Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 674 insertions, 0 deletions

diff --git a/src/home/homework-fscrypt.c b/src/home/homework-fscrypt.c
new file mode 100644
index 0000000..6aae1d2
--- /dev/null
+++ b/src/home/homework-fscrypt.c
@@ -0,0 +1,674 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <linux/fs.h>
+#include <openssl/evp.h>
+#include <openssl/sha.h>
+#include <sys/ioctl.h>
+#include <sys/xattr.h>
+
+#include "errno-util.h"
+#include "fd-util.h"
+#include "hexdecoct.h"
+#include "homework-fscrypt.h"
+#include "homework-mount.h"
+#include "homework-quota.h"
+#include "memory-util.h"
+#include "missing_keyctl.h"
+#include "missing_syscall.h"
+#include "mkdir.h"
+#include "mount-util.h"
+#include "nulstr-util.h"
+#include "openssl-util.h"
+#include "parse-util.h"
+#include "process-util.h"
+#include "random-util.h"
+#include "rm-rf.h"
+#include "stdio-util.h"
+#include "strv.h"
+#include "tmpfile-util.h"
+#include "user-util.h"
+#include "xattr-util.h"
+
+static int fscrypt_upload_volume_key(
+                const uint8_t key_descriptor[static FS_KEY_DESCRIPTOR_SIZE],
+                const void *volume_key,
+                size_t volume_key_size,
+                key_serial_t where) {
+
+        _cleanup_free_ char *hex = NULL;
+        const char *description;
+        struct fscrypt_key key;
+        key_serial_t serial;
+
+        assert(key_descriptor);
+        assert(volume_key);
+        assert(volume_key_size > 0);
+
+        if (volume_key_size > sizeof(key.raw))
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Volume key too long.");
+
+        hex = hexmem(key_descriptor, FS_KEY_DESCRIPTOR_SIZE);
+        if (!hex)
+                return log_oom();
+
+        description = strjoina("fscrypt:", hex);
+
+        key = (struct fscrypt_key) {
+                .size = volume_key_size,
+        };
+        memcpy(key.raw, volume_key, volume_key_size);
+
+        CLEANUP_ERASE(key);
+
+        /* Upload to the kernel */
+        serial = add_key("logon", description, &key, sizeof(key), where);
+        if (serial < 0)
+                return log_error_errno(errno, "Failed to install master key in keyring: %m");
+
+        log_info("Uploaded encryption key to kernel.");
+
+        return 0;
+}
+
+static void calculate_key_descriptor(
+                const void *key,
+                size_t key_size,
+                uint8_t ret_key_descriptor[static FS_KEY_DESCRIPTOR_SIZE]) {
+
+        uint8_t hashed[512 / 8] = {}, hashed2[512 / 8] = {};
+
+        /* Derive the key descriptor from the volume key via double SHA512, in order to be compatible with e4crypt */
+
+        assert_se(SHA512(key, key_size, hashed) == hashed);
+        assert_se(SHA512(hashed, sizeof(hashed), hashed2) == hashed2);
+
+        assert_cc(sizeof(hashed2) >= FS_KEY_DESCRIPTOR_SIZE);
+
+        memcpy(ret_key_descriptor, hashed2, FS_KEY_DESCRIPTOR_SIZE);
+}
+
+static int fscrypt_slot_try_one(
+                const char *password,
+                const void *salt, size_t salt_size,
+                const void *encrypted, size_t encrypted_size,
+                const uint8_t match_key_descriptor[static FS_KEY_DESCRIPTOR_SIZE],
+                void **ret_decrypted, size_t *ret_decrypted_size) {
+
+
+        _cleanup_(EVP_CIPHER_CTX_freep) EVP_CIPHER_CTX *context = NULL;
+        _cleanup_(erase_and_freep) void *decrypted = NULL;
+        uint8_t key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
+        int decrypted_size_out1, decrypted_size_out2;
+        uint8_t derived[512 / 8] = {};
+        size_t decrypted_size;
+        const EVP_CIPHER *cc;
+        int r;
+
+        assert(password);
+        assert(salt);
+        assert(salt_size > 0);
+        assert(encrypted);
+        assert(encrypted_size > 0);
+        assert(match_key_descriptor);
+
+        /* Our construction is like this:
+         *
+         *   1. In each key slot we store a salt value plus the encrypted volume key
+         *
+         *   2. Unlocking is via calculating PBKDF2-HMAC-SHA512 of the supplied password (in combination with
+         *      the salt), then using the first 256 bit of the hash as key for decrypting the encrypted
+         *      volume key in AES256 counter mode.
+         *
+         *   3. Writing a password is similar: calculate PBKDF2-HMAC-SHA512 of the supplied password (in
+         *      combination with the salt), then encrypt the volume key in AES256 counter mode with the
+         *      resulting hash.
+         */
+
+        CLEANUP_ERASE(derived);
+
+        if (PKCS5_PBKDF2_HMAC(
+                            password, strlen(password),
+                            salt, salt_size,
+                            0xFFFF, EVP_sha512(),
+                            sizeof(derived), derived) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "PBKDF2 failed");
+
+        context = EVP_CIPHER_CTX_new();
+        if (!context)
+                return log_oom();
+
+        /* We use AES256 in counter mode */
+        assert_se(cc = EVP_aes_256_ctr());
+
+        /* We only use the first half of the derived key */
+        assert(sizeof(derived) >= (size_t) EVP_CIPHER_key_length(cc));
+
+        if (EVP_DecryptInit_ex(context, cc, NULL, derived, NULL) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize decryption context.");
+
+        decrypted_size = encrypted_size + EVP_CIPHER_key_length(cc) * 2;
+        decrypted = malloc(decrypted_size);
+        if (!decrypted)
+                return log_oom();
+
+        if (EVP_DecryptUpdate(context, (uint8_t*) decrypted, &decrypted_size_out1, encrypted, encrypted_size) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to decrypt volume key.");
+
+        assert((size_t) decrypted_size_out1 <= decrypted_size);
+
+        if (EVP_DecryptFinal_ex(context, (uint8_t*) decrypted_size + decrypted_size_out1, &decrypted_size_out2) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finish decryption of volume key.");
+
+        assert((size_t) decrypted_size_out1 + (size_t) decrypted_size_out2 < decrypted_size);
+        decrypted_size = (size_t) decrypted_size_out1 + (size_t) decrypted_size_out2;
+
+        calculate_key_descriptor(decrypted, decrypted_size, key_descriptor);
+
+        if (memcmp(key_descriptor, match_key_descriptor, FS_KEY_DESCRIPTOR_SIZE) != 0)
+                return -ENOANO; /* don't log here */
+
+        r = fscrypt_upload_volume_key(key_descriptor, decrypted, decrypted_size, KEY_SPEC_THREAD_KEYRING);
+        if (r < 0)
+                return r;
+
+        if (ret_decrypted)
+                *ret_decrypted = TAKE_PTR(decrypted);
+        if (ret_decrypted_size)
+                *ret_decrypted_size = decrypted_size;
+
+        return 0;
+}
+
+static int fscrypt_slot_try_many(
+                char **passwords,
+                const void *salt, size_t salt_size,
+                const void *encrypted, size_t encrypted_size,
+                const uint8_t match_key_descriptor[static FS_KEY_DESCRIPTOR_SIZE],
+                void **ret_decrypted, size_t *ret_decrypted_size) {
+
+        int r;
+
+        STRV_FOREACH(i, passwords) {
+                r = fscrypt_slot_try_one(*i, salt, salt_size, encrypted, encrypted_size, match_key_descriptor, ret_decrypted, ret_decrypted_size);
+                if (r != -ENOANO)
+                        return r;
+        }
+
+        return -ENOANO;
+}
+
+static int fscrypt_setup(
+                const PasswordCache *cache,
+                char **password,
+                HomeSetup *setup,
+                void **ret_volume_key,
+                size_t *ret_volume_key_size) {
+
+        _cleanup_free_ char *xattr_buf = NULL;
+        int r;
+
+        assert(setup);
+        assert(setup->root_fd >= 0);
+
+        r = flistxattr_malloc(setup->root_fd, &xattr_buf);
+        if (r < 0)
+                return log_error_errno(errno, "Failed to retrieve xattr list: %m");
+
+        NULSTR_FOREACH(xa, xattr_buf) {
+                _cleanup_free_ void *salt = NULL, *encrypted = NULL;
+                _cleanup_free_ char *value = NULL;
+                size_t salt_size, encrypted_size;
+                const char *nr, *e;
+                char **list;
+                int n;
+
+                /* Check if this xattr has the format 'trusted.fscrypt_slot<nr>' where '<nr>' is a 32-bit unsigned integer */
+                nr = startswith(xa, "trusted.fscrypt_slot");
+                if (!nr)
+                        continue;
+                if (safe_atou32(nr, NULL) < 0)
+                        continue;
+
+                n = fgetxattr_malloc(setup->root_fd, xa, &value);
+                if (n == -ENODATA) /* deleted by now? */
+                        continue;
+                if (n < 0)
+                        return log_error_errno(n, "Failed to read %s xattr: %m", xa);
+
+                e = memchr(value, ':', n);
+                if (!e)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "xattr %s lacks ':' separator: %m", xa);
+
+                r = unbase64mem(value, e - value, &salt, &salt_size);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to decode salt of %s: %m", xa);
+                r = unbase64mem(e+1, n - (e - value) - 1, &encrypted, &encrypted_size);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to decode encrypted key of %s: %m", xa);
+
+                r = -ENOANO;
+                FOREACH_POINTER(list, cache->pkcs11_passwords, cache->fido2_passwords, password) {
+                        r = fscrypt_slot_try_many(
+                                        list,
+                                        salt, salt_size,
+                                        encrypted, encrypted_size,
+                                        setup->fscrypt_key_descriptor,
+                                        ret_volume_key, ret_volume_key_size);
+                        if (r != -ENOANO)
+                                break;
+                }
+                if (r < 0) {
+                        if (r != -ENOANO)
+                                return r;
+                } else
+                        return 0;
+        }
+
+        return log_error_errno(SYNTHETIC_ERRNO(ENOKEY), "Failed to set up home directory with provided passwords.");
+}
+
+int home_setup_fscrypt(
+                UserRecord *h,
+                HomeSetup *setup,
+                const PasswordCache *cache) {
+
+        _cleanup_(erase_and_freep) void *volume_key = NULL;
+        struct fscrypt_policy policy = {};
+        size_t volume_key_size = 0;
+        const char *ip;
+        int r;
+
+        assert(h);
+        assert(user_record_storage(h) == USER_FSCRYPT);
+        assert(setup);
+        assert(setup->root_fd < 0);
+
+        assert_se(ip = user_record_image_path(h));
+
+        setup->root_fd = open(ip, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
+        if (setup->root_fd < 0)
+                return log_error_errno(errno, "Failed to open home directory: %m");
+
+        if (ioctl(setup->root_fd, FS_IOC_GET_ENCRYPTION_POLICY, &policy) < 0) {
+                if (errno == ENODATA)
+                        return log_error_errno(errno, "Home directory %s is not encrypted.", ip);
+                if (ERRNO_IS_NOT_SUPPORTED(errno)) {
+                        log_error_errno(errno, "File system does not support fscrypt: %m");
+                        return -ENOLINK; /* make recognizable */
+                }
+                return log_error_errno(errno, "Failed to acquire encryption policy of %s: %m", ip);
+        }
+
+        memcpy(setup->fscrypt_key_descriptor, policy.master_key_descriptor, FS_KEY_DESCRIPTOR_SIZE);
+
+        r = fscrypt_setup(
+                        cache,
+                        h->password,
+                        setup,
+                        &volume_key,
+                        &volume_key_size);
+        if (r < 0)
+                return r;
+
+        /* Also install the access key in the user's own keyring */
+
+        if (uid_is_valid(h->uid)) {
+                r = safe_fork("(sd-addkey)",
+                              FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_DEATHSIG_SIGTERM|FORK_LOG|FORK_WAIT|FORK_REOPEN_LOG,
+                              NULL);
+                if (r < 0)
+                        return log_error_errno(r, "Failed install encryption key in user's keyring: %m");
+                if (r == 0) {
+                        gid_t gid;
+
+                        /* Child */
+
+                        gid = user_record_gid(h);
+                        if (setresgid(gid, gid, gid) < 0) {
+                                log_error_errno(errno, "Failed to change GID to " GID_FMT ": %m", gid);
+                                _exit(EXIT_FAILURE);
+                        }
+
+                        if (setgroups(0, NULL) < 0) {
+                                log_error_errno(errno, "Failed to reset auxiliary groups list: %m");
+                                _exit(EXIT_FAILURE);
+                        }
+
+                        if (setresuid(h->uid, h->uid, h->uid) < 0) {
+                                log_error_errno(errno, "Failed to change UID to " UID_FMT ": %m", h->uid);
+                                _exit(EXIT_FAILURE);
+                        }
+
+                        r = fscrypt_upload_volume_key(
+                                        setup->fscrypt_key_descriptor,
+                                        volume_key,
+                                        volume_key_size,
+                                        KEY_SPEC_USER_KEYRING);
+                        if (r < 0)
+                                _exit(EXIT_FAILURE);
+
+                        _exit(EXIT_SUCCESS);
+                }
+        }
+
+        /* 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;
+
+        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;
+
+        safe_close(setup->root_fd);
+        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;
+}
+
+static int fscrypt_slot_set(
+                int root_fd,
+                const void *volume_key,
+                size_t volume_key_size,
+                const char *password,
+                uint32_t nr) {
+
+        _cleanup_free_ char *salt_base64 = NULL, *encrypted_base64 = NULL, *joined = NULL;
+        char label[STRLEN("trusted.fscrypt_slot") + DECIMAL_STR_MAX(nr) + 1];
+        _cleanup_(EVP_CIPHER_CTX_freep) EVP_CIPHER_CTX *context = NULL;
+        int r, encrypted_size_out1, encrypted_size_out2;
+        uint8_t salt[64], derived[512 / 8] = {};
+        _cleanup_free_ void *encrypted = NULL;
+        const EVP_CIPHER *cc;
+        size_t encrypted_size;
+        ssize_t ss;
+
+        r = crypto_random_bytes(salt, sizeof(salt));
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate salt: %m");
+
+        CLEANUP_ERASE(derived);
+
+        if (PKCS5_PBKDF2_HMAC(
+                            password, strlen(password),
+                            salt, sizeof(salt),
+                            0xFFFF, EVP_sha512(),
+                            sizeof(derived), derived) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "PBKDF2 failed");
+
+        context = EVP_CIPHER_CTX_new();
+        if (!context)
+                return log_oom();
+
+        /* We use AES256 in counter mode */
+        cc = EVP_aes_256_ctr();
+
+        /* We only use the first half of the derived key */
+        assert(sizeof(derived) >= (size_t) EVP_CIPHER_key_length(cc));
+
+        if (EVP_EncryptInit_ex(context, cc, NULL, derived, NULL) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize encryption context.");
+
+        encrypted_size = volume_key_size + EVP_CIPHER_key_length(cc) * 2;
+        encrypted = malloc(encrypted_size);
+        if (!encrypted)
+                return log_oom();
+
+        if (EVP_EncryptUpdate(context, (uint8_t*) encrypted, &encrypted_size_out1, volume_key, volume_key_size) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to encrypt volume key.");
+
+        assert((size_t) encrypted_size_out1 <= encrypted_size);
+
+        if (EVP_EncryptFinal_ex(context, (uint8_t*) encrypted_size + encrypted_size_out1, &encrypted_size_out2) != 1)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finish encryption of volume key.");
+
+        assert((size_t) encrypted_size_out1 + (size_t) encrypted_size_out2 < encrypted_size);
+        encrypted_size = (size_t) encrypted_size_out1 + (size_t) encrypted_size_out2;
+
+        ss = base64mem(salt, sizeof(salt), &salt_base64);
+        if (ss < 0)
+                return log_oom();
+
+        ss = base64mem(encrypted, encrypted_size, &encrypted_base64);
+        if (ss < 0)
+                return log_oom();
+
+        joined = strjoin(salt_base64, ":", encrypted_base64);
+        if (!joined)
+                return log_oom();
+
+        xsprintf(label, "trusted.fscrypt_slot%" PRIu32, nr);
+        if (fsetxattr(root_fd, label, joined, strlen(joined), 0) < 0)
+                return log_error_errno(errno, "Failed to write xattr %s: %m", label);
+
+        log_info("Written key slot %s.", label);
+
+        return 0;
+}
+
+int home_create_fscrypt(
+                UserRecord *h,
+                HomeSetup *setup,
+                char **effective_passwords,
+                UserRecord **ret_home) {
+
+        _cleanup_(rm_rf_physical_and_freep) char *temporary = NULL;
+        _cleanup_(user_record_unrefp) UserRecord *new_home = NULL;
+        _cleanup_(erase_and_freep) void *volume_key = NULL;
+        _cleanup_close_ int mount_fd = -EBADF;
+        struct fscrypt_policy policy = {};
+        size_t volume_key_size = 512 / 8;
+        _cleanup_free_ char *d = NULL;
+        uint32_t nr = 0;
+        const char *ip;
+        int r;
+
+        assert(h);
+        assert(user_record_storage(h) == USER_FSCRYPT);
+        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);
+
+        if (mkdir(d, 0700) < 0)
+                return log_error_errno(errno, "Failed to create temporary home directory %s: %m", d);
+
+        temporary = TAKE_PTR(d); /* Needs to be destroyed now */
+
+        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");
+
+        if (ioctl(setup->root_fd, FS_IOC_GET_ENCRYPTION_POLICY, &policy) < 0) {
+                if (ERRNO_IS_NOT_SUPPORTED(errno)) {
+                        log_error_errno(errno, "File system does not support fscrypt: %m");
+                        return -ENOLINK; /* make recognizable */
+                }
+                if (errno != ENODATA)
+                        return log_error_errno(errno, "Failed to get fscrypt policy of directory: %m");
+        } else
+                return log_error_errno(SYNTHETIC_ERRNO(EBUSY), "Parent of %s already encrypted, refusing.", d);
+
+        volume_key = malloc(volume_key_size);
+        if (!volume_key)
+                return log_oom();
+
+        r = crypto_random_bytes(volume_key, volume_key_size);
+        if (r < 0)
+                return log_error_errno(r, "Failed to acquire volume key: %m");
+
+        log_info("Generated volume key of size %zu.", volume_key_size);
+
+        policy = (struct fscrypt_policy) {
+                .contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS,
+                .filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS,
+                .flags = FS_POLICY_FLAGS_PAD_32,
+        };
+
+        calculate_key_descriptor(volume_key, volume_key_size, policy.master_key_descriptor);
+
+        r = fscrypt_upload_volume_key(policy.master_key_descriptor, volume_key, volume_key_size, KEY_SPEC_THREAD_KEYRING);
+        if (r < 0)
+                return r;
+
+        log_info("Uploaded volume key to kernel.");
+
+        if (ioctl(setup->root_fd, FS_IOC_SET_ENCRYPTION_POLICY, &policy) < 0)
+                return log_error_errno(errno, "Failed to set fscrypt policy on directory: %m");
+
+        log_info("Encryption policy set.");
+
+        STRV_FOREACH(i, effective_passwords) {
+                r = fscrypt_slot_set(setup->root_fd, volume_key, volume_key_size, *i, nr);
+                if (r < 0)
+                        return r;
+
+                nr++;
+        }
+
+        (void) home_update_quota_classic(h, temporary);
+
+        r = home_shift_uid(setup->root_fd, HOME_RUNTIME_WORK_DIR, 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_FSCRYPT,
+                        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);
+
+        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_passwd_fscrypt(
+                UserRecord *h,
+                HomeSetup *setup,
+                const PasswordCache *cache,         /* the passwords acquired via PKCS#11/FIDO2 security tokens */
+                char **effective_passwords          /* new passwords */) {
+
+        _cleanup_(erase_and_freep) void *volume_key = NULL;
+        _cleanup_free_ char *xattr_buf = NULL;
+        size_t volume_key_size = 0;
+        uint32_t slot = 0;
+        int r;
+
+        assert(h);
+        assert(user_record_storage(h) == USER_FSCRYPT);
+        assert(setup);
+
+        r = fscrypt_setup(
+                        cache,
+                        h->password,
+                        setup,
+                        &volume_key,
+                        &volume_key_size);
+        if (r < 0)
+                return r;
+
+        STRV_FOREACH(p, effective_passwords) {
+                r = fscrypt_slot_set(setup->root_fd, volume_key, volume_key_size, *p, slot);
+                if (r < 0)
+                        return r;
+
+                slot++;
+        }
+
+        r = flistxattr_malloc(setup->root_fd, &xattr_buf);
+        if (r < 0)
+                return log_error_errno(errno, "Failed to retrieve xattr list: %m");
+
+        NULSTR_FOREACH(xa, xattr_buf) {
+                const char *nr;
+                uint32_t z;
+
+                /* Check if this xattr has the format 'trusted.fscrypt_slot<nr>' where '<nr>' is a 32-bit unsigned integer */
+                nr = startswith(xa, "trusted.fscrypt_slot");
+                if (!nr)
+                        continue;
+                if (safe_atou32(nr, &z) < 0)
+                        continue;
+
+                if (z < slot)
+                        continue;
+
+                if (fremovexattr(setup->root_fd, xa) < 0)
+                        if (errno != ENODATA)
+                                log_warning_errno(errno, "Failed to remove xattr %s: %m", xa);
+        }
+
+        return 0;
+}