Mschaara/2.6.5.pil4dfs

src/client/dfs/dfs_internal.h

@@ -1,5 +1,6 @@
 /**
  * (C) Copyright 2019-2024 Intel Corporation.
+ * (C) Copyright 2026 Hewlett Packard Enterprise Development LP
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -419,4 +420,7 @@ update_stbuf_times(struct dfs_entry entry, daos_epoch_t max_epoch, struct stat *
 int
 lookup_rel_path(dfs_t *dfs, dfs_obj_t *root, const char *path, int flags, dfs_obj_t **_obj,
 		mode_t *mode, struct stat *stbuf, size_t depth);
+int
+follow_symlink(dfs_t *dfs, dfs_obj_t *parent, const char *value, int flags, dfs_obj_t **_obj,
+	       mode_t *mode, struct stat *stbuf, size_t depth);
 #endif /* __DFS_INTERNAL_H__ */

src/client/dfs/lookup.c

@@ -14,6 +14,22 @@
 
 #include "dfs_internal.h"
 
+/* A symlink value is resolved from the directory holding the link. dfs has no notion of the
+ * process root that POSIX resolves an absolute value from, so such a value is rejected wherever
+ * the link sits and left to a caller that can resolve it, as dfuse and pil4dfs do with the kernel.
+ */
+int
+follow_symlink(dfs_t *dfs, dfs_obj_t *parent, const char *value, int flags, dfs_obj_t **_obj,
+	       mode_t *mode, struct stat *stbuf, size_t depth)
+{
+	if (value[0] == '/') {
+		D_DEBUG(DB_TRACE, "Cannot follow absolute symlink value %s\n", value);
+		return EINVAL;
+	}
+
+	return lookup_rel_path(dfs, parent, value, flags, _obj, mode, stbuf, depth);
+}
+
 int
 lookup_rel_path(dfs_t *dfs, dfs_obj_t *root, const char *path, int flags, dfs_obj_t **_obj,
 		mode_t *mode, struct stat *stbuf, size_t depth)
@@ -195,8 +211,8 @@ lookup_rel_path(dfs_t *dfs, dfs_obj_t *root, const char *path, int flags, dfs_ob
 					D_GOTO(err_obj, rc = ENOTSUP);
 				}
 
-				rc = lookup_rel_path(dfs, &parent, entry.value, flags, &sym, NULL,
-						     NULL, depth + 1);
+				rc = follow_symlink(dfs, &parent, entry.value, flags, &sym, NULL,
+						    NULL, depth + 1);
 				if (rc) {
 					D_DEBUG(DB_TRACE, "Failed to lookup symlink %s\n",
 						entry.value);
@@ -229,8 +245,8 @@ lookup_rel_path(dfs_t *dfs, dfs_obj_t *root, const char *path, int flags, dfs_ob
 					D_GOTO(err_obj, rc = ENOTSUP);
 				}
 
-				rc = lookup_rel_path(dfs, &parent, entry.value, flags, &sym, mode,
-						     stbuf, depth + 1);
+				rc = follow_symlink(dfs, &parent, entry.value, flags, &sym, mode,
+						    stbuf, depth + 1);
 				if (rc) {
 					D_DEBUG(DB_TRACE, "Failed to lookup symlink %s\n",
 						entry.value);
@@ -506,7 +522,7 @@ lookup_rel_int(dfs_t *dfs, dfs_obj_t *parent, const char *name, int flags, dfs_o
 			if (entry.value == NULL)
 				D_GOTO(err_obj, rc = EIO);
 			/* dereference the symlink */
-			rc = lookup_rel_path(dfs, parent, entry.value, flags, &sym, mode, stbuf, 0);
+			rc = follow_symlink(dfs, parent, entry.value, flags, &sym, mode, stbuf, 0);
 			if (rc) {
 				D_DEBUG(DB_TRACE, "Failed to lookup symlink %s\n", entry.value);
 				D_FREE(entry.value);

src/client/dfs/obj.c

@@ -1139,7 +1139,7 @@ dfs_access(dfs_t *dfs, dfs_obj_t *parent, const char *name, int mask)
 
 	D_ASSERT(entry.value);
 
-	rc = lookup_rel_path(dfs, parent, entry.value, O_RDONLY, &sym, NULL, NULL, 0);
+	rc = follow_symlink(dfs, parent, entry.value, O_RDONLY, &sym, NULL, NULL, 0);
 	if (rc) {
 		D_DEBUG(DB_TRACE, "Failed to lookup symlink %s\n", entry.value);
 		D_GOTO(out, rc);
@@ -1214,7 +1214,7 @@ dfs_chmod(dfs_t *dfs, dfs_obj_t *parent, const char *name, mode_t mode)
 	if (S_ISLNK(entry.mode)) {
 		D_ASSERT(entry.value);
 
-		rc = lookup_rel_path(dfs, parent, entry.value, O_RDWR, &sym, NULL, NULL, 0);
+		rc = follow_symlink(dfs, parent, entry.value, O_RDWR, &sym, NULL, NULL, 0);
 		if (rc) {
 			D_ERROR("Failed to lookup symlink %s\n", entry.value);
 			D_FREE(entry.value);
@@ -1341,7 +1341,7 @@ dfs_chown(dfs_t *dfs, dfs_obj_t *parent, const char *name, uid_t uid, gid_t gid,
 	/** resolve symlink */
 	if (!(flags & O_NOFOLLOW) && S_ISLNK(entry.mode)) {
 		D_ASSERT(entry.value);
-		rc = lookup_rel_path(dfs, parent, entry.value, O_RDWR, &sym, NULL, NULL, 0);
+		rc = follow_symlink(dfs, parent, entry.value, O_RDWR, &sym, NULL, NULL, 0);
 		if (rc) {
 			D_DEBUG(DB_TRACE, "Failed to lookup symlink '%s': %d (%s)\n", entry.value,
 				rc, strerror(rc));

src/client/dfuse/pil4dfs/dfs_dcache.c

@@ -1,5 +1,6 @@
 /**
  * (C) Copyright 2022-2024 Intel Corporation.
+ * (C) Copyright 2026 Hewlett Packard Enterprise Development LP
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -674,8 +675,17 @@ dcache_find_insert_act(dfs_dcache_t *dcache, char *path, size_t path_len, dcache
 		name_len = 0;
 		while (name + name_len < path + path_len && name[name_len] != '/')
 			++name_len;
-		if (name_len == 0)
+		if (name_len == 0) {
+			/* An empty component would silently return a partial parent. The path is
+			 * normalized by the caller, so this is a bug rather than a user error.
+			 */
+			if (name < path + path_len) {
+				D_ERROR("empty component in path " DF_PATH "\n", DP_PATH(path));
+				drec_decref(dcache, rec_tmp);
+				D_GOTO(out, rc = -DER_INVAL);
+			}
 			break;
+		}
 
 		key_prefix = &rec_tmp->dr_key_child_prefix[0];
 		parent     = rec_tmp;