When looking up the DFS cache with a referral path that has more than
two path components, and is a complete prefix of an existing cache
entry, do not request another referral and just return the matched
entry as specified in MS-DFSC 3.2.5.5 Receiving a Root Referral
Request or Link Referral Request.
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxx>
---
fs/cifs/dfs_cache.c | 79 ++++++++++++++++++++++++++++++++++++++-------
1 file changed, 68 insertions(+), 11 deletions(-)
diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
index df81c718d2fa..dae2f41e4f21 100644
--- a/fs/cifs/dfs_cache.c
+++ b/fs/cifs/dfs_cache.c
@@ -490,16 +490,7 @@ static int add_cache_entry(const char *path, unsigned int hash,
return 0;
}
-/*
- * Find a DFS cache entry in hash table and optionally check prefix path against
- * @path.
- * Use whole path components in the match.
- * Must be called with htable_rw_lock held.
- *
- * Return ERR_PTR(-ENOENT) if the entry is not found.
- */
-static struct cache_entry *lookup_cache_entry(const char *path,
- unsigned int *hash)
+static struct cache_entry *__lookup_cache_entry(const char *path)
{
struct cache_entry *ce;
unsigned int h;
@@ -517,9 +508,75 @@ static struct cache_entry *lookup_cache_entry(const char *path,
if (!found)
ce = ERR_PTR(-ENOENT);
+ return ce;
+}
+
+/*
+ * Find a DFS cache entry in hash table and optionally check prefix path against
+ * @path.
+ * Use whole path components in the match.
+ * Must be called with htable_rw_lock held.
+ *
+ * Return ERR_PTR(-ENOENT) if the entry is not found.
+ */
+static struct cache_entry *lookup_cache_entry(const char *path, unsigned int *hash)
+{
+ struct cache_entry *ce = ERR_PTR(-ENOENT);
+ unsigned int h;
+ int cnt = 0;
+ char *npath;
+ char *s, *e;
+ char sep;
+
+ npath = kstrndup(path, strlen(path), GFP_KERNEL);
+ if (!npath)
+ return ERR_PTR(-ENOMEM);
+
+ s = npath;
+ sep = *npath;
+ while ((s = strchr(s, sep)) && ++cnt < 3)
+ s++;
+
+ if (cnt < 3) {
+ h = cache_entry_hash(path, strlen(path));
+ ce = __lookup_cache_entry(path);
+ goto out;
+ }
+ /*
+ * Handle paths that have more than two path components and are a complete prefix of the DFS
+ * referral request path (@path).
+ *
+ * See MS-DFSC 3.2.5.5 "Receiving a Root Referral Request or Link Referral Request".
+ */
+ h = cache_entry_hash(npath, strlen(npath));
+ e = npath + strlen(npath) - 1;
+ while (e > s) {
+ char tmp;
+
+ /* skip separators */
+ while (e > s && *e == sep)
+ e--;
+ if (e == s)
+ goto out;
+
+ tmp = *(e+1);
+ *(e+1) = 0;
+
+ ce = __lookup_cache_entry(npath);
+ if (!IS_ERR(ce)) {
+ h = cache_entry_hash(npath, strlen(npath));
+ break;
+ }
+
+ *(e+1) = tmp;
+ /* backward until separator */
+ while (e > s && *e != sep)
+ e--;
+ }
+out:
if (hash)
*hash = h;
-
+ kfree(npath);
return ce;
}
--
2.27.0
