bus: basic implementation of kdbus client side

1 files changed, 388 insertions, 0 deletions

diff --git a/src/libsystemd-bus/bus-kernel.c b/src/libsystemd-bus/bus-kernel.c
new file mode 100644
index 0000000000..c10fcc54df
--- /dev/null
+++ b/src/libsystemd-bus/bus-kernel.c
@@ -0,0 +1,388 @@
+/*-*- 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 <fcntl.h>
+
+#include "util.h"
+
+#include "bus-internal.h"
+#include "bus-message.h"
+#include "bus-kernel.h"
+
+#define KDBUS_MSG_FOREACH_DATA(d, k)                                    \
+        for ((d) = (k)->data;                                           \
+             (uint8_t*) (d) < (uint8_t*) (k) + (k)->size;               \
+             (d) = (struct kdbus_msg_data*) ((uint8_t*) (d) + ALIGN8((d)->size)))
+
+
+
+static int parse_unique_name(const char *s, uint64_t *id) {
+        int r;
+
+        assert(s);
+        assert(id);
+
+        if (!startswith(s, ":1."))
+                return 0;
+
+        r = safe_atou64(s + 3, id);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static void append_payload_vec(struct kdbus_msg_data **d, const void *p, size_t sz) {
+        assert(d);
+        assert(p);
+        assert(sz > 0);
+
+        (*d)->size = offsetof(struct kdbus_msg_data, vec) + sizeof(struct kdbus_vec);
+        (*d)->type = KDBUS_MSG_PAYLOAD_VEC;
+        (*d)->vec.address = (uint64_t) p;
+        (*d)->vec.size = sz;
+
+        *d = (struct kdbus_msg_data*) ((uint8_t*) *d + ALIGN8((*d)->size));
+}
+
+static void append_destination(struct kdbus_msg_data **d, const char *s, size_t length) {
+        assert(d);
+        assert(d);
+
+        (*d)->size = offsetof(struct kdbus_msg_data, data) + length + 1;
+        (*d)->type = KDBUS_MSG_DST_NAME;
+        memcpy((*d)->data, s, length + 1);
+
+        *d = (struct kdbus_msg_data*) ((uint8_t*) *d + ALIGN8((*d)->size));
+}
+
+static int bus_message_setup_kmsg(sd_bus_message *m) {
+        struct kdbus_msg_data *d;
+        bool well_known;
+        uint64_t unique;
+        size_t sz, dl;
+        int r;
+
+        assert(m);
+        assert(m->sealed);
+        assert(!m->kdbus);
+
+        if (m->destination) {
+                r = parse_unique_name(m->destination, &unique);
+                if (r < 0)
+                        return r;
+
+                well_known = r == 0;
+        } else
+                well_known = false;
+
+        sz = offsetof(struct kdbus_msg, data);
+
+        /* Add in fixed header, fields header, fields header padding and payload */
+        sz += 4 * ALIGN8(offsetof(struct kdbus_msg_data, vec) + sizeof(struct kdbus_vec));
+
+        /* Add in well-known destination header */
+        if (well_known) {
+                dl = strlen(m->destination);
+                sz += ALIGN8(offsetof(struct kdbus_msg, data) + dl + 1);
+        }
+
+        m->kdbus = malloc0(sz);
+        if (!m->kdbus)
+                return -ENOMEM;
+
+        m->kdbus->flags =
+                ((m->header->flags & SD_BUS_MESSAGE_NO_REPLY_EXPECTED) ? 0 : KDBUS_MSG_FLAGS_EXPECT_REPLY) |
+                ((m->header->flags & SD_BUS_MESSAGE_NO_AUTO_START) ? KDBUS_MSG_FLAGS_NO_AUTO_START : 0);
+        m->kdbus->dst_id =
+                well_known ? 0 :
+                m->destination ? unique : (uint64_t) -1;
+        m->kdbus->payload_type = KDBUS_PAYLOAD_DBUS1;
+        m->kdbus->cookie = m->header->serial;
+
+        m->kdbus->timeout_ns = m->timeout * NSEC_PER_USEC;
+
+        d = m->kdbus->data;
+
+        if (well_known)
+                append_destination(&d, m->destination, dl);
+
+        append_payload_vec(&d, m->header, sizeof(*m->header));
+
+        if (m->fields) {
+                append_payload_vec(&d, m->fields, m->header->fields_size);
+
+                if (m->header->fields_size % 8 != 0) {
+                        static const uint8_t padding[7] = {};
+
+                        append_payload_vec(&d, padding, 8 - (m->header->fields_size % 8));
+                }
+        }
+
+        if (m->body)
+                append_payload_vec(&d, m->body, m->header->body_size);
+
+        m->kdbus->size = (uint8_t*) m - (uint8_t*) m->kdbus;
+        assert(m->kdbus->size <= sz);
+
+        return 0;
+}
+
+int bus_kernel_take_fd(sd_bus *b) {
+        struct kdbus_cmd_hello hello = {};
+        int r;
+
+        assert(b);
+
+        r = ioctl(b->input_fd, KDBUS_CMD_HELLO, &hello);
+        if (r < 0)
+                return -errno;
+
+        b->is_kernel = true;
+
+        r = bus_start_running(b);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+int bus_kernel_connect(sd_bus *b) {
+        assert(b);
+        assert(b->input_fd < 0);
+        assert(b->output_fd < 0);
+        assert(b->kernel);
+
+        b->input_fd = open(b->kernel, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (b->input_fd)
+                return -errno;
+
+        b->output_fd = b->input_fd;
+
+        return bus_kernel_take_fd(b);
+}
+
+int bus_kernel_write_message(sd_bus *bus, sd_bus_message *m) {
+        int r;
+
+        assert(bus);
+        assert(m);
+        assert(bus->state == BUS_RUNNING);
+
+        r = bus_message_setup_kmsg(m);
+        if (r < 0)
+                return r;
+
+        r = ioctl(bus->output_fd, KDBUS_CMD_MSG_SEND, m->kdbus);
+        if (r < 0)
+                return errno == EAGAIN ? 0 : -errno;
+
+        return 0;
+}
+
+static void close_kdbus_msg(struct kdbus_msg *k) {
+        struct kdbus_msg_data *d;
+
+        KDBUS_MSG_FOREACH_DATA(d, k) {
+
+                if (d->type != KDBUS_MSG_UNIX_FDS)
+                        continue;
+
+                close_many(d->fds, (d->size - offsetof(struct kdbus_msg_data, fds)) / sizeof(int));
+        }
+}
+
+static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k, sd_bus_message **ret) {
+        sd_bus_message *m = NULL;
+        struct kdbus_msg_data *d;
+        unsigned n_payload = 0, n_fds = 0;
+        _cleanup_free_ int *fds = NULL;
+        struct bus_header *h = NULL;
+        size_t total, n_bytes = 0, idx = 0;
+        int r;
+
+        assert(bus);
+        assert(k);
+        assert(ret);
+
+        if (k->payload_type != KDBUS_PAYLOAD_DBUS1)
+                return 0;
+
+        KDBUS_MSG_FOREACH_DATA(d, k) {
+                size_t l;
+
+                l = d->size - offsetof(struct kdbus_msg_data, data);
+
+                if (d->type == KDBUS_MSG_PAYLOAD) {
+
+                        if (!h) {
+                                if (l < sizeof(struct bus_header))
+                                        return -EBADMSG;
+
+                                h = (struct bus_header*) d->data;
+                        }
+
+                        n_payload++;
+                        n_bytes += l;
+
+                } else if (d->type == KDBUS_MSG_UNIX_FDS) {
+                        int *f;
+                        unsigned j;
+
+                        j = l / sizeof(int);
+                        f = realloc(fds, sizeof(int) * (n_fds + j));
+                        if (!f)
+                                return -ENOMEM;
+
+                        fds = f;
+                        memcpy(fds + n_fds, d->fds, j);
+                        n_fds += j;
+                }
+        }
+
+        if (!h)
+                return -EBADMSG;
+
+        r = bus_header_size(h, &total);
+        if (r < 0)
+                return r;
+
+        if (n_bytes != total)
+                return -EBADMSG;
+
+        r = bus_message_from_header(h, sizeof(struct bus_header), fds, n_fds, NULL, NULL, 0, &m);
+        if (r < 0)
+                return r;
+
+        KDBUS_MSG_FOREACH_DATA(d, k) {
+                size_t l;
+
+                if (d->type != KDBUS_MSG_PAYLOAD)
+                        continue;
+
+                l = d->size - offsetof(struct kdbus_msg_data, data);
+
+                if (idx == sizeof(struct bus_header) &&
+                    l == BUS_MESSAGE_FIELDS_SIZE(m))
+                        m->fields = d->data;
+                else if (idx == sizeof(struct bus_header) + ALIGN8(BUS_MESSAGE_FIELDS_SIZE(m)) &&
+                         l == BUS_MESSAGE_BODY_SIZE(m))
+                        m->body = d->data;
+                else {
+                        sd_bus_message_unref(m);
+                        return -EBADMSG;
+                }
+
+                idx += l;
+        }
+
+        r = bus_message_parse_fields(m);
+        if (r < 0) {
+                sd_bus_message_unref(m);
+                return r;
+        }
+
+        /* We take possession of the kmsg struct now */
+        m->kdbus = k;
+        m->free_kdbus = true;
+        m->free_fds = true;
+
+        fds = NULL;
+
+        *ret = m;
+        return 1;
+}
+
+int bus_kernel_read_message(sd_bus *bus, sd_bus_message **m) {
+        struct kdbus_msg *k;
+        size_t sz = 128;
+        int r;
+
+        assert(bus);
+        assert(m);
+
+        for (;;) {
+                void *q;
+
+                q = realloc(bus->rbuffer, sz);
+                if (!q)
+                        return -errno;
+
+                k = bus->rbuffer = q;
+                k->size = sz;
+
+                r = ioctl(bus->input_fd, KDBUS_CMD_MSG_RECV, bus->rbuffer);
+                if (r >= 0)
+                        break;
+
+                if (errno == EAGAIN)
+                        return 0;
+
+                if (errno != -EMSGSIZE)
+                        return -errno;
+
+                sz *= 2;
+        }
+
+        r = bus_kernel_make_message(bus, k, m);
+        if (r > 0)
+                bus->rbuffer = NULL;
+        else
+                close_kdbus_msg(k);
+
+        return r;
+}
+
+int bus_kernel_create(const char *name, char **s) {
+        struct kdbus_cmd_fname *fname;
+        size_t l;
+        int fd;
+        char *p;
+
+        assert(name);
+        assert(s);
+
+        fd = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        l = strlen(name);
+        fname = alloca(offsetof(struct kdbus_cmd_fname, name) + DECIMAL_STR_MAX(uid_t) + 1 + l + 1);
+        sprintf(fname->name, "%lu-%s", (unsigned long) getuid(), name);
+        fname->size = offsetof(struct kdbus_cmd_fname, name) + strlen(fname->name) + 1;
+        fname->kernel_flags = KDBUS_CMD_FNAME_ACCESS_WORLD;
+        fname->user_flags = 0;
+
+        p = strjoin("/dev/kdbus/", fname->name, "/bus", NULL);
+        if (!p)
+                return -ENOMEM;
+
+        if (ioctl(fd, KDBUS_CMD_BUS_MAKE, &fname) < 0) {
+                close_nointr_nofail(fd);
+                free(p);
+                return -errno;
+        }
+
+        if (s)
+                *s = p;
+
+        return fd;
+}