cifs: fix composing of mount options for DFS referrals
With the change to ignore the unc= and prefixpath= mount options, there
is no longer any need to add them to the options string when mounting.
By the same token, we now need to build a device name that includes the
prefixpath when mounting.
To make things neater, the delimiters on the devicename are changed
to '/' since that's preferred when mounting anyway.
v2: fix some comments and don't bother looking at whether there is
a prepath in the ref->node_name when deciding whether to pass
a prepath to cifs_build_devname.
v3: rebase on top of potential buffer overrun fix for stable
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 8e5a181..58df174 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -49,58 +49,74 @@
}
/**
- * cifs_get_share_name - extracts share name from UNC
- * @node_name: pointer to UNC string
+ * cifs_build_devname - build a devicename from a UNC and optional prepath
+ * @nodename: pointer to UNC string
+ * @prepath: pointer to prefixpath (or NULL if there isn't one)
*
- * Extracts sharename form full UNC.
- * i.e. strips from UNC trailing path that is not part of share
- * name and fixup missing '\' in the beginning of DFS node refferal
- * if necessary.
- * Returns pointer to share name on success or ERR_PTR on error.
- * Caller is responsible for freeing returned string.
+ * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
+ * big enough to hold the final thing. Copy the UNC from the nodename, and
+ * concatenate the prepath onto the end of it if there is one.
+ *
+ * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
+ * for freeing the returned string.
*/
-static char *cifs_get_share_name(const char *node_name)
+static char *
+cifs_build_devname(char *nodename, const char *prepath)
{
- int len;
- char *UNC;
- char *pSep;
+ size_t pplen;
+ size_t unclen;
+ char *dev;
+ char *pos;
- len = strlen(node_name);
- UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
- GFP_KERNEL);
- if (!UNC)
+ /* skip over any preceding delimiters */
+ nodename += strspn(nodename, "\\");
+ if (!*nodename)
+ return ERR_PTR(-EINVAL);
+
+ /* get length of UNC and set pos to last char */
+ unclen = strlen(nodename);
+ pos = nodename + unclen - 1;
+
+ /* trim off any trailing delimiters */
+ while (*pos == '\\') {
+ --pos;
+ --unclen;
+ }
+
+ /* allocate a buffer:
+ * +2 for preceding "//"
+ * +1 for delimiter between UNC and prepath
+ * +1 for trailing NULL
+ */
+ pplen = prepath ? strlen(prepath) : 0;
+ dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
+ if (!dev)
return ERR_PTR(-ENOMEM);
- /* get share name and server name */
- if (node_name[1] != '\\') {
- UNC[0] = '\\';
- strncpy(UNC+1, node_name, len);
- len++;
- UNC[len] = 0;
- } else {
- strncpy(UNC, node_name, len);
- UNC[len] = 0;
+ pos = dev;
+ /* add the initial "//" */
+ *pos = '/';
+ ++pos;
+ *pos = '/';
+ ++pos;
+
+ /* copy in the UNC portion from referral */
+ memcpy(pos, nodename, unclen);
+ pos += unclen;
+
+ /* copy the prefixpath remainder (if there is one) */
+ if (pplen) {
+ *pos = '/';
+ ++pos;
+ memcpy(pos, prepath, pplen);
+ pos += pplen;
}
- /* find server name end */
- pSep = memchr(UNC+2, '\\', len-2);
- if (!pSep) {
- cifs_dbg(VFS, "%s: no server name end in node name: %s\n",
- __func__, node_name);
- kfree(UNC);
- return ERR_PTR(-EINVAL);
- }
+ /* NULL terminator */
+ *pos = '\0';
- /* find sharename end */
- pSep++;
- pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
- if (pSep) {
- /* trim path up to sharename end
- * now we have share name in UNC */
- *pSep = 0;
- }
-
- return UNC;
+ convert_delimiter(dev, '/');
+ return dev;
}
@@ -124,6 +140,7 @@
{
int rc;
char *mountdata = NULL;
+ const char *prepath = NULL;
int md_len;
char *tkn_e;
char *srvIP = NULL;
@@ -133,7 +150,10 @@
if (sb_mountdata == NULL)
return ERR_PTR(-EINVAL);
- *devname = cifs_get_share_name(ref->node_name);
+ if (strlen(fullpath) - ref->path_consumed)
+ prepath = fullpath + ref->path_consumed;
+
+ *devname = cifs_build_devname(ref->node_name, prepath);
if (IS_ERR(*devname)) {
rc = PTR_ERR(*devname);
*devname = NULL;
@@ -147,13 +167,14 @@
goto compose_mount_options_err;
}
- /* md_len = strlen(...) + 12 for 'sep+prefixpath='
- * assuming that we have 'unc=' and 'ip=' in
- * the original sb_mountdata
+ /*
+ * In most cases, we'll be building a shorter string than the original,
+ * but we do have to assume that the address in the ip= option may be
+ * much longer than the original. Add the max length of an address
+ * string to the length of the original string to allow for worst case.
*/
- md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12 +
- INET6_ADDRSTRLEN;
- mountdata = kzalloc(md_len+1, GFP_KERNEL);
+ md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
+ mountdata = kzalloc(md_len + 1, GFP_KERNEL);
if (mountdata == NULL) {
rc = -ENOMEM;
goto compose_mount_options_err;
@@ -197,26 +218,6 @@
strncat(mountdata, &sep, 1);
strcat(mountdata, "ip=");
strcat(mountdata, srvIP);
- strncat(mountdata, &sep, 1);
- strcat(mountdata, "unc=");
- strcat(mountdata, *devname);
-
- /* find & copy prefixpath */
- tkn_e = strchr(ref->node_name + 2, '\\');
- if (tkn_e == NULL) {
- /* invalid unc, missing share name*/
- rc = -EINVAL;
- goto compose_mount_options_err;
- }
-
- 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);
- }
/*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
/*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/