lxc-unshare: uid_t is unsigned.

so we can't use uid==-1 as "don't do setuid"

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

diff --git a/src/lxc/lxc_unshare.c b/src/lxc/lxc_unshare.c
index ed3bf478a7232f7aa96f52681d85dca628c0b828..946cdaee9df12acdbde3c629216c2b7c05beb5d2 100644 (file)
--- a/src/lxc/lxc_unshare.c
+++ b/src/lxc/lxc_unshare.c
@@ -66,35 +66,33 @@ static void usage(char *cmd)
        _exit(1);
 }
 
-static uid_t lookup_user(const char *optarg)
+static bool lookup_user(const char *optarg, uid_t *uid)
 {
        char name[sysconf(_SC_LOGIN_NAME_MAX)];
-       uid_t uid = -1;
        struct passwd *pwent = NULL;
 
        if (!optarg || (optarg[0] == '\0'))
-               return uid;
+               return false;
 
-       if (sscanf(optarg, "%u", &uid) < 1) {
+       if (sscanf(optarg, "%u", uid) < 1) {
                /* not a uid -- perhaps a username */
                if (sscanf(optarg, "%s", name) < 1)
-                       return uid;
+                       return false;
 
                pwent = getpwnam(name);
                if (!pwent) {
                        ERROR("invalid username %s", name);
-                       return uid;
+                       return false;
                }
-               uid = pwent->pw_uid;
+               *uid = pwent->pw_uid;
        } else {
-               pwent = getpwuid(uid);
+               pwent = getpwuid(*uid);
                if (!pwent) {
-                       ERROR("invalid uid %d", uid);
-                       uid = -1;
-                       return uid;
+                       ERROR("invalid uid %u", *uid);
+                       return false;
                }
        }
-       return uid;
+       return true;
 }
 
 
@@ -102,6 +100,7 @@ struct start_arg {
        char ***args;
        int *flags;
        uid_t *uid;
+       bool setuid;
         int want_default_mounts;
         const char *want_hostname;
 };
@@ -125,7 +124,7 @@ static int do_start(void *arg)
                }
 
        // Setuid is useful even without a new user id space
-       if ( uid >= 0 && setuid(uid)) {
+       if (start_arg->setuid && setuid(uid)) {
                ERROR("failed to set uid %d: %s", uid, strerror(errno));
                exit(1);
        }
@@ -144,12 +143,13 @@ int main(int argc, char *argv[])
        char **args;
        int flags = 0;
        int daemonize = 0;
-       uid_t uid = -1; /* valid only if (flags & CLONE_NEWUSER) */
+       uid_t uid = 0; /* valid only if (flags & CLONE_NEWUSER) */
        pid_t pid;
        struct my_iflist *tmpif, *my_iflist = NULL;
        struct start_arg start_arg = {
                .args = &args,
                .uid = &uid,
+               .setuid = false,
                .flags = &flags,
                .want_hostname = NULL,
                .want_default_mounts = 0,
@@ -182,9 +182,9 @@ int main(int argc, char *argv[])
                        usage(argv[0]);
                        break;
                case 'u':
-                       uid = lookup_user(optarg);
-                       if (uid == -1)
+                       if (!lookup_user(optarg, &uid))
                                return 1;
+                       start_arg.setuid = true;
                }
        }