--- /dev/null
+/*
+ * Handle group entries via struct group
+ *
+ * Copyright (C) 2019 Simon Ruderich
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <pthread.h>
+
+#include "cash.h"
+#include "cash_nss.h"
+#include "file.h"
+#include "search.h"
+
+
+// NOTE: This file is very similar to pw.c, keep in sync!
+
+struct group_entry {
+ uint64_t gid;
+
+ // off_name = 0
+ uint16_t off_passwd;
+ uint16_t off_mem_off;
+
+ uint16_t mem_count; // group member count
+
+ /*
+ * Data contains all strings (name, passwd) concatenated, with their
+ * trailing NUL. The off_* variables point to beginning of each string.
+ *
+ * After that the offsets of the members of the group are stored as
+ * mem_count uint16_t values, followed by the member names concatenated as
+ * with the strings above.
+ *
+ * All offsets are relative to the beginning of data.
+ */
+ uint16_t data_size;
+ char data[];
+} __attribute__((packed));
+
+static bool entry_to_group(const struct group_entry *e, struct group *g, char *tmp, size_t space) {
+ const size_t mem_size = (size_t)(e->mem_count + 1) * sizeof(char *);
+
+ if (space < e->data_size + mem_size) {
+ return false;
+ }
+
+ char **groups = (char **)tmp;
+
+ const uint16_t *offs_mem = (const uint16_t *)(e->data + e->off_mem_off);
+ for (uint16_t i = 0; i < e->mem_count; i++) {
+ groups[i] = tmp + mem_size + offs_mem[i];
+ }
+ groups[e->mem_count] = NULL;
+
+ // This unnecessarily copies offs_mem[] as well but keeps the code simpler
+ // and the meaning of variables consistent with pw.c
+ memcpy(tmp + mem_size, e->data, e->data_size);
+
+ g->gr_gid = (gid_t)e->gid;
+ g->gr_name = tmp + mem_size + 0;
+ g->gr_passwd = tmp + mem_size + e->off_passwd;
+ g->gr_mem = groups;
+
+ return true;
+}
+
+
+static struct file static_file = {
+ .fd = -1,
+};
+static pthread_mutex_t static_file_lock = PTHREAD_MUTEX_INITIALIZER;
+
+enum nss_status _nss_cash_setgrent(int x) {
+ (void)x;
+
+ pthread_mutex_lock(&static_file_lock);
+ // Unmap is necessary to detect changes when the file was replaced on
+ // disk
+ unmap_file(&static_file);
+ // getgrent_r will open the file if necessary when called
+ pthread_mutex_unlock(&static_file_lock);
+
+ return NSS_STATUS_SUCCESS;
+}
+
+enum nss_status _nss_cash_endgrent(void) {
+ pthread_mutex_lock(&static_file_lock);
+ unmap_file(&static_file);
+ pthread_mutex_unlock(&static_file_lock);
+
+ return NSS_STATUS_SUCCESS;
+}
+
+static enum nss_status internal_getgrent_r(struct group *result, char *buffer, size_t buflen) {
+ // First call to getgrent_r, load file from disk
+ if (static_file.header == NULL) {
+ if (!map_file(NSSCASH_GROUP_FILE, &static_file)) {
+ return NSS_STATUS_UNAVAIL;
+ }
+ }
+
+ const struct header *h = static_file.header;
+ // End of "file", stop
+ if (static_file.next_index >= h->count) {
+ errno = ENOENT;
+ return NSS_STATUS_NOTFOUND;
+ }
+
+ uint64_t *off_orig = (uint64_t *)(h->data + h->off_orig_index);
+ const char *e = h->data + h->off_data + off_orig[static_file.next_index];
+ if (!entry_to_group((struct group_entry *)e, result, buffer, buflen)) {
+ errno = ERANGE;
+ return NSS_STATUS_TRYAGAIN;
+ }
+ static_file.next_index++;
+
+ return NSS_STATUS_SUCCESS;
+}
+enum nss_status _nss_cash_getgrent_r(struct group *result, char *buffer, size_t buflen, int *errnop) {
+ pthread_mutex_lock(&static_file_lock);
+ enum nss_status s = internal_getgrent_r(result, buffer, buflen);
+ pthread_mutex_unlock(&static_file_lock);
+ if (s != NSS_STATUS_SUCCESS) {
+ *errnop = errno;
+ }
+ return s;
+}
+
+
+static enum nss_status internal_getgr(struct search_key *key, struct group *result, char *buffer, size_t buflen, int *errnop) {
+ struct file f;
+ if (!map_file(NSSCASH_GROUP_FILE, &f)) {
+ *errnop = errno;
+ return NSS_STATUS_UNAVAIL;
+ }
+ const struct header *h = f.header;
+
+ key->data = h->data + h->off_data;
+ uint64_t off_index = (key->id != NULL)
+ ? h->off_id_index
+ : h->off_name_index;
+ uint64_t *off = search(key, h->data + off_index, h->count);
+ if (off == NULL) {
+ unmap_file(&f);
+ errno = ENOENT;
+ *errnop = errno;
+ return NSS_STATUS_NOTFOUND;
+ }
+
+ const char *e = h->data + h->off_data + *off;
+ if (!entry_to_group((struct group_entry *)e, result, buffer, buflen)) {
+ unmap_file(&f);
+ errno = ERANGE;
+ *errnop = errno;
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ unmap_file(&f);
+ return NSS_STATUS_SUCCESS;
+}
+
+enum nss_status _nss_cash_getgrgid_r(gid_t gid, struct group *result, char *buffer, size_t buflen, int *errnop) {
+ uint64_t id = (uint64_t)gid;
+ struct search_key key = {
+ .id = &id,
+ .offset = offsetof(struct group_entry, gid),
+ };
+ return internal_getgr(&key, result, buffer, buflen, errnop);
+}
+
+enum nss_status _nss_cash_getgrnam_r(const char *name, struct group *result, char *buffer, size_t buflen, int *errnop) {
+ struct search_key key = {
+ .name = name,
+ .offset = sizeof(struct group_entry), // name is first value in data[]
+ };
+ return internal_getgr(&key, result, buffer, buflen, errnop);
+}
ruderich.org/simon / nsscash / nsscash.git / blobdiff