picnoir
/
Systemd
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
Systemd/src/journal/journald-native.c

546 lines
19 KiB
C
Raw Blame History

/***
This file is part of systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stddef.h>
#include <sys/epoll.h>
#include <sys/mman.h>
#include <sys/statvfs.h>
#include <unistd.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "fs-util.h"
#include "io-util.h"
#include "journal-importer.h"
#include "journald-console.h"
#include "journald-kmsg.h"
#include "journald-native.h"
#include "journald-server.h"
#include "journald-syslog.h"
#include "journald-wall.h"
#include "memfd-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "selinux-util.h"
#include "socket-util.h"
#include "string-util.h"
#include "unaligned.h"
bool valid_user_field(const char *p, size_t l, bool allow_protected) {
const char *a;
/* We kinda enforce POSIX syntax recommendations for
environment variables here, but make a couple of additional
requirements.
http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap08.html */
/* No empty field names */
if (l <= 0)
return false;
/* Don't allow names longer than 64 chars */
if (l > 64)
return false;
/* Variables starting with an underscore are protected */
if (!allow_protected && p[0] == '_')
return false;
/* Don't allow digits as first character */
if (p[0] >= '0' && p[0] <= '9')
return false;
/* Only allow A-Z0-9 and '_' */
for (a = p; a < p + l; a++)
if ((*a < 'A' || *a > 'Z') &&
(*a < '0' || *a > '9') &&
*a != '_')
return false;
return true;
}
static bool allow_object_pid(const struct ucred *ucred) {
return ucred && ucred->uid == 0;
}
static void server_process_entry_meta(
const char *p, size_t l,
const struct ucred *ucred,
int *priority,
char **identifier,
char **message,
pid_t *object_pid) {
/* We need to determine the priority of this entry for the rate limiting logic */
if (l == 10 &&
startswith(p, "PRIORITY=") &&
p[9] >= '0' && p[9] <= '9')
*priority = (*priority & LOG_FACMASK) | (p[9] - '0');
else if (l == 17 &&
startswith(p, "SYSLOG_FACILITY=") &&
p[16] >= '0' && p[16] <= '9')
*priority = (*priority & LOG_PRIMASK) | ((p[16] - '0') << 3);
else if (l == 18 &&
startswith(p, "SYSLOG_FACILITY=") &&
p[16] >= '0' && p[16] <= '9' &&
p[17] >= '0' && p[17] <= '9')
*priority = (*priority & LOG_PRIMASK) | (((p[16] - '0')*10 + (p[17] - '0')) << 3);
else if (l >= 19 &&
startswith(p, "SYSLOG_IDENTIFIER=")) {
char *t;
t = strndup(p + 18, l - 18);
if (t) {
free(*identifier);
*identifier = t;
}
} else if (l >= 8 &&
startswith(p, "MESSAGE=")) {
char *t;
t = strndup(p + 8, l - 8);
if (t) {
free(*message);
*message = t;
}
} else if (l > strlen("OBJECT_PID=") &&
l < strlen("OBJECT_PID=") + DECIMAL_STR_MAX(pid_t) &&
startswith(p, "OBJECT_PID=") &&
allow_object_pid(ucred)) {
char buf[DECIMAL_STR_MAX(pid_t)];
memcpy(buf, p + strlen("OBJECT_PID="), l - strlen("OBJECT_PID="));
buf[l-strlen("OBJECT_PID=")] = '\0';
(void) parse_pid(buf, object_pid);
}
}
static int server_process_entry(
Server *s,
const void *buffer, size_t *remaining,
ClientContext *context,
const struct ucred *ucred,
const struct timeval *tv,
const char *label, size_t label_len) {
/* Process a single entry from a native message.
* Returns 0 if nothing special happened and the message processing should continue,
* and a negative or positive value otherwise.
*
* Note that *remaining is altered on both success and failure. */
struct iovec *iovec = NULL;
unsigned n = 0, j, tn = (unsigned) -1;
const char *p;
size_t m = 0, entry_size = 0;
int priority = LOG_INFO;
char *identifier = NULL, *message = NULL;
pid_t object_pid = 0;
int r = 0;
p = buffer;
while (*remaining > 0) {
const char *e, *q;
e = memchr(p, '\n', *remaining);
if (!e) {
/* Trailing noise, let's ignore it, and flush what we collected */
log_debug("Received message with trailing noise, ignoring.");
r = 1; /* finish processing of the message */
break;
}
if (e == p) {
/* Entry separator */
*remaining -= 1;
break;
}
if (*p == '.' || *p == '#') {
/* Ignore control commands for now, and
* comments too. */
*remaining -= (e - p) + 1;
p = e + 1;
continue;
}
/* A property follows */
/* n existing properties, 1 new, +1 for _TRANSPORT */
if (!GREEDY_REALLOC(iovec, m, n + 2 + N_IOVEC_META_FIELDS + N_IOVEC_OBJECT_FIELDS)) {
r = log_oom();
break;
}
q = memchr(p, '=', e - p);
if (q) {
if (valid_user_field(p, q - p, false)) {
size_t l;
l = e - p;
/* If the field name starts with an
* underscore, skip the variable,
* since that indicates a trusted
* field */
iovec[n].iov_base = (char*) p;
iovec[n].iov_len = l;
entry_size += l;
n++;
server_process_entry_meta(p, l, ucred,
&priority,
&identifier,
&message,
&object_pid);
}
*remaining -= (e - p) + 1;
p = e + 1;
continue;
} else {
uint64_t l;
char *k;
if (*remaining < e - p + 1 + sizeof(uint64_t) + 1) {
log_debug("Failed to parse message, ignoring.");
break;
}
l = unaligned_read_le64(e + 1);
if (l > DATA_SIZE_MAX) {
log_debug("Received binary data block of %"PRIu64" bytes is too large, ignoring.", l);
break;
}
if ((uint64_t) *remaining < e - p + 1 + sizeof(uint64_t) + l + 1 ||
e[1+sizeof(uint64_t)+l] != '\n') {
log_debug("Failed to parse message, ignoring.");
break;
}
k = malloc((e - p) + 1 + l);
if (!k) {
log_oom();
break;
}
memcpy(k, p, e - p);
k[e - p] = '=';
memcpy(k + (e - p) + 1, e + 1 + sizeof(uint64_t), l);
if (valid_user_field(p, e - p, false)) {
iovec[n].iov_base = k;
iovec[n].iov_len = (e - p) + 1 + l;
entry_size += iovec[n].iov_len;
n++;
server_process_entry_meta(k, (e - p) + 1 + l, ucred,
&priority,
&identifier,
&message,
&object_pid);
} else
free(k);
*remaining -= (e - p) + 1 + sizeof(uint64_t) + l + 1;
p = e + 1 + sizeof(uint64_t) + l + 1;
}
}
if (n <= 0) {
r = 1;
goto finish;
}
tn = n++;
iovec[tn] = IOVEC_MAKE_STRING("_TRANSPORT=journal");
entry_size += strlen("_TRANSPORT=journal");
if (entry_size + n + 1 > ENTRY_SIZE_MAX) { /* data + separators + trailer */
log_debug("Entry is too big with %u properties and %zu bytes, ignoring.",
n, entry_size);
goto finish;
}
if (message) {
if (s->forward_to_syslog)
server_forward_syslog(s, syslog_fixup_facility(priority), identifier, message, ucred, tv);
if (s->forward_to_kmsg)
server_forward_kmsg(s, priority, identifier, message, ucred);
if (s->forward_to_console)
server_forward_console(s, priority, identifier, message, ucred);
if (s->forward_to_wall)
server_forward_wall(s, priority, identifier, message, ucred);
}
server_dispatch_message(s, iovec, n, m, context, tv, priority, object_pid);
finish:
for (j = 0; j < n; j++) {
if (j == tn)
continue;
if (iovec[j].iov_base < buffer ||
(const char*) iovec[j].iov_base >= p + *remaining)
free(iovec[j].iov_base);
}
free(iovec);
free(identifier);
free(message);
return r;
}
void server_process_native_message(
Server *s,
const void *buffer, size_t buffer_size,
const struct ucred *ucred,
const struct timeval *tv,
const char *label, size_t label_len) {
size_t remaining = buffer_size;
ClientContext *context;
int r;
assert(s);
assert(buffer || buffer_size == 0);
if (ucred && pid_is_valid(ucred->pid)) {
r = client_context_get(s, ucred->pid, ucred, label, label_len, NULL, &context);
if (r < 0)
log_warning_errno(r, "Failed to retrieve credentials for PID " PID_FMT ", ignoring: %m", ucred->pid);
}
do {
r = server_process_entry(s,
(const uint8_t*) buffer + (buffer_size - remaining), &remaining,
context, ucred, tv, label, label_len);
} while (r == 0);
}
void server_process_native_file(
Server *s,
int fd,
const struct ucred *ucred,
const struct timeval *tv,
const char *label, size_t label_len) {
struct stat st;
bool sealed;
int r;
/* Data is in the passed fd, since it didn't fit in a
* datagram. */
assert(s);
assert(fd >= 0);
/* If it's a memfd, check if it is sealed. If so, we can just
* use map it and use it, and do not need to copy the data
* out. */
sealed = memfd_get_sealed(fd) > 0;
if (!sealed && (!ucred || ucred->uid != 0)) {
_cleanup_free_ char *sl = NULL, *k = NULL;
const char *e;
/* If this is not a sealed memfd, and the peer is unknown or
* unprivileged, then verify the path. */
if (asprintf(&sl, "/proc/self/fd/%i", fd) < 0) {
log_oom();
return;
}
r = readlink_malloc(sl, &k);
if (r < 0) {
log_error_errno(r, "readlink(%s) failed: %m", sl);
return;
}
e = path_startswith(k, "/dev/shm/");
if (!e)
e = path_startswith(k, "/tmp/");
if (!e)
e = path_startswith(k, "/var/tmp/");
if (!e) {
log_error("Received file outside of allowed directories. Refusing.");
return;
}
if (!filename_is_valid(e)) {
log_error("Received file in subdirectory of allowed directories. Refusing.");
return;
}
}
if (fstat(fd, &st) < 0) {
log_error_errno(errno, "Failed to stat passed file, ignoring: %m");
return;
}
if (!S_ISREG(st.st_mode)) {
log_error("File passed is not regular. Ignoring.");
return;
}
if (st.st_size <= 0)
return;
if (st.st_size > ENTRY_SIZE_MAX) {
log_error("File passed too large. Ignoring.");
return;
}
if (sealed) {
void *p;
size_t ps;
/* The file is sealed, we can just map it and use it. */
ps = PAGE_ALIGN(st.st_size);
p = mmap(NULL, ps, PROT_READ, MAP_PRIVATE, fd, 0);
if (p == MAP_FAILED) {
log_error_errno(errno, "Failed to map memfd, ignoring: %m");
return;
}
server_process_native_message(s, p, st.st_size, ucred, tv, label, label_len);
assert_se(munmap(p, ps) >= 0);
} else {
_cleanup_free_ void *p = NULL;
struct statvfs vfs;
ssize_t n;
if (fstatvfs(fd, &vfs) < 0) {
log_error_errno(errno, "Failed to stat file system of passed file, ignoring: %m");
return;
}
/* Refuse operating on file systems that have
* mandatory locking enabled, see:
*
* https://github.com/systemd/systemd/issues/1822
*/
if (vfs.f_flag & ST_MANDLOCK) {
log_error("Received file descriptor from file system with mandatory locking enable, refusing.");
return;
}
/* Make the fd non-blocking. On regular files this has
* the effect of bypassing mandatory locking. Of
* course, this should normally not be necessary given
* the check above, but let's better be safe than
* sorry, after all NFS is pretty confusing regarding
* file system flags, and we better don't trust it,
* and so is SMB. */
r = fd_nonblock(fd, true);
if (r < 0) {
log_error_errno(r, "Failed to make fd non-blocking, ignoring: %m");
return;
}
/* The file is not sealed, we can't map the file here, since
* clients might then truncate it and trigger a SIGBUS for
* us. So let's stupidly read it */
p = malloc(st.st_size);
if (!p) {
log_oom();
return;
}
n = pread(fd, p, st.st_size, 0);
if (n < 0)
log_error_errno(errno, "Failed to read file, ignoring: %m");
else if (n > 0)
server_process_native_message(s, p, n, ucred, tv, label, label_len);
}
}
int server_open_native_socket(Server*s) {
static const union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
.un.sun_path = "/run/systemd/journal/socket",
};
static const int one = 1;
int r;
assert(s);
if (s->native_fd < 0) {
s->native_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (s->native_fd < 0)
return log_error_errno(errno, "socket() failed: %m");
(void) unlink(sa.un.sun_path);
r = bind(s->native_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
if (r < 0)
return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
(void) chmod(sa.un.sun_path, 0666);
} else
fd_nonblock(s->native_fd, 1);
r = setsockopt(s->native_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
if (r < 0)
return log_error_errno(errno, "SO_PASSCRED failed: %m");
#if HAVE_SELINUX
if (mac_selinux_use()) {
r = setsockopt(s->native_fd, SOL_SOCKET, SO_PASSSEC, &one, sizeof(one));
if (r < 0)
log_warning_errno(errno, "SO_PASSSEC failed: %m");
}
#endif
r = setsockopt(s->native_fd, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one));
if (r < 0)
return log_error_errno(errno, "SO_TIMESTAMP failed: %m");
r = sd_event_add_io(s->event, &s->native_event_source, s->native_fd, EPOLLIN, server_process_datagram, s);
if (r < 0)
return log_error_errno(r, "Failed to add native server fd to event loop: %m");
r = sd_event_source_set_priority(s->native_event_source, SD_EVENT_PRIORITY_NORMAL+5);
if (r < 0)
return log_error_errno(r, "Failed to adjust native event source priority: %m");
return 0;
}
Reference in New Issue View Git Blame Copy Permalink