From: Bruce Rogers <brogers@suse.com>
Date: Tue, 2 Aug 2016 11:36:02 -0600
Subject: qemu-bridge-helper: reduce security profile
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References: boo#988279

Change from using glib alloc and free routines to those
from libc. Also perform safety measure of dropping privs
to user if configured no-caps.

Signed-off-by: Bruce Rogers <brogers@suse.com>
[AF: Rebased for v2.7.0-rc2]
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 qemu-bridge-helper.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c
index 88b26747fc866116637716264dea..9ed35df944fa6968045e675e023a 100644
--- a/qemu-bridge-helper.c
+++ b/qemu-bridge-helper.c
@@ -123,7 +123,12 @@ static int parse_acl_file(const char *filename, ACLList *acl_list)
         }
 
         if (strcmp(cmd, "deny") == 0) {
-            acl_rule = g_malloc(sizeof(*acl_rule));
+            acl_rule = calloc(1, sizeof(*acl_rule));
+            if (!acl_rule) {
+                fclose(f);
+                errno = ENOMEM;
+                return -1;
+            }
             if (strcmp(arg, "all") == 0) {
                 acl_rule->type = ACL_DENY_ALL;
             } else {
@@ -132,7 +137,12 @@ static int parse_acl_file(const char *filename, ACLList *acl_list)
             }
             QSIMPLEQ_INSERT_TAIL(acl_list, acl_rule, entry);
         } else if (strcmp(cmd, "allow") == 0) {
-            acl_rule = g_malloc(sizeof(*acl_rule));
+            acl_rule = calloc(1, sizeof(*acl_rule));
+            if (!acl_rule) {
+                fclose(f);
+                errno = ENOMEM;
+                return -1;
+            }
             if (strcmp(arg, "all") == 0) {
                 acl_rule->type = ACL_ALLOW_ALL;
             } else {
@@ -433,6 +443,18 @@ int main(int argc, char **argv)
         goto cleanup;
     }
 
+#ifndef CONFIG_LIBCAP
+    /*
+     * avoid sending the fd as root user if running suid to not fool
+     * peer credentials to daemons that dont expect that
+     */
+    if (setuid(getuid()) < 0) {
+        fprintf(stderr, "Failed to drop privileges.\n");
+        ret = EXIT_FAILURE;
+        goto cleanup;
+    }
+#endif
+
     /* write fd to the domain socket */
     if (send_fd(unixfd, fd) == -1) {
         fprintf(stderr, "failed to write fd to unix socket: %s\n",
@@ -454,7 +476,7 @@ cleanup:
     }
     while ((acl_rule = QSIMPLEQ_FIRST(&acl_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&acl_list, entry);
-        g_free(acl_rule);
+        free(acl_rule);
     }
 
     return ret;