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samba-mirror/source3/lib/messages_dgm.c

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/*
* Unix SMB/CIFS implementation.
* Samba internal messaging functions
* Copyright (C) 2013 by Volker Lendecke
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "lib/util/data_blob.h"
#include "lib/util/debug.h"
#include "lib/unix_msg/unix_msg.h"
#include "system/filesys.h"
#include "messages.h"
#include "lib/param/param.h"
#include "poll_funcs/poll_funcs_tevent.h"
#include "unix_msg/unix_msg.h"
#include "librpc/gen_ndr/messaging.h"
struct messaging_dgm_context {
struct messaging_context *msg_ctx;
struct poll_funcs *msg_callbacks;
void *tevent_handle;
struct unix_msg_ctx *dgm_ctx;
char *cache_dir;
int lockfile_fd;
};
struct messaging_dgm_hdr {
uint32_t msg_version;
enum messaging_type msg_type;
struct server_id dst;
struct server_id src;
};
static NTSTATUS messaging_dgm_send(struct messaging_context *msg_ctx,
struct server_id pid, int msg_type,
const DATA_BLOB *data,
struct messaging_backend *backend);
static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
uint8_t *msg, size_t msg_len,
void *private_data);
static int messaging_dgm_context_destructor(struct messaging_dgm_context *c);
static int messaging_dgm_lockfile_create(const char *cache_dir, pid_t pid,
int *plockfile_fd, uint64_t unique)
{
char buf[PATH_MAX];
char *dir, *to_free;
ssize_t dirlen;
char *lockfile_name;
int lockfile_fd;
struct flock lck = {};
int unique_len, ret;
ssize_t written;
bool ok;
dirlen = full_path_tos(cache_dir, "lck", buf, sizeof(buf),
&dir, &to_free);
if (dirlen == -1) {
return ENOMEM;
}
ok = directory_create_or_exist_strict(dir, sec_initial_uid(), 0755);
if (!ok) {
ret = errno;
DEBUG(1, ("%s: Could not create lock directory: %s\n",
__func__, strerror(ret)));
TALLOC_FREE(to_free);
return ret;
}
lockfile_name = talloc_asprintf(talloc_tos(), "%s/%u", dir,
(unsigned)pid);
TALLOC_FREE(to_free);
if (lockfile_name == NULL) {
DEBUG(1, ("%s: talloc_asprintf failed\n", __func__));
return ENOMEM;
}
/* no O_EXCL, existence check is via the fcntl lock */
lockfile_fd = open(lockfile_name, O_NONBLOCK|O_CREAT|O_WRONLY, 0644);
if (lockfile_fd == -1) {
ret = errno;
DEBUG(1, ("%s: open failed: %s\n", __func__, strerror(errno)));
goto fail_free;
}
lck.l_type = F_WRLCK;
lck.l_whence = SEEK_SET;
lck.l_start = 0;
lck.l_len = 0;
ret = fcntl(lockfile_fd, F_SETLK, &lck);
if (ret == -1) {
ret = errno;
DEBUG(1, ("%s: fcntl failed: %s\n", __func__, strerror(ret)));
goto fail_close;
}
unique_len = snprintf(buf, sizeof(buf), "%"PRIu64, unique);
/* shorten a potentially preexisting file */
ret = ftruncate(lockfile_fd, unique_len);
if (ret == -1) {
ret = errno;
DEBUG(1, ("%s: ftruncate failed: %s\n", __func__,
strerror(ret)));
goto fail_unlink;
}
written = write(lockfile_fd, buf, unique_len);
if (written != unique_len) {
ret = errno;
DEBUG(1, ("%s: write failed: %s\n", __func__, strerror(ret)));
goto fail_unlink;
}
*plockfile_fd = lockfile_fd;
return 0;
fail_unlink:
unlink(lockfile_name);
fail_close:
close(lockfile_fd);
fail_free:
TALLOC_FREE(lockfile_name);
return ret;
}
static int messaging_dgm_lockfile_remove(const char *cache_dir, pid_t pid)
{
fstring fname;
char buf[PATH_MAX];
char *lockfile_name, *to_free;
ssize_t len;
int ret;
fstr_sprintf(fname, "lck/%u", (unsigned)pid);
len = full_path_tos(cache_dir, fname, buf, sizeof(buf),
&lockfile_name, &to_free);
if (len == -1) {
return ENOMEM;
}
ret = unlink(lockfile_name);
if (ret == -1) {
ret = errno;
DEBUG(10, ("%s: unlink failed: %s\n", __func__,
strerror(ret)));
}
TALLOC_FREE(to_free);
return ret;
}
NTSTATUS messaging_dgm_init(struct messaging_context *msg_ctx,
TALLOC_CTX *mem_ctx,
struct messaging_backend **presult)
{
struct messaging_backend *result;
struct messaging_dgm_context *ctx;
struct server_id pid = messaging_server_id(msg_ctx);
int ret;
bool ok;
const char *cache_dir;
char *socket_dir, *socket_name;
uint64_t cookie;
cache_dir = lp_cache_directory();
if (cache_dir == NULL) {
NTSTATUS status = map_nt_error_from_unix(errno);
return status;
}
result = talloc(mem_ctx, struct messaging_backend);
if (result == NULL) {
goto fail_nomem;
}
ctx = talloc_zero(result, struct messaging_dgm_context);
if (ctx == NULL) {
goto fail_nomem;
}
result->private_data = ctx;
result->send_fn = messaging_dgm_send;
ctx->msg_ctx = msg_ctx;
ctx->cache_dir = talloc_strdup(ctx, cache_dir);
if (ctx->cache_dir == NULL) {
goto fail_nomem;
}
socket_dir = talloc_asprintf(ctx, "%s/msg", cache_dir);
if (socket_dir == NULL) {
goto fail_nomem;
}
socket_name = talloc_asprintf(ctx, "%s/%u", socket_dir,
(unsigned)pid.pid);
if (socket_name == NULL) {
goto fail_nomem;
}
sec_init();
ret = messaging_dgm_lockfile_create(cache_dir, pid.pid,
&ctx->lockfile_fd, pid.unique_id);
if (ret != 0) {
DEBUG(1, ("%s: messaging_dgm_create_lockfile failed: %s\n",
__func__, strerror(ret)));
TALLOC_FREE(result);
return map_nt_error_from_unix(ret);
}
ctx->msg_callbacks = poll_funcs_init_tevent(ctx);
if (ctx->msg_callbacks == NULL) {
TALLOC_FREE(result);
return NT_STATUS_NO_MEMORY;
}
ctx->tevent_handle = poll_funcs_tevent_register(
ctx, ctx->msg_callbacks, msg_ctx->event_ctx);
if (ctx->tevent_handle == NULL) {
TALLOC_FREE(result);
return NT_STATUS_NO_MEMORY;
}
ok = directory_create_or_exist_strict(socket_dir, sec_initial_uid(),
0700);
if (!ok) {
DEBUG(1, ("Could not create socket directory\n"));
TALLOC_FREE(result);
return NT_STATUS_ACCESS_DENIED;
}
TALLOC_FREE(socket_dir);
unlink(socket_name);
generate_random_buffer((uint8_t *)&cookie, sizeof(cookie));
ret = unix_msg_init(socket_name, ctx->msg_callbacks, 1024, cookie,
messaging_dgm_recv, ctx, &ctx->dgm_ctx);
TALLOC_FREE(socket_name);
if (ret != 0) {
DEBUG(1, ("unix_msg_init failed: %s\n", strerror(ret)));
TALLOC_FREE(result);
return map_nt_error_from_unix(ret);
}
talloc_set_destructor(ctx, messaging_dgm_context_destructor);
*presult = result;
return NT_STATUS_OK;
fail_nomem:
TALLOC_FREE(result);
return NT_STATUS_NO_MEMORY;
}
static int messaging_dgm_context_destructor(struct messaging_dgm_context *c)
{
struct server_id pid = messaging_server_id(c->msg_ctx);
/*
* First delete the socket to avoid races. The lockfile is the
* indicator that we're still around.
*/
unix_msg_free(c->dgm_ctx);
if (getpid() == pid.pid) {
(void)messaging_dgm_lockfile_remove(c->cache_dir, pid.pid);
}
close(c->lockfile_fd);
return 0;
}
static NTSTATUS messaging_dgm_send(struct messaging_context *msg_ctx,
struct server_id pid, int msg_type,
const DATA_BLOB *data,
struct messaging_backend *backend)
{
struct messaging_dgm_context *ctx = talloc_get_type_abort(
backend->private_data, struct messaging_dgm_context);
fstring pid_str;
char buf[PATH_MAX];
char *dst_sock, *to_free;
struct messaging_dgm_hdr hdr;
struct iovec iov[2];
ssize_t pathlen;
int ret;
fstr_sprintf(pid_str, "msg/%u", (unsigned)pid.pid);
pathlen = full_path_tos(ctx->cache_dir, pid_str, buf, sizeof(buf),
&dst_sock, &to_free);
if (pathlen == -1) {
return NT_STATUS_NO_MEMORY;
}
hdr.msg_version = MESSAGE_VERSION;
hdr.msg_type = msg_type & MSG_TYPE_MASK;
hdr.dst = pid;
hdr.src = msg_ctx->id;
DEBUG(10, ("%s: Sending message 0x%x len %u to %s\n", __func__,
(unsigned)hdr.msg_type, (unsigned)data->length,
server_id_str(talloc_tos(), &pid)));
iov[0].iov_base = &hdr;
iov[0].iov_len = sizeof(hdr);
iov[1].iov_base = data->data;
iov[1].iov_len = data->length;
become_root();
ret = unix_msg_send(ctx->dgm_ctx, dst_sock, iov, ARRAY_SIZE(iov));
unbecome_root();
TALLOC_FREE(to_free);
if (ret != 0) {
return map_nt_error_from_unix(ret);
}
return NT_STATUS_OK;
}
static void messaging_dgm_recv(struct unix_msg_ctx *ctx,
uint8_t *msg, size_t msg_len,
void *private_data)
{
struct messaging_dgm_context *dgm_ctx = talloc_get_type_abort(
private_data, struct messaging_dgm_context);
struct messaging_dgm_hdr *hdr;
struct messaging_rec rec;
if (msg_len < sizeof(*hdr)) {
DEBUG(1, ("message too short: %u\n", (unsigned)msg_len));
return;
}
/*
* unix_msg guarantees alignment, so we can cast here
*/
hdr = (struct messaging_dgm_hdr *)msg;
rec.msg_version = hdr->msg_version;
rec.msg_type = hdr->msg_type;
rec.dest = hdr->dst;
rec.src = hdr->src;
rec.buf.data = msg + sizeof(*hdr);
rec.buf.length = msg_len - sizeof(*hdr);
DEBUG(10, ("%s: Received message 0x%x len %u from %s\n", __func__,
(unsigned)hdr->msg_type, (unsigned)rec.buf.length,
server_id_str(talloc_tos(), &rec.src)));
messaging_dispatch_rec(dgm_ctx->msg_ctx, &rec);
}
NTSTATUS messaging_dgm_cleanup(struct messaging_context *msg_ctx, pid_t pid)
{
struct messaging_dgm_context *ctx = talloc_get_type_abort(
msg_ctx->local->private_data, struct messaging_dgm_context);
char *lockfile_name, *socket_name;
int fd, ret;
struct flock lck = {};
NTSTATUS status = NT_STATUS_OK;
lockfile_name = talloc_asprintf(talloc_tos(), "%s/lck/%u",
ctx->cache_dir, (unsigned)pid);
if (lockfile_name == NULL) {
return NT_STATUS_NO_MEMORY;
}
socket_name = talloc_asprintf(lockfile_name, "%s/msg/%u",
ctx->cache_dir, (unsigned)pid);
if (socket_name == NULL) {
TALLOC_FREE(lockfile_name);
return NT_STATUS_NO_MEMORY;
}
fd = open(lockfile_name, O_NONBLOCK|O_WRONLY, 0);
if (fd == -1) {
status = map_nt_error_from_unix(errno);
DEBUG(10, ("%s: open(%s) failed: %s\n", __func__,
lockfile_name, strerror(errno)));
return status;
}
lck.l_type = F_WRLCK;
lck.l_whence = SEEK_SET;
lck.l_start = 0;
lck.l_len = 0;
ret = fcntl(fd, F_SETLK, &lck);
if (ret != 0) {
status = map_nt_error_from_unix(errno);
DEBUG(10, ("%s: Could not get lock: %s\n", __func__,
strerror(errno)));
TALLOC_FREE(lockfile_name);
close(fd);
return status;
}
(void)unlink(socket_name);
(void)unlink(lockfile_name);
(void)close(fd);
TALLOC_FREE(lockfile_name);
return NT_STATUS_OK;
}
NTSTATUS messaging_dgm_wipe(struct messaging_context *msg_ctx)
{
struct messaging_dgm_context *ctx = talloc_get_type_abort(
msg_ctx->local->private_data, struct messaging_dgm_context);
char *msgdir_name;
DIR *msgdir;
struct dirent *dp;
pid_t our_pid = getpid();
/*
* We scan the socket directory and not the lock directory. Otherwise
* we would race against messaging_dgm_lockfile_create's open(O_CREAT)
* and fcntl(SETLK).
*/
msgdir_name = talloc_asprintf(talloc_tos(), "%s/msg", ctx->cache_dir);
if (msgdir_name == NULL) {
return NT_STATUS_NO_MEMORY;
}
msgdir = opendir(msgdir_name);
TALLOC_FREE(msgdir_name);
if (msgdir == NULL) {
return map_nt_error_from_unix(errno);
}
while ((dp = readdir(msgdir)) != NULL) {
NTSTATUS status;
unsigned long pid;
pid = strtoul(dp->d_name, NULL, 10);
if (pid == 0) {
/*
* . and .. and other malformed entries
*/
continue;
}
if (pid == our_pid) {
/*
* fcntl(F_GETLK) will succeed for ourselves, we hold
* that lock ourselves.
*/
continue;
}
status = messaging_dgm_cleanup(msg_ctx, pid);
DEBUG(10, ("messaging_dgm_cleanup(%lu) returned %s\n",
pid, nt_errstr(status)));
}
closedir(msgdir);
return NT_STATUS_OK;
}
void *messaging_dgm_register_tevent_context(TALLOC_CTX *mem_ctx,
struct messaging_context *msg_ctx,
struct tevent_context *ev)
{
struct messaging_dgm_context *ctx = talloc_get_type_abort(
msg_ctx->local->private_data, struct messaging_dgm_context);
return poll_funcs_tevent_register(mem_ctx, ctx->msg_callbacks, ev);
}