diff options
Diffstat (limited to 'src/libsystemd-bus/bus-socket.c')
| -rw-r--r-- | src/libsystemd-bus/bus-socket.c | 628 |
1 files changed, 628 insertions, 0 deletions
diff --git a/src/libsystemd-bus/bus-socket.c b/src/libsystemd-bus/bus-socket.c new file mode 100644 index 0000000000..f40aa59f51 --- /dev/null +++ b/src/libsystemd-bus/bus-socket.c @@ -0,0 +1,628 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2013 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 <endian.h> +#include <assert.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/poll.h> +#include <byteswap.h> + +#include "util.h" +#include "macro.h" +#include "missing.h" +#include "strv.h" + +#include "sd-bus.h" +#include "bus-socket.h" +#include "bus-internal.h" +#include "bus-message.h" + +static void iovec_advance(struct iovec *iov, unsigned *idx, size_t size) { + + while (size > 0) { + struct iovec *i = iov + *idx; + + if (i->iov_len > size) { + i->iov_base = (uint8_t*) i->iov_base + size; + i->iov_len -= size; + return; + } + + size -= i->iov_len; + + i->iov_base = NULL; + i->iov_len = 0; + + (*idx) ++; + } +} + +static int bus_socket_write_auth(sd_bus *b) { + struct msghdr mh; + ssize_t k; + + assert(b); + assert(b->state == BUS_AUTHENTICATING); + + if (b->auth_index >= ELEMENTSOF(b->auth_iovec)) + return 0; + + if (b->auth_timeout == 0) + b->auth_timeout = now(CLOCK_MONOTONIC) + BUS_DEFAULT_TIMEOUT; + + zero(mh); + mh.msg_iov = b->auth_iovec + b->auth_index; + mh.msg_iovlen = ELEMENTSOF(b->auth_iovec) - b->auth_index; + + k = sendmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL); + if (k < 0) + return errno == EAGAIN ? 0 : -errno; + + iovec_advance(b->auth_iovec, &b->auth_index, (size_t) k); + + return 1; +} + +static int bus_socket_auth_verify(sd_bus *b) { + char *e, *f, *start; + sd_id128_t peer; + unsigned i; + int r; + + /* We expect two response lines: "OK" and possibly + * "AGREE_UNIX_FD" */ + + e = memmem(b->rbuffer, b->rbuffer_size, "\r\n", 2); + if (!e) + return 0; + + if (b->negotiate_fds) { + f = memmem(e + 2, b->rbuffer_size - (e - (char*) b->rbuffer) - 2, "\r\n", 2); + if (!f) + return 0; + + start = f + 2; + } else { + f = NULL; + start = e + 2; + } + + /* Nice! We got all the lines we need. First check the OK + * line */ + + if (e - (char*) b->rbuffer != 3 + 32) + return -EPERM; + + if (memcmp(b->rbuffer, "OK ", 3)) + return -EPERM; + + for (i = 0; i < 32; i += 2) { + int x, y; + + x = unhexchar(((char*) b->rbuffer)[3 + i]); + y = unhexchar(((char*) b->rbuffer)[3 + i + 1]); + + if (x < 0 || y < 0) + return -EINVAL; + + peer.bytes[i/2] = ((uint8_t) x << 4 | (uint8_t) y); + } + + if (!sd_id128_equal(b->peer, SD_ID128_NULL) && + !sd_id128_equal(b->peer, peer)) + return -EPERM; + + b->peer = peer; + + /* And possibly check the second line, too */ + + if (f) + b->can_fds = + (f - e == sizeof("\r\nAGREE_UNIX_FD") - 1) && + memcmp(e + 2, "AGREE_UNIX_FD", sizeof("AGREE_UNIX_FD") - 1) == 0; + + b->rbuffer_size -= (start - (char*) b->rbuffer); + memmove(b->rbuffer, start, b->rbuffer_size); + + r = bus_start_running(b); + if (r < 0) + return r; + + return 1; +} + +static int bus_socket_read_auth(sd_bus *b) { + struct msghdr mh; + struct iovec iov; + size_t n; + ssize_t k; + int r; + void *p; + + assert(b); + + r = bus_socket_auth_verify(b); + if (r != 0) + return r; + + n = MAX(3 + 32 + 2 + sizeof("AGREE_UNIX_FD") - 1 + 2, b->rbuffer_size * 2); + + if (n > BUS_AUTH_SIZE_MAX) + n = BUS_AUTH_SIZE_MAX; + + if (b->rbuffer_size >= n) + return -ENOBUFS; + + p = realloc(b->rbuffer, n); + if (!p) + return -ENOMEM; + + b->rbuffer = p; + + zero(iov); + iov.iov_base = (uint8_t*) b->rbuffer + b->rbuffer_size; + iov.iov_len = n - b->rbuffer_size; + + zero(mh); + mh.msg_iov = &iov; + mh.msg_iovlen = 1; + + k = recvmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL); + if (k < 0) + return errno == EAGAIN ? 0 : -errno; + if (k == 0) + return -ECONNRESET; + + b->rbuffer_size += k; + + r = bus_socket_auth_verify(b); + if (r != 0) + return r; + + return 1; +} + +static int bus_socket_setup(sd_bus *b) { + int one; + + assert(b); + + /* Enable SO_PASSCRED + SO_PASSEC. We try this on any socket, + * just in case. This is actually irrelavant for */ + one = 1; + setsockopt(b->fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)); + setsockopt(b->fd, SOL_SOCKET, SO_PASSSEC, &one, sizeof(one)); + + /* Increase the buffers to a MB */ + fd_inc_rcvbuf(b->fd, 1024*1024); + fd_inc_sndbuf(b->fd, 1024*1024); + + return 0; +} + +static int bus_socket_start_auth(sd_bus *b) { + static const char auth_prefix[] = "\0AUTH EXTERNAL "; + static const char auth_suffix_with_unix_fd[] = "\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n"; + static const char auth_suffix_without_unix_fd[] = "\r\nBEGIN\r\n"; + + char text[20 + 1]; /* enough space for a 64bit integer plus NUL */ + size_t l; + const char *auth_suffix; + int domain = 0, r; + socklen_t sl; + + assert(b); + + b->state = BUS_AUTHENTICATING; + + sl = sizeof(domain); + r = getsockopt(b->fd, SOL_SOCKET, SO_DOMAIN, &domain, &sl); + if (r < 0) + return -errno; + + if (domain != AF_UNIX) + b->negotiate_fds = false; + + snprintf(text, sizeof(text), "%llu", (unsigned long long) geteuid()); + char_array_0(text); + + l = strlen(text); + b->auth_uid = hexmem(text, l); + if (!b->auth_uid) + return -ENOMEM; + + auth_suffix = b->negotiate_fds ? auth_suffix_with_unix_fd : auth_suffix_without_unix_fd; + + b->auth_iovec[0].iov_base = (void*) auth_prefix; + b->auth_iovec[0].iov_len = sizeof(auth_prefix) -1; + b->auth_iovec[1].iov_base = (void*) b->auth_uid; + b->auth_iovec[1].iov_len = l * 2; + b->auth_iovec[2].iov_base = (void*) auth_suffix; + b->auth_iovec[2].iov_len = strlen(auth_suffix); + b->auth_size = sizeof(auth_prefix) - 1 + l * 2 + sizeof(auth_suffix) - 1; + + return bus_socket_write_auth(b); +} + +int bus_socket_connect(sd_bus *b) { + int r; + + assert(b); + assert(b->fd < 0); + assert(b->sockaddr.sa.sa_family != AF_UNSPEC); + + b->fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + if (b->fd < 0) + return -errno; + + r = bus_socket_setup(b); + if (r < 0) + return r; + + r = connect(b->fd, &b->sockaddr.sa, b->sockaddr_size); + if (r < 0) { + if (errno == EINPROGRESS) + return 1; + + return -errno; + } + + return bus_socket_start_auth(b); +} + +int bus_socket_exec(sd_bus *b) { + int s[2]; + pid_t pid; + + assert(b); + assert(b->fd < 0); + assert(b->exec_path); + + b->fd = socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, s); + if (b->fd < 0) + return -errno; + + pid = fork(); + if (pid < 0) { + close_pipe(s); + return -errno; + } + if (pid == 0) { + /* Child */ + + close_all_fds(s, 2); + close_nointr_nofail(s[0]); + + assert_se(dup3(s[1], STDIN_FILENO, 0) == STDIN_FILENO); + assert_se(dup3(s[1], STDOUT_FILENO, 0) == STDOUT_FILENO); + + if (s[1] != STDIN_FILENO && s[1] != STDOUT_FILENO) + close_nointr_nofail(s[1]); + + fd_cloexec(STDIN_FILENO, false); + fd_cloexec(STDOUT_FILENO, false); + fd_nonblock(STDIN_FILENO, false); + fd_nonblock(STDOUT_FILENO, false); + + if (b->exec_argv) + execvp(b->exec_path, b->exec_argv); + else { + const char *argv[] = { b->exec_path, NULL }; + execvp(b->exec_path, (char**) argv); + } + + _exit(EXIT_FAILURE); + } + + close_nointr_nofail(s[1]); + b->fd = s[0]; + + return bus_socket_start_auth(b); +} + +int bus_socket_take_fd(sd_bus *b) { + int r; + assert(b); + + r = bus_socket_setup(b); + if (r < 0) + return r; + + return bus_socket_start_auth(b); +} + +int bus_socket_write_message(sd_bus *bus, sd_bus_message *m, size_t *idx) { + struct msghdr mh; + struct iovec *iov; + ssize_t k; + size_t n; + unsigned j; + + assert(bus); + assert(m); + assert(idx); + assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO); + + if (*idx >= m->size) + return 0; + zero(mh); + + if (m->n_fds > 0) { + struct cmsghdr *control; + control = alloca(CMSG_SPACE(sizeof(int) * m->n_fds)); + + mh.msg_control = control; + control->cmsg_level = SOL_SOCKET; + control->cmsg_type = SCM_RIGHTS; + mh.msg_controllen = control->cmsg_len = CMSG_LEN(sizeof(int) * m->n_fds); + memcpy(CMSG_DATA(control), m->fds, sizeof(int) * m->n_fds); + } + + n = m->n_iovec * sizeof(struct iovec); + iov = alloca(n); + memcpy(iov, m->iovec, n); + + j = 0; + iovec_advance(iov, &j, *idx); + + mh.msg_iov = iov; + mh.msg_iovlen = m->n_iovec; + + k = sendmsg(bus->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL); + if (k < 0) + return errno == EAGAIN ? 0 : -errno; + + *idx += (size_t) k; + return 1; +} + +static int bus_socket_read_message_need(sd_bus *bus, size_t *need) { + uint32_t a, b; + uint8_t e; + uint64_t sum; + + assert(bus); + assert(need); + assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO); + + if (bus->rbuffer_size < sizeof(struct bus_header)) { + *need = sizeof(struct bus_header) + 8; + + /* Minimum message size: + * + * Header + + * + * Method Call: +2 string headers + * Signal: +3 string headers + * Method Error: +1 string headers + * +1 uint32 headers + * Method Reply: +1 uint32 headers + * + * A string header is at least 9 bytes + * A uint32 header is at least 8 bytes + * + * Hence the minimum message size of a valid message + * is header + 8 bytes */ + + return 0; + } + + a = ((const uint32_t*) bus->rbuffer)[1]; + b = ((const uint32_t*) bus->rbuffer)[3]; + + e = ((const uint8_t*) bus->rbuffer)[0]; + if (e == SD_BUS_LITTLE_ENDIAN) { + a = le32toh(a); + b = le32toh(b); + } else if (e == SD_BUS_BIG_ENDIAN) { + a = be32toh(a); + b = be32toh(b); + } else + return -EBADMSG; + + sum = (uint64_t) sizeof(struct bus_header) + (uint64_t) ALIGN_TO(b, 8) + (uint64_t) a; + if (sum >= BUS_MESSAGE_SIZE_MAX) + return -ENOBUFS; + + *need = (size_t) sum; + return 0; +} + +static int bus_socket_make_message(sd_bus *bus, size_t size, sd_bus_message **m) { + sd_bus_message *t; + void *b; + int r; + + assert(bus); + assert(m); + assert(bus->rbuffer_size >= size); + assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO); + + if (bus->rbuffer_size > size) { + b = memdup((const uint8_t*) bus->rbuffer + size, + bus->rbuffer_size - size); + if (!b) + return -ENOMEM; + } else + b = NULL; + + r = bus_message_from_malloc(bus->rbuffer, size, + bus->fds, bus->n_fds, + bus->ucred_valid ? &bus->ucred : NULL, + bus->label[0] ? bus->label : NULL, + &t); + if (r < 0) { + free(b); + return r; + } + + bus->rbuffer = b; + bus->rbuffer_size -= size; + + bus->fds = NULL; + bus->n_fds = 0; + + *m = t; + return 1; +} + +int bus_socket_read_message(sd_bus *bus, sd_bus_message **m) { + struct msghdr mh; + struct iovec iov; + ssize_t k; + size_t need; + int r; + void *b; + union { + struct cmsghdr cmsghdr; + uint8_t buf[CMSG_SPACE(sizeof(int) * BUS_FDS_MAX) + + CMSG_SPACE(sizeof(struct ucred)) + + CMSG_SPACE(NAME_MAX)]; /*selinux label */ + } control; + struct cmsghdr *cmsg; + + assert(bus); + assert(m); + assert(bus->state == BUS_RUNNING || bus->state == BUS_HELLO); + + r = bus_socket_read_message_need(bus, &need); + if (r < 0) + return r; + + if (bus->rbuffer_size >= need) + return bus_socket_make_message(bus, need, m); + + b = realloc(bus->rbuffer, need); + if (!b) + return -ENOMEM; + + bus->rbuffer = b; + + zero(iov); + iov.iov_base = (uint8_t*) bus->rbuffer + bus->rbuffer_size; + iov.iov_len = need - bus->rbuffer_size; + + zero(mh); + mh.msg_iov = &iov; + mh.msg_iovlen = 1; + mh.msg_control = &control; + mh.msg_controllen = sizeof(control); + + k = recvmsg(bus->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC); + if (k < 0) + return errno == EAGAIN ? 0 : -errno; + if (k == 0) + return -ECONNRESET; + + bus->rbuffer_size += k; + + for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) { + if (cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_RIGHTS) { + int n, *f; + + n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int); + + f = realloc(bus->fds, sizeof(int) + (bus->n_fds + n)); + if (!f) { + close_many((int*) CMSG_DATA(cmsg), n); + return -ENOMEM; + } + + memcpy(f + bus->n_fds, CMSG_DATA(cmsg), n * sizeof(int)); + bus->fds = f; + bus->n_fds += n; + } else if (cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_CREDENTIALS && + cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) { + + memcpy(&bus->ucred, CMSG_DATA(cmsg), sizeof(struct ucred)); + bus->ucred_valid = true; + + } else if (cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_SECURITY) { + + size_t l; + l = cmsg->cmsg_len - CMSG_LEN(0); + memcpy(&bus->label, CMSG_DATA(cmsg), l); + bus->label[l] = 0; + } + } + + r = bus_socket_read_message_need(bus, &need); + if (r < 0) + return r; + + if (bus->rbuffer_size >= need) + return bus_socket_make_message(bus, need, m); + + return 1; +} + +int bus_socket_process_opening(sd_bus *b) { + int error = 0; + socklen_t slen = sizeof(error); + struct pollfd p; + int r; + + assert(b); + assert(b->state == BUS_OPENING); + + zero(p); + p.fd = b->fd; + p.events = POLLOUT; + + r = poll(&p, 1, 0); + if (r < 0) + return -errno; + + if (!(p.revents & (POLLOUT|POLLERR|POLLHUP))) + return 0; + + r = getsockopt(b->fd, SOL_SOCKET, SO_ERROR, &error, &slen); + if (r < 0) + b->last_connect_error = errno; + else if (error != 0) + b->last_connect_error = error; + else if (p.revents & (POLLERR|POLLHUP)) + b->last_connect_error = ECONNREFUSED; + else + return bus_socket_start_auth(b); + + return bus_next_address(b); +} + +int bus_socket_process_authenticating(sd_bus *b) { + int r; + + assert(b); + assert(b->state == BUS_AUTHENTICATING); + + if (now(CLOCK_MONOTONIC) >= b->auth_timeout) + return -ETIMEDOUT; + + r = bus_socket_write_auth(b); + if (r != 0) + return r; + + return bus_socket_read_auth(b); +} |