automatically trim trailing slashes for whitelisting, fix mountinfo test

Command-line autocompletion adds a trailing slash to directories, which leads to a usability
problem for whitelisting. So before doing any path validation it is attempted to trim trailing
slashes and dots.

1 files changed, 20 insertions, 14 deletions

diff --git a/src/firejail/fs_whitelist.c b/src/firejail/fs_whitelist.c
index 8d7d45c13..74ca8ac25 100644
--- a/src/firejail/fs_whitelist.c
+++ b/src/firejail/fs_whitelist.c
@@ -29,8 +29,7 @@
 
 // mountinfo functionality test;
 // 1. enable TEST_MOUNTINFO definition
-// 2. set a symlink in /tmp: ln -s /etc /tmp/etc
-// 3. run firejail --debug --whitelist=/tmp/etc
+// 2. run firejail --whitelist=/any/directory
 //#define TEST_MOUNTINFO
 
 #define EMPTY_STRING ("")
@@ -218,7 +217,6 @@ static void whitelist_path(ProfileEntry *entry) {
 
         // confirm again the mount source exists and there is no symlink
         struct stat wfilestat;
-#ifndef TEST_MOUNTINFO
         EUID_USER();
         int fd = safe_fd(wfile, O_PATH|O_NOFOLLOW|O_CLOEXEC);
         EUID_ROOT();
@@ -237,6 +235,10 @@ static void whitelist_path(ProfileEntry *entry) {
                 free(wfile);
                 return;
         }
+
+#ifdef TEST_MOUNTINFO
+        printf("TEST_MOUNTINFO\n");
+        path = "/etc/.";
 #endif
 
         // create path of the mount target if necessary
@@ -557,6 +559,21 @@ void fs_whitelist(void) {
                 // replace ~/ or ${HOME} into /home/username
                 new_name = expand_home(dataptr, cfg.homedir);
                 assert(new_name);
+
+                // trim trailing slashes or dots
+                char *end = strrchr(new_name, '\0');
+                assert(end);
+                if ((end - new_name) > 1) {
+                        end--;
+                        while (*end == '/' ||
+                                  (*end == '.' && *(end - 1) == '/')) {
+                                *end = '\0';
+                                end--;
+                                if (end == new_name)
+                                        break;
+                        }
+                }
+
                 if (arg_debug || arg_debug_whitelists)
                         fprintf(stderr, "Debug %d: new_name #%s#, %s\n", __LINE__, new_name, (nowhitelist_flag)? "nowhitelist": "whitelist");
 
@@ -567,15 +584,6 @@ void fs_whitelist(void) {
                         goto errexit;
                 }
 
-                // no trailing slash and no trailing dot
-                char *p = strrchr(new_name, '/');
-                if (!p)
-                        errExit("strrchr");
-                if (*(p + 1) == '\0')
-                        goto errexit;
-                if (*(p + 1) == '.' && *(p + 2) == '\0')
-                        goto errexit;
-
                 // extract the absolute path of the file
                 // realpath function will fail with ENOENT if the file is not found
                 // special processing for /dev/fd, /dev/stdin, /dev/stdout and /dev/stderr
@@ -686,12 +694,10 @@ void fs_whitelist(void) {
                         entry->tmp_dir = 1;
                         tmp_dir = 1;
 
-#ifndef TEST_MOUNTINFO
                         // both path and absolute path are under /tmp
                         if (strncmp(fname, "/tmp/", 5) != 0) {
                                 goto errexit;
                         }
-#endif
                 }
                 else if (strncmp(new_name, "/media/", 7) == 0) {
                         entry->media_dir = 1;