mount id: drop effective user id assertions

as functions operate on a file descriptor
it should be safe to remove them; this
sets the stage for improvements to the
whitelist code

1 files changed, 20 insertions, 19 deletions

diff --git a/src/firejail/mountinfo.c b/src/firejail/mountinfo.c
index 7d30d21d9..56c0bda30 100644
--- a/src/firejail/mountinfo.c
+++ b/src/firejail/mountinfo.c
@@ -146,11 +146,10 @@ MountData *get_last_mount(void) {
 
 // Returns mount id, or -1 if fd refers to a procfs or sysfs file
 static int get_mount_id_from_handle(int fd) {
-        EUID_ASSERT();
-
         char *proc;
         if (asprintf(&proc, "/proc/self/fd/%d", fd) == -1)
                 errExit("asprintf");
+
         struct file_handle *fh = malloc(sizeof *fh);
         if (!fh)
                 errExit("malloc");
@@ -172,40 +171,42 @@ static int get_mount_id_from_handle(int fd) {
 
 // Returns mount id, or -1 on kernels < 3.15
 static int get_mount_id_from_fdinfo(int fd) {
-        EUID_ASSERT();
-        int rv = -1;
-
         char *proc;
         if (asprintf(&proc, "/proc/self/fdinfo/%d", fd) == -1)
                 errExit("asprintf");
-        EUID_ROOT();
+
+        int called_as_root = 0;
+        if (geteuid() == 0)
+                called_as_root = 1;
+
+        if (called_as_root == 0)
+                EUID_ROOT();
+
         FILE *fp = fopen(proc, "re");
-        EUID_USER();
-        if (!fp)
-                goto errexit;
+        if (!fp) {
+                fprintf(stderr, "Error: cannot read proc file\n");
+                exit(1);
+        }
 
+        if (called_as_root == 0)
+                EUID_USER();
+
+        int rv = -1;
         char buf[MAX_BUF];
         while (fgets(buf, MAX_BUF, fp)) {
-                if (strncmp(buf, "mnt_id:", 7) == 0) {
-                        if (sscanf(buf + 7, "%d", &rv) == 1)
+                if (sscanf(buf, "mnt_id: %d", &rv) == 1)
                                 break;
-                        goto errexit;
-                }
         }
 
         free(proc);
         fclose(fp);
         return rv;
-
-errexit:
-        fprintf(stderr, "Error: cannot read proc file\n");
-        exit(1);
 }
 
 int get_mount_id(int fd) {
-        int rv = get_mount_id_from_fdinfo(fd);
+        int rv = get_mount_id_from_handle(fd);
         if (rv < 0)
-                rv = get_mount_id_from_handle(fd);
+                rv = get_mount_id_from_fdinfo(fd);
         return rv;
 }