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Merge pull request #3093 from poettering/nspawn-userns-magic

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nspawn automatic user namespaces
This commit is contained in:
Lennart Poettering
2016-04-26 14:57:04 +02:00
parent 6e3930c40f 4aeb20f5aa
commit d7fe83bbc2
17 changed files with 1088 additions and 72 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/nspawn/nspawn-gperf.gperf
+3 -1
View File
@@ -16,7 +16,7 @@ struct ConfigPerfItem;
%includes
%%
Exec.Boot, config_parse_boot, 0, 0
Exec.ProcessTwo, config_parse_pid2, 0, 0,
Exec.ProcessTwo, config_parse_pid2, 0, 0
Exec.Parameters, config_parse_strv, 0, offsetof(Settings, parameters)
Exec.Environment, config_parse_strv, 0, offsetof(Settings, environment)
Exec.User, config_parse_string, 0, offsetof(Settings, user)
@@ -26,11 +26,13 @@ Exec.KillSignal, config_parse_signal, 0, offsetof(Settings,
Exec.Personality, config_parse_personality, 0, offsetof(Settings, personality)
Exec.MachineID, config_parse_id128, 0, offsetof(Settings, machine_id)
Exec.WorkingDirectory, config_parse_path, 0, offsetof(Settings, working_directory)
Exec.PrivateUsers, config_parse_private_users, 0, 0
Files.ReadOnly, config_parse_tristate, 0, offsetof(Settings, read_only)
Files.Volatile, config_parse_volatile_mode, 0, offsetof(Settings, volatile_mode)
Files.Bind, config_parse_bind, 0, 0
Files.BindReadOnly, config_parse_bind, 1, 0
Files.TemporaryFileSystem, config_parse_tmpfs, 0, 0
Files.PrivateUsersChown, config_parse_tristate, 0, offsetof(Settings, userns_chown)
Network.Private, config_parse_tristate, 0, offsetof(Settings, private_network)
Network.Interface, config_parse_strv, 0, offsetof(Settings, network_interfaces)
Network.MACVLAN, config_parse_strv, 0, offsetof(Settings, network_macvlan)
src/nspawn/nspawn-patch-uid.c
+469
View File
@@ -0,0 +1,469 @@
/***
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>
#include <linux/magic.h>
#ifdef HAVE_ACL
#include <sys/acl.h>
#endif
#include <sys/stat.h>
#include <sys/vfs.h>
#include <unistd.h>
#include "acl-util.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "missing.h"
#include "nspawn-patch-uid.h"
#include "stat-util.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 is_procfs_sysfs_or_suchlike(int fd) {
struct statfs sfs;
assert(fd >= 0);
if (fstatfs(fd, &sfs) < 0)
return -errno;
return F_TYPE_EQUAL(sfs.f_type, BINFMTFS_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, CGROUP_SUPER_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, CGROUP2_SUPER_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, DEBUGFS_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, DEVPTS_SUPER_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, EFIVARFS_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, HUGETLBFS_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, MQUEUE_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, PROC_SUPER_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, PSTOREFS_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, SELINUX_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, SMACK_MAGIC) ||
F_TYPE_EQUAL(sfs.f_type, SYSFS_MAGIC);
}
static int recurse_fd(int fd, bool donate_fd, const struct stat *st, uid_t shift, bool is_toplevel) {
bool changed = false;
int r;
assert(fd >= 0);
/* We generally want to permit crossing of mount boundaries when patching the UIDs/GIDs. However, we
* probably shouldn't do this for /proc and /sys if that is already mounted into place. Hence, let's
* stop the recursion when we hit a procfs or sysfs file system. */
r = is_procfs_sysfs_or_suchlike(fd);
if (r < 0)
goto finish;
if (r > 0) {
r = 0; /* don't recurse */
goto finish;
}
r = patch_fd(fd, NULL, st, shift);
if (r == -EROFS) {
_cleanup_free_ char *name = NULL;
if (!is_toplevel) {
/* When we hit a ready-only subtree we simply skip it, but log about it. */
(void) fd_get_path(fd, &name);
log_debug("Skippping read-only file or directory %s.", strna(name));
r = 0;
}
goto finish;
}
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) {
r = -errno;
goto finish;
}
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, false);
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, true);
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);
}
src/nspawn/nspawn-patch-uid.h
+23
View File
@@ -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);
src/nspawn/nspawn-settings.c
+86
View File
@@ -25,7 +25,9 @@
#include "parse-util.h"
#include "process-util.h"
#include "strv.h"
#include "user-util.h"
#include "util.h"
#include "string-util.h"
int settings_load(FILE *f, const char *path, Settings **ret) {
_cleanup_(settings_freep) Settings *s = NULL;
@@ -40,9 +42,13 @@ int settings_load(FILE *f, const char *path, Settings **ret) {
s->start_mode = _START_MODE_INVALID;
s->personality = PERSONALITY_INVALID;
s->userns_mode = _USER_NAMESPACE_MODE_INVALID;
s->uid_shift = UID_INVALID;
s->uid_range = UID_INVALID;
s->read_only = -1;
s->volatile_mode = _VOLATILE_MODE_INVALID;
s->userns_chown = -1;
s->private_network = -1;
s->network_veth = -1;
@@ -59,6 +65,16 @@ int settings_load(FILE *f, const char *path, Settings **ret) {
if (r < 0)
return r;
/* Make sure that if userns_mode is set, userns_chown is set to something appropriate, and vice versa. Either
* both fields shall be initialized or neither. */
if (s->userns_mode == USER_NAMESPACE_PICK)
s->userns_chown = true;
else if (s->userns_mode != _USER_NAMESPACE_MODE_INVALID && s->userns_chown < 0)
s->userns_chown = false;
if (s->userns_chown >= 0 && s->userns_mode == _USER_NAMESPACE_MODE_INVALID)
s->userns_mode = USER_NAMESPACE_NO;
*ret = s;
s = NULL;
@@ -392,3 +408,73 @@ conflict:
log_syntax(unit, LOG_ERR, filename, line, r, "Conflicting Boot= or ProcessTwo= setting found. Ignoring.");
return 0;
}
int config_parse_private_users(
const char *unit,
const char *filename,
unsigned line,
const char *section,
unsigned section_line,
const char *lvalue,
int ltype,
const char *rvalue,
void *data,
void *userdata) {
Settings *settings = data;
int r;
assert(filename);
assert(lvalue);
assert(rvalue);
r = parse_boolean(rvalue);
if (r == 0) {
/* no: User namespacing off */
settings->userns_mode = USER_NAMESPACE_NO;
settings->uid_shift = UID_INVALID;
settings->uid_range = UINT32_C(0x10000);
} else if (r > 0) {
/* yes: User namespacing on, UID range is read from root dir */
settings->userns_mode = USER_NAMESPACE_FIXED;
settings->uid_shift = UID_INVALID;
settings->uid_range = UINT32_C(0x10000);
} else if (streq(rvalue, "pick")) {
/* pick: User namespacing on, UID range is picked randomly */
settings->userns_mode = USER_NAMESPACE_PICK;
settings->uid_shift = UID_INVALID;
settings->uid_range = UINT32_C(0x10000);
} else {
const char *range, *shift;
uid_t sh, rn;
/* anything else: User namespacing on, UID range is explicitly configured */
range = strchr(rvalue, ':');
if (range) {
shift = strndupa(rvalue, range - rvalue);
range++;
r = safe_atou32(range, &rn);
if (r < 0 || rn <= 0) {
log_syntax(unit, LOG_ERR, filename, line, r, "UID/GID range invalid, ignoring: %s", range);
return 0;
}
} else {
shift = rvalue;
rn = UINT32_C(0x10000);
}
r = parse_uid(shift, &sh);
if (r < 0) {
log_syntax(unit, LOG_ERR, filename, line, r, "UID/GID shift invalid, ignoring: %s", range);
return 0;
}
settings->userns_mode = USER_NAMESPACE_FIXED;
settings->uid_shift = sh;
settings->uid_range = rn;
}
return 0;
}
src/nspawn/nspawn-settings.h
+14 -1
View File
@@ -33,6 +33,14 @@ typedef enum StartMode {
_START_MODE_INVALID = -1
} StartMode;
typedef enum UserNamespaceMode {
USER_NAMESPACE_NO,
USER_NAMESPACE_FIXED,
USER_NAMESPACE_PICK,
_USER_NAMESPACE_MODE_MAX,
_USER_NAMESPACE_MODE_INVALID = -1,
} UserNamespaceMode;
typedef enum SettingsMask {
SETTING_START_MODE = 1 << 0,
SETTING_ENVIRONMENT = 1 << 1,
@@ -47,7 +55,8 @@ typedef enum SettingsMask {
SETTING_VOLATILE_MODE = 1 << 10,
SETTING_CUSTOM_MOUNTS = 1 << 11,
SETTING_WORKING_DIRECTORY = 1 << 12,
_SETTINGS_MASK_ALL = (1 << 13) -1
SETTING_USERNS = 1 << 13,
_SETTINGS_MASK_ALL = (1 << 14) -1
} SettingsMask;
typedef struct Settings {
@@ -62,12 +71,15 @@ typedef struct Settings {
unsigned long personality;
sd_id128_t machine_id;
char *working_directory;
UserNamespaceMode userns_mode;
uid_t uid_shift, uid_range;
/* [Image] */
int read_only;
VolatileMode volatile_mode;
CustomMount *custom_mounts;
unsigned n_custom_mounts;
int userns_chown;
/* [Network] */
int private_network;
@@ -99,3 +111,4 @@ int config_parse_tmpfs(const char *unit, const char *filename, unsigned line, co
int config_parse_veth_extra(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
int config_parse_boot(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
int config_parse_pid2(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
int config_parse_private_users(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
src/nspawn/nspawn.c
+309 -41
View File
@@ -22,7 +22,9 @@
#endif
#include <errno.h>
#include <getopt.h>
#include <grp.h>
#include <linux/loop.h>
#include <pwd.h>
#include <sched.h>
#ifdef HAVE_SECCOMP
#include <seccomp.h>
@@ -75,6 +77,7 @@
#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"
@@ -101,6 +104,11 @@
#include "user-util.h"
#include "util.h"
/* Note that devpts's gid= parameter parses GIDs as signed values, hence we stay away from the upper half of the 32bit
* UID range here */
#define UID_SHIFT_PICK_MIN ((uid_t) UINT32_C(0x00080000))
#define UID_SHIFT_PICK_MAX ((uid_t) UINT32_C(0x6FFF0000))
typedef enum ContainerStatus {
CONTAINER_TERMINATED,
CONTAINER_REBOOTED
@@ -173,8 +181,9 @@ static char *arg_image = NULL;
static VolatileMode arg_volatile_mode = VOLATILE_NO;
static ExposePort *arg_expose_ports = NULL;
static char **arg_property = NULL;
static UserNamespaceMode arg_userns_mode = USER_NAMESPACE_NO;
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;
@@ -202,8 +211,10 @@ static void help(void) {
" --uuid=UUID Set a specific machine UUID for the container\n"
" -S --slice=SLICE Place the container in the specified slice\n"
" --property=NAME=VALUE Set scope unit property\n"
" -U --private-users=pick Run within user namespace, pick UID/GID range automatically\n"
" --private-users[=UIDBASE[:NUIDS]]\n"
" Run within user namespace\n"
" Run within user namespace, user configured UID/GID range\n"
" --private-user-chown Adjust OS tree file ownership for private UID/GID range\n"
" --private-network Disable network in container\n"
" --network-interface=INTERFACE\n"
" Assign an existing network interface to the\n"
@@ -272,9 +283,15 @@ static int custom_mounts_prepare(void) {
for (i = 0; i < arg_n_custom_mounts; i++) {
CustomMount *m = &arg_custom_mounts[i];
if (arg_userns && arg_uid_shift == UID_INVALID && path_equal(m->destination, "/")) {
log_error("--private-users with automatic UID shift may not be combined with custom root mounts.");
return -EINVAL;
if (path_equal(m->destination, "/") && arg_userns_mode != USER_NAMESPACE_NO) {
if (arg_userns_chown) {
log_error("--private-users-chown may not be combined with custom root mounts.");
return -EINVAL;
} else if (arg_uid_shift == UID_INVALID) {
log_error("--private-users with automatic UID shift may not be combined with custom root mounts.");
return -EINVAL;
}
}
if (m->type != CUSTOM_MOUNT_OVERLAY)
@@ -349,6 +366,7 @@ 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 +410,7 @@ 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 },
@@ -406,7 +425,7 @@ static int parse_argv(int argc, char *argv[]) {
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "+hD:u:abL:M:jS:Z:qi:xp:n", options, NULL)) >= 0)
while ((c = getopt_long(argc, argv, "+hD:u:abL:M:jS:Z:qi:xp:nU", options, NULL)) >= 0)
switch (c) {
@@ -797,10 +816,29 @@ static int parse_argv(int argc, char *argv[]) {
break;
case ARG_PRIVATE_USERS:
if (optarg) {
r = optarg ? parse_boolean(optarg) : 1;
if (r == 0) {
/* no: User namespacing off */
arg_userns_mode = USER_NAMESPACE_NO;
arg_uid_shift = UID_INVALID;
arg_uid_range = UINT32_C(0x10000);
} else if (r > 0) {
/* yes: User namespacing on, UID range is read from root dir */
arg_userns_mode = USER_NAMESPACE_FIXED;
arg_uid_shift = UID_INVALID;
arg_uid_range = UINT32_C(0x10000);
} else if (streq(optarg, "pick")) {
/* pick: User namespacing on, UID range is picked randomly */
arg_userns_mode = USER_NAMESPACE_PICK;
arg_uid_shift = UID_INVALID;
arg_uid_range = UINT32_C(0x10000);
} else {
_cleanup_free_ char *buffer = NULL;
const char *range, *shift;
/* anything else: User namespacing on, UID range is explicitly configured */
range = strchr(optarg, ':');
if (range) {
buffer = strndup(optarg, range - optarg);
@@ -820,9 +858,28 @@ static int parse_argv(int argc, char *argv[]) {
log_error("Failed to parse UID: %s", optarg);
return -EINVAL;
}
arg_userns_mode = USER_NAMESPACE_FIXED;
}
arg_userns = true;
arg_settings_mask |= SETTING_USERNS;
break;
case 'U':
if (userns_supported()) {
arg_userns_mode = USER_NAMESPACE_PICK;
arg_uid_shift = UID_INVALID;
arg_uid_range = UINT32_C(0x10000);
arg_settings_mask |= SETTING_USERNS;
}
break;
case ARG_PRIVATE_USERS_CHOWN:
arg_userns_chown = true;
arg_settings_mask |= SETTING_USERNS;
break;
case ARG_KILL_SIGNAL:
@@ -893,6 +950,9 @@ static int parse_argv(int argc, char *argv[]) {
if (arg_share_system)
arg_register = false;
if (arg_userns_mode == USER_NAMESPACE_PICK)
arg_userns_chown = true;
if (arg_start_mode != START_PID1 && arg_share_system) {
log_error("--boot and --share-system may not be combined.");
return -EINVAL;
@@ -933,8 +993,15 @@ 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_mode != USER_NAMESPACE_NO && !userns_supported()) {
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);
@@ -993,7 +1060,7 @@ static int verify_arguments(void) {
static int userns_lchown(const char *p, uid_t uid, gid_t gid) {
assert(p);
if (!arg_userns)
if (arg_userns_mode == USER_NAMESPACE_NO)
return 0;
if (uid == UID_INVALID && gid == GID_INVALID)
@@ -2218,6 +2285,29 @@ 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_mode == USER_NAMESPACE_NO || !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,
@@ -2435,7 +2525,7 @@ static int determine_names(void) {
static int determine_uid_shift(const char *directory) {
int r;
if (!arg_userns) {
if (arg_userns_mode == USER_NAMESPACE_NO) {
arg_uid_shift = 0;
return 0;
}
@@ -2462,7 +2552,6 @@ static int determine_uid_shift(const char *directory) {
return -EINVAL;
}
log_info("Using user namespaces with base " UID_FMT " and range " UID_FMT ".", arg_uid_shift, arg_uid_range);
return 0;
}
@@ -2499,7 +2588,7 @@ static int inner_child(
cg_unified_flush();
if (arg_userns) {
if (arg_userns_mode != USER_NAMESPACE_NO) {
/* Tell the parent, that it now can write the UID map. */
(void) barrier_place(barrier); /* #1 */
@@ -2510,7 +2599,14 @@ static int inner_child(
}
}
r = mount_all(NULL, arg_userns, true, arg_uid_shift, arg_private_network, arg_uid_range, arg_selinux_apifs_context);
r = mount_all(NULL,
arg_userns_mode != USER_NAMESPACE_NO,
true,
arg_private_network,
arg_uid_shift,
arg_uid_range,
arg_selinux_apifs_context);
if (r < 0)
return r;
@@ -2749,7 +2845,8 @@ static int outer_child(
if (r < 0)
return r;
if (arg_userns) {
if (arg_userns_mode != USER_NAMESPACE_NO) {
/* Let the parent know which UID shift we read from the image */
l = send(uid_shift_socket, &arg_uid_shift, sizeof(arg_uid_shift), MSG_NOSIGNAL);
if (l < 0)
return log_error_errno(errno, "Failed to send UID shift: %m");
@@ -2757,17 +2854,49 @@ static int outer_child(
log_error("Short write while sending UID shift.");
return -EIO;
}
if (arg_userns_mode == USER_NAMESPACE_PICK) {
/* When we are supposed to pick the UID shift, the parent will check now whether the UID shift
* we just read from the image is available. If yes, it will send the UID shift back to us, if
* not it will pick a different one, and send it back to us. */
l = recv(uid_shift_socket, &arg_uid_shift, sizeof(arg_uid_shift), 0);
if (l < 0)
return log_error_errno(errno, "Failed to recv UID shift: %m");
if (l != sizeof(arg_uid_shift)) {
log_error("Short read while recieving UID shift.");
return -EIO;
}
}
log_info("Selected user namespace base " UID_FMT " and range " UID_FMT ".", arg_uid_shift, arg_uid_range);
}
/* Turn directory into bind mount */
if (mount(directory, directory, NULL, MS_BIND|MS_REC, NULL) < 0)
return log_error_errno(errno, "Failed to make bind mount: %m");
r = setup_volatile(directory, arg_volatile_mode, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_context);
r = recursive_chown(directory, arg_uid_shift, arg_uid_range);
if (r < 0)
return r;
r = setup_volatile_state(directory, arg_volatile_mode, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_context);
r = setup_volatile(
directory,
arg_volatile_mode,
arg_userns_mode != USER_NAMESPACE_NO,
arg_uid_shift,
arg_uid_range,
arg_selinux_context);
if (r < 0)
return r;
r = setup_volatile_state(
directory,
arg_volatile_mode,
arg_userns_mode != USER_NAMESPACE_NO,
arg_uid_shift,
arg_uid_range,
arg_selinux_context);
if (r < 0)
return r;
@@ -2781,7 +2910,13 @@ static int outer_child(
return log_error_errno(r, "Failed to make tree read-only: %m");
}
r = mount_all(directory, arg_userns, false, arg_private_network, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
r = mount_all(directory,
arg_userns_mode != USER_NAMESPACE_NO,
false,
arg_private_network,
arg_uid_shift,
arg_uid_range,
arg_selinux_apifs_context);
if (r < 0)
return r;
@@ -2823,11 +2958,24 @@ static int outer_child(
if (r < 0)
return r;
r = mount_custom(directory, arg_custom_mounts, arg_n_custom_mounts, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
r = mount_custom(
directory,
arg_custom_mounts,
arg_n_custom_mounts,
arg_userns_mode != USER_NAMESPACE_NO,
arg_uid_shift,
arg_uid_range,
arg_selinux_apifs_context);
if (r < 0)
return r;
r = mount_cgroups(directory, arg_unified_cgroup_hierarchy, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
r = mount_cgroups(
directory,
arg_unified_cgroup_hierarchy,
arg_userns_mode != USER_NAMESPACE_NO,
arg_uid_shift,
arg_uid_range,
arg_selinux_apifs_context);
if (r < 0)
return r;
@@ -2838,7 +2986,7 @@ static int outer_child(
pid = raw_clone(SIGCHLD|CLONE_NEWNS|
(arg_share_system ? 0 : CLONE_NEWIPC|CLONE_NEWPID|CLONE_NEWUTS) |
(arg_private_network ? CLONE_NEWNET : 0) |
(arg_userns ? CLONE_NEWUSER : 0),
(arg_userns_mode != USER_NAMESPACE_NO ? CLONE_NEWUSER : 0),
NULL);
if (pid < 0)
return log_error_errno(errno, "Failed to fork inner child: %m");
@@ -2882,6 +3030,61 @@ static int outer_child(
return 0;
}
static int uid_shift_pick(uid_t *shift, LockFile *ret_lock_file) {
unsigned n_tries = 100;
uid_t candidate;
int r;
assert(shift);
assert(ret_lock_file);
assert(arg_userns_mode == USER_NAMESPACE_PICK);
assert(arg_uid_range == 0x10000U);
candidate = *shift;
(void) mkdir("/run/systemd/nspawn-uid", 0755);
for (;;) {
char lock_path[strlen("/run/systemd/nspawn-uid/") + DECIMAL_STR_MAX(uid_t) + 1];
_cleanup_release_lock_file_ LockFile lf = LOCK_FILE_INIT;
if (--n_tries <= 0)
return -EBUSY;
if (candidate < UID_SHIFT_PICK_MIN || candidate > UID_SHIFT_PICK_MAX)
goto next;
if ((candidate & UINT32_C(0xFFFF)) != 0)
goto next;
xsprintf(lock_path, "/run/systemd/nspawn-uid/" UID_FMT, candidate);
r = make_lock_file(lock_path, LOCK_EX|LOCK_NB, &lf);
if (r == -EBUSY) /* Range already taken by another nspawn instance */
goto next;
if (r < 0)
return r;
/* Make some superficial checks whether the range is currently known in the user database */
if (getpwuid(candidate))
goto next;
if (getpwuid(candidate + UINT32_C(0xFFFE)))
goto next;
if (getgrgid(candidate))
goto next;
if (getgrgid(candidate + UINT32_C(0xFFFE)))
goto next;
*ret_lock_file = lf;
lf = (struct LockFile) LOCK_FILE_INIT;
*shift = candidate;
return 0;
next:
random_bytes(&candidate, sizeof(candidate));
candidate = (candidate % (UID_SHIFT_PICK_MAX - UID_SHIFT_PICK_MIN)) + UID_SHIFT_PICK_MIN;
candidate &= (uid_t) UINT32_C(0xFFFF0000);
}
}
static int setup_uid_map(pid_t pid) {
char uid_map[strlen("/proc//uid_map") + DECIMAL_STR_MAX(uid_t) + 1], line[DECIMAL_STR_MAX(uid_t)*3+3+1];
int r;
@@ -3113,6 +3316,19 @@ static int load_settings(void) {
}
}
if ((arg_settings_mask & SETTING_USERNS) == 0 &&
settings->userns_mode != _USER_NAMESPACE_MODE_INVALID) {
if (!arg_settings_trusted)
log_warning("Ignoring PrivateUsers= and PrivateUsersChown= settings, file %s is not trusted.", p);
else {
arg_userns_mode = settings->userns_mode;
arg_uid_shift = settings->uid_shift;
arg_uid_range = settings->uid_range;
arg_userns_chown = settings->userns_chown;
}
}
return 0;
}
@@ -3351,20 +3567,42 @@ int main(int argc, char *argv[]) {
}
for (;;) {
_cleanup_close_pair_ int kmsg_socket_pair[2] = { -1, -1 }, rtnl_socket_pair[2] = { -1, -1 },
pid_socket_pair[2] = { -1, -1 }, uuid_socket_pair[2] = { -1, -1 }, uid_shift_socket_pair[2] = { -1, -1 };
ContainerStatus container_status;
_cleanup_(barrier_destroy) Barrier barrier = BARRIER_NULL;
static const struct sigaction sa = {
.sa_handler = nop_signal_handler,
.sa_flags = SA_NOCLDSTOP,
};
int ifi = 0;
ssize_t l;
_cleanup_release_lock_file_ LockFile uid_shift_lock = LOCK_FILE_INIT;
_cleanup_close_ int etc_passwd_lock = -1;
_cleanup_close_pair_ int
kmsg_socket_pair[2] = { -1, -1 },
rtnl_socket_pair[2] = { -1, -1 },
pid_socket_pair[2] = { -1, -1 },
uuid_socket_pair[2] = { -1, -1 },
uid_shift_socket_pair[2] = { -1, -1 };
_cleanup_(barrier_destroy) Barrier barrier = BARRIER_NULL;
_cleanup_(sd_event_unrefp) sd_event *event = NULL;
_cleanup_(pty_forward_freep) PTYForward *forward = NULL;
_cleanup_(sd_netlink_unrefp) sd_netlink *rtnl = NULL;
ContainerStatus container_status;
char last_char = 0;
int ifi = 0;
ssize_t l;
if (arg_userns_mode == USER_NAMESPACE_PICK) {
/* When we shall pick the UID/GID range, let's first lock /etc/passwd, so that we can safely
* check with getpwuid() if the specific user already exists. Note that /etc might be
* read-only, in which case this will fail with EROFS. But that's really OK, as in that case we
* can be reasonably sure that no users are going to be added. Note that getpwuid() checks are
* really just an extra safety net. We kinda assume that the UID range we allocate from is
* really ours. */
etc_passwd_lock = take_etc_passwd_lock(NULL);
if (etc_passwd_lock < 0 && etc_passwd_lock != -EROFS) {
log_error_errno(r, "Failed to take /etc/passwd lock: %m");
goto finish;
}
}
r = barrier_create(&barrier);
if (r < 0) {
@@ -3392,7 +3630,7 @@ int main(int argc, char *argv[]) {
goto finish;
}
if (arg_userns)
if (arg_userns_mode != USER_NAMESPACE_NO)
if (socketpair(AF_UNIX, SOCK_SEQPACKET|SOCK_CLOEXEC, 0, uid_shift_socket_pair) < 0) {
r = log_error_errno(errno, "Failed to create uid shift socket pair: %m");
goto finish;
@@ -3468,6 +3706,43 @@ int main(int argc, char *argv[]) {
uuid_socket_pair[1] = safe_close(uuid_socket_pair[1]);
uid_shift_socket_pair[1] = safe_close(uid_shift_socket_pair[1]);
if (arg_userns_mode != USER_NAMESPACE_NO) {
/* The child just let us know the UID shift it might have read from the image. */
l = recv(uid_shift_socket_pair[0], &arg_uid_shift, sizeof(arg_uid_shift), 0);
if (l < 0) {
r = log_error_errno(errno, "Failed to read UID shift: %m");
goto finish;
}
if (l != sizeof(arg_uid_shift)) {
log_error("Short read while reading UID shift.");
r = EIO;
goto finish;
}
if (arg_userns_mode == USER_NAMESPACE_PICK) {
/* If we are supposed to pick the UID shift, let's try to use the shift read from the
* image, but if that's already in use, pick a new one, and report back to the child,
* which one we now picked. */
r = uid_shift_pick(&arg_uid_shift, &uid_shift_lock);
if (r < 0) {
log_error_errno(r, "Failed to pick suitable UID/GID range: %m");
goto finish;
}
l = send(uid_shift_socket_pair[0], &arg_uid_shift, sizeof(arg_uid_shift), MSG_NOSIGNAL);
if (l < 0) {
r = log_error_errno(errno, "Failed to send UID shift: %m");
goto finish;
}
if (l != sizeof(arg_uid_shift)) {
log_error("Short write while writing UID shift.");
r = -EIO;
goto finish;
}
}
}
/* Wait for the outer child. */
r = wait_for_terminate_and_warn("namespace helper", pid, NULL);
if (r < 0)
@@ -3504,24 +3779,13 @@ int main(int argc, char *argv[]) {
log_debug("Init process invoked as PID " PID_FMT, pid);
if (arg_userns) {
if (arg_userns_mode != USER_NAMESPACE_NO) {
if (!barrier_place_and_sync(&barrier)) { /* #1 */
log_error("Child died too early.");
r = -ESRCH;
goto finish;
}
l = recv(uid_shift_socket_pair[0], &arg_uid_shift, sizeof(arg_uid_shift), 0);
if (l < 0) {
r = log_error_errno(errno, "Failed to read UID shift: %m");
goto finish;
}
if (l != sizeof(arg_uid_shift)) {
log_error("Short read while reading UID shift.");
r = EIO;
goto finish;
}
r = setup_uid_map(pid);
if (r < 0)
goto finish;
@@ -3619,6 +3883,10 @@ int main(int argc, char *argv[]) {
goto finish;
}
/* At this point we have made use of the UID we picked, and thus nss-mymachines will make them appear
* in getpwuid(), thus we can release the /etc/passwd lock. */
etc_passwd_lock = safe_close(etc_passwd_lock);
sd_notifyf(false,
"READY=1\n"
"STATUS=Container running.\n"
src/nspawn/test-patch-uid.c
+61
View File
@@ -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;
}