[thirdparty/systemd.git] / src / home / homework-directory.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <sys/mount.h>

#include "btrfs-util.h"
#include "fd-util.h"
#include "homework-directory.h"
#include "homework-mount.h"
#include "homework-quota.h"
#include "mkdir.h"
#include "mount-util.h"
#include "path-util.h"
#include "rm-rf.h"
#include "tmpfile-util.h"
#include "umask-util.h"
#include "user-util.h"

int home_setup_directory(UserRecord *h, HomeSetup *setup) {
        const char *ip;
        int r;

        assert(h);
        assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME));
        assert(setup);
        assert(!setup->undo_mount);
        assert(setup->root_fd < 0);

        /* We'll bind mount the image directory to a new mount point where we'll start adjusting it. Only
         * once that's complete we'll move the thing to its final place eventually. */
        r = home_unshare_and_mkdir();
        if (r < 0)
                return r;

        assert_se(ip = user_record_image_path(h));

        r = mount_follow_verbose(LOG_ERR, ip, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND, NULL);
        if (r < 0)
                return r;

        setup->undo_mount = true;

        /* Turn off any form of propagation for this */
        r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_PRIVATE, NULL);
        if (r < 0)
                return r;

        /* Adjust MS_SUID and similar flags */
        r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND|MS_REMOUNT|user_record_mount_flags(h), NULL);
        if (r < 0)
                return r;

        setup->root_fd = open(HOME_RUNTIME_WORK_DIR, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW);
        if (setup->root_fd < 0)
                return log_error_errno(errno, "Failed to open home directory: %m");

        return 0;
}

int home_activate_directory(
                UserRecord *h,
                HomeSetupFlags flags,
                HomeSetup *setup,
                PasswordCache *cache,
                UserRecord **ret_home) {

        _cleanup_(user_record_unrefp) UserRecord *new_home = NULL, *header_home = NULL;
        const char *hd, *hdo;
        int r;

        assert(h);
        assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME, USER_FSCRYPT));
        assert(setup);
        assert(ret_home);

        assert_se(hdo = user_record_home_directory(h));
        hd = strdupa_safe(hdo);

        r = home_setup(h, flags, setup, cache, &header_home);
        if (r < 0)
                return r;

        r = home_refresh(h, flags, setup, header_home, cache, NULL, &new_home);
        if (r < 0)
                return r;

        r = home_extend_embedded_identity(new_home, h, setup);
        if (r < 0)
                return r;

        /* Close fd to private mount before moving mount */
        setup->root_fd = safe_close(setup->root_fd);

        /* We are now done with everything, move the mount into place */
        r = home_move_mount(NULL, hd);
        if (r < 0)
                return r;

        setup->undo_mount = false;

        setup->do_drop_caches = false;

        log_info("Everything completed.");

        *ret_home = TAKE_PTR(new_home);
        return 0;
}

int home_create_directory_or_subvolume(UserRecord *h, HomeSetup *setup, UserRecord **ret_home) {
        _cleanup_(rm_rf_subvolume_and_freep) char *temporary = NULL;
        _cleanup_(user_record_unrefp) UserRecord *new_home = NULL;
        _cleanup_close_ int mount_fd = -EBADF;
        _cleanup_free_ char *d = NULL;
        bool is_subvolume = false;
        const char *ip;
        int r;

        assert(h);
        assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME));
        assert(setup);
        assert(ret_home);

        assert_se(ip = user_record_image_path(h));

        r = tempfn_random(ip, "homework", &d);
        if (r < 0)
                return log_error_errno(r, "Failed to allocate temporary directory: %m");

        (void) mkdir_parents(d, 0755);

        switch (user_record_storage(h)) {

        case USER_SUBVOLUME:
                WITH_UMASK(0077)
                        r = btrfs_subvol_make(AT_FDCWD, d);

                if (r >= 0) {
                        log_info("Subvolume created.");
                        is_subvolume = true;

                        if (h->disk_size != UINT64_MAX) {

                                /* Enable quota for the subvolume we just created. Note we don't check for
                                 * errors here and only log about debug level about this. */
                                r = btrfs_quota_enable(d, true);
                                if (r < 0)
                                        log_debug_errno(r, "Failed to enable quota on %s, ignoring: %m", d);

                                r = btrfs_subvol_auto_qgroup(d, 0, false);
                                if (r < 0)
                                        log_debug_errno(r, "Failed to set up automatic quota group on %s, ignoring: %m", d);

                                /* Actually configure the quota. We also ignore errors here, but we do log
                                 * about them loudly, to keep things discoverable even though we don't
                                 * consider lacking quota support in kernel fatal. */
                                (void) home_update_quota_btrfs(h, d);
                        }

                        break;
                }
                if (r != -ENOTTY)
                        return log_error_errno(r, "Failed to create temporary home directory subvolume %s: %m", d);

                log_info("Creating subvolume %s is not supported, as file system does not support subvolumes. Falling back to regular directory.", d);
                _fallthrough_;

        case USER_DIRECTORY:

                if (mkdir(d, 0700) < 0)
                        return log_error_errno(errno, "Failed to create temporary home directory %s: %m", d);

                (void) home_update_quota_classic(h, d);
                break;

        default:
                assert_not_reached();
        }

        temporary = TAKE_PTR(d); /* Needs to be destroyed now */

        /* Let's decouple namespaces now, so that we can possibly mount a UID map mount into
         * /run/systemd/user-home-mount/ that no one will see but us. */
        r = home_unshare_and_mkdir();
        if (r < 0)
                return r;

        setup->root_fd = open(temporary, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW);
        if (setup->root_fd < 0)
                return log_error_errno(errno, "Failed to open temporary home directory: %m");

        /* Try to apply a UID shift, so that the directory is actually owned by "nobody", and is only mapped
         * to the proper UID while active. — Well, that's at least the theory. Unfortunately, only btrfs does
         * per-subvolume quota. The others do per-uid quota. Which means mapping all home directories to the
         * same UID of "nobody" makes quota impossible. Hence unless we actually managed to create a btrfs
         * subvolume for this user we'll map the user's UID to itself. Now you might ask: why bother mapping
         * at all? It's because we want to restrict the UIDs used on the home directory: we leave all other
         * UIDs of the homed UID range unmapped, thus making them unavailable to programs accessing the
         * mount. */
        r = home_shift_uid(setup->root_fd, HOME_RUNTIME_WORK_DIR, is_subvolume ? UID_NOBODY : h->uid, h->uid, &mount_fd);
        if (r > 0)
                setup->undo_mount = true; /* If uidmaps worked we have a mount to undo again */

        if (mount_fd >= 0) {
                /* If we have established a new mount, then we can use that as new root fd to our home directory. */
                safe_close(setup->root_fd);

                setup->root_fd = fd_reopen(mount_fd, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
                if (setup->root_fd < 0)
                        return log_error_errno(setup->root_fd, "Unable to convert mount fd into proper directory fd: %m");

                mount_fd = safe_close(mount_fd);
        }

        r = home_populate(h, setup->root_fd);
        if (r < 0)
                return r;

        r = home_sync_and_statfs(setup->root_fd, NULL);
        if (r < 0)
                return r;

        r = user_record_clone(h, USER_RECORD_LOAD_MASK_SECRET|USER_RECORD_PERMISSIVE, &new_home);
        if (r < 0)
                return log_error_errno(r, "Failed to clone record: %m");

        r = user_record_add_binding(
                        new_home,
                        user_record_storage(h),
                        ip,
                        SD_ID128_NULL,
                        SD_ID128_NULL,
                        SD_ID128_NULL,
                        NULL,
                        NULL,
                        UINT64_MAX,
                        NULL,
                        NULL,
                        h->uid,
                        (gid_t) h->uid);
        if (r < 0)
                return log_error_errno(r, "Failed to add binding to record: %m");

        setup->root_fd = safe_close(setup->root_fd);

        /* Unmount mapped mount before we move the dir into place */
        r = home_setup_undo_mount(setup, LOG_ERR);
        if (r < 0)
                return r;

        if (rename(temporary, ip) < 0)
                return log_error_errno(errno, "Failed to rename %s to %s: %m", temporary, ip);

        temporary = mfree(temporary);

        log_info("Everything completed.");

        *ret_home = TAKE_PTR(new_home);
        return 0;
}

int home_resize_directory(
                UserRecord *h,
                HomeSetupFlags flags,
                HomeSetup *setup,
                PasswordCache *cache,
                UserRecord **ret_home) {

        _cleanup_(user_record_unrefp) UserRecord *embedded_home = NULL, *new_home = NULL;
        int r;

        assert(h);
        assert(setup);
        assert(ret_home);
        assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME, USER_FSCRYPT));

        r = home_setup(h, flags, setup, cache, NULL);
        if (r < 0)
                return r;

        r = home_load_embedded_identity(h, setup->root_fd, NULL, USER_RECONCILE_REQUIRE_NEWER_OR_EQUAL, cache, &embedded_home, &new_home);
        if (r < 0)
                return r;

        r = home_maybe_shift_uid(h, flags, setup);
        if (r < 0)
                return r;

        r = home_update_quota_auto(h, NULL);
        if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
                return -ESOCKTNOSUPPORT; /* make recognizable */
        if (r < 0)
                return r;

        r = home_store_embedded_identity(new_home, setup->root_fd, embedded_home);
        if (r < 0)
                return r;

        r = home_extend_embedded_identity(new_home, h, setup);
        if (r < 0)
                return r;

        r = home_sync_and_statfs(setup->root_fd, NULL);
        if (r < 0)
                return r;

        r = home_setup_done(setup);
        if (r < 0)
                return r;

        log_info("Everything completed.");

        *ret_home = TAKE_PTR(new_home);
        return 0;
}
Commit	Line	Data
db9ecf05	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
70a5db58 LP	2
	3	#include <sys/mount.h>
	4
	5	#include "btrfs-util.h"
	6	#include "fd-util.h"
	7	#include "homework-directory.h"
2ba38f78	8	#include "homework-mount.h"
70a5db58 LP	9	#include "homework-quota.h"
	10	#include "mkdir.h"
	11	#include "mount-util.h"
	12	#include "path-util.h"
	13	#include "rm-rf.h"
	14	#include "tmpfile-util.h"
	15	#include "umask-util.h"
cf5115f6	16	#include "user-util.h"
70a5db58	17
e1df968b	18	int home_setup_directory(UserRecord h, HomeSetup setup) {
2ba38f78 LP	19	const char *ip;
	20	int r;
	21
70a5db58	22	assert(h);
cf5115f6	23	assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME));
70a5db58	24	assert(setup);
cf5115f6	25	assert(!setup->undo_mount);
2ba38f78 LP	26	assert(setup->root_fd < 0);
	27
	28	/* We'll bind mount the image directory to a new mount point where we'll start adjusting it. Only
	29	* once that's complete we'll move the thing to its final place eventually. */
	30	r = home_unshare_and_mkdir();
	31	if (r < 0)
	32	return r;
	33
	34	assert_se(ip = user_record_image_path(h));
	35
	36	r = mount_follow_verbose(LOG_ERR, ip, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND, NULL);
	37	if (r < 0)
	38	return r;
70a5db58	39
2ba38f78 LP	40	setup->undo_mount = true;
	41
	42	/* Turn off any form of propagation for this */
	43	r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_PRIVATE, NULL);
	44	if (r < 0)
	45	return r;
	46
	47	/* Adjust MS_SUID and similar flags */
	48	r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND\|MS_REMOUNT\|user_record_mount_flags(h), NULL);
	49	if (r < 0)
	50	return r;
	51
	52	setup->root_fd = open(HOME_RUNTIME_WORK_DIR, O_RDONLY\|O_CLOEXEC\|O_DIRECTORY\|O_NOFOLLOW);
70a5db58 LP	53	if (setup->root_fd < 0)
	54	return log_error_errno(errno, "Failed to open home directory: %m");
	55
	56	return 0;
	57	}
	58
	59	int home_activate_directory(
	60	UserRecord *h,
6f2c8136	61	HomeSetupFlags flags,
a74e2e44	62	HomeSetup *setup,
7b78db28	63	PasswordCache *cache,
70a5db58 LP	64	UserRecord **ret_home) {
	65
	66	_cleanup_(user_record_unrefp) UserRecord new_home = NULL, header_home = NULL;
2ba38f78	67	const char hd, hdo;
70a5db58 LP	68	int r;
	69
	70	assert(h);
	71	assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME, USER_FSCRYPT));
a74e2e44	72	assert(setup);
70a5db58 LP	73	assert(ret_home);
70a5db58 LP	74
70a5db58	75	assert_se(hdo = user_record_home_directory(h));
2f82562b	76	hd = strdupa_safe(hdo);
70a5db58	77
6f2c8136	78	r = home_setup(h, flags, setup, cache, &header_home);
70a5db58 LP	79	if (r < 0)
	80	return r;
	81
6f2c8136	82	r = home_refresh(h, flags, setup, header_home, cache, NULL, &new_home);
70a5db58 LP	83	if (r < 0)
	84	return r;
	85
cfef46f5 LP	86	r = home_extend_embedded_identity(new_home, h, setup);
	87	if (r < 0)
	88	return r;
	89
2ba38f78	90	/* Close fd to private mount before moving mount */
a74e2e44	91	setup->root_fd = safe_close(setup->root_fd);
70a5db58	92
2ba38f78 LP	93	/* We are now done with everything, move the mount into place */
2ba38f78 LP	94	r = home_move_mount(NULL, hd);
70a5db58 LP	95	if (r < 0)
	96	return r;
	97
2ba38f78	98	setup->undo_mount = false;
70a5db58	99
aa0379f1 LP	100	setup->do_drop_caches = false;
aa0379f1 LP	101
70a5db58 LP	102	log_info("Everything completed.");
	103
	104	*ret_home = TAKE_PTR(new_home);
	105	return 0;
	106	}
	107
e1aeaf27	108	int home_create_directory_or_subvolume(UserRecord h, HomeSetup setup, UserRecord **ret_home) {
70a5db58 LP	109	_cleanup_(rm_rf_subvolume_and_freep) char *temporary = NULL;
70a5db58 LP	110	_cleanup_(user_record_unrefp) UserRecord *new_home = NULL;
254d1313	111	_cleanup_close_ int mount_fd = -EBADF;
70a5db58	112	_cleanup_free_ char *d = NULL;
cf5115f6	113	bool is_subvolume = false;
70a5db58 LP	114	const char *ip;
	115	int r;
	116
	117	assert(h);
	118	assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME));
e1aeaf27	119	assert(setup);
70a5db58 LP	120	assert(ret_home);
	121
	122	assert_se(ip = user_record_image_path(h));
	123
	124	r = tempfn_random(ip, "homework", &d);
	125	if (r < 0)
	126	return log_error_errno(r, "Failed to allocate temporary directory: %m");
	127
	128	(void) mkdir_parents(d, 0755);
	129
	130	switch (user_record_storage(h)) {
	131
	132	case USER_SUBVOLUME:
2053593f	133	WITH_UMASK(0077)
e54c79cc	134	r = btrfs_subvol_make(AT_FDCWD, d);
70a5db58 LP	135
	136	if (r >= 0) {
	137	log_info("Subvolume created.");
cf5115f6	138	is_subvolume = true;
70a5db58 LP	139
	140	if (h->disk_size != UINT64_MAX) {
	141
	142	/* Enable quota for the subvolume we just created. Note we don't check for
	143	* errors here and only log about debug level about this. */
	144	r = btrfs_quota_enable(d, true);
	145	if (r < 0)
	146	log_debug_errno(r, "Failed to enable quota on %s, ignoring: %m", d);
	147
	148	r = btrfs_subvol_auto_qgroup(d, 0, false);
	149	if (r < 0)
	150	log_debug_errno(r, "Failed to set up automatic quota group on %s, ignoring: %m", d);
	151
	152	/* Actually configure the quota. We also ignore errors here, but we do log
	153	* about them loudly, to keep things discoverable even though we don't
	154	* consider lacking quota support in kernel fatal. */
	155	(void) home_update_quota_btrfs(h, d);
	156	}
	157
	158	break;
	159	}
	160	if (r != -ENOTTY)
	161	return log_error_errno(r, "Failed to create temporary home directory subvolume %s: %m", d);
	162
	163	log_info("Creating subvolume %s is not supported, as file system does not support subvolumes. Falling back to regular directory.", d);
	164	_fallthrough_;
	165
	166	case USER_DIRECTORY:
	167
	168	if (mkdir(d, 0700) < 0)
	169	return log_error_errno(errno, "Failed to create temporary home directory %s: %m", d);
	170
	171	(void) home_update_quota_classic(h, d);
	172	break;
	173
	174	default:
04499a70	175	assert_not_reached();
70a5db58 LP	176	}
	177
	178	temporary = TAKE_PTR(d); /* Needs to be destroyed now */
	179
cf5115f6	180	/* Let's decouple namespaces now, so that we can possibly mount a UID map mount into
a6f44d61	181	* /run/systemd/user-home-mount/ that no one will see but us. */
cf5115f6 LP	182	r = home_unshare_and_mkdir();
	183	if (r < 0)
	184	return r;
	185
e1aeaf27 LP	186	setup->root_fd = open(temporary, O_RDONLY\|O_CLOEXEC\|O_DIRECTORY\|O_NOFOLLOW);
e1aeaf27 LP	187	if (setup->root_fd < 0)
70a5db58 LP	188	return log_error_errno(errno, "Failed to open temporary home directory: %m");
70a5db58 LP	189
cf5115f6 LP	190	/* Try to apply a UID shift, so that the directory is actually owned by "nobody", and is only mapped
	191	* to the proper UID while active. — Well, that's at least the theory. Unfortunately, only btrfs does
	192	* per-subvolume quota. The others do per-uid quota. Which means mapping all home directories to the
	193	* same UID of "nobody" makes quota impossible. Hence unless we actually managed to create a btrfs
	194	* subvolume for this user we'll map the user's UID to itself. Now you might ask: why bother mapping
	195	* at all? It's because we want to restrict the UIDs used on the home directory: we leave all other
	196	* UIDs of the homed UID range unmapped, thus making them unavailable to programs accessing the
	197	* mount. */
	198	r = home_shift_uid(setup->root_fd, HOME_RUNTIME_WORK_DIR, is_subvolume ? UID_NOBODY : h->uid, h->uid, &mount_fd);
	199	if (r > 0)
	200	setup->undo_mount = true; /* If uidmaps worked we have a mount to undo again */
	201
	202	if (mount_fd >= 0) {
	203	/* If we have established a new mount, then we can use that as new root fd to our home directory. */
	204	safe_close(setup->root_fd);
	205
	206	setup->root_fd = fd_reopen(mount_fd, O_RDONLY\|O_CLOEXEC\|O_DIRECTORY);
	207	if (setup->root_fd < 0)
	208	return log_error_errno(setup->root_fd, "Unable to convert mount fd into proper directory fd: %m");
	209
	210	mount_fd = safe_close(mount_fd);
	211	}
	212
e1aeaf27	213	r = home_populate(h, setup->root_fd);
70a5db58 LP	214	if (r < 0)
	215	return r;
	216
e1aeaf27	217	r = home_sync_and_statfs(setup->root_fd, NULL);
70a5db58 LP	218	if (r < 0)
	219	return r;
	220
bfc0cc1a	221	r = user_record_clone(h, USER_RECORD_LOAD_MASK_SECRET\|USER_RECORD_PERMISSIVE, &new_home);
70a5db58 LP	222	if (r < 0)
	223	return log_error_errno(r, "Failed to clone record: %m");
	224
	225	r = user_record_add_binding(
	226	new_home,
	227	user_record_storage(h),
	228	ip,
	229	SD_ID128_NULL,
	230	SD_ID128_NULL,
	231	SD_ID128_NULL,
	232	NULL,
	233	NULL,
	234	UINT64_MAX,
	235	NULL,
	236	NULL,
	237	h->uid,
	238	(gid_t) h->uid);
	239	if (r < 0)
	240	return log_error_errno(r, "Failed to add binding to record: %m");
	241
cf5115f6 LP	242	setup->root_fd = safe_close(setup->root_fd);
	243
	244	/* Unmount mapped mount before we move the dir into place */
55166094 LP	245	r = home_setup_undo_mount(setup, LOG_ERR);
	246	if (r < 0)
	247	return r;
cf5115f6	248
70a5db58 LP	249	if (rename(temporary, ip) < 0)
	250	return log_error_errno(errno, "Failed to rename %s to %s: %m", temporary, ip);
	251
	252	temporary = mfree(temporary);
	253
	254	log_info("Everything completed.");
	255
	256	*ret_home = TAKE_PTR(new_home);
	257	return 0;
	258	}
	259
	260	int home_resize_directory(
	261	UserRecord *h,
e1df968b	262	HomeSetupFlags flags,
70a5db58	263	HomeSetup *setup,
c00b2ddc	264	PasswordCache *cache,
70a5db58 LP	265	UserRecord **ret_home) {
	266
	267	_cleanup_(user_record_unrefp) UserRecord embedded_home = NULL, new_home = NULL;
	268	int r;
	269
	270	assert(h);
	271	assert(setup);
	272	assert(ret_home);
	273	assert(IN_SET(user_record_storage(h), USER_DIRECTORY, USER_SUBVOLUME, USER_FSCRYPT));
	274
c00b2ddc	275	r = home_setup(h, flags, setup, cache, NULL);
70a5db58 LP	276	if (r < 0)
	277	return r;
	278
7b78db28	279	r = home_load_embedded_identity(h, setup->root_fd, NULL, USER_RECONCILE_REQUIRE_NEWER_OR_EQUAL, cache, &embedded_home, &new_home);
70a5db58 LP	280	if (r < 0)
	281	return r;
	282
6f2c8136	283	r = home_maybe_shift_uid(h, flags, setup);
cf5115f6 LP	284	if (r < 0)
	285	return r;
	286
70a5db58	287	r = home_update_quota_auto(h, NULL);
bb44fd07 ZJS	288	if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
	289	return -ESOCKTNOSUPPORT; /* make recognizable */
	290	if (r < 0)
70a5db58 LP	291	return r;
70a5db58 LP	292
285ad523	293	r = home_store_embedded_identity(new_home, setup->root_fd, embedded_home);
70a5db58 LP	294	if (r < 0)
	295	return r;
	296
	297	r = home_extend_embedded_identity(new_home, h, setup);
	298	if (r < 0)
	299	return r;
	300
	301	r = home_sync_and_statfs(setup->root_fd, NULL);
	302	if (r < 0)
	303	return r;
	304
66aa51f8	305	r = home_setup_done(setup);
70a5db58 LP	306	if (r < 0)
	307	return r;
	308
	309	log_info("Everything completed.");
	310
	311	*ret_home = TAKE_PTR(new_home);
	312	return 0;
	313	}