summaryrefslogtreecommitdiff
path: root/src/core/execute.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/core/execute.c')
-rw-r--r--src/core/execute.c195
1 files changed, 182 insertions, 13 deletions
diff --git a/src/core/execute.c b/src/core/execute.c
index 77a75245cb..6019df7ea6 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -25,6 +25,7 @@
#include <signal.h>
#include <string.h>
#include <sys/capability.h>
+#include <sys/eventfd.h>
#include <sys/mman.h>
#include <sys/personality.h>
#include <sys/prctl.h>
@@ -427,7 +428,7 @@ static int setup_input(
return STDIN_FILENO;
}
- i = fixup_input(context->std_input, socket_fd, params->apply_tty_stdin);
+ i = fixup_input(context->std_input, socket_fd, params->flags & EXEC_APPLY_TTY_STDIN);
switch (i) {
@@ -502,7 +503,7 @@ static int setup_output(
return STDERR_FILENO;
}
- i = fixup_input(context->std_input, socket_fd, params->apply_tty_stdin);
+ i = fixup_input(context->std_input, socket_fd, params->flags & EXEC_APPLY_TTY_STDIN);
o = fixup_output(context->std_output, socket_fd);
if (fileno == STDERR_FILENO) {
@@ -1425,7 +1426,7 @@ static int build_environment(
our_env[n_env++] = x;
}
- if (p->watchdog_usec > 0) {
+ if ((p->flags & EXEC_SET_WATCHDOG) && p->watchdog_usec > 0) {
if (asprintf(&x, "WATCHDOG_PID="PID_FMT, getpid()) < 0)
return -ENOMEM;
our_env[n_env++] = x;
@@ -1552,6 +1553,159 @@ static bool exec_needs_mount_namespace(
return false;
}
+static int setup_private_users(uid_t uid, gid_t gid) {
+ _cleanup_free_ char *uid_map = NULL, *gid_map = NULL;
+ _cleanup_close_pair_ int errno_pipe[2] = { -1, -1 };
+ _cleanup_close_ int unshare_ready_fd = -1;
+ _cleanup_(sigkill_waitp) pid_t pid = 0;
+ uint64_t c = 1;
+ siginfo_t si;
+ ssize_t n;
+ int r;
+
+ /* Set up a user namespace and map root to root, the selected UID/GID to itself, and everything else to
+ * nobody. In order to be able to write this mapping we need CAP_SETUID in the original user namespace, which
+ * we however lack after opening the user namespace. To work around this we fork() a temporary child process,
+ * which waits for the parent to create the new user namespace while staying in the original namespace. The
+ * child then writes the UID mapping, under full privileges. The parent waits for the child to finish and
+ * continues execution normally. */
+
+ if (uid != 0 && uid_is_valid(uid))
+ asprintf(&uid_map,
+ "0 0 1\n" /* Map root → root */
+ UID_FMT " " UID_FMT " 1\n", /* Map $UID → $UID */
+ uid, uid); /* The case where the above is the same */
+ else
+ uid_map = strdup("0 0 1\n");
+ if (!uid_map)
+ return -ENOMEM;
+
+ if (gid != 0 && gid_is_valid(gid))
+ asprintf(&gid_map,
+ "0 0 1\n" /* Map root → root */
+ GID_FMT " " GID_FMT " 1\n", /* Map $GID → $GID */
+ gid, gid);
+ else
+ gid_map = strdup("0 0 1\n"); /* The case where the above is the same */
+ if (!gid_map)
+ return -ENOMEM;
+
+ /* Create a communication channel so that the parent can tell the child when it finished creating the user
+ * namespace. */
+ unshare_ready_fd = eventfd(0, EFD_CLOEXEC);
+ if (unshare_ready_fd < 0)
+ return -errno;
+
+ /* Create a communication channel so that the child can tell the parent a proper error code in case it
+ * failed. */
+ if (pipe2(errno_pipe, O_CLOEXEC) < 0)
+ return -errno;
+
+ pid = fork();
+ if (pid < 0)
+ return -errno;
+
+ if (pid == 0) {
+ _cleanup_close_ int fd = -1;
+ const char *a;
+ pid_t ppid;
+
+ /* Child process, running in the original user namespace. Let's update the parent's UID/GID map from
+ * here, after the parent opened its own user namespace. */
+
+ ppid = getppid();
+ errno_pipe[0] = safe_close(errno_pipe[0]);
+
+ /* Wait until the parent unshared the user namespace */
+ if (read(unshare_ready_fd, &c, sizeof(c)) < 0) {
+ r = -errno;
+ goto child_fail;
+ }
+
+ /* Disable the setgroups() system call in the child user namespace, for good. */
+ a = procfs_file_alloca(ppid, "setgroups");
+ fd = open(a, O_WRONLY|O_CLOEXEC);
+ if (fd < 0) {
+ if (errno != ENOENT) {
+ r = -errno;
+ goto child_fail;
+ }
+
+ /* If the file is missing the kernel is too old, let's continue anyway. */
+ } else {
+ if (write(fd, "deny\n", 5) < 0) {
+ r = -errno;
+ goto child_fail;
+ }
+
+ fd = safe_close(fd);
+ }
+
+ /* First write the GID map */
+ a = procfs_file_alloca(ppid, "gid_map");
+ fd = open(a, O_WRONLY|O_CLOEXEC);
+ if (fd < 0) {
+ r = -errno;
+ goto child_fail;
+ }
+ if (write(fd, gid_map, strlen(gid_map)) < 0) {
+ r = -errno;
+ goto child_fail;
+ }
+ fd = safe_close(fd);
+
+ /* The write the UID map */
+ a = procfs_file_alloca(ppid, "uid_map");
+ fd = open(a, O_WRONLY|O_CLOEXEC);
+ if (fd < 0) {
+ r = -errno;
+ goto child_fail;
+ }
+ if (write(fd, uid_map, strlen(uid_map)) < 0) {
+ r = -errno;
+ goto child_fail;
+ }
+
+ _exit(EXIT_SUCCESS);
+
+ child_fail:
+ (void) write(errno_pipe[1], &r, sizeof(r));
+ _exit(EXIT_FAILURE);
+ }
+
+ errno_pipe[1] = safe_close(errno_pipe[1]);
+
+ if (unshare(CLONE_NEWUSER) < 0)
+ return -errno;
+
+ /* Let the child know that the namespace is ready now */
+ if (write(unshare_ready_fd, &c, sizeof(c)) < 0)
+ return -errno;
+
+ /* Try to read an error code from the child */
+ n = read(errno_pipe[0], &r, sizeof(r));
+ if (n < 0)
+ return -errno;
+ if (n == sizeof(r)) { /* an error code was sent to us */
+ if (r < 0)
+ return r;
+ return -EIO;
+ }
+ if (n != 0) /* on success we should have read 0 bytes */
+ return -EIO;
+
+ r = wait_for_terminate(pid, &si);
+ if (r < 0)
+ return r;
+ pid = 0;
+
+ /* If something strange happened with the child, let's consider this fatal, too */
+ if (si.si_code != CLD_EXITED || si.si_status != 0)
+ return -EIO;
+
+ return 0;
+}
+
static void append_socket_pair(int *array, unsigned *n, int pair[2]) {
assert(array);
assert(n);
@@ -1675,7 +1829,7 @@ static int exec_child(
exec_context_tty_reset(context, params);
- if (params->confirm_spawn) {
+ if (params->flags & EXEC_CONFIRM_SPAWN) {
char response;
r = ask_for_confirmation(&response, argv);
@@ -1940,7 +2094,7 @@ static int exec_child(
umask(context->umask);
- if (params->apply_permissions && !command->privileged) {
+ if ((params->flags & EXEC_APPLY_PERMISSIONS) && !command->privileged) {
r = enforce_groups(context, username, gid);
if (r < 0) {
*exit_status = EXIT_GROUP;
@@ -2010,7 +2164,7 @@ static int exec_child(
}
r = setup_namespace(
- params->apply_chroot ? context->root_directory : NULL,
+ (params->flags & EXEC_APPLY_CHROOT) ? context->root_directory : NULL,
context->read_write_paths,
context->read_only_paths,
context->inaccessible_paths,
@@ -2041,7 +2195,7 @@ static int exec_child(
else
wd = "/";
- if (params->apply_chroot) {
+ if (params->flags & EXEC_APPLY_CHROOT) {
if (!needs_mount_namespace && context->root_directory)
if (chroot(context->root_directory) < 0) {
*exit_status = EXIT_CHROOT;
@@ -2065,7 +2219,12 @@ static int exec_child(
}
#ifdef HAVE_SELINUX
- if (params->apply_permissions && mac_selinux_use() && params->selinux_context_net && socket_fd >= 0 && !command->privileged) {
+ if ((params->flags & EXEC_APPLY_PERMISSIONS) &&
+ mac_selinux_use() &&
+ params->selinux_context_net &&
+ socket_fd >= 0 &&
+ !command->privileged) {
+
r = mac_selinux_get_child_mls_label(socket_fd, command->path, context->selinux_context, &mac_selinux_context_net);
if (r < 0) {
*exit_status = EXIT_SELINUX_CONTEXT;
@@ -2074,6 +2233,14 @@ static int exec_child(
}
#endif
+ if ((params->flags & EXEC_APPLY_PERMISSIONS) && context->private_users) {
+ r = setup_private_users(uid, gid);
+ if (r < 0) {
+ *exit_status = EXIT_USER;
+ return r;
+ }
+ }
+
/* We repeat the fd closing here, to make sure that
* nothing is leaked from the PAM modules. Note that
* we are more aggressive this time since socket_fd
@@ -2090,7 +2257,7 @@ static int exec_child(
return r;
}
- if (params->apply_permissions && !command->privileged) {
+ if ((params->flags & EXEC_APPLY_PERMISSIONS) && !command->privileged) {
bool use_address_families = context->address_families_whitelist ||
!set_isempty(context->address_families);
@@ -2635,8 +2802,9 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
"%sRootDirectory: %s\n"
"%sNonBlocking: %s\n"
"%sPrivateTmp: %s\n"
- "%sPrivateNetwork: %s\n"
"%sPrivateDevices: %s\n"
+ "%sPrivateNetwork: %s\n"
+ "%sPrivateUsers: %s\n"
"%sProtectHome: %s\n"
"%sProtectSystem: %s\n"
"%sIgnoreSIGPIPE: %s\n"
@@ -2647,8 +2815,9 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
prefix, c->root_directory ? c->root_directory : "/",
prefix, yes_no(c->non_blocking),
prefix, yes_no(c->private_tmp),
- prefix, yes_no(c->private_network),
prefix, yes_no(c->private_devices),
+ prefix, yes_no(c->private_network),
+ prefix, yes_no(c->private_users),
prefix, protect_home_to_string(c->protect_home),
prefix, protect_system_to_string(c->protect_system),
prefix, yes_no(c->ignore_sigpipe),
@@ -2964,12 +3133,12 @@ void exec_status_dump(ExecStatus *s, FILE *f, const char *prefix) {
"%sPID: "PID_FMT"\n",
prefix, s->pid);
- if (s->start_timestamp.realtime > 0)
+ if (dual_timestamp_is_set(&s->start_timestamp))
fprintf(f,
"%sStart Timestamp: %s\n",
prefix, format_timestamp(buf, sizeof(buf), s->start_timestamp.realtime));
- if (s->exit_timestamp.realtime > 0)
+ if (dual_timestamp_is_set(&s->exit_timestamp))
fprintf(f,
"%sExit Timestamp: %s\n"
"%sExit Code: %s\n"
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-08-07 23:39:45 +0000