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-rw-r--r--src/nspawn/nspawn-patch-uid.c417
-rw-r--r--src/nspawn/nspawn-patch-uid.h23
-rw-r--r--src/nspawn/nspawn.c47
-rw-r--r--src/nspawn/test-patch-uid.c61
4 files changed, 546 insertions, 2 deletions
diff --git a/src/nspawn/nspawn-patch-uid.c b/src/nspawn/nspawn-patch-uid.c
new file mode 100644
index 0000000000..f53164fbbf
--- /dev/null
+++ b/src/nspawn/nspawn-patch-uid.c
@@ -0,0 +1,417 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2016 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <fcntl.h>
+#ifdef HAVE_ACL
+#include <sys/acl.h>
+#endif
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "acl-util.h"
+#include "dirent-util.h"
+#include "fd-util.h"
+#include "nspawn-patch-uid.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "user-util.h"
+
+#ifdef HAVE_ACL
+
+static int get_acl(int fd, const char *name, acl_type_t type, acl_t *ret) {
+ char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
+ acl_t acl;
+
+ assert(fd >= 0);
+ assert(ret);
+
+ if (name) {
+ _cleanup_close_ int child_fd = -1;
+
+ child_fd = openat(fd, name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
+ if (child_fd < 0)
+ return -errno;
+
+ xsprintf(procfs_path, "/proc/self/fd/%i", child_fd);
+ acl = acl_get_file(procfs_path, type);
+ } else if (type == ACL_TYPE_ACCESS)
+ acl = acl_get_fd(fd);
+ else {
+ xsprintf(procfs_path, "/proc/self/fd/%i", fd);
+ acl = acl_get_file(procfs_path, type);
+ }
+ if (!acl)
+ return -errno;
+
+ *ret = acl;
+ return 0;
+}
+
+static int set_acl(int fd, const char *name, acl_type_t type, acl_t acl) {
+ char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
+ int r;
+
+ assert(fd >= 0);
+ assert(acl);
+
+ if (name) {
+ _cleanup_close_ int child_fd = -1;
+
+ child_fd = openat(fd, name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
+ if (child_fd < 0)
+ return -errno;
+
+ xsprintf(procfs_path, "/proc/self/fd/%i", child_fd);
+ r = acl_set_file(procfs_path, type, acl);
+ } else if (type == ACL_TYPE_ACCESS)
+ r = acl_set_fd(fd, acl);
+ else {
+ xsprintf(procfs_path, "/proc/self/fd/%i", fd);
+ r = acl_set_file(procfs_path, type, acl);
+ }
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
+
+static int shift_acl(acl_t acl, uid_t shift, acl_t *ret) {
+ _cleanup_(acl_freep) acl_t copy = NULL;
+ acl_entry_t i;
+ int r;
+
+ assert(acl);
+ assert(ret);
+
+ r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
+ if (r < 0)
+ return -errno;
+ while (r > 0) {
+ uid_t *old_uid, new_uid;
+ bool modify = false;
+ acl_tag_t tag;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ if (IN_SET(tag, ACL_USER, ACL_GROUP)) {
+
+ /* We don't distuingish here between uid_t and gid_t, let's make sure the compiler checks that
+ * this is actually OK */
+ assert_cc(sizeof(uid_t) == sizeof(gid_t));
+
+ old_uid = acl_get_qualifier(i);
+ if (!old_uid)
+ return -errno;
+
+ new_uid = shift | (*old_uid & UINT32_C(0xFFFF));
+ if (!uid_is_valid(new_uid))
+ return -EINVAL;
+
+ modify = new_uid != *old_uid;
+ if (modify && !copy) {
+ int n;
+
+ /* There's no copy of the ACL yet? if so, let's create one, and start the loop from the
+ * beginning, so that we copy all entries, starting from the first, this time. */
+
+ n = acl_entries(acl);
+ if (n < 0)
+ return -errno;
+
+ copy = acl_init(n);
+ if (!copy)
+ return -errno;
+
+ /* Seek back to the beginning */
+ r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
+ if (r < 0)
+ return -errno;
+ continue;
+ }
+ }
+
+ if (copy) {
+ acl_entry_t new_entry;
+
+ if (acl_create_entry(&copy, &new_entry) < 0)
+ return -errno;
+
+ if (acl_copy_entry(new_entry, i) < 0)
+ return -errno;
+
+ if (modify)
+ if (acl_set_qualifier(new_entry, &new_uid) < 0)
+ return -errno;
+ }
+
+ r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i);
+ if (r < 0)
+ return -errno;
+ }
+
+ *ret = copy;
+ copy = NULL;
+
+ return !!*ret;
+}
+
+static int patch_acls(int fd, const char *name, const struct stat *st, uid_t shift) {
+ _cleanup_(acl_freep) acl_t acl = NULL, shifted = NULL;
+ bool changed = false;
+ int r;
+
+ assert(fd >= 0);
+ assert(st);
+
+ /* ACLs are not supported on symlinks, there's no point in trying */
+ if (S_ISLNK(st->st_mode))
+ return 0;
+
+ r = get_acl(fd, name, ACL_TYPE_ACCESS, &acl);
+ if (r == -EOPNOTSUPP)
+ return 0;
+ if (r < 0)
+ return r;
+
+ r = shift_acl(acl, shift, &shifted);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ r = set_acl(fd, name, ACL_TYPE_ACCESS, shifted);
+ if (r < 0)
+ return r;
+
+ changed = true;
+ }
+
+ if (S_ISDIR(st->st_mode)) {
+ acl_free(acl);
+ acl_free(shifted);
+
+ acl = shifted = NULL;
+
+ r = get_acl(fd, name, ACL_TYPE_DEFAULT, &acl);
+ if (r < 0)
+ return r;
+
+ r = shift_acl(acl, shift, &shifted);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ r = set_acl(fd, name, ACL_TYPE_DEFAULT, shifted);
+ if (r < 0)
+ return r;
+
+ changed = true;
+ }
+ }
+
+ return changed;
+}
+
+#else
+
+static int patch_acls(int fd, const char *name, const struct stat *st, uid_t shift) {
+ return 0;
+}
+
+#endif
+
+static int patch_fd(int fd, const char *name, const struct stat *st, uid_t shift) {
+ uid_t new_uid;
+ gid_t new_gid;
+ bool changed = false;
+ int r;
+
+ assert(fd >= 0);
+ assert(st);
+
+ new_uid = shift | (st->st_uid & UINT32_C(0xFFFF));
+ new_gid = (gid_t) shift | (st->st_gid & UINT32_C(0xFFFF));
+
+ if (!uid_is_valid(new_uid) || !gid_is_valid(new_gid))
+ return -EINVAL;
+
+ if (st->st_uid != new_uid || st->st_gid != new_gid) {
+ if (name)
+ r = fchownat(fd, name, new_uid, new_gid, AT_SYMLINK_NOFOLLOW);
+ else
+ r = fchown(fd, new_uid, new_gid);
+ if (r < 0)
+ return -errno;
+
+ /* The Linux kernel alters the mode in some cases of chown(). Let's undo this. */
+ if (name && !S_ISLNK(st->st_mode))
+ r = fchmodat(fd, name, st->st_mode, 0);
+ else
+ r = fchmod(fd, st->st_mode);
+ if (r < 0)
+ return -errno;
+
+ changed = true;
+ }
+
+ r = patch_acls(fd, name, st, shift);
+ if (r < 0)
+ return r;
+
+ return r > 0 || changed;
+}
+
+static int recurse_fd(int fd, bool donate_fd, const struct stat *st, uid_t shift) {
+ bool changed = false;
+ int r;
+
+ assert(fd >= 0);
+
+ r = patch_fd(fd, NULL, st, shift);
+ if (r < 0)
+ goto finish;
+
+ if (S_ISDIR(st->st_mode)) {
+ _cleanup_closedir_ DIR *d = NULL;
+ struct dirent *de;
+
+ if (!donate_fd) {
+ int copy;
+
+ copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
+ if (copy < 0)
+ return -errno;
+
+ fd = copy;
+ donate_fd = true;
+ }
+
+ d = fdopendir(fd);
+ if (!d) {
+ r = -errno;
+ goto finish;
+ }
+ fd = -1;
+
+ FOREACH_DIRENT_ALL(de, d, r = -errno; goto finish) {
+ struct stat fst;
+
+ if (STR_IN_SET(de->d_name, ".", ".."))
+ continue;
+
+ if (fstatat(dirfd(d), de->d_name, &fst, AT_SYMLINK_NOFOLLOW) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ if (S_ISDIR(fst.st_mode)) {
+ int subdir_fd;
+
+ subdir_fd = openat(dirfd(d), de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
+ if (subdir_fd < 0) {
+ r = -errno;
+ goto finish;
+
+ }
+
+ r = recurse_fd(subdir_fd, true, &fst, shift);
+ if (r < 0)
+ goto finish;
+ if (r > 0)
+ changed = true;
+
+ } else {
+ r = patch_fd(dirfd(d), de->d_name, &fst, shift);
+ if (r < 0)
+ goto finish;
+ if (r > 0)
+ changed = true;
+ }
+ }
+ }
+
+ r = changed;
+
+finish:
+ if (donate_fd)
+ safe_close(fd);
+
+ return r;
+}
+
+static int fd_patch_uid_internal(int fd, bool donate_fd, uid_t shift, uid_t range) {
+ struct stat st;
+ int r;
+
+ assert(fd >= 0);
+
+ /* Recursively adjusts the UID/GIDs of all files of a directory tree. This is used to automatically fix up an
+ * OS tree to the used user namespace UID range. Note that this automatic adjustment only works for UID ranges
+ * following the concept that the upper 16bit of a UID identify the container, and the lower 16bit are the actual
+ * UID within the container. */
+
+ if ((shift & 0xFFFF) != 0) {
+ /* We only support containers where the shift starts at a 2^16 boundary */
+ r = -EOPNOTSUPP;
+ goto finish;
+ }
+
+ if (range != 0x10000) {
+ /* We only support containers with 16bit UID ranges for the patching logic */
+ r = -EOPNOTSUPP;
+ goto finish;
+ }
+
+ if (fstat(fd, &st) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ if ((uint32_t) st.st_uid >> 16 != (uint32_t) st.st_gid >> 16) {
+ /* We only support containers where the uid/gid container ID match */
+ r = -EBADE;
+ goto finish;
+ }
+
+ /* Try to detect if the range is already right. Of course, this a pretty drastic optimization, as we assume
+ * that if the top-level dir has the right upper 16bit assigned, then everything below will have too... */
+ if (((uint32_t) (st.st_uid ^ shift) >> 16) == 0)
+ return 0;
+
+ return recurse_fd(fd, donate_fd, &st, shift);
+
+finish:
+ if (donate_fd)
+ safe_close(fd);
+
+ return r;
+}
+
+int fd_patch_uid(int fd, uid_t shift, uid_t range) {
+ return fd_patch_uid_internal(fd, false, shift, range);
+}
+
+int path_patch_uid(const char *path, uid_t shift, uid_t range) {
+ int fd;
+
+ fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
+ if (fd < 0)
+ return -errno;
+
+ return fd_patch_uid_internal(fd, true, shift, range);
+}
diff --git a/src/nspawn/nspawn-patch-uid.h b/src/nspawn/nspawn-patch-uid.h
new file mode 100644
index 0000000000..55d0990016
--- /dev/null
+++ b/src/nspawn/nspawn-patch-uid.h
@@ -0,0 +1,23 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2016 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/types.h>
+
+int fd_patch_uid(int fd, uid_t shift, uid_t range);
+int path_patch_uid(const char *path, uid_t shift, uid_t range);
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index e1d37d383a..a3190545fa 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -75,6 +75,7 @@
#include "nspawn-expose-ports.h"
#include "nspawn-mount.h"
#include "nspawn-network.h"
+#include "nspawn-patch-uid.h"
#include "nspawn-register.h"
#include "nspawn-settings.h"
#include "nspawn-setuid.h"
@@ -175,6 +176,7 @@ static ExposePort *arg_expose_ports = NULL;
static char **arg_property = NULL;
static uid_t arg_uid_shift = UID_INVALID, arg_uid_range = 0x10000U;
static bool arg_userns = false;
+static bool arg_userns_chown = false;
static int arg_kill_signal = 0;
static bool arg_unified_cgroup_hierarchy = false;
static SettingsMask arg_settings_mask = 0;
@@ -204,6 +206,7 @@ static void help(void) {
" --property=NAME=VALUE Set scope unit property\n"
" --private-users[=UIDBASE[:NUIDS]]\n"
" Run within user namespace\n"
+ " --private-user-chown Adjust OS tree file ownership for private user range\n"
" --private-network Disable network in container\n"
" --network-interface=INTERFACE\n"
" Assign an existing network interface to the\n"
@@ -349,6 +352,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_KILL_SIGNAL,
ARG_SETTINGS,
ARG_CHDIR,
+ ARG_PRIVATE_USERS_CHOWN,
};
static const struct option options[] = {
@@ -392,6 +396,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "port", required_argument, NULL, 'p' },
{ "property", required_argument, NULL, ARG_PROPERTY },
{ "private-users", optional_argument, NULL, ARG_PRIVATE_USERS },
+ { "private-users-chown", optional_argument, NULL, ARG_PRIVATE_USERS_CHOWN},
{ "kill-signal", required_argument, NULL, ARG_KILL_SIGNAL },
{ "settings", required_argument, NULL, ARG_SETTINGS },
{ "chdir", required_argument, NULL, ARG_CHDIR },
@@ -825,6 +830,10 @@ static int parse_argv(int argc, char *argv[]) {
arg_userns = true;
break;
+ case ARG_PRIVATE_USERS_CHOWN:
+ arg_userns_chown = true;
+ break;
+
case ARG_KILL_SIGNAL:
arg_kill_signal = signal_from_string_try_harder(optarg);
if (arg_kill_signal < 0) {
@@ -933,8 +942,15 @@ static int parse_argv(int argc, char *argv[]) {
return -EINVAL;
}
- if (arg_userns && access("/proc/self/uid_map", F_OK) < 0)
- return log_error_errno(EOPNOTSUPP, "--private-users= is not supported, kernel compiled without user namespace support.");
+ if (arg_userns && access("/proc/self/uid_map", F_OK) < 0) {
+ log_error("--private-users= is not supported, kernel compiled without user namespace support.");
+ return -EOPNOTSUPP;
+ }
+
+ if (arg_userns_chown && arg_read_only) {
+ log_error("--read-only and --private-users-chown may not be combined.");
+ return -EINVAL;
+ }
if (argc > optind) {
arg_parameters = strv_copy(argv + optind);
@@ -2218,6 +2234,29 @@ static int setup_machine_id(const char *directory) {
return 0;
}
+static int recursive_chown(const char *directory, uid_t shift, uid_t range) {
+ int r;
+
+ assert(directory);
+
+ if (!arg_userns || !arg_userns_chown)
+ return 0;
+
+ r = path_patch_uid(directory, arg_uid_shift, arg_uid_range);
+ if (r == -EOPNOTSUPP)
+ return log_error_errno(r, "Automatic UID/GID adjusting is only supported for UID/GID ranges starting at multiples of 2^16 with a range of 2^16.");
+ if (r == -EBADE)
+ return log_error_errno(r, "Upper 16 bits of root directory UID and GID do not match.");
+ if (r < 0)
+ return log_error_errno(r, "Failed to adjust UID/GID shift of OS tree: %m");
+ if (r == 0)
+ log_debug("Root directory of image is already owned by the right UID/GID range, skipping recursive chown operation.");
+ else
+ log_debug("Patched directory tree to match UID/GID range.");
+
+ return r;
+}
+
static int mount_devices(
const char *where,
const char *root_device, bool root_device_rw,
@@ -2763,6 +2802,10 @@ static int outer_child(
if (mount(directory, directory, NULL, MS_BIND|MS_REC, NULL) < 0)
return log_error_errno(errno, "Failed to make bind mount: %m");
+ r = recursive_chown(directory, arg_uid_shift, arg_uid_range);
+ if (r < 0)
+ return r;
+
r = setup_volatile(directory, arg_volatile_mode, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_context);
if (r < 0)
return r;
diff --git a/src/nspawn/test-patch-uid.c b/src/nspawn/test-patch-uid.c
new file mode 100644
index 0000000000..11c5321788
--- /dev/null
+++ b/src/nspawn/test-patch-uid.c
@@ -0,0 +1,61 @@
+/***
+ This file is part of systemd.
+
+ Copyright 2016 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+
+#include "log.h"
+#include "nspawn-patch-uid.h"
+#include "user-util.h"
+#include "util.h"
+
+int main(int argc, char *argv[]) {
+ uid_t shift, range;
+ int r;
+
+ log_set_max_level(LOG_DEBUG);
+ log_parse_environment();
+ log_open();
+
+ if (argc != 4) {
+ log_error("Expected PATH SHIFT RANGE parameters.");
+ return EXIT_FAILURE;
+ }
+
+ r = parse_uid(argv[2], &shift);
+ if (r < 0) {
+ log_error_errno(r, "Failed to parse UID shift %s.", argv[2]);
+ return EXIT_FAILURE;
+ }
+
+ r = parse_gid(argv[3], &range);
+ if (r < 0) {
+ log_error_errno(r, "Failed to parse UID range %s.", argv[3]);
+ return EXIT_FAILURE;
+ }
+
+ r = path_patch_uid(argv[1], shift, range);
+ if (r < 0) {
+ log_error_errno(r, "Failed to patch directory tree: %m");
+ return EXIT_FAILURE;
+ }
+
+ log_info("Changed: %s", yes_no(r));
+
+ return EXIT_SUCCESS;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-12-19 16:55:17 +0000