[PATCH 1/5] cifs: shared-superblock: create a root dentry/inode for EACCES error

[s***@gmail.com]

From: shirish <***@gmail.com>

It is possible that an authenticated user has access to a subdirectory being
mounted but does not have access to the share directory at the server to be
mounted on a root directory.
Create an dummy inode with ROOT_I and continue the mount process.

Signed-off-by: Shirish Pargaonkar <***@suse.com>
---
fs/cifs/inode.c | 36 ++++++++++++++++++++++++++++++++----
1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 41de393..fd5941b 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -889,8 +889,10 @@ inode_has_hashed_dentries(struct inode *inode)
spin_lock(&inode->i_lock);
hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
if (!d_unhashed(dentry) || IS_ROOT(dentry)) {
- spin_unlock(&inode->i_lock);
- return true;
+ if (!(dentry->d_flags & DCACHE_DISCONNECTED)) {
+ spin_unlock(&inode->i_lock);
+ return true;
+ }
}
}
spin_unlock(&inode->i_lock);
@@ -942,6 +944,23 @@ retry_iget5_locked:
return inode;
}

+void
+fill_phfattr(struct cifs_fattr *cf, struct super_block *sb)
+{
+
+ struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+
+ memset(cf, 0, sizeof(*cf));
+ cf->cf_uniqueid = ROOT_I;
+ cf->cf_nlink = 1;
+ cf->cf_atime = CURRENT_TIME;
+ cf->cf_ctime = CURRENT_TIME;
+ cf->cf_mtime = CURRENT_TIME;
+ cf->cf_mode = S_IFDIR | S_IXUGO | S_IRWXU;
+ cf->cf_uid = cifs_sb->mnt_uid;
+ cf->cf_gid = cifs_sb->mnt_gid;
+}
+
/* gets root inode */
struct inode *cifs_root_iget(struct super_block *sb)
{
@@ -950,6 +969,7 @@ struct inode *cifs_root_iget(struct super_block *sb)
struct inode *inode = NULL;
long rc;
struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+ struct cifs_fattr phfattr;

xid = get_xid();
if (tcon->unix_ext)
@@ -958,8 +978,16 @@ struct inode *cifs_root_iget(struct super_block *sb)
rc = cifs_get_inode_info(&inode, "", NULL, sb, xid, NULL);

if (!inode) {
- inode = ERR_PTR(rc);
- goto out;
+ if (rc == -EACCES) {
+ fill_phfattr(&phfattr, sb);
+ inode = cifs_iget(sb, &phfattr);
+ if (inode)
+ rc = 0;
+ }
+ if (rc) {
+ inode = ERR_PTR(rc);
+ goto out;
+ }
}

#ifdef CONFIG_CIFS_FSCACHE