/*
* Unix SMB/CIFS implementation.
* Copyright (C) Volker Lendecke 2013
*
* 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 .
*/
#include "replace.h"
#include "unix_msg.h"
#include "system/select.h"
#include "system/time.h"
#include "system/network.h"
#include "dlinklist.h"
#include "pthreadpool/pthreadpool.h"
#include "lib/util/iov_buf.h"
#include "lib/msghdr.h"
#include
/*
* This file implements two abstractions: The "unix_dgram" functions implement
* queueing for unix domain datagram sockets. You can send to a destination
* socket, and if that has no free space available, it will fall back to an
* anonymous socket that will poll for writability. "unix_dgram" expects the
* data size not to exceed the system limit.
*
* The "unix_msg" functions implement the fragmentation of large messages on
* top of "unix_dgram". This is what is exposed to the user of this API.
*/
struct unix_dgram_msg {
struct unix_dgram_msg *prev, *next;
int sock;
ssize_t sent;
int sys_errno;
};
struct unix_dgram_send_queue {
struct unix_dgram_send_queue *prev, *next;
struct unix_dgram_ctx *ctx;
int sock;
struct unix_dgram_msg *msgs;
char path[];
};
struct unix_dgram_ctx {
int sock;
pid_t created_pid;
const struct poll_funcs *ev_funcs;
size_t max_msg;
void (*recv_callback)(struct unix_dgram_ctx *ctx,
uint8_t *msg, size_t msg_len,
int *fds, size_t num_fds,
void *private_data);
void *private_data;
struct poll_watch *sock_read_watch;
struct unix_dgram_send_queue *send_queues;
struct pthreadpool *send_pool;
struct poll_watch *pool_read_watch;
uint8_t *recv_buf;
char path[];
};
static void unix_dgram_recv_handler(struct poll_watch *w, int fd, short events,
void *private_data);
/* Set socket non blocking. */
static int prepare_socket_nonblock(int sock)
{
int flags;
#ifdef O_NONBLOCK
#define FLAG_TO_SET O_NONBLOCK
#else
#ifdef SYSV
#define FLAG_TO_SET O_NDELAY
#else /* BSD */
#define FLAG_TO_SET FNDELAY
#endif
#endif
flags = fcntl(sock, F_GETFL);
if (flags == -1) {
return errno;
}
flags |= FLAG_TO_SET;
if (fcntl(sock, F_SETFL, flags) == -1) {
return errno;
}
#undef FLAG_TO_SET
return 0;
}
/* Set socket close on exec. */
static int prepare_socket_cloexec(int sock)
{
#ifdef FD_CLOEXEC
int flags;
flags = fcntl(sock, F_GETFD, 0);
if (flags == -1) {
return errno;
}
flags |= FD_CLOEXEC;
if (fcntl(sock, F_SETFD, flags) == -1) {
return errno;
}
#endif
return 0;
}
/* Set socket non blocking and close on exec. */
static int prepare_socket(int sock)
{
int ret = prepare_socket_nonblock(sock);
if (ret) {
return ret;
}
return prepare_socket_cloexec(sock);
}
static size_t unix_dgram_msg_size(void)
{
size_t msgsize = sizeof(struct unix_dgram_msg);
msgsize = (msgsize + 15) & ~15; /* align to 16 */
return msgsize;
}
static struct msghdr_buf *unix_dgram_msghdr(struct unix_dgram_msg *msg)
{
/*
* Not portable in C99, but "msg" is aligned and so is
* unix_dgram_msg_size()
*/
return (struct msghdr_buf *)(((char *)msg) + unix_dgram_msg_size());
}
static void close_fd_array(int *fds, size_t num_fds)
{
size_t i;
for (i = 0; i < num_fds; i++) {
if (fds[i] == -1) {
continue;
}
close(fds[i]);
fds[i] = -1;
}
}
static void close_fd_array_dgram_msg(struct unix_dgram_msg *dmsg)
{
struct msghdr_buf *hdr = unix_dgram_msghdr(dmsg);
struct msghdr *msg = msghdr_buf_msghdr(hdr);
size_t num_fds = msghdr_extract_fds(msg, NULL, 0);
int fds[num_fds];
msghdr_extract_fds(msg, fds, num_fds);
close_fd_array(fds, num_fds);
}
static int unix_dgram_init(const struct sockaddr_un *addr, size_t max_msg,
const struct poll_funcs *ev_funcs,
void (*recv_callback)(struct unix_dgram_ctx *ctx,
uint8_t *msg, size_t msg_len,
int *fds, size_t num_fds,
void *private_data),
void *private_data,
struct unix_dgram_ctx **result)
{
struct unix_dgram_ctx *ctx;
size_t pathlen;
int ret;
if (addr != NULL) {
pathlen = strlen(addr->sun_path)+1;
} else {
pathlen = 1;
}
ctx = malloc(offsetof(struct unix_dgram_ctx, path) + pathlen);
if (ctx == NULL) {
return ENOMEM;
}
if (addr != NULL) {
memcpy(ctx->path, addr->sun_path, pathlen);
} else {
ctx->path[0] = '\0';
}
*ctx = (struct unix_dgram_ctx) {
.max_msg = max_msg,
.ev_funcs = ev_funcs,
.recv_callback = recv_callback,
.private_data = private_data,
.created_pid = (pid_t)-1
};
ctx->recv_buf = malloc(max_msg);
if (ctx->recv_buf == NULL) {
free(ctx);
return ENOMEM;
}
ctx->sock = socket(AF_UNIX, SOCK_DGRAM, 0);
if (ctx->sock == -1) {
ret = errno;
goto fail_free;
}
/* Set non-blocking and close-on-exec. */
ret = prepare_socket(ctx->sock);
if (ret != 0) {
goto fail_close;
}
if (addr != NULL) {
ret = bind(ctx->sock,
(const struct sockaddr *)(const void *)addr,
sizeof(*addr));
if (ret == -1) {
ret = errno;
goto fail_close;
}
ctx->created_pid = getpid();
ctx->sock_read_watch = ctx->ev_funcs->watch_new(
ctx->ev_funcs, ctx->sock, POLLIN,
unix_dgram_recv_handler, ctx);
if (ctx->sock_read_watch == NULL) {
ret = ENOMEM;
goto fail_close;
}
}
*result = ctx;
return 0;
fail_close:
close(ctx->sock);
fail_free:
free(ctx->recv_buf);
free(ctx);
return ret;
}
static void unix_dgram_recv_handler(struct poll_watch *w, int fd, short events,
void *private_data)
{
struct unix_dgram_ctx *ctx = (struct unix_dgram_ctx *)private_data;
ssize_t received;
int flags = 0;
struct msghdr msg;
struct iovec iov;
size_t bufsize = msghdr_prep_recv_fds(NULL, NULL, 0, INT8_MAX);
uint8_t buf[bufsize];
iov = (struct iovec) {
.iov_base = (void *)ctx->recv_buf,
.iov_len = ctx->max_msg,
};
msg = (struct msghdr) {
.msg_iov = &iov,
.msg_iovlen = 1,
};
msghdr_prep_recv_fds(&msg, buf, bufsize, INT8_MAX);
#ifdef MSG_CMSG_CLOEXEC
flags |= MSG_CMSG_CLOEXEC;
#endif
received = recvmsg(fd, &msg, flags);
if (received == -1) {
if ((errno == EAGAIN) ||
(errno == EWOULDBLOCK) ||
(errno == EINTR) || (errno == ENOMEM)) {
/* Not really an error - just try again. */
return;
}
/* Problem with the socket. Set it unreadable. */
ctx->ev_funcs->watch_update(w, 0);
return;
}
if (received > ctx->max_msg) {
/* More than we expected, not for us */
return;
}
{
size_t num_fds = msghdr_extract_fds(&msg, NULL, 0);
int fds[num_fds];
int i;
msghdr_extract_fds(&msg, fds, num_fds);
for (i = 0; i < num_fds; i++) {
int err;
err = prepare_socket_cloexec(fds[i]);
if (err != 0) {
close_fd_array(fds, num_fds);
num_fds = 0;
}
}
ctx->recv_callback(ctx, ctx->recv_buf, received,
fds, num_fds, ctx->private_data);
}
}
static void unix_dgram_job_finished(struct poll_watch *w, int fd, short events,
void *private_data);
static int unix_dgram_init_pthreadpool(struct unix_dgram_ctx *ctx)
{
int ret, signalfd;
if (ctx->send_pool != NULL) {
return 0;
}
ret = pthreadpool_init(0, &ctx->send_pool);
if (ret != 0) {
return ret;
}
signalfd = pthreadpool_signal_fd(ctx->send_pool);
ctx->pool_read_watch = ctx->ev_funcs->watch_new(
ctx->ev_funcs, signalfd, POLLIN,
unix_dgram_job_finished, ctx);
if (ctx->pool_read_watch == NULL) {
pthreadpool_destroy(ctx->send_pool);
ctx->send_pool = NULL;
return ENOMEM;
}
return 0;
}
static int unix_dgram_send_queue_init(
struct unix_dgram_ctx *ctx, const struct sockaddr_un *dst,
struct unix_dgram_send_queue **result)
{
struct unix_dgram_send_queue *q;
size_t pathlen;
int ret, err;
pathlen = strlen(dst->sun_path)+1;
q = malloc(offsetof(struct unix_dgram_send_queue, path) + pathlen);
if (q == NULL) {
return ENOMEM;
}
q->ctx = ctx;
q->msgs = NULL;
memcpy(q->path, dst->sun_path, pathlen);
q->sock = socket(AF_UNIX, SOCK_DGRAM, 0);
if (q->sock == -1) {
err = errno;
goto fail_free;
}
err = prepare_socket_cloexec(q->sock);
if (err != 0) {
goto fail_close;
}
do {
ret = connect(q->sock,
(const struct sockaddr *)(const void *)dst,
sizeof(*dst));
} while ((ret == -1) && (errno == EINTR));
if (ret == -1) {
err = errno;
goto fail_close;
}
err = unix_dgram_init_pthreadpool(ctx);
if (err != 0) {
goto fail_close;
}
DLIST_ADD(ctx->send_queues, q);
*result = q;
return 0;
fail_close:
close(q->sock);
fail_free:
free(q);
return err;
}
static void unix_dgram_send_queue_free(struct unix_dgram_send_queue *q)
{
struct unix_dgram_ctx *ctx = q->ctx;
while (q->msgs != NULL) {
struct unix_dgram_msg *msg;
msg = q->msgs;
DLIST_REMOVE(q->msgs, msg);
close_fd_array_dgram_msg(msg);
free(msg);
}
close(q->sock);
DLIST_REMOVE(ctx->send_queues, q);
free(q);
}
static struct unix_dgram_send_queue *find_send_queue(
struct unix_dgram_ctx *ctx, const char *dst_sock)
{
struct unix_dgram_send_queue *s;
for (s = ctx->send_queues; s != NULL; s = s->next) {
if (strcmp(s->path, dst_sock) == 0) {
return s;
}
}
return NULL;
}
static int queue_msg(struct unix_dgram_send_queue *q,
const struct iovec *iov, int iovcnt,
const int *fds, size_t num_fds)
{
struct unix_dgram_msg *msg;
struct msghdr_buf *hdr;
size_t msglen, needed;
ssize_t msghdrlen;
int fds_copy[MIN(num_fds, INT8_MAX)];
int i, ret;
for (i=0; isock = q->sock;
msghdr_copy(hdr, msghdrlen, NULL, 0, iov, iovcnt,
fds_copy, num_fds);
DLIST_ADD_END(q->msgs, msg, struct unix_dgram_msg);
return 0;
fail:
close_fd_array(fds_copy, num_fds);
return ret;
}
static void unix_dgram_send_job(void *private_data)
{
struct unix_dgram_msg *dmsg = private_data;
do {
struct msghdr_buf *hdr = unix_dgram_msghdr(dmsg);
struct msghdr *msg = msghdr_buf_msghdr(hdr);
dmsg->sent = sendmsg(dmsg->sock, msg, 0);
} while ((dmsg->sent == -1) && (errno == EINTR));
if (dmsg->sent == -1) {
dmsg->sys_errno = errno;
}
}
static void unix_dgram_job_finished(struct poll_watch *w, int fd, short events,
void *private_data)
{
struct unix_dgram_ctx *ctx = private_data;
struct unix_dgram_send_queue *q;
struct unix_dgram_msg *msg;
int ret, job;
ret = pthreadpool_finished_jobs(ctx->send_pool, &job, 1);
if (ret != 1) {
return;
}
for (q = ctx->send_queues; q != NULL; q = q->next) {
if (job == q->sock) {
break;
}
}
if (q == NULL) {
/* Huh? Should not happen */
return;
}
msg = q->msgs;
DLIST_REMOVE(q->msgs, msg);
close_fd_array_dgram_msg(msg);
free(msg);
if (q->msgs != NULL) {
ret = pthreadpool_add_job(ctx->send_pool, q->sock,
unix_dgram_send_job, q->msgs);
if (ret == 0) {
return;
}
}
unix_dgram_send_queue_free(q);
}
static int unix_dgram_send(struct unix_dgram_ctx *ctx,
const struct sockaddr_un *dst,
const struct iovec *iov, int iovlen,
const int *fds, size_t num_fds)
{
struct unix_dgram_send_queue *q;
struct msghdr msg;
ssize_t fdlen;
int ret;
int i;
if (num_fds > INT8_MAX) {
return EINVAL;
}
#if !defined(HAVE_STRUCT_MSGHDR_MSG_CONTROL) && !defined(HAVE_STRUCT_MSGHDR_MSG_ACCRIGHTS)
if (num_fds > 0) {
return ENOSYS;
}
#endif
for (i = 0; i < num_fds; i++) {
/*
* Make sure we only allow fd passing
* for communication channels,
* e.g. sockets, pipes, fifos, ...
*/
ret = lseek(fds[i], 0, SEEK_CUR);
if (ret == -1 && errno == ESPIPE) {
/* ok */
continue;
}
/*
* Reject the message as we may need to call dup(),
* if we queue the message.
*
* That might result in unexpected behavior for the caller
* for files and broken posix locking.
*/
return EINVAL;
}
/*
* To preserve message ordering, we have to queue a message when
* others are waiting in line already.
*/
q = find_send_queue(ctx, dst->sun_path);
if (q != NULL) {
return queue_msg(q, iov, iovlen, fds, num_fds);
}
/*
* Try a cheap nonblocking send
*/
msg = (struct msghdr) {
.msg_name = discard_const_p(struct sockaddr_un, dst),
.msg_namelen = sizeof(*dst),
.msg_iov = discard_const_p(struct iovec, iov),
.msg_iovlen = iovlen
};
fdlen = msghdr_prep_fds(&msg, NULL, 0, fds, num_fds);
if (fdlen == -1) {
return EINVAL;
}
{
uint8_t buf[fdlen];
msghdr_prep_fds(&msg, buf, fdlen, fds, num_fds);
ret = sendmsg(ctx->sock, &msg, 0);
}
if (ret >= 0) {
return 0;
}
if ((errno != EWOULDBLOCK) &&
(errno != EAGAIN) &&
#ifdef ENOBUFS
/* FreeBSD can give this for large messages */
(errno != ENOBUFS) &&
#endif
(errno != EINTR)) {
return errno;
}
ret = unix_dgram_send_queue_init(ctx, dst, &q);
if (ret != 0) {
return ret;
}
ret = queue_msg(q, iov, iovlen, fds, num_fds);
if (ret != 0) {
unix_dgram_send_queue_free(q);
return ret;
}
ret = pthreadpool_add_job(ctx->send_pool, q->sock,
unix_dgram_send_job, q->msgs);
if (ret != 0) {
unix_dgram_send_queue_free(q);
return ret;
}
return 0;
}
static int unix_dgram_sock(struct unix_dgram_ctx *ctx)
{
return ctx->sock;
}
static int unix_dgram_free(struct unix_dgram_ctx *ctx)
{
if (ctx->send_queues != NULL) {
return EBUSY;
}
if (ctx->send_pool != NULL) {
int ret = pthreadpool_destroy(ctx->send_pool);
if (ret != 0) {
return ret;
}
ctx->ev_funcs->watch_free(ctx->pool_read_watch);
}
ctx->ev_funcs->watch_free(ctx->sock_read_watch);
close(ctx->sock);
if (getpid() == ctx->created_pid) {
/* If we created it, unlink. Otherwise someone else might
* still have it open */
unlink(ctx->path);
}
free(ctx->recv_buf);
free(ctx);
return 0;
}
/*
* Every message starts with a uint64_t cookie.
*
* A value of 0 indicates a single-fragment message which is complete in
* itself. The data immediately follows the cookie.
*
* Every multi-fragment message has a cookie != 0 and starts with a cookie
* followed by a struct unix_msg_header and then the data. The pid and sock
* fields are used to assure uniqueness on the receiver side.
*/
struct unix_msg_hdr {
size_t msglen;
pid_t pid;
int sock;
};
struct unix_msg {
struct unix_msg *prev, *next;
size_t msglen;
size_t received;
pid_t sender_pid;
int sender_sock;
uint64_t cookie;
uint8_t buf[1];
};
struct unix_msg_ctx {
struct unix_dgram_ctx *dgram;
size_t fragment_len;
uint64_t cookie;
void (*recv_callback)(struct unix_msg_ctx *ctx,
uint8_t *msg, size_t msg_len,
int *fds, size_t num_fds,
void *private_data);
void *private_data;
struct unix_msg *msgs;
};
static void unix_msg_recv(struct unix_dgram_ctx *dgram_ctx,
uint8_t *buf, size_t buflen,
int *fds, size_t num_fds,
void *private_data);
int unix_msg_init(const struct sockaddr_un *addr,
const struct poll_funcs *ev_funcs,
size_t fragment_len,
void (*recv_callback)(struct unix_msg_ctx *ctx,
uint8_t *msg, size_t msg_len,
int *fds, size_t num_fds,
void *private_data),
void *private_data,
struct unix_msg_ctx **result)
{
struct unix_msg_ctx *ctx;
int ret;
ctx = malloc(sizeof(*ctx));
if (ctx == NULL) {
return ENOMEM;
}
*ctx = (struct unix_msg_ctx) {
.fragment_len = fragment_len,
.cookie = 1,
.recv_callback = recv_callback,
.private_data = private_data
};
ret = unix_dgram_init(addr, fragment_len, ev_funcs,
unix_msg_recv, ctx, &ctx->dgram);
if (ret != 0) {
free(ctx);
return ret;
}
*result = ctx;
return 0;
}
int unix_msg_send(struct unix_msg_ctx *ctx, const struct sockaddr_un *dst,
const struct iovec *iov, int iovlen,
const int *fds, size_t num_fds)
{
ssize_t msglen;
size_t sent;
int ret = 0;
struct iovec iov_copy[iovlen+2];
struct unix_msg_hdr hdr;
struct iovec src_iov;
if (iovlen < 0) {
return EINVAL;
}
msglen = iov_buflen(iov, iovlen);
if (msglen == -1) {
return EINVAL;
}
if (num_fds > INT8_MAX) {
return EINVAL;
}
if (msglen <= (ctx->fragment_len - sizeof(uint64_t))) {
uint64_t cookie = 0;
iov_copy[0].iov_base = &cookie;
iov_copy[0].iov_len = sizeof(cookie);
if (iovlen > 0) {
memcpy(&iov_copy[1], iov,
sizeof(struct iovec) * iovlen);
}
return unix_dgram_send(ctx->dgram, dst, iov_copy, iovlen+1,
fds, num_fds);
}
hdr = (struct unix_msg_hdr) {
.msglen = msglen,
.pid = getpid(),
.sock = unix_dgram_sock(ctx->dgram)
};
iov_copy[0].iov_base = &ctx->cookie;
iov_copy[0].iov_len = sizeof(ctx->cookie);
iov_copy[1].iov_base = &hdr;
iov_copy[1].iov_len = sizeof(hdr);
sent = 0;
src_iov = iov[0];
/*
* The following write loop sends the user message in pieces. We have
* filled the first two iovecs above with "cookie" and "hdr". In the
* following loops we pull message chunks from the user iov array and
* fill iov_copy piece by piece, possibly truncating chunks from the
* caller's iov array. Ugly, but hopefully efficient.
*/
while (sent < msglen) {
size_t fragment_len;
size_t iov_index = 2;
fragment_len = sizeof(ctx->cookie) + sizeof(hdr);
while (fragment_len < ctx->fragment_len) {
size_t space, chunk;
space = ctx->fragment_len - fragment_len;
chunk = MIN(space, src_iov.iov_len);
iov_copy[iov_index].iov_base = src_iov.iov_base;
iov_copy[iov_index].iov_len = chunk;
iov_index += 1;
src_iov.iov_base = (char *)src_iov.iov_base + chunk;
src_iov.iov_len -= chunk;
fragment_len += chunk;
if (src_iov.iov_len == 0) {
iov += 1;
iovlen -= 1;
if (iovlen == 0) {
break;
}
src_iov = iov[0];
}
}
sent += (fragment_len - sizeof(ctx->cookie) - sizeof(hdr));
/*
* only the last fragment should pass the fd array.
* That simplifies the receiver a lot.
*/
if (sent < msglen) {
ret = unix_dgram_send(ctx->dgram, dst,
iov_copy, iov_index,
NULL, 0);
} else {
ret = unix_dgram_send(ctx->dgram, dst,
iov_copy, iov_index,
fds, num_fds);
}
if (ret != 0) {
break;
}
}
ctx->cookie += 1;
if (ctx->cookie == 0) {
ctx->cookie += 1;
}
return ret;
}
static void unix_msg_recv(struct unix_dgram_ctx *dgram_ctx,
uint8_t *buf, size_t buflen,
int *fds, size_t num_fds,
void *private_data)
{
struct unix_msg_ctx *ctx = (struct unix_msg_ctx *)private_data;
struct unix_msg_hdr hdr;
struct unix_msg *msg;
size_t space;
uint64_t cookie;
if (buflen < sizeof(cookie)) {
goto close_fds;
}
memcpy(&cookie, buf, sizeof(cookie));
buf += sizeof(cookie);
buflen -= sizeof(cookie);
if (cookie == 0) {
ctx->recv_callback(ctx, buf, buflen, fds, num_fds,
ctx->private_data);
return;
}
if (buflen < sizeof(hdr)) {
goto close_fds;
}
memcpy(&hdr, buf, sizeof(hdr));
buf += sizeof(hdr);
buflen -= sizeof(hdr);
for (msg = ctx->msgs; msg != NULL; msg = msg->next) {
if ((msg->sender_pid == hdr.pid) &&
(msg->sender_sock == hdr.sock)) {
break;
}
}
if ((msg != NULL) && (msg->cookie != cookie)) {
DLIST_REMOVE(ctx->msgs, msg);
free(msg);
msg = NULL;
}
if (msg == NULL) {
msg = malloc(offsetof(struct unix_msg, buf) + hdr.msglen);
if (msg == NULL) {
goto close_fds;
}
*msg = (struct unix_msg) {
.msglen = hdr.msglen,
.sender_pid = hdr.pid,
.sender_sock = hdr.sock,
.cookie = cookie
};
DLIST_ADD(ctx->msgs, msg);
}
space = msg->msglen - msg->received;
if (buflen > space) {
goto close_fds;
}
memcpy(msg->buf + msg->received, buf, buflen);
msg->received += buflen;
if (msg->received < msg->msglen) {
goto close_fds;
}
DLIST_REMOVE(ctx->msgs, msg);
ctx->recv_callback(ctx, msg->buf, msg->msglen, fds, num_fds,
ctx->private_data);
free(msg);
return;
close_fds:
close_fd_array(fds, num_fds);
}
int unix_msg_free(struct unix_msg_ctx *ctx)
{
int ret;
ret = unix_dgram_free(ctx->dgram);
if (ret != 0) {
return ret;
}
while (ctx->msgs != NULL) {
struct unix_msg *msg = ctx->msgs;
DLIST_REMOVE(ctx->msgs, msg);
free(msg);
}
free(ctx);
return 0;
}