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nspawn: add --set-credential= and --load-credential=

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Let's allow passing in creds to containers, so that PID 1 inside the
container can pick them up.
This commit is contained in:
Lennart Poettering 2020-07-23 08:47:08 +02:00
parent bbb4e7f39f
commit 3652872add
5 changed files with 231 additions and 4 deletions
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2
src/nspawn/meson.build
View File

@ -3,6 +3,8 @@
libnspawn_core_sources = files('''
nspawn-cgroup.c
nspawn-cgroup.h
nspawn-creds.c
nspawn-creds.h
nspawn-def.h
nspawn-expose-ports.c
nspawn-expose-ports.h

25
src/nspawn/nspawn-creds.c Normal file
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@ -0,0 +1,25 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#include "alloc-util.h"
#include "macro.h"
#include "memory-util.h"
#include "nspawn-creds.h"
static void credential_free(Credential *cred) {
assert(cred);
cred->id = mfree(cred->id);
cred->data = erase_and_free(cred->data);
cred->size = 0;
}
void credential_free_all(Credential *creds, size_t n) {
size_t i;
assert(creds || n == 0);
for (i = 0; i < n; i++)
credential_free(creds + i);
free(creds);
}

12
src/nspawn/nspawn-creds.h Normal file
View File

@ -0,0 +1,12 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
#include <sys/types.h>
typedef struct Credential {
char *id;
void *data;
size_t size;
} Credential;
void credential_free_all(Credential *creds, size_t n);

7
src/nspawn/nspawn-settings.h
View File

@ -116,9 +116,10 @@ typedef enum SettingsMask {
SETTING_USE_CGNS = UINT64_C(1) << 27,
SETTING_CLONE_NS_FLAGS = UINT64_C(1) << 28,
SETTING_CONSOLE_MODE = UINT64_C(1) << 29,
SETTING_RLIMIT_FIRST = UINT64_C(1) << 30, /* we define one bit per resource limit here */
SETTING_RLIMIT_LAST = UINT64_C(1) << (30 + _RLIMIT_MAX - 1),
_SETTINGS_MASK_ALL = (UINT64_C(1) << (30 + _RLIMIT_MAX)) -1,
SETTING_CREDENTIALS = UINT64_C(1) << 30,
SETTING_RLIMIT_FIRST = UINT64_C(1) << 31, /* we define one bit per resource limit here */
SETTING_RLIMIT_LAST = UINT64_C(1) << (31 + _RLIMIT_MAX - 1),
_SETTINGS_MASK_ALL = (UINT64_C(1) << (31 + _RLIMIT_MAX)) -1,
_SETTING_FORCE_ENUM_WIDTH = UINT64_MAX
} SettingsMask;

189
src/nspawn/nspawn.c
View File

@ -36,6 +36,7 @@
#include "dev-setup.h"
#include "dissect-image.h"
#include "env-util.h"
#include "escape.h"
#include "fd-util.h"
#include "fdset.h"
#include "fileio.h"
@ -45,6 +46,7 @@
#include "hexdecoct.h"
#include "hostname-util.h"
#include "id128-util.h"
#include "io-util.h"
#include "log.h"
#include "loop-util.h"
#include "loopback-setup.h"
@ -58,6 +60,7 @@
#include "namespace-util.h"
#include "netlink-util.h"
#include "nspawn-cgroup.h"
#include "nspawn-creds.h"
#include "nspawn-def.h"
#include "nspawn-expose-ports.h"
#include "nspawn-mount.h"
@ -219,6 +222,8 @@ static DeviceNode* arg_extra_nodes = NULL;
static size_t arg_n_extra_nodes = 0;
static char **arg_sysctl = NULL;
static ConsoleMode arg_console_mode = _CONSOLE_MODE_INVALID;
static Credential *arg_credentials = NULL;
static size_t arg_n_credentials = 0;
STATIC_DESTRUCTOR_REGISTER(arg_directory, freep);
STATIC_DESTRUCTOR_REGISTER(arg_template, freep);
@ -406,7 +411,13 @@ static int help(void) {
"%3$sInput/Output:%4$s\n"
" --console=MODE Select how stdin/stdout/stderr and /dev/console are\n"
" set up for the container.\n"
" -P --pipe Equivalent to --console=pipe\n"
" -P --pipe Equivalent to --console=pipe\n\n"
"%3$sCredentials:%4$s\n"
" --set-credential=ID:VALUE\n"
" Pass a credential with literal value to container.\n"
" --load-credential=ID:PATH\n"
" Load credential to pass to container from file or\n"
" AF_UNIX stream socket.\n"
"\nSee the %2$s for details.\n"
, program_invocation_short_name
, link
@ -675,6 +686,8 @@ static int parse_argv(int argc, char *argv[]) {
ARG_NO_PAGER,
ARG_VERITY_DATA,
ARG_ROOT_HASH_SIG,
ARG_SET_CREDENTIAL,
ARG_LOAD_CREDENTIAL,
};
static const struct option options[] = {
@ -742,6 +755,8 @@ static int parse_argv(int argc, char *argv[]) {
{ "no-pager", no_argument, NULL, ARG_NO_PAGER },
{ "verity-data", required_argument, NULL, ARG_VERITY_DATA },
{ "root-hash-sig", required_argument, NULL, ARG_ROOT_HASH_SIG },
{ "set-credential", required_argument, NULL, ARG_SET_CREDENTIAL },
{ "load-credential", required_argument, NULL, ARG_LOAD_CREDENTIAL },
{}
};
@ -1496,6 +1511,105 @@ static int parse_argv(int argc, char *argv[]) {
arg_pager_flags |= PAGER_DISABLE;
break;
case ARG_SET_CREDENTIAL: {
_cleanup_free_ char *word = NULL, *data = NULL;
const char *p = optarg;
Credential *a;
size_t i;
int l;
r = extract_first_word(&p, &word, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
if (r == -ENOMEM)
return log_oom();
if (r < 0)
return log_error_errno(r, "Failed to parse --set-credential= parameter: %m");
if (r == 0 || !p)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Missing value for --set-credential=: %s", optarg);
if (!credential_name_valid(word))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Credential name is not valid: %s", word);
for (i = 0; i < arg_n_credentials; i++)
if (streq(arg_credentials[i].id, word))
return log_error_errno(SYNTHETIC_ERRNO(EEXIST), "Duplicate credential '%s', refusing.", word);
l = cunescape(p, UNESCAPE_ACCEPT_NUL, &data);
if (l < 0)
return log_error_errno(l, "Failed to unescape credential data: %s", p);
a = reallocarray(arg_credentials, arg_n_credentials + 1, sizeof(Credential));
if (!a)
return log_oom();
a[arg_n_credentials++] = (Credential) {
.id = TAKE_PTR(word),
.data = TAKE_PTR(data),
.size = l,
};
arg_credentials = a;
arg_settings_mask |= SETTING_CREDENTIALS;
break;
}
case ARG_LOAD_CREDENTIAL: {
ReadFullFileFlags flags = READ_FULL_FILE_SECURE;
_cleanup_(erase_and_freep) char *data = NULL;
_cleanup_free_ char *word = NULL, *j = NULL;
const char *p = optarg;
Credential *a;
size_t size, i;
r = extract_first_word(&p, &word, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
if (r == -ENOMEM)
return log_oom();
if (r < 0)
return log_error_errno(r, "Failed to parse --set-credential= parameter: %m");
if (r == 0 || !p)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Missing value for --set-credential=: %s", optarg);
if (!credential_name_valid(word))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Credential name is not valid: %s", word);
for (i = 0; i < arg_n_credentials; i++)
if (streq(arg_credentials[i].id, word))
return log_error_errno(SYNTHETIC_ERRNO(EEXIST), "Duplicate credential '%s', refusing.", word);
if (path_is_absolute(p))
flags |= READ_FULL_FILE_CONNECT_SOCKET;
else {
const char *e;
e = getenv("CREDENTIALS_DIRECTORY");
if (!e)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Credential not available (no credentials passed at all): %s", word);
j = path_join(e, p);
if (!j)
return log_oom();
}
r = read_full_file_full(AT_FDCWD, j ?: p, flags, &data, &size);
if (r < 0)
return log_error_errno(r, "Failed to read credential '%s': %m", j ?: p);
a = reallocarray(arg_credentials, arg_n_credentials + 1, sizeof(Credential));
if (!a)
return log_oom();
a[arg_n_credentials++] = (Credential) {
.id = TAKE_PTR(word),
.data = TAKE_PTR(data),
.size = size,
};
arg_credentials = a;
arg_settings_mask |= SETTING_CREDENTIALS;
break;
}
case '?':
return -EINVAL;
@ -2228,6 +2342,66 @@ static int setup_keyring(void) {
return 0;
}
static int setup_credentials(const char *root) {
const char *q;
int r;
if (arg_n_credentials <= 0)
return 0;
r = userns_mkdir(root, "/run/host", 0755, 0, 0);
if (r < 0)
return log_error_errno(r, "Failed to create /run/host: %m");
r = userns_mkdir(root, "/run/host/credentials", 0700, 0, 0);
if (r < 0)
return log_error_errno(r, "Failed to create /run/host/credentials: %m");
q = prefix_roota(root, "/run/host/credentials");
r = mount_verbose(LOG_ERR, NULL, q, "ramfs", MS_NOSUID|MS_NOEXEC|MS_NODEV, "mode=0700");
if (r < 0)
return r;
for (size_t i = 0; i < arg_n_credentials; i++) {
_cleanup_free_ char *j = NULL;
_cleanup_close_ int fd = -1;
j = path_join(q, arg_credentials[i].id);
if (!j)
return log_oom();
fd = open(j, O_CREAT|O_EXCL|O_WRONLY|O_CLOEXEC|O_NOFOLLOW, 0600);
if (fd < 0)
return log_error_errno(errno, "Failed to create credential file %s: %m", j);
r = loop_write(fd, arg_credentials[i].data, arg_credentials[i].size, /* do_poll= */ false);
if (r < 0)
return log_error_errno(r, "Failed to write credential to file %s: %m", j);
if (fchmod(fd, 0400) < 0)
return log_error_errno(errno, "Failed to adjust access mode of %s: %m", j);
if (arg_userns_mode != USER_NAMESPACE_NO) {
if (fchown(fd, arg_uid_shift, arg_uid_shift) < 0)
return log_error_errno(errno, "Failed to adjust ownership of %s: %m", j);
}
}
if (chmod(q, 0500) < 0)
return log_error_errno(errno, "Failed to adjust access mode of %s: %m", q);
r = userns_lchown(q, 0, 0);
if (r < 0)
return r;
/* Make both mount and superblock read-only now */
r = mount_verbose(LOG_ERR, NULL, q, NULL, MS_REMOUNT|MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL);
if (r < 0)
return r;
return mount_verbose(LOG_ERR, NULL, q, NULL, MS_REMOUNT|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, "mode=0500");
}
static int setup_kmsg(int kmsg_socket) {
_cleanup_(unlink_and_freep) char *from = NULL;
_cleanup_free_ char *fifo = NULL;
@ -2941,6 +3115,7 @@ static int inner_child(
NULL, /* LISTEN_FDS */
NULL, /* LISTEN_PID */
NULL, /* NOTIFY_SOCKET */
NULL, /* CREDENTIALS_DIRECTORY */
NULL
};
const char *exec_target;
@ -3191,6 +3366,13 @@ static int inner_child(
if (asprintf((char **)(envp + n_env++), "NOTIFY_SOCKET=%s", NSPAWN_NOTIFY_SOCKET_PATH) < 0)
return log_oom();
if (arg_n_credentials > 0) {
envp[n_env] = strdup("CREDENTIALS_DIRECTORY=/run/host/credentials");
if (!envp[n_env])
return log_oom();
n_env++;
}
env_use = strv_env_merge(3, envp, os_release_pairs, arg_setenv);
if (!env_use)
return log_oom();
@ -3538,6 +3720,10 @@ static int outer_child(
if (r < 0)
return r;
r = setup_credentials(directory);
if (r < 0)
return r;
r = mount_custom(
directory,
arg_custom_mounts,
@ -5339,6 +5525,7 @@ finish:
expose_port_free_all(arg_expose_ports);
rlimit_free_all(arg_rlimit);
device_node_array_free(arg_extra_nodes, arg_n_extra_nodes);
credential_free_all(arg_credentials, arg_n_credentials);
if (r < 0)
return r;