475 lines
17 KiB
C
475 lines
17 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2011 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <unistd.h>
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#include <stddef.h>
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#include <sys/epoll.h>
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#include <sys/mman.h>
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#include "socket-util.h"
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#include "path-util.h"
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#include "selinux-util.h"
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#include "journald-server.h"
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#include "journald-native.h"
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#include "journald-kmsg.h"
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#include "journald-console.h"
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#include "journald-syslog.h"
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#include "journald-wall.h"
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bool valid_user_field(const char *p, size_t l, bool allow_protected) {
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const char *a;
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/* We kinda enforce POSIX syntax recommendations for
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environment variables here, but make a couple of additional
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requirements.
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http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap08.html */
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/* No empty field names */
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if (l <= 0)
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return false;
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/* Don't allow names longer than 64 chars */
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if (l > 64)
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return false;
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/* Variables starting with an underscore are protected */
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if (!allow_protected && p[0] == '_')
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return false;
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/* Don't allow digits as first character */
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if (p[0] >= '0' && p[0] <= '9')
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return false;
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/* Only allow A-Z0-9 and '_' */
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for (a = p; a < p + l; a++)
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if ((*a < 'A' || *a > 'Z') &&
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(*a < '0' || *a > '9') &&
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*a != '_')
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return false;
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return true;
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}
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static bool allow_object_pid(struct ucred *ucred) {
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return ucred && ucred->uid == 0;
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}
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void server_process_native_message(
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Server *s,
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const void *buffer, size_t buffer_size,
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struct ucred *ucred,
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struct timeval *tv,
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const char *label, size_t label_len) {
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struct iovec *iovec = NULL;
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unsigned n = 0, j, tn = (unsigned) -1;
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const char *p;
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size_t remaining, m = 0, entry_size = 0;
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int priority = LOG_INFO;
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char *identifier = NULL, *message = NULL;
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pid_t object_pid = 0;
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assert(s);
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assert(buffer || buffer_size == 0);
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p = buffer;
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remaining = buffer_size;
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while (remaining > 0) {
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const char *e, *q;
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e = memchr(p, '\n', remaining);
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if (!e) {
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/* Trailing noise, let's ignore it, and flush what we collected */
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log_debug("Received message with trailing noise, ignoring.");
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break;
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}
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if (e == p) {
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/* Entry separator */
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if (entry_size + n + 1 > ENTRY_SIZE_MAX) { /* data + separators + trailer */
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log_debug("Entry is too big with %u properties and %zu bytes, ignoring.", n, entry_size);
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continue;
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}
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server_dispatch_message(s, iovec, n, m, ucred, tv, label, label_len, NULL, priority, object_pid);
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n = 0;
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priority = LOG_INFO;
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entry_size = 0;
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p++;
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remaining--;
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continue;
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}
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if (*p == '.' || *p == '#') {
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/* Ignore control commands for now, and
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* comments too. */
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remaining -= (e - p) + 1;
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p = e + 1;
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continue;
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}
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/* A property follows */
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/* n received properties, +1 for _TRANSPORT */
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if (!GREEDY_REALLOC(iovec, m, n + 1 + N_IOVEC_META_FIELDS + !!object_pid * N_IOVEC_OBJECT_FIELDS)) {
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log_oom();
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break;
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}
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q = memchr(p, '=', e - p);
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if (q) {
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if (valid_user_field(p, q - p, false)) {
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size_t l;
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l = e - p;
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/* If the field name starts with an
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* underscore, skip the variable,
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* since that indidates a trusted
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* field */
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iovec[n].iov_base = (char*) p;
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iovec[n].iov_len = l;
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entry_size += iovec[n].iov_len;
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n++;
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/* We need to determine the priority
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* of this entry for the rate limiting
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* logic */
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if (l == 10 &&
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startswith(p, "PRIORITY=") &&
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p[9] >= '0' && p[9] <= '9')
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priority = (priority & LOG_FACMASK) | (p[9] - '0');
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else if (l == 17 &&
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startswith(p, "SYSLOG_FACILITY=") &&
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p[16] >= '0' && p[16] <= '9')
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priority = (priority & LOG_PRIMASK) | ((p[16] - '0') << 3);
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else if (l == 18 &&
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startswith(p, "SYSLOG_FACILITY=") &&
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p[16] >= '0' && p[16] <= '9' &&
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p[17] >= '0' && p[17] <= '9')
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priority = (priority & LOG_PRIMASK) | (((p[16] - '0')*10 + (p[17] - '0')) << 3);
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else if (l >= 19 &&
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startswith(p, "SYSLOG_IDENTIFIER=")) {
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char *t;
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t = strndup(p + 18, l - 18);
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if (t) {
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free(identifier);
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identifier = t;
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}
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} else if (l >= 8 &&
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startswith(p, "MESSAGE=")) {
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char *t;
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t = strndup(p + 8, l - 8);
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if (t) {
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free(message);
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message = t;
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}
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} else if (l > strlen("OBJECT_PID=") &&
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l < strlen("OBJECT_PID=") + DECIMAL_STR_MAX(pid_t) &&
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startswith(p, "OBJECT_PID=") &&
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allow_object_pid(ucred)) {
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char buf[DECIMAL_STR_MAX(pid_t)];
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memcpy(buf, p + strlen("OBJECT_PID="), l - strlen("OBJECT_PID="));
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char_array_0(buf);
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/* ignore error */
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parse_pid(buf, &object_pid);
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}
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}
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remaining -= (e - p) + 1;
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p = e + 1;
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continue;
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} else {
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le64_t l_le;
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uint64_t l;
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char *k;
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if (remaining < e - p + 1 + sizeof(uint64_t) + 1) {
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log_debug("Failed to parse message, ignoring.");
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break;
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}
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memcpy(&l_le, e + 1, sizeof(uint64_t));
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l = le64toh(l_le);
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if (l > DATA_SIZE_MAX) {
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log_debug("Received binary data block of %"PRIu64" bytes is too large, ignoring.", l);
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break;
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}
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if ((uint64_t) remaining < e - p + 1 + sizeof(uint64_t) + l + 1 ||
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e[1+sizeof(uint64_t)+l] != '\n') {
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log_debug("Failed to parse message, ignoring.");
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break;
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}
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k = malloc((e - p) + 1 + l);
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if (!k) {
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log_oom();
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break;
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}
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memcpy(k, p, e - p);
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k[e - p] = '=';
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memcpy(k + (e - p) + 1, e + 1 + sizeof(uint64_t), l);
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if (valid_user_field(p, e - p, false)) {
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iovec[n].iov_base = k;
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iovec[n].iov_len = (e - p) + 1 + l;
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entry_size += iovec[n].iov_len;
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n++;
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} else
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free(k);
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remaining -= (e - p) + 1 + sizeof(uint64_t) + l + 1;
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p = e + 1 + sizeof(uint64_t) + l + 1;
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}
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}
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if (n <= 0)
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goto finish;
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tn = n++;
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IOVEC_SET_STRING(iovec[tn], "_TRANSPORT=journal");
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entry_size += strlen("_TRANSPORT=journal");
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if (entry_size + n + 1 > ENTRY_SIZE_MAX) { /* data + separators + trailer */
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log_debug("Entry is too big with %u properties and %zu bytes, ignoring.",
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n, entry_size);
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goto finish;
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}
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if (message) {
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if (s->forward_to_syslog)
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server_forward_syslog(s, priority, identifier, message, ucred, tv);
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if (s->forward_to_kmsg)
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server_forward_kmsg(s, priority, identifier, message, ucred);
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if (s->forward_to_console)
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server_forward_console(s, priority, identifier, message, ucred);
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if (s->forward_to_wall)
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server_forward_wall(s, priority, identifier, message, ucred);
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}
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server_dispatch_message(s, iovec, n, m, ucred, tv, label, label_len, NULL, priority, object_pid);
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finish:
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for (j = 0; j < n; j++) {
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if (j == tn)
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continue;
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if (iovec[j].iov_base < buffer ||
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(const uint8_t*) iovec[j].iov_base >= (const uint8_t*) buffer + buffer_size)
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free(iovec[j].iov_base);
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}
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free(iovec);
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free(identifier);
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free(message);
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}
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void server_process_native_file(
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Server *s,
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int fd,
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struct ucred *ucred,
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struct timeval *tv,
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const char *label, size_t label_len) {
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struct stat st;
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bool sealed;
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int r;
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/* Data is in the passed fd, since it didn't fit in a
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* datagram. */
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assert(s);
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assert(fd >= 0);
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/* If it's a memfd, check if it is sealed. If so, we can just
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* use map it and use it, and do not need to copy the data
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* out. */
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r = fcntl(fd, F_GET_SEALS);
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sealed = r >= 0 &&
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(r & (F_SEAL_SHRINK|F_SEAL_GROW|F_SEAL_WRITE|F_SEAL_SEAL)) == (F_SEAL_SHRINK|F_SEAL_GROW|F_SEAL_WRITE|F_SEAL_SEAL);
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if (!sealed && (!ucred || ucred->uid != 0)) {
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_cleanup_free_ char *sl = NULL, *k = NULL;
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const char *e;
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/* If this is not a sealed memfd, and the peer is unknown or
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* unprivileged, then verify the path. */
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if (asprintf(&sl, "/proc/self/fd/%i", fd) < 0) {
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log_oom();
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return;
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}
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r = readlink_malloc(sl, &k);
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if (r < 0) {
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log_error("readlink(%s) failed: %m", sl);
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return;
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}
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e = path_startswith(k, "/dev/shm/");
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if (!e)
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e = path_startswith(k, "/tmp/");
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if (!e)
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e = path_startswith(k, "/var/tmp/");
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if (!e) {
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log_error("Received file outside of allowed directories. Refusing.");
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return;
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}
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if (!filename_is_safe(e)) {
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log_error("Received file in subdirectory of allowed directories. Refusing.");
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return;
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}
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}
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if (fstat(fd, &st) < 0) {
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log_error("Failed to stat passed file, ignoring: %m");
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return;
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}
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if (!S_ISREG(st.st_mode)) {
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log_error("File passed is not regular. Ignoring.");
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return;
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}
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if (st.st_size <= 0)
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return;
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if (st.st_size > ENTRY_SIZE_MAX) {
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log_error("File passed too large. Ignoring.");
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return;
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}
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if (sealed) {
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void *p;
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size_t ps;
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/* The file is sealed, we can just map it and use it. */
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ps = PAGE_ALIGN(st.st_size);
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p = mmap(NULL, ps, PROT_READ, MAP_PRIVATE, fd, 0);
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if (p == MAP_FAILED) {
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log_error("Failed to map memfd, ignoring: %m");
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return;
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}
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server_process_native_message(s, p, st.st_size, ucred, tv, label, label_len);
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assert_se(munmap(p, ps) >= 0);
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} else {
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_cleanup_free_ void *p = NULL;
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ssize_t n;
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/* The file is not sealed, we can't map the file here, since
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* clients might then truncate it and trigger a SIGBUS for
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* us. So let's stupidly read it */
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p = malloc(st.st_size);
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if (!p) {
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log_oom();
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return;
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}
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n = pread(fd, p, st.st_size, 0);
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if (n < 0)
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log_error("Failed to read file, ignoring: %s", strerror(-n));
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else if (n > 0)
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server_process_native_message(s, p, n, ucred, tv, label, label_len);
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}
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}
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int server_open_native_socket(Server*s) {
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int one, r;
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assert(s);
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if (s->native_fd < 0) {
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union sockaddr_union sa = {
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.un.sun_family = AF_UNIX,
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.un.sun_path = "/run/systemd/journal/socket",
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};
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s->native_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (s->native_fd < 0) {
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log_error("socket() failed: %m");
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return -errno;
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}
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unlink(sa.un.sun_path);
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r = bind(s->native_fd, &sa.sa, offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path));
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if (r < 0) {
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log_error("bind(%s) failed: %m", sa.un.sun_path);
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return -errno;
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}
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chmod(sa.un.sun_path, 0666);
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} else
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fd_nonblock(s->native_fd, 1);
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one = 1;
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r = setsockopt(s->native_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
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if (r < 0) {
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log_error("SO_PASSCRED failed: %m");
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return -errno;
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}
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#ifdef HAVE_SELINUX
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if (mac_selinux_use()) {
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one = 1;
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r = setsockopt(s->native_fd, SOL_SOCKET, SO_PASSSEC, &one, sizeof(one));
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if (r < 0)
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log_warning("SO_PASSSEC failed: %m");
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}
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#endif
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one = 1;
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r = setsockopt(s->native_fd, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one));
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if (r < 0) {
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log_error("SO_TIMESTAMP failed: %m");
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return -errno;
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}
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r = sd_event_add_io(s->event, &s->native_event_source, s->native_fd, EPOLLIN, process_datagram, s);
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if (r < 0) {
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log_error("Failed to add native server fd to event loop: %s", strerror(-r));
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return r;
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}
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return 0;
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}
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