/*-*- 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 . ***/ #include #include #include #include #include #include #include "util.h" #include "macro.h" #include "missing.h" #include "strv.h" #include "utf8.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) ++; } } bool bus_socket_auth_needs_write(sd_bus *b) { unsigned i; if (b->auth_index >= ELEMENTSOF(b->auth_iovec)) return false; for (i = b->auth_index; i < ELEMENTSOF(b->auth_iovec); i++) { struct iovec *j = b->auth_iovec + i; if (j->iov_len > 0) return true; } return false; } static int bus_socket_write_auth(sd_bus *b) { struct msghdr mh; ssize_t k; assert(b); assert(b->state == BUS_AUTHENTICATING); if (!bus_socket_auth_needs_write(b)) return 0; 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_client(sd_bus *b) { char *e, *f, *start; sd_id128_t peer; unsigned i; int r; assert(b); /* 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; b->auth = b->anonymous_auth ? BUS_AUTH_ANONYMOUS : BUS_AUTH_EXTERNAL; 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 bool line_equals(const char *s, size_t m, const char *line) { size_t l; l = strlen(line); if (l != m) return false; return memcmp(s, line, l) == 0; } static bool line_begins(const char *s, size_t m, const char *word) { size_t l; l = strlen(word); if (m < l) return false; if (memcmp(s, word, l) != 0) return false; return m == l || (m > l && s[l] == ' '); } static int verify_anonymous_token(sd_bus *b, const char *p, size_t l) { _cleanup_free_ char *token = NULL; if (!b->anonymous_auth) return 0; if (l <= 0) return 1; assert(p[0] == ' '); p++; l--; if (l % 2 != 0) return 0; token = unhexmem(p, l); if (!token) return -ENOMEM; if (memchr(token, 0, l/2)) return 0; return !!utf8_is_valid(token); } static int verify_external_token(sd_bus *b, const char *p, size_t l) { _cleanup_free_ char *token = NULL; uid_t u; int r; /* We don't do any real authentication here. Instead, we if * the owner of this bus wanted authentication he should have * checked SO_PEERCRED before even creating the bus object. */ if (!b->ucred_valid) return 0; if (l <= 0) return 1; assert(p[0] == ' '); p++; l--; if (l % 2 != 0) return 0; token = unhexmem(p, l); if (!token) return -ENOMEM; if (memchr(token, 0, l/2)) return 0; r = parse_uid(token, &u); if (r < 0) return 0; if (u != b->ucred.uid) return 0; return 1; } static int bus_socket_auth_write(sd_bus *b, const char *t) { char *p; size_t l; assert(b); assert(t); /* We only make use of the first iovec */ assert(b->auth_index == 0 || b->auth_index == 1); l = strlen(t); p = malloc(b->auth_iovec[0].iov_len + l); if (!p) return -ENOMEM; memcpy(p, b->auth_iovec[0].iov_base, b->auth_iovec[0].iov_len); memcpy(p + b->auth_iovec[0].iov_len, t, l); b->auth_iovec[0].iov_base = p; b->auth_iovec[0].iov_len += l; free(b->auth_buffer); b->auth_buffer = p; b->auth_index = 0; return 0; } static int bus_socket_auth_write_ok(sd_bus *b) { char t[3 + 32 + 2 + 1]; assert(b); snprintf(t, sizeof(t), "OK " SD_ID128_FORMAT_STR "\r\n", SD_ID128_FORMAT_VAL(b->peer)); char_array_0(t); return bus_socket_auth_write(b, t); } static int bus_socket_auth_verify_server(sd_bus *b) { char *e; const char *line; size_t l; bool processed = false; int r; assert(b); if (b->rbuffer_size < 3) return 0; /* First char must be a NUL byte */ if (*(char*) b->rbuffer != 0) return -EIO; /* Begin with the first line */ if (b->auth_rbegin <= 0) b->auth_rbegin = 1; for (;;) { /* Check if line is complete */ line = (char*) b->rbuffer + b->auth_rbegin; e = memmem(line, b->rbuffer_size - b->auth_rbegin, "\r\n", 2); if (!e) return processed; l = e - line; if (line_begins(line, l, "AUTH ANONYMOUS")) { r = verify_anonymous_token(b, line + 14, l - 14); if (r < 0) return r; if (r == 0) r = bus_socket_auth_write(b, "REJECTED\r\n"); else { b->auth = BUS_AUTH_ANONYMOUS; r = bus_socket_auth_write_ok(b); } } else if (line_begins(line, l, "AUTH EXTERNAL")) { r = verify_external_token(b, line + 13, l - 13); if (r < 0) return r; if (r == 0) r = bus_socket_auth_write(b, "REJECTED\r\n"); else { b->auth = BUS_AUTH_EXTERNAL; r = bus_socket_auth_write_ok(b); } } else if (line_begins(line, l, "AUTH")) r = bus_socket_auth_write(b, "REJECTED EXTERNAL ANONYMOUS\r\n"); else if (line_equals(line, l, "CANCEL") || line_begins(line, l, "ERROR")) { b->auth = _BUS_AUTH_INVALID; r = bus_socket_auth_write(b, "REJECTED\r\n"); } else if (line_equals(line, l, "BEGIN")) { if (b->auth == _BUS_AUTH_INVALID) r = bus_socket_auth_write(b, "ERROR\r\n"); else { /* We can't leave from the auth phase * before we haven't written * everything queued, so let's check * that */ if (bus_socket_auth_needs_write(b)) return 1; b->rbuffer_size -= (e + 2 - (char*) b->rbuffer); memmove(b->rbuffer, e + 2, b->rbuffer_size); return bus_start_running(b); } } else if (line_begins(line, l, "DATA")) { if (b->auth == _BUS_AUTH_INVALID) r = bus_socket_auth_write(b, "ERROR\r\n"); else { if (b->auth == BUS_AUTH_ANONYMOUS) r = verify_anonymous_token(b, line + 4, l - 4); else r = verify_external_token(b, line + 4, l - 4); if (r < 0) return r; if (r == 0) { b->auth = _BUS_AUTH_INVALID; r = bus_socket_auth_write(b, "REJECTED\r\n"); } else r = bus_socket_auth_write_ok(b); } } else if (line_equals(line, l, "NEGOTIATE_UNIX_FD")) { if (b->auth == _BUS_AUTH_INVALID || !b->negotiate_fds) r = bus_socket_auth_write(b, "ERROR\r\n"); else { b->can_fds = true; r = bus_socket_auth_write(b, "AGREE_UNIX_FD\r\n"); } } else r = bus_socket_auth_write(b, "ERROR\r\n"); if (r < 0) return r; b->auth_rbegin = e + 2 - (char*) b->rbuffer; processed = true; } } static int bus_socket_auth_verify(sd_bus *b) { assert(b); if (b->is_server) return bus_socket_auth_verify_server(b); else return bus_socket_auth_verify_client(b); } 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; 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(b); assert(b->state == BUS_AUTHENTICATING); r = bus_socket_auth_verify(b); if (r != 0) return r; n = MAX(256, 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; mh.msg_control = &control; mh.msg_controllen = sizeof(control); k = recvmsg(b->fd, &mh, MSG_DONTWAIT|MSG_NOSIGNAL|MSG_CMSG_CLOEXEC); if (k < 0) return errno == EAGAIN ? 0 : -errno; if (k == 0) return -ECONNRESET; b->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 j; /* Whut? We received fds during the auth * protocol? Somebody is playing games with * us. Close them all, and fail */ j = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int); close_many((int*) CMSG_DATA(cmsg), j); return -EIO; } else if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_CREDENTIALS && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) { memcpy(&b->ucred, CMSG_DATA(cmsg), sizeof(struct ucred)); b->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(&b->label, CMSG_DATA(cmsg), l); b->label[l] = 0; } } r = bus_socket_auth_verify(b); if (r != 0) return r; return 1; } static int bus_socket_setup(sd_bus *b) { int enable; assert(b); /* Enable SO_PASSCRED + SO_PASSEC. We try this on any * socket, just in case. */ enable = !b->bus_client; setsockopt(b->fd, SOL_SOCKET, SO_PASSCRED, &enable, sizeof(enable)); setsockopt(b->fd, SOL_SOCKET, SO_PASSSEC, &enable, sizeof(enable)); /* 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_client(sd_bus *b) { size_t l; const char *auth_suffix, *auth_prefix; assert(b); if (b->anonymous_auth) { auth_prefix = "\0AUTH ANONYMOUS "; /* For ANONYMOUS auth we send some arbitrary "trace" string */ l = 9; b->auth_buffer = hexmem("anonymous", l); } else { char text[20 + 1]; /* enough space for a 64bit integer plus NUL */ auth_prefix = "\0AUTH EXTERNAL "; snprintf(text, sizeof(text), "%lu", (unsigned long) geteuid()); char_array_0(text); l = strlen(text); b->auth_buffer = hexmem(text, l); } if (!b->auth_buffer) return -ENOMEM; if (b->negotiate_fds) auth_suffix = "\r\nNEGOTIATE_UNIX_FD\r\nBEGIN\r\n"; else auth_suffix = "\r\nBEGIN\r\n"; b->auth_iovec[0].iov_base = (void*) auth_prefix; b->auth_iovec[0].iov_len = 1 + strlen(auth_prefix + 1); b->auth_iovec[1].iov_base = (void*) b->auth_buffer; 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); return bus_socket_write_auth(b); } static int bus_socket_start_auth(sd_bus *b) { int domain = 0, r; socklen_t sl; assert(b); b->state = BUS_AUTHENTICATING; b->auth_timeout = now(CLOCK_MONOTONIC) + BUS_DEFAULT_TIMEOUT; 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; if (b->is_server) return bus_socket_read_auth(b); else return bus_socket_start_auth_client(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); if (!bus->can_fds) { /* Whut? We received fds but this * isn't actually enabled? Close them, * and fail */ close_many((int*) CMSG_DATA(cmsg), n); return -EIO; } 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); }