shaba/systemd
1
0
Fork 0
mirror of https://github.com/systemd/systemd.git synced 2025-03-31 14:50:15 +03:00
Code

nspawn: allow configuration of user namespaces in .nspawn files

Browse Source 
In order to implement this we change the bool arg_userns into an enum
UserNamespaceMode, which can take one of NO, PICK or FIXED, and replace the
arg_uid_range_pick bool with it.
This commit is contained in:
Lennart Poettering 2016-04-22 13:02:53 +02:00
parent 19aac838fc
commit 0de7accea9
4 changed files with 223 additions and 61 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/nspawn/nspawn-gperf.gperf
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)

86
src/nspawn/nspawn-settings.c
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;
}

15
src/nspawn/nspawn-settings.h
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);

179
src/nspawn/nspawn.c
View File

@ -181,10 +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 bool arg_userns = false;
static bool arg_userns_chown = false;
static UserNamespaceMode arg_userns_mode = USER_NAMESPACE_NO;
static uid_t arg_uid_shift = UID_INVALID, arg_uid_range = 0x10000U;
static bool arg_uid_shift_pick = 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;
@ -284,7 +283,7 @@ static int custom_mounts_prepare(void) {
for (i = 0; i < arg_n_custom_mounts; i++) {
CustomMount *m = &arg_custom_mounts[i];
if (path_equal(m->destination, "/") && arg_userns) {
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.");
@ -817,56 +816,67 @@ 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;
if (streq(optarg, "pick")) {
arg_uid_shift = UID_INVALID;
arg_uid_range = 0x10000U;
arg_uid_shift_pick = true;
} else {
range = strchr(optarg, ':');
if (range) {
buffer = strndup(optarg, range - optarg);
if (!buffer)
return log_oom();
shift = buffer;
/* anything else: User namespacing on, UID range is explicitly configured */
range++;
if (safe_atou32(range, &arg_uid_range) < 0 || arg_uid_range <= 0) {
log_error("Failed to parse UID range: %s", range);
return -EINVAL;
}
} else
shift = optarg;
range = strchr(optarg, ':');
if (range) {
buffer = strndup(optarg, range - optarg);
if (!buffer)
return log_oom();
shift = buffer;
if (parse_uid(shift, &arg_uid_shift) < 0) {
log_error("Failed to parse UID: %s", optarg);
range++;
if (safe_atou32(range, &arg_uid_range) < 0 || arg_uid_range <= 0) {
log_error("Failed to parse UID range: %s", range);
return -EINVAL;
}
} else
shift = optarg;
arg_uid_shift_pick = false;
if (parse_uid(shift, &arg_uid_shift) < 0) {
log_error("Failed to parse UID: %s", optarg);
return -EINVAL;
}
} else {
arg_uid_shift = UID_INVALID;
arg_uid_range = 0x10000U;
arg_uid_shift_pick = false;
arg_userns_mode = USER_NAMESPACE_FIXED;
}
arg_userns = true;
arg_settings_mask |= SETTING_USERNS;
break;
case 'U':
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;
break;
case 'U':
arg_userns = true;
arg_userns_chown = true;
arg_uid_shift = UID_INVALID;
arg_uid_range = 0x10000U;
arg_uid_shift_pick = true;
arg_settings_mask |= SETTING_USERNS;
break;
case ARG_KILL_SIGNAL:
@ -937,7 +947,7 @@ static int parse_argv(int argc, char *argv[]) {
if (arg_share_system)
arg_register = false;
if (arg_uid_shift_pick)
if (arg_userns_mode == USER_NAMESPACE_PICK)
arg_userns_chown = true;
if (arg_start_mode != START_PID1 && arg_share_system) {
@ -980,7 +990,7 @@ static int parse_argv(int argc, char *argv[]) {
return -EINVAL;
}
if (arg_userns && access("/proc/self/uid_map", F_OK) < 0) {
if (arg_userns_mode != USER_NAMESPACE_NO && access("/proc/self/uid_map", F_OK) < 0) {
log_error("--private-users= is not supported, kernel compiled without user namespace support.");
return -EOPNOTSUPP;
}
@ -1047,7 +1057,7 @@ 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)
@ -2277,7 +2287,7 @@ static int recursive_chown(const char *directory, uid_t shift, uid_t range) {
assert(directory);
if (!arg_userns || !arg_userns_chown)
if (arg_userns_mode == USER_NAMESPACE_NO || !arg_userns_chown)
return 0;
r = path_patch_uid(directory, arg_uid_shift, arg_uid_range);
@ -2512,7 +2522,7 @@ 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;
}
@ -2575,7 +2585,7 @@ 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 */
@ -2586,7 +2596,14 @@ 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;
@ -2825,7 +2842,7 @@ 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)
@ -2835,7 +2852,7 @@ static int outer_child(
return -EIO;
}
if (arg_uid_shift_pick) {
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. */
@ -2860,11 +2877,23 @@ static int outer_child(
if (r < 0)
return r;
r = setup_volatile(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, arg_uid_shift, arg_uid_range, arg_selinux_context);
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;
@ -2878,7 +2907,13 @@ 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;
@ -2920,11 +2955,24 @@ 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;
@ -2935,7 +2983,7 @@ 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");
@ -2986,7 +3034,7 @@ static int uid_shift_pick(uid_t *shift, LockFile *ret_lock_file) {
assert(shift);
assert(ret_lock_file);
assert(arg_uid_shift_pick);
assert(arg_userns_mode == USER_NAMESPACE_PICK);
assert(arg_uid_range == 0x10000U);
candidate = *shift;
@ -3265,6 +3313,19 @@ 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;
}
@ -3525,7 +3586,7 @@ int main(int argc, char *argv[]) {
int ifi = 0;
ssize_t l;
if (arg_uid_shift_pick) {
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
@ -3566,7 +3627,7 @@ 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;
@ -3642,7 +3703,7 @@ 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) {
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) {
@ -3655,7 +3716,7 @@ int main(int argc, char *argv[]) {
goto finish;
}
if (arg_uid_shift_pick) {
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. */
@ -3715,7 +3776,7 @@ 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;