, struct inode *newdir,
struct dentry *new)
{
@@ -670,7 +682,7 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
goto out_drop_write;
if (ovl_is_metacopy_dentry(old)) {
- err = ovl_set_redirect(old, false);
+ err = ovl_set_link_redirect(old);
if (err)
goto out_drop_write;
}