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Systemd/src/libsystemd-bus/bus-kernel.c

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/*-*- 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/>.
***/
#ifdef HAVE_VALGRIND_MEMCHECK_H
#include <valgrind/memcheck.h>
#endif
#include <fcntl.h>
#include <malloc.h>
#include <sys/mman.h>
#include "util.h"
#include "bus-internal.h"
#include "bus-message.h"
#include "bus-kernel.h"
#include "bus-bloom.h"
int bus_kernel_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_item **d, const void *p, size_t sz) {
assert(d);
assert(sz > 0);
*d = ALIGN8_PTR(*d);
/* Note that p can be NULL, which encodes a region full of
* zeroes, which is useful to optimize certain padding
* conditions */
(*d)->size = offsetof(struct kdbus_item, vec) + sizeof(struct kdbus_vec);
(*d)->type = KDBUS_MSG_PAYLOAD_VEC;
(*d)->vec.address = PTR_TO_UINT64(p);
(*d)->vec.size = sz;
*d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
}
static void append_payload_memfd(struct kdbus_item **d, int memfd, size_t sz) {
assert(d);
assert(memfd >= 0);
assert(sz > 0);
*d = ALIGN8_PTR(*d);
(*d)->size = offsetof(struct kdbus_item, memfd) + sizeof(struct kdbus_memfd);
(*d)->type = KDBUS_MSG_PAYLOAD_MEMFD;
(*d)->memfd.fd = memfd;
(*d)->memfd.size = sz;
*d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
}
static void append_destination(struct kdbus_item **d, const char *s, size_t length) {
assert(d);
assert(s);
*d = ALIGN8_PTR(*d);
(*d)->size = offsetof(struct kdbus_item, str) + length + 1;
(*d)->type = KDBUS_MSG_DST_NAME;
memcpy((*d)->str, s, length + 1);
*d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
}
static void* append_bloom(struct kdbus_item **d, size_t length) {
void *r;
assert(d);
*d = ALIGN8_PTR(*d);
(*d)->size = offsetof(struct kdbus_item, data) + length;
(*d)->type = KDBUS_MSG_BLOOM;
r = (*d)->data;
*d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
return r;
}
static void append_fds(struct kdbus_item **d, const int fds[], unsigned n_fds) {
assert(d);
assert(fds);
assert(n_fds > 0);
*d = ALIGN8_PTR(*d);
(*d)->size = offsetof(struct kdbus_item, fds) + sizeof(int) * n_fds;
(*d)->type = KDBUS_MSG_FDS;
memcpy((*d)->fds, fds, sizeof(int) * n_fds);
*d = (struct kdbus_item *) ((uint8_t*) *d + (*d)->size);
}
static int bus_message_setup_bloom(sd_bus_message *m, void *bloom) {
unsigned i;
int r;
assert(m);
assert(bloom);
memset(bloom, 0, BLOOM_SIZE);
bloom_add_pair(bloom, "message-type", bus_message_type_to_string(m->header->type));
if (m->interface)
bloom_add_pair(bloom, "interface", m->interface);
if (m->member)
bloom_add_pair(bloom, "member", m->member);
if (m->path) {
bloom_add_pair(bloom, "path", m->path);
bloom_add_prefixes(bloom, "path-slash-prefix", m->path, '/');
}
r = sd_bus_message_rewind(m, true);
if (r < 0)
return r;
for (i = 0; i < 64; i++) {
char type;
const char *t;
char buf[sizeof("arg")-1 + 2 + sizeof("-slash-prefix")];
char *e;
r = sd_bus_message_peek_type(m, &type, NULL);
if (r < 0)
return r;
if (type != SD_BUS_TYPE_STRING &&
type != SD_BUS_TYPE_OBJECT_PATH &&
type != SD_BUS_TYPE_SIGNATURE)
break;
r = sd_bus_message_read_basic(m, type, &t);
if (r < 0)
return r;
e = stpcpy(buf, "arg");
if (i < 10)
*(e++) = '0' + i;
else {
*(e++) = '0' + (i / 10);
*(e++) = '0' + (i % 10);
}
*e = 0;
bloom_add_pair(bloom, buf, t);
strcpy(e, "-dot-prefix");
bloom_add_prefixes(bloom, buf, t, '.');
strcpy(e, "-slash-prefix");
bloom_add_prefixes(bloom, buf, t, '/');
}
return 0;
}
static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
struct bus_body_part *part;
struct kdbus_item *d;
bool well_known;
uint64_t unique;
size_t sz, dl;
unsigned i;
int r;
assert(b);
assert(m);
assert(m->sealed);
if (m->kdbus)
return 0;
if (m->destination) {
r = bus_kernel_parse_unique_name(m->destination, &unique);
if (r < 0)
return r;
well_known = r == 0;
} else
well_known = false;
sz = offsetof(struct kdbus_msg, items);
assert_cc(ALIGN8(offsetof(struct kdbus_item, vec) + sizeof(struct kdbus_vec)) ==
ALIGN8(offsetof(struct kdbus_item, memfd) + sizeof(struct kdbus_memfd)));
/* Add in fixed header, fields header and payload */
sz += (1 + m->n_body_parts) *
ALIGN8(offsetof(struct kdbus_item, vec) + sizeof(struct kdbus_vec));
/* Add space for bloom filter */
sz += ALIGN8(offsetof(struct kdbus_item, data) + BLOOM_SIZE);
/* Add in well-known destination header */
if (well_known) {
dl = strlen(m->destination);
sz += ALIGN8(offsetof(struct kdbus_item, str) + dl + 1);
}
/* Add space for unix fds */
if (m->n_fds > 0)
sz += ALIGN8(offsetof(struct kdbus_item, fds) + sizeof(int)*m->n_fds);
m->kdbus = memalign(8, sz);
if (!m->kdbus) {
r = -ENOMEM;
goto fail;
}
m->free_kdbus = true;
memset(m->kdbus, 0, sz);
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 : KDBUS_DST_ID_BROADCAST;
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->items;
if (well_known)
append_destination(&d, m->destination, dl);
append_payload_vec(&d, m->header, BUS_MESSAGE_BODY_BEGIN(m));
MESSAGE_FOREACH_PART(part, i, m) {
if (part->is_zero) {
/* If this is padding then simply send a
* vector with a NULL data pointer which the
* kernel will just pass through. This is the
* most efficient way to encode zeroes */
append_payload_vec(&d, NULL, part->size);
continue;
}
if (part->memfd >= 0 && part->sealed && m->destination) {
/* Try to send a memfd, if the part is
* sealed and this is not a broadcast. Since we can only */
append_payload_memfd(&d, part->memfd, part->size);
continue;
}
/* Otherwise let's send a vector to the actual data,
* for that we need to map it first. */
r = bus_body_part_map(part);
if (r < 0)
goto fail;
append_payload_vec(&d, part->data, part->size);
}
if (m->kdbus->dst_id == KDBUS_DST_ID_BROADCAST) {
void *p;
p = append_bloom(&d, BLOOM_SIZE);
r = bus_message_setup_bloom(m, p);
if (r < 0)
goto fail;
}
if (m->n_fds > 0)
append_fds(&d, m->fds, m->n_fds);
m->kdbus->size = (uint8_t*) d - (uint8_t*) m->kdbus;
assert(m->kdbus->size <= sz);
return 0;
fail:
m->poisoned = true;
return r;
}
int bus_kernel_take_fd(sd_bus *b) {
uint8_t h[ALIGN8(sizeof(struct kdbus_cmd_hello)) +
ALIGN8(KDBUS_ITEM_HEADER_SIZE) +
ALIGN8(sizeof(struct kdbus_vec))] = {};
struct kdbus_cmd_hello *hello = (struct kdbus_cmd_hello*) h;
int r;
assert(b);
if (b->is_server)
return -EINVAL;
if (!b->kdbus_buffer) {
b->kdbus_buffer = mmap(NULL, KDBUS_POOL_SIZE, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
if (b->kdbus_buffer == MAP_FAILED) {
b->kdbus_buffer = NULL;
return -errno;
}
}
hello->size = sizeof(h);
hello->conn_flags = b->hello_flags;
hello->items[0].type = KDBUS_HELLO_POOL;
hello->items[0].size = KDBUS_ITEM_HEADER_SIZE + sizeof(struct kdbus_vec);
hello->items[0].vec.address = (uint64_t) b->kdbus_buffer;
hello->items[0].vec.size = KDBUS_POOL_SIZE;
r = ioctl(b->input_fd, KDBUS_CMD_HELLO, hello);
if (r < 0)
return -errno;
/* The higher 32bit of both flags fields are considered
* 'incompatible flags'. Refuse them all for now. */
if (hello->bus_flags > 0xFFFFFFFFULL ||
hello->conn_flags > 0xFFFFFFFFULL)
return -ENOTSUP;
if (hello->bloom_size != BLOOM_SIZE)
return -ENOTSUP;
if (asprintf(&b->unique_name, ":1.%llu", (unsigned long long) hello->id) < 0)
return -ENOMEM;
b->is_kernel = true;
b->bus_client = true;
b->can_fds = !!(hello->conn_flags & KDBUS_HELLO_ACCEPT_FD);
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);
if (b->is_server)
return -EINVAL;
b->input_fd = open(b->kernel, O_RDWR|O_NOCTTY|O_CLOEXEC);
if (b->input_fd < 0)
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(bus, 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 1;
}
static void close_kdbus_msg(sd_bus *bus, struct kdbus_msg *k) {
struct kdbus_item *d;
assert(bus);
assert(k);
ioctl(bus->input_fd, KDBUS_CMD_MSG_RELEASE, k);
KDBUS_ITEM_FOREACH(d, k) {
if (d->type == KDBUS_MSG_FDS)
close_many(d->fds, (d->size - offsetof(struct kdbus_item, fds)) / sizeof(int));
else if (d->type == KDBUS_MSG_PAYLOAD_MEMFD)
close_nointr_nofail(d->memfd.fd);
}
}
static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k, sd_bus_message **ret) {
sd_bus_message *m = NULL;
struct kdbus_item *d;
unsigned n_fds = 0;
_cleanup_free_ int *fds = NULL;
struct bus_header *h = NULL;
size_t total, n_bytes = 0, idx = 0;
const char *destination = NULL, *seclabel = NULL;
int r;
assert(bus);
assert(k);
assert(ret);
if (k->payload_type != KDBUS_PAYLOAD_DBUS1)
return 0;
KDBUS_ITEM_FOREACH(d, k) {
size_t l;
l = d->size - offsetof(struct kdbus_item, data);
if (d->type == KDBUS_MSG_PAYLOAD_VEC) {
if (!h) {
h = UINT64_TO_PTR(d->vec.address);
if (!bus_header_is_complete(h, d->vec.size))
return -EBADMSG;
}
n_bytes += d->vec.size;
} else if (d->type == KDBUS_MSG_PAYLOAD_MEMFD) {
if (!h)
return -EBADMSG;
n_bytes += d->memfd.size;
} else if (d->type == KDBUS_MSG_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, sizeof(int) * j);
n_fds += j;
} else if (d->type == KDBUS_MSG_SRC_SECLABEL)
seclabel = d->str;
}
if (!h)
return -EBADMSG;
r = bus_header_message_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, seclabel, 0, &m);
if (r < 0)
return r;
KDBUS_ITEM_FOREACH(d, k) {
size_t l;
l = d->size - offsetof(struct kdbus_item, data);
if (d->type == KDBUS_MSG_PAYLOAD_VEC) {
size_t begin_body;
begin_body = BUS_MESSAGE_BODY_BEGIN(m);
if (idx + d->vec.size > begin_body) {
struct bus_body_part *part;
/* Contains body material */
part = message_append_part(m);
if (!part) {
r = -ENOMEM;
goto fail;
}
if (idx >= begin_body) {
part->data = UINT64_TO_PTR(d->vec.address);
part->size = d->vec.size;
} else {
part->data = d->vec.address != 0 ? (uint8_t*) UINT64_TO_PTR(d->vec.address) + (begin_body - idx) : NULL;
part->size = d->vec.size - (begin_body - idx);
}
part->is_zero = d->vec.address == 0;
part->sealed = true;
}
idx += d->vec.size;
} else if (d->type == KDBUS_MSG_PAYLOAD_MEMFD) {
struct bus_body_part *part;
if (idx < BUS_MESSAGE_BODY_BEGIN(m)) {
r = -EBADMSG;
goto fail;
}
part = message_append_part(m);
if (!part) {
r = -ENOMEM;
goto fail;
}
part->memfd = d->memfd.fd;
part->size = d->memfd.size;
part->sealed = true;
idx += d->memfd.size;
} else if (d->type == KDBUS_MSG_SRC_CREDS) {
m->pid_starttime = d->creds.starttime / NSEC_PER_USEC;
m->uid = d->creds.uid;
m->gid = d->creds.gid;
m->pid = d->creds.pid;
m->tid = d->creds.tid;
m->uid_valid = m->gid_valid = true;
} else if (d->type == KDBUS_MSG_TIMESTAMP) {
m->realtime = d->timestamp.realtime_ns / NSEC_PER_USEC;
m->monotonic = d->timestamp.monotonic_ns / NSEC_PER_USEC;
} else if (d->type == KDBUS_MSG_SRC_PID_COMM)
m->comm = d->str;
else if (d->type == KDBUS_MSG_SRC_TID_COMM)
m->tid_comm = d->str;
else if (d->type == KDBUS_MSG_SRC_EXE)
m->exe = d->str;
else if (d->type == KDBUS_MSG_SRC_CMDLINE) {
m->cmdline = d->str;
m->cmdline_length = l;
} else if (d->type == KDBUS_MSG_SRC_CGROUP)
m->cgroup = d->str;
else if (d->type == KDBUS_MSG_SRC_AUDIT)
m->audit = &d->audit;
else if (d->type == KDBUS_MSG_SRC_CAPS) {
m->capability = d->data;
m->capability_size = l;
} else if (d->type == KDBUS_MSG_DST_NAME)
destination = d->str;
else if (d->type != KDBUS_MSG_FDS &&
d->type != KDBUS_MSG_SRC_SECLABEL)
log_debug("Got unknown field from kernel %llu", d->type);
}
r = bus_message_parse_fields(m);
if (r < 0)
goto fail;
if (k->src_id == KDBUS_SRC_ID_KERNEL)
m->sender = "org.freedesktop.DBus";
else {
snprintf(m->sender_buffer, sizeof(m->sender_buffer), ":1.%llu", (unsigned long long) k->src_id);
m->sender = m->sender_buffer;
}
if (!m->destination) {
if (destination)
m->destination = destination;
else if (k->dst_id != KDBUS_DST_ID_WELL_KNOWN_NAME &&
k->dst_id != KDBUS_DST_ID_BROADCAST) {
snprintf(m->destination_buffer, sizeof(m->destination_buffer), ":1.%llu", (unsigned long long) k->dst_id);
m->destination = m->destination_buffer;
}
}
/* We take possession of the kmsg struct now */
m->kdbus = k;
m->bus = sd_bus_ref(bus);
m->release_kdbus = true;
m->free_fds = true;
fds = NULL;
*ret = m;
return 1;
fail:
if (m) {
struct bus_body_part *part;
unsigned i;
/* Make sure the memfds are not freed twice */
MESSAGE_FOREACH_PART(part, i, m)
if (part->memfd >= 0)
part->memfd = -1;
sd_bus_message_unref(m);
}
return r;
}
int bus_kernel_read_message(sd_bus *bus, sd_bus_message **m) {
uint64_t addr;
struct kdbus_msg *k;
int r;
assert(bus);
assert(m);
r = ioctl(bus->input_fd, KDBUS_CMD_MSG_RECV, &addr);
if (r < 0) {
if (errno == EAGAIN)
return 0;
return -errno;
}
k = UINT64_TO_PTR(addr);
r = bus_kernel_make_message(bus, k, m);
if (r <= 0)
close_kdbus_msg(bus, k);
return r < 0 ? r : 1;
}
int bus_kernel_create(const char *name, char **s) {
struct kdbus_cmd_bus_make *make;
struct kdbus_item *n, *cg;
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);
make = alloca0(offsetof(struct kdbus_cmd_bus_make, items) +
KDBUS_ITEM_HEADER_SIZE + sizeof(uint64_t) +
KDBUS_ITEM_HEADER_SIZE + DECIMAL_STR_MAX(uid_t) + 1 + l + 1);
cg = make->items;
cg->type = KDBUS_MAKE_CGROUP;
cg->data64[0] = 1;
cg->size = KDBUS_ITEM_HEADER_SIZE + sizeof(uint64_t);
n = KDBUS_ITEM_NEXT(cg);
n->type = KDBUS_MAKE_NAME;
sprintf(n->str, "%lu-%s", (unsigned long) getuid(), name);
n->size = KDBUS_ITEM_HEADER_SIZE + strlen(n->str) + 1;
make->size = offsetof(struct kdbus_cmd_bus_make, items) + cg->size + n->size;
make->flags = KDBUS_MAKE_POLICY_OPEN;
make->bus_flags = 0;
make->bloom_size = BLOOM_SIZE;
assert_cc(BLOOM_SIZE % 8 == 0);
p = strjoin("/dev/kdbus/", n->str, "/bus", NULL);
if (!p)
return -ENOMEM;
if (ioctl(fd, KDBUS_CMD_BUS_MAKE, make) < 0) {
close_nointr_nofail(fd);
free(p);
return -errno;
}
if (s)
*s = p;
return fd;
}
int bus_kernel_pop_memfd(sd_bus *bus, void **address, size_t *size) {
struct memfd_cache *c;
int fd;
assert(address);
assert(size);
if (!bus || !bus->is_kernel)
return -ENOTSUP;
assert_se(pthread_mutex_lock(&bus->memfd_cache_mutex) == 0);
if (bus->n_memfd_cache <= 0) {
int r;
assert_se(pthread_mutex_unlock(&bus->memfd_cache_mutex) == 0);
r = ioctl(bus->input_fd, KDBUS_CMD_MEMFD_NEW, &fd);
if (r < 0)
return -errno;
*address = NULL;
*size = 0;
return fd;
}
c = &bus->memfd_cache[-- bus->n_memfd_cache];
assert(c->fd >= 0);
assert(c->size == 0 || c->address);
*address = c->address;
*size = c->size;
fd = c->fd;
assert_se(pthread_mutex_unlock(&bus->memfd_cache_mutex) == 0);
return fd;
}
static void close_and_munmap(int fd, void *address, size_t size) {
if (size > 0)
assert_se(munmap(address, PAGE_ALIGN(size)) == 0);
close_nointr_nofail(fd);
}
void bus_kernel_push_memfd(sd_bus *bus, int fd, void *address, size_t size) {
struct memfd_cache *c;
assert(fd >= 0);
assert(size == 0 || address);
if (!bus || !bus->is_kernel) {
close_and_munmap(fd, address, size);
return;
}
assert_se(pthread_mutex_lock(&bus->memfd_cache_mutex) == 0);
if (bus->n_memfd_cache >= ELEMENTSOF(bus->memfd_cache)) {
assert_se(pthread_mutex_unlock(&bus->memfd_cache_mutex) == 0);
close_and_munmap(fd, address, size);
return;
}
c = &bus->memfd_cache[bus->n_memfd_cache++];
c->fd = fd;
c->address = address;
/* If overly long, let's return a bit to the OS */
if (size > MEMFD_CACHE_ITEM_SIZE_MAX) {
uint64_t sz = MEMFD_CACHE_ITEM_SIZE_MAX;
ioctl(bus->input_fd, KDBUS_CMD_MEMFD_SIZE_SET, &sz);
c->size = MEMFD_CACHE_ITEM_SIZE_MAX;
} else
c->size = size;
assert_se(pthread_mutex_unlock(&bus->memfd_cache_mutex) == 0);
}
void bus_kernel_flush_memfd(sd_bus *b) {
unsigned i;
assert(b);
for (i = 0; i < b->n_memfd_cache; i++) {
if (b->memfd_cache[i].size > 0)
assert_se(munmap(b->memfd_cache[i].address, PAGE_ALIGN(b->memfd_cache[i].size)) == 0);
close_nointr_nofail(b->memfd_cache[i].fd);
}
}
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