[Asterisk-code-review] res stasis recording: Allow symbolic links in configured rec... (asterisk[15])

[Corey Farrell]

Corey Farrell has uploaded this change for review. ( https://gerrit.asterisk.org/7955


Change subject: res_stasis_recording: Allow symbolic links in configured recordings dir.
......................................................................

res_stasis_recording: Allow symbolic links in configured recordings dir.

If any component of ast_config_AST_RECORDING_DIR is a symbolic link we
would incorrectly assume the ARI user was trying to escape the recording
path.  Create additional check to check the recording directory's
realpath, only deny access if both do not match.

This is needed by the testsuite when run by 'run-local'.

Change-Id: I9145e841865edadcb5f75cead3471ad06bbb56c0
---
M res/stasis_recording/stored.c
1 file changed, 18 insertions(+), 7 deletions(-)



  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/55/7955/1

diff --git a/res/stasis_recording/stored.c b/res/stasis_recording/stored.c
index 9df5d75..ac216ff 100644
--- a/res/stasis_recording/stored.c
+++ b/res/stasis_recording/stored.c
@@ -330,6 +330,7 @@
 	RAII_VAR(char *, file_with_ext, NULL, ast_free);
 	int res;
 	struct stat file_stat;
+	int prefix_len = strlen(ast_config_AST_RECORDING_DIR);
 
 	errno = 0;
 
@@ -350,18 +351,28 @@
 	ast_string_field_build(recording, file, "%s/%s", dir, file);
 
 	if (!ast_begins_with(dir, ast_config_AST_RECORDING_DIR)) {
-		/* Attempt to escape the recording directory */
-		ast_log(LOG_WARNING, "Attempt to access invalid recording %s\n",
-			name);
-		errno = EACCES;
-		return NULL;
+		/* It's possible that one or more component of the recording path is
+		 * a symbolic link, this would prevent dir from ever matching. */
+		char *real_basedir = realpath(ast_config_AST_RECORDING_DIR, NULL);
+
+		if (!real_basedir || !ast_begins_with(dir, real_basedir)) {
+			/* Attempt to escape the recording directory */
+			ast_log(LOG_WARNING, "Attempt to access invalid recording directory %s\n",
+				dir);
+			ast_std_free(real_basedir);
+			errno = EACCES;
+
+			return NULL;
+		}
+
+		prefix_len = strlen(real_basedir);
+		ast_std_free(real_basedir);
 	}
 
 	/* The actual name of the recording is file with the config dir
 	 * prefix removed.
 	 */
-	ast_string_field_set(recording, name,
-		recording->file + strlen(ast_config_AST_RECORDING_DIR) + 1);
+	ast_string_field_set(recording, name, recording->file + prefix_len + 1);
 
 	file_with_ext = find_recording(dir, file);
 	if (!file_with_ext) {

-- 
To view, visit https://gerrit.asterisk.org/7955
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Gerrit-Project: asterisk
Gerrit-Branch: 15
Gerrit-MessageType: newchange
Gerrit-Change-Id: I9145e841865edadcb5f75cead3471ad06bbb56c0
Gerrit-Change-Number: 7955
Gerrit-PatchSet: 1
Gerrit-Owner: Corey Farrell <git at cfware.com>
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