So far redirect could be placed on directories only and now it can be
placed on regular files as well. Also it could be completely removed
when a metacopy copy up file's data is copied up. That means if a redirect
is present during ovl_lookup(), it could be gone by the time ovl_get_inode()
happens.
Or it is possible that ovl_lookup() does not see a redirect and a rename
is taking place on a hard link and that places a redirect. And by the
time ovl_lookup() calls ovl_get_inode(), it sets ovl_inode->redirect = NULL
(Assume inode got flushed out of cache and was allocated new).
IOW, because we check and process redirect without locks in ovl_lookup(),
many possibilities open up for regular files. So for such cases, do not
use the redirect provided by the caller. Instead query it and install
in ovl_inode->redirect.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
fs/overlayfs/inode.c | 19 ++++++++++++++++++-
fs/overlayfs/overlayfs.h | 1 +
fs/overlayfs/util.c | 42 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 61 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 3dccfa1ee123..6a0c85699024 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -694,6 +694,7 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index);
bool is_dir, metacopy = false;
int err = -ENOMEM;
+ char *new_redirect = NULL;
if (!realinode)
realinode = d_inode(lowerdentry);
@@ -754,7 +755,18 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
if (upperdentry && !metacopy)
ovl_set_flag(OVL_UPPERDATA, inode);
- OVL_I(inode)->redirect = redirect;
+ if (!metacopy) {
+ OVL_I(inode)->redirect = redirect;
+ redirect = NULL;
+ } else if (upperdentry) {
+ new_redirect = ovl_get_redirect_xattr(upperdentry);
+ if (IS_ERR(new_redirect)) {
+ err = PTR_ERR(new_redirect);
+ goto out_err_inode;
+ }
+ OVL_I(inode)->redirect = new_redirect;
+ new_redirect = NULL;
+ }
/* Check for non-merge dir that may have whiteouts */
if (is_dir) {
@@ -764,11 +776,16 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
}
}
+ kfree(redirect);
if (inode->i_state & I_NEW)
unlock_new_inode(inode);
out:
return inode;
+out_err_inode:
+ if (inode->i_state & I_NEW)
+ unlock_new_inode(inode);
+ iput(inode);
out_err:
inode = ERR_PTR(err);
goto out;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 429713653b3b..a3bee7619fbb 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -279,6 +279,7 @@ void ovl_nlink_end_locked(struct dentry *dentry);
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
int ovl_check_metacopy_xattr(struct dentry *dentry);
bool ovl_is_metacopy_dentry(struct dentry *dentry);
+char *ovl_get_redirect_xattr(struct dentry *dentry);
static inline bool ovl_is_impuredir(struct dentry *dentry)
{
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 961d65bd25c9..3d090b6f9fc2 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -833,3 +833,45 @@ bool ovl_is_metacopy_dentry(struct dentry *dentry)
return (oe->numlower > 1);
}
+
+char *ovl_get_redirect_xattr(struct dentry *dentry)
+{
+ int res;
+ char *s, *next, *buf = NULL;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return NULL;
+ return ERR_PTR(res);
+ }
+
+ buf = kzalloc(res + 1, GFP_KERNEL);
+ if (!buf)
+ return ERR_PTR(-ENOMEM);
+
+ res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
+ if (res < 0) {
+ kfree(buf);
+ return ERR_PTR(res);
+ }
+ if (res == 0)
+ goto invalid;
+
+ if (buf[0] == '/') {
+ for (s = buf; *s++ == '/'; s = next) {
+ next = strchrnul(s, '/');
+ if (s == next)
+ goto invalid;
+ }
+ } else {
+ if (strchr(buf, '/') != NULL)
+ goto invalid;
+ }
+
+ return buf;
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
+ kfree(buf);
+ return ERR_PTR(-EINVAL);
+}
--
2.13.6
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