fs/cifs: make share unaccessible at root level mountable

[firefly-linux-kernel-4.4.55.git] / fs / cifs / dir.c

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index c3eb998a99bd18a2ed9b7b843c99be15fedab9df..b95bffcee8aa05df96ef9fac8ab2c0fef2d5d741 100644 (file)
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -84,6 +84,7 @@ build_path_from_dentry(struct dentry *direntry)
        struct dentry *temp;
        int namelen;
        int dfsplen;
+       int pplen = 0;
        char *full_path;
        char dirsep;
        struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
@@ -95,8 +96,12 @@ build_path_from_dentry(struct dentry *direntry)
                dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
        else
                dfsplen = 0;
+
+       if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
+               pplen = cifs_sb->prepath ? strlen(cifs_sb->prepath) + 1 : 0;
+
 cifs_bp_rename_retry:
-       namelen = dfsplen;
+       namelen = dfsplen + pplen;
        seq = read_seqbegin(&rename_lock);
        rcu_read_lock();
        for (temp = direntry; !IS_ROOT(temp);) {
@@ -137,7 +142,7 @@ cifs_bp_rename_retry:
                }
        }
        rcu_read_unlock();
-       if (namelen != dfsplen || read_seqretry(&rename_lock, seq)) {
+       if (namelen != dfsplen + pplen || read_seqretry(&rename_lock, seq)) {
                cifs_dbg(FYI, "did not end path lookup where expected. namelen=%ddfsplen=%d\n",
                         namelen, dfsplen);
                /* presumably this is only possible if racing with a rename
@@ -153,6 +158,17 @@ cifs_bp_rename_retry:
           those safely to '/' if any are found in the middle of the prepath */
        /* BB test paths to Windows with '/' in the midst of prepath */
 
+       if (pplen) {
+               int i;
+
+               cifs_dbg(FYI, "using cifs_sb prepath <%s>\n", cifs_sb->prepath);
+               memcpy(full_path+dfsplen+1, cifs_sb->prepath, pplen-1);
+               full_path[dfsplen] = '\\';
+               for (i = 0; i < pplen-1; i++)
+                       if (full_path[dfsplen+1+i] == '/')
+                               full_path[dfsplen+1+i] = CIFS_DIR_SEP(cifs_sb);
+       }
+
        if (dfsplen) {
                strncpy(full_path, tcon->treeName, dfsplen);
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {