Fixed parsing of mount options when doing DFS submount

Since these hit the same routines, and are relatively small, it is easier to review
them as one patch.

Fixed incorrect handling of the last option in some cases
Fixed prefixpath handling convert path_consumed into host depended string length (in bytes)
Use non default separator if it is provided in the original mount options

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Igor Mammedov <niallain@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 47 insertions, 24 deletions

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index d2c8eef84f3c..e1c18362ba46 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -106,7 +106,8 @@ static char *cifs_get_share_name(const char *node_name)
 /**
  * compose_mount_options        -       creates mount options for refferral
  * @sb_mountdata:       parent/root DFS mount options (template)
- * @ref_unc:            refferral server UNC
+ * @dentry:             point where we are going to mount
+ * @ref:                server's referral
  * @devname:            pointer for saving device name
  *
  * creates mount options for submount based on template options sb_mountdata
@@ -116,7 +117,8 @@ static char *cifs_get_share_name(const char *node_name)
  * Caller is responcible for freeing retunrned value if it is not error.
  */
 static char *compose_mount_options(const char *sb_mountdata,
-                                   const char *ref_unc,
+                                   struct dentry *dentry,
+                                   const struct dfs_info3_param *ref,
                                    char **devname)
 {
         int rc;
@@ -126,11 +128,12 @@ static char *compose_mount_options(const char *sb_mountdata,
         char *srvIP = NULL;
         char sep = ',';
         int off, noff;
+        char *fullpath;
 
         if (sb_mountdata == NULL)
                 return ERR_PTR(-EINVAL);
 
-        *devname = cifs_get_share_name(ref_unc);
+        *devname = cifs_get_share_name(ref->node_name);
         rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
         if (rc != 0) {
                 cERROR(1, ("%s: Failed to resolve server part of %s to IP",
@@ -138,7 +141,12 @@ static char *compose_mount_options(const char *sb_mountdata,
                 mountdata = ERR_PTR(rc);
                 goto compose_mount_options_out;
         }
-        md_len = strlen(sb_mountdata) + strlen(srvIP) + strlen(ref_unc) + 3;
+        /* md_len = strlen(...) + 12 for 'sep+prefixpath='
+         * assuming that we have 'unc=' and 'ip=' in
+         * the original sb_mountdata
+         */
+        md_len = strlen(sb_mountdata) + strlen(srvIP) +
+                strlen(ref->node_name) + 12;
         mountdata = kzalloc(md_len+1, GFP_KERNEL);
         if (mountdata == NULL) {
                 mountdata = ERR_PTR(-ENOMEM);
@@ -152,41 +160,56 @@ static char *compose_mount_options(const char *sb_mountdata,
                         strncpy(mountdata, sb_mountdata, 5);
                         off += 5;
         }
-        while ((tkn_e = strchr(sb_mountdata+off, sep))) {
-                noff = (tkn_e - (sb_mountdata+off)) + 1;
-                if (strnicmp(sb_mountdata+off, "unc=", 4) == 0) {
+
+        do {
+                tkn_e = strchr(sb_mountdata + off, sep);
+                if (tkn_e == NULL)
+                        noff = strlen(sb_mountdata + off);
+                else
+                        noff = tkn_e - (sb_mountdata + off) + 1;
+
+                if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
                         off += noff;
                         continue;
                 }
-                if (strnicmp(sb_mountdata+off, "ip=", 3) == 0) {
+                if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
                         off += noff;
                         continue;
                 }
-                if (strnicmp(sb_mountdata+off, "prefixpath=", 3) == 0) {
+                if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
                         off += noff;
                         continue;
                 }
-                strncat(mountdata, sb_mountdata+off, noff);
+                strncat(mountdata, sb_mountdata + off, noff);
                 off += noff;
-        }
-        strcat(mountdata, sb_mountdata+off);
+        } while (tkn_e);
+        strcat(mountdata, sb_mountdata + off);
         mountdata[md_len] = '\0';
 
         /* copy new IP and ref share name */
-        strcat(mountdata, ",ip=");
+        if (mountdata[strlen(mountdata) - 1] != sep)
+                strncat(mountdata, &sep, 1);
+        strcat(mountdata, "ip=");
         strcat(mountdata, srvIP);
-        strcat(mountdata, ",unc=");
+        strncat(mountdata, &sep, 1);
+        strcat(mountdata, "unc=");
         strcat(mountdata, *devname);
 
         /* find & copy prefixpath */
-        tkn_e = strchr(ref_unc+2, '\\');
-        if (tkn_e) {
-                tkn_e = strchr(tkn_e+1, '\\');
-                if (tkn_e) {
-                        strcat(mountdata, ",prefixpath=");
-                        strcat(mountdata, tkn_e+1);
-                }
+        tkn_e = strchr(ref->node_name + 2, '\\');
+        if (tkn_e == NULL) /* invalid unc, missing share name*/
+                goto compose_mount_options_out;
+
+        fullpath = build_path_from_dentry(dentry);
+        tkn_e = strchr(tkn_e + 1, '\\');
+        if (tkn_e || strlen(fullpath) - (ref->path_consumed)) {
+                strncat(mountdata, &sep, 1);
+                strcat(mountdata, "prefixpath=");
+                if (tkn_e)
+                        strcat(mountdata, tkn_e + 1);
+                strcat(mountdata, fullpath + (ref->path_consumed));
         }
+        kfree(fullpath);
 
         /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/
         /*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/
@@ -198,7 +221,7 @@ compose_mount_options_out:
 
 
 static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
-                struct dentry *dentry, char *ref_unc)
+                struct dentry *dentry, const struct dfs_info3_param *ref)
 {
         struct cifs_sb_info *cifs_sb;
         struct vfsmount *mnt;
@@ -207,7 +230,7 @@ static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
 
         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
         mountdata = compose_mount_options(cifs_sb->mountdata,
-                                                ref_unc, &devname);
+                                                dentry, ref, &devname);
 
         if (IS_ERR(mountdata))
                 return (struct vfsmount *)mountdata;
@@ -310,7 +333,7 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
                         }
                         mnt = cifs_dfs_do_refmount(nd->path.mnt,
                                                 nd->path.dentry,
-                                                referrals[i].node_name);
+                                                referrals + i);
                         cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p",
                                          __func__,
                                         referrals[i].node_name, mnt));