bus: split socket related code into bus-socket.[ch], to prepare for kdbus backend

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);
+}