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src/nspawn/nspawn-bind-user.c
217 строк
8 KB
Daan De Meyer
nspawn-bind-user: Write membership records
31 окт 2025, 10:57
31 окт 2025, 10:57
b430f2b
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/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include <unistd.h> #include "sd-json.h" #include "alloc-util.h" #include "chase.h" #include "fd-util.h" #include "fileio.h" #include "format-util.h" #include "io-util.h" #include "log.h" #include "nspawn.h" #include "machine-bind-user.h" #include "nspawn-bind-user.h" #include "strv.h" #include "user-record.h" #include "group-record.h" #include "path-util.h" #include "string-util.h" #include "user-util.h" static int write_and_symlink( const char *root, sd_json_variant *v, const char *name, uid_t uid, const char *suffix, WriteStringFileFlags extra_flags) { _cleanup_free_ char *j = NULL, *f = NULL, *p = NULL, *q = NULL; int r; assert(root); assert(v); assert(name); assert(uid_is_valid(uid)); assert(suffix); r = sd_json_variant_format(v, SD_JSON_FORMAT_NEWLINE, &j); if (r < 0) return log_error_errno(r, "Failed to format user record JSON: %m"); f = strjoin(name, suffix); if (!f) return log_oom(); p = path_join(root, "/run/host/userdb/", f); if (!p) return log_oom(); if (asprintf(&q, "%s/run/host/userdb/" UID_FMT "%s", root, uid, suffix) < 0) return log_oom(); if (symlink(f, q) < 0) return log_error_errno(errno, "Failed to create symlink '%s': %m", q); r = userns_lchown(q, 0, 0); if (r < 0) return log_error_errno(r, "Failed to adjust access mode of '%s': %m", q); r = write_string_file(p, j, WRITE_STRING_FILE_CREATE|extra_flags); if (r < 0) return log_error_errno(r, "Failed to write %s: %m", p); r = userns_lchown(p, 0, 0); if (r < 0) return log_error_errno(r, "Failed to adjust access mode of '%s': %m", p); return 0; } static int write_membership(const char *root, const char *user, const char *group) { int r; assert(user); assert(group); _cleanup_free_ char *membership = strjoin(user, ":", group, ".membership"); if (!membership) return log_oom(); _cleanup_free_ char *p = path_join("/run/host/userdb/", membership); if (!p) return log_oom(); _cleanup_close_ int fd = chase_and_open( p, root, CHASE_PREFIX_ROOT|CHASE_NO_AUTOFS, O_WRONLY|O_CREAT|O_CLOEXEC, /* ret_path= */ NULL); if (fd < 0) return log_error_errno(errno, "Failed to create %s: %m", p); r = userns_chown_at(fd, /* fname= */ NULL, /* uid= */ 0, /* gid= */ 0, /* flags= */ 0); if (r < 0) return log_error_errno(r, "Failed to adjust access mode of '%s': %m", p); r = loop_write(fd, "{}\n", SIZE_MAX); if (r < 0) return log_error_errno(r, "Failed to write empty JSON object into %s: %m", p); return 0; } int bind_user_setup(const MachineBindUserContext *c, const char *root) { static const UserRecordLoadFlags strip_flags = /* Removes privileged info */ USER_RECORD_LOAD_MASK_PRIVILEGED| USER_RECORD_PERMISSIVE; static const UserRecordLoadFlags shadow_flags = /* Extracts privileged info */ USER_RECORD_EXTRACT_PRIVILEGED| USER_RECORD_EMPTY_OK| USER_RECORD_PERMISSIVE; int r; assert(root); if (!c || c->n_data == 0) return 0; r = make_run_host(root); if (r < 0) return r; r = userns_mkdir(root, "/run/host/home", 0755, 0, 0); if (r < 0) return log_error_errno(r, "Failed to create /run/host/home: %m"); r = userns_mkdir(root, "/run/host/userdb", 0755, 0, 0); if (r < 0) return log_error_errno(r, "Failed to create /run/host/userdb: %m"); FOREACH_ARRAY(d, c->data, c->n_data) { _cleanup_(group_record_unrefp) GroupRecord *stripped_group = NULL, *shadow_group = NULL; _cleanup_(user_record_unrefp) UserRecord *stripped_user = NULL, *shadow_user = NULL; /* First, write shadow (i.e. privileged) data for group record */ r = group_record_clone(d->payload_group, shadow_flags, &shadow_group); if (r < 0) return log_error_errno(r, "Failed to extract privileged information from group record: %m"); if (!sd_json_variant_is_blank_object(shadow_group->json)) { r = write_and_symlink( root, shadow_group->json, d->payload_group->group_name, d->payload_group->gid, ".group-privileged", WRITE_STRING_FILE_MODE_0600); if (r < 0) return r; } /* Second, write main part of group record. */ r = group_record_clone(d->payload_group, strip_flags, &stripped_group); if (r < 0) return log_error_errno(r, "Failed to strip privileged information from group record: %m"); r = write_and_symlink( root, stripped_group->json, d->payload_group->group_name, d->payload_group->gid, ".group", 0); if (r < 0) return r; STRV_FOREACH(u, stripped_group->members) { r = write_membership(root, *u, stripped_group->group_name); if (r < 0) return r; } /* Third, write out user shadow data. i.e. extract privileged info from user record */ r = user_record_clone(d->payload_user, shadow_flags, &shadow_user); if (r < 0) return log_error_errno(r, "Failed to extract privileged information from user record: %m"); if (!sd_json_variant_is_blank_object(shadow_user->json)) { r = write_and_symlink( root, shadow_user->json, d->payload_user->user_name, d->payload_user->uid, ".user-privileged", WRITE_STRING_FILE_MODE_0600); if (r < 0) return r; } /* Finally write out the main part of the user record */ r = user_record_clone(d->payload_user, strip_flags, &stripped_user); if (r < 0) return log_error_errno(r, "Failed to strip privileged information from user record: %m"); r = write_and_symlink( root, stripped_user->json, d->payload_user->user_name, d->payload_user->uid, ".user", 0); if (r < 0) return r; STRV_FOREACH(g, stripped_user->member_of) { r = write_membership(root, stripped_user->user_name, *g); if (r < 0) return r; } } return 1; }