jail: don't always CLONE_NEWUTS

[project/procd.git] / jail / jail.c

diff --git a/jail/jail.c b/jail/jail.c
index e86ee14..c442847 100644 (file)
--- a/jail/jail.c
+++ b/jail/jail.c
@@ -76,7 +76,7 @@ static int mkdir_p(char *dir, mode_t mask)
                return 0;
 
        if (ret)
-               ERROR("mkdir failed on %s: %s\n", dir, strerror(errno));
+               ERROR("mkdir(%s, %d) failed: %s\n", dir, mask, strerror(errno));
 
        return ret;
 }
@@ -100,7 +100,7 @@ int mount_bind(const char *root, const char *path, int readonly, int error)
                snprintf(new, sizeof(new), "%s%s", root, path);
                fd = creat(new, 0644);
                if (fd == -1) {
-                       ERROR("failed to create %s: %s\n", new, strerror(errno));
+                       ERROR("creat(%s) failed: %s\n", new, strerror(errno));
                        return -1;
                }
                close(fd);
@@ -116,7 +116,7 @@ int mount_bind(const char *root, const char *path, int readonly, int error)
                return -1;
        }
 
-       DEBUG("mount -B %s %s\n", path, new);
+       DEBUG("mount -B %s %s (%s)\n", path, new, readonly?"ro":"rw");
 
        return 0;
 }
@@ -125,7 +125,13 @@ static int build_jail_fs(void)
 {
        char jail_root[] = "/tmp/ujail-XXXXXX";
        if (mkdtemp(jail_root) == NULL) {
-               ERROR("mkdtemp(jail_root) failed: %s\n", strerror(errno));
+               ERROR("mkdtemp(%s) failed: %s\n", jail_root, strerror(errno));
+               return -1;
+       }
+
+       /* oldroot can't be MS_SHARED else pivot_root() fails */
+       if (mount("none", "/", NULL, MS_REC|MS_PRIVATE, NULL)) {
+               ERROR("private mount failed %s\n", strerror(errno));
                return -1;
        }
 
@@ -135,7 +141,7 @@ static int build_jail_fs(void)
        }
 
        if (chdir(jail_root)) {
-               ERROR("failed to chdir() in the jail root\n");
+               ERROR("chdir(%s) (jail_root) failed: %s\n", jail_root, strerror(errno));
                return -1;
        }
 
@@ -149,11 +155,11 @@ static int build_jail_fs(void)
        mkdir(dirbuf, 0755);
 
        if (pivot_root(jail_root, dirbuf) == -1) {
-               ERROR("pivot_root failed: %s\n", strerror(errno));
+               ERROR("pivot_root(%s, %s) failed: %s\n", jail_root, dirbuf, strerror(errno));
                return -1;
        }
        if (chdir("/")) {
-               ERROR("chdir(/) failed: %s\n", strerror(errno));
+               ERROR("chdir(/) (after pivot_root) failed: %s\n", strerror(errno));
                return -1;
        }
 
@@ -228,7 +234,7 @@ ujail will not use namespace/build a jail,\n\
 and will only drop capabilities/apply seccomp filter.\n\n");
 }
 
-static int exec_jail(void)
+static int exec_jail(void *_notused)
 {
        if (opts.capabilities && drop_capabilities(opts.capabilities))
                exit(EXIT_FAILURE);
@@ -238,6 +244,17 @@ static int exec_jail(void)
                exit(EXIT_FAILURE);
        }
 
+       if (opts.namespace && opts.hostname && strlen(opts.hostname) > 0
+                       && sethostname(opts.hostname, strlen(opts.hostname))) {
+               ERROR("sethostname(%s) failed: %s\n", opts.hostname, strerror(errno));
+               exit(EXIT_FAILURE);
+       }
+
+       if (opts.namespace && build_jail_fs()) {
+               ERROR("failed to build jail fs\n");
+               exit(EXIT_FAILURE);
+       }
+
        char **envp = build_envp(opts.seccomp);
        if (!envp)
                exit(EXIT_FAILURE);
@@ -249,20 +266,6 @@ static int exec_jail(void)
        exit(EXIT_FAILURE);
 }
 
-static int spawn_jail(void *_notused)
-{
-       if (opts.hostname && sethostname(opts.hostname, strlen(opts.hostname))) {
-               ERROR("sethostname(%s) failed: %s\n", opts.hostname, strerror(errno));
-       }
-
-       if (build_jail_fs()) {
-               ERROR("failed to build jail fs");
-               exit(EXIT_FAILURE);
-       }
-
-       return exec_jail();
-}
-
 static int jail_running = 1;
 static int jail_return_code = 0;
 
@@ -322,7 +325,6 @@ int main(int argc, char **argv)
                        break;
                case 'C':
                        opts.capabilities = optarg;
-                       add_mount(optarg, 1, -1);
                        break;
                case 'c':
                        opts.no_new_privs = 1;
@@ -384,9 +386,10 @@ int main(int argc, char **argv)
 
        uloop_init();
        if (opts.namespace) {
-               jail_process.pid = clone(spawn_jail,
-                       child_stack + STACK_SIZE,
-                       CLONE_NEWUTS | CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD, NULL);
+               int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD;
+               if (opts.hostname)
+                       flags |= CLONE_NEWUTS;
+               jail_process.pid = clone(exec_jail, child_stack + STACK_SIZE, flags, NULL);
        } else {
                jail_process.pid = fork();
        }
@@ -404,7 +407,7 @@ int main(int argc, char **argv)
                return jail_return_code;
        } else if (jail_process.pid == 0) {
                /* fork child process */
-               return exec_jail();
+               return exec_jail(NULL);
        } else {
                ERROR("failed to clone/fork: %s\n", strerror(errno));
                return EXIT_FAILURE;