This source file includes following definitions.
- udev_monitor_new
- udev_has_devtmpfs
- udev_monitor_new_from_netlink_fd
- udev_monitor_new_from_netlink
- bpf_stmt
- bpf_jmp
- udev_monitor_filter_update
- udev_monitor_allow_unicast_sender
- udev_monitor_enable_receiving
- udev_monitor_set_receive_buffer_size
- udev_monitor_disconnect
- udev_monitor_ref
- udev_monitor_unref
- udev_monitor_get_udev
- udev_monitor_get_fd
- passes_filter
- udev_monitor_receive_device
- udev_monitor_send_device
- udev_monitor_filter_add_match_subsystem_devtype
- udev_monitor_filter_add_match_tag
- udev_monitor_filter_remove
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <dirent.h>
#include <sys/poll.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <linux/netlink.h>
#include <linux/filter.h>
#include "libudev.h"
#include "libudev-private.h"
#include "socket-util.h"
#include "missing.h"
struct udev_monitor {
struct udev *udev;
int refcount;
int sock;
union sockaddr_union snl;
union sockaddr_union snl_trusted_sender;
union sockaddr_union snl_destination;
socklen_t addrlen;
struct udev_list filter_subsystem_list;
struct udev_list filter_tag_list;
bool bound;
};
enum udev_monitor_netlink_group {
UDEV_MONITOR_NONE,
UDEV_MONITOR_KERNEL,
UDEV_MONITOR_UDEV,
};
#define UDEV_MONITOR_MAGIC 0xfeedcafe
struct udev_monitor_netlink_header {
char prefix[8];
unsigned int magic;
unsigned int header_size;
unsigned int properties_off;
unsigned int properties_len;
unsigned int filter_subsystem_hash;
unsigned int filter_devtype_hash;
unsigned int filter_tag_bloom_hi;
unsigned int filter_tag_bloom_lo;
};
static struct udev_monitor *udev_monitor_new(struct udev *udev)
{
struct udev_monitor *udev_monitor;
udev_monitor = new0(struct udev_monitor, 1);
if (udev_monitor == NULL)
return NULL;
udev_monitor->refcount = 1;
udev_monitor->udev = udev;
udev_list_init(udev, &udev_monitor->filter_subsystem_list, false);
udev_list_init(udev, &udev_monitor->filter_tag_list, true);
return udev_monitor;
}
static bool udev_has_devtmpfs(struct udev *udev) {
union file_handle_union h = {
.handle.handle_bytes = MAX_HANDLE_SZ
};
_cleanup_fclose_ FILE *f = NULL;
char line[LINE_MAX], *e;
int mount_id;
int r;
r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0);
if (r < 0) {
if (errno != EOPNOTSUPP)
udev_err(udev, "name_to_handle_at on /dev: %m\n");
return false;
}
f = fopen("/proc/self/mountinfo", "re");
if (!f)
return false;
FOREACH_LINE(line, f, return false) {
int mid;
if (sscanf(line, "%i", &mid) != 1)
continue;
if (mid != mount_id)
continue;
e = strstr(line, " - ");
if (!e)
continue;
if (startswith(e + 3, "devtmpfs"))
return true;
}
return false;
}
struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const char *name, int fd)
{
struct udev_monitor *udev_monitor;
unsigned int group;
if (udev == NULL)
return NULL;
if (name == NULL)
group = UDEV_MONITOR_NONE;
else if (streq(name, "udev")) {
if (access("/run/udev/control", F_OK) < 0 && !udev_has_devtmpfs(udev)) {
udev_dbg(udev, "the udev service seems not to be active, disable the monitor\n");
group = UDEV_MONITOR_NONE;
} else
group = UDEV_MONITOR_UDEV;
} else if (streq(name, "kernel"))
group = UDEV_MONITOR_KERNEL;
else
return NULL;
udev_monitor = udev_monitor_new(udev);
if (udev_monitor == NULL)
return NULL;
if (fd < 0) {
udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
if (udev_monitor->sock == -1) {
udev_err(udev, "error getting socket: %m\n");
free(udev_monitor);
return NULL;
}
} else {
udev_monitor->bound = true;
udev_monitor->sock = fd;
}
udev_monitor->snl.nl.nl_family = AF_NETLINK;
udev_monitor->snl.nl.nl_groups = group;
udev_monitor->snl_destination.nl.nl_family = AF_NETLINK;
udev_monitor->snl_destination.nl.nl_groups = UDEV_MONITOR_UDEV;
return udev_monitor;
}
_public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
{
return udev_monitor_new_from_netlink_fd(udev, name, -1);
}
static inline void bpf_stmt(struct sock_filter *inss, unsigned int *i,
unsigned short code, unsigned int data)
{
struct sock_filter *ins = &inss[*i];
ins->code = code;
ins->k = data;
(*i)++;
}
static inline void bpf_jmp(struct sock_filter *inss, unsigned int *i,
unsigned short code, unsigned int data,
unsigned short jt, unsigned short jf)
{
struct sock_filter *ins = &inss[*i];
ins->code = code;
ins->jt = jt;
ins->jf = jf;
ins->k = data;
(*i)++;
}
_public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor)
{
struct sock_filter ins[512];
struct sock_fprog filter;
unsigned int i;
struct udev_list_entry *list_entry;
int err;
if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL &&
udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
return 0;
memzero(ins, sizeof(ins));
i = 0;
bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
if (udev_list_get_entry(&udev_monitor->filter_tag_list) != NULL) {
int tag_matches;
tag_matches = 0;
udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list))
tag_matches++;
udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
uint64_t tag_bloom_bits = util_string_bloom64(udev_list_entry_get_name(list_entry));
uint32_t tag_bloom_hi = tag_bloom_bits >> 32;
uint32_t tag_bloom_lo = tag_bloom_bits & 0xffffffff;
bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_hi));
bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_hi);
bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_hi, 0, 3);
bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_tag_bloom_lo));
bpf_stmt(ins, &i, BPF_ALU|BPF_AND|BPF_K, tag_bloom_lo);
tag_matches--;
bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, tag_bloom_lo, 1 + (tag_matches * 6), 0);
}
bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
}
if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) != NULL) {
udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
unsigned int hash = util_string_hash32(udev_list_entry_get_name(list_entry));
bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem_hash));
if (udev_list_entry_get_value(list_entry) == NULL) {
bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
} else {
bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype_hash));
hash = util_string_hash32(udev_list_entry_get_value(list_entry));
bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
}
bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
if (i+1 >= ELEMENTSOF(ins))
return -E2BIG;
}
bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
}
bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
memzero(&filter, sizeof(filter));
filter.len = i;
filter.filter = ins;
err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
return err < 0 ? -errno : 0;
}
int udev_monitor_allow_unicast_sender(struct udev_monitor *udev_monitor, struct udev_monitor *sender)
{
udev_monitor->snl_trusted_sender.nl.nl_pid = sender->snl.nl.nl_pid;
return 0;
}
_public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
{
int err = 0;
const int on = 1;
udev_monitor_filter_update(udev_monitor);
if (!udev_monitor->bound) {
err = bind(udev_monitor->sock,
&udev_monitor->snl.sa, sizeof(struct sockaddr_nl));
if (err == 0)
udev_monitor->bound = true;
}
if (err >= 0) {
union sockaddr_union snl;
socklen_t addrlen;
addrlen = sizeof(struct sockaddr_nl);
err = getsockname(udev_monitor->sock, &snl.sa, &addrlen);
if (err == 0)
udev_monitor->snl.nl.nl_pid = snl.nl.nl_pid;
} else {
udev_err(udev_monitor->udev, "bind failed: %m\n");
return -errno;
}
err = setsockopt(udev_monitor->sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
if (err < 0)
udev_err(udev_monitor->udev, "setting SO_PASSCRED failed: %m\n");
return 0;
}
_public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size)
{
if (udev_monitor == NULL)
return -EINVAL;
return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_RCVBUFFORCE, &size, sizeof(size));
}
int udev_monitor_disconnect(struct udev_monitor *udev_monitor)
{
int err;
err = close(udev_monitor->sock);
udev_monitor->sock = -1;
return err < 0 ? -errno : 0;
}
_public_ struct udev_monitor *udev_monitor_ref(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return NULL;
udev_monitor->refcount++;
return udev_monitor;
}
_public_ struct udev_monitor *udev_monitor_unref(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return NULL;
udev_monitor->refcount--;
if (udev_monitor->refcount > 0)
return NULL;
if (udev_monitor->sock >= 0)
close(udev_monitor->sock);
udev_list_cleanup(&udev_monitor->filter_subsystem_list);
udev_list_cleanup(&udev_monitor->filter_tag_list);
free(udev_monitor);
return NULL;
}
_public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return NULL;
return udev_monitor->udev;
}
_public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
{
if (udev_monitor == NULL)
return -EINVAL;
return udev_monitor->sock;
}
static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
{
struct udev_list_entry *list_entry;
if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
goto tag;
udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
const char *subsys = udev_list_entry_get_name(list_entry);
const char *dsubsys = udev_device_get_subsystem(udev_device);
const char *devtype;
const char *ddevtype;
if (!streq(dsubsys, subsys))
continue;
devtype = udev_list_entry_get_value(list_entry);
if (devtype == NULL)
goto tag;
ddevtype = udev_device_get_devtype(udev_device);
if (ddevtype == NULL)
continue;
if (streq(ddevtype, devtype))
goto tag;
}
return 0;
tag:
if (udev_list_get_entry(&udev_monitor->filter_tag_list) == NULL)
return 1;
udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_tag_list)) {
const char *tag = udev_list_entry_get_name(list_entry);
if (udev_device_has_tag(udev_device, tag))
return 1;
}
return 0;
}
_public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor)
{
struct udev_device *udev_device;
struct msghdr smsg;
struct iovec iov;
char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
struct cmsghdr *cmsg;
union sockaddr_union snl;
struct ucred *cred;
char buf[8192];
ssize_t buflen;
ssize_t bufpos;
retry:
if (udev_monitor == NULL)
return NULL;
iov.iov_base = &buf;
iov.iov_len = sizeof(buf);
memzero(&smsg, sizeof(struct msghdr));
smsg.msg_iov = &iov;
smsg.msg_iovlen = 1;
smsg.msg_control = cred_msg;
smsg.msg_controllen = sizeof(cred_msg);
smsg.msg_name = &snl;
smsg.msg_namelen = sizeof(snl);
buflen = recvmsg(udev_monitor->sock, &smsg, 0);
if (buflen < 0) {
if (errno != EINTR)
udev_dbg(udev_monitor->udev, "unable to receive message\n");
return NULL;
}
if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
udev_dbg(udev_monitor->udev, "invalid message length\n");
return NULL;
}
if (snl.nl.nl_groups == 0) {
if (udev_monitor->snl_trusted_sender.nl.nl_pid == 0 ||
snl.nl.nl_pid != udev_monitor->snl_trusted_sender.nl.nl_pid) {
udev_dbg(udev_monitor->udev, "unicast netlink message ignored\n");
return NULL;
}
} else if (snl.nl.nl_groups == UDEV_MONITOR_KERNEL) {
if (snl.nl.nl_pid > 0) {
udev_dbg(udev_monitor->udev, "multicast kernel netlink message from pid %d ignored\n",
snl.nl.nl_pid);
return NULL;
}
}
cmsg = CMSG_FIRSTHDR(&smsg);
if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
udev_dbg(udev_monitor->udev, "no sender credentials received, message ignored\n");
return NULL;
}
cred = (struct ucred *)CMSG_DATA(cmsg);
if (cred->uid != 0) {
udev_dbg(udev_monitor->udev, "sender uid=%d, message ignored\n", cred->uid);
return NULL;
}
udev_device = udev_device_new(udev_monitor->udev);
if (udev_device == NULL)
return NULL;
if (memcmp(buf, "libudev", 8) == 0) {
struct udev_monitor_netlink_header *nlh;
nlh = (struct udev_monitor_netlink_header *) buf;
if (nlh->magic != htonl(UDEV_MONITOR_MAGIC)) {
udev_err(udev_monitor->udev, "unrecognized message signature (%x != %x)\n",
nlh->magic, htonl(UDEV_MONITOR_MAGIC));
udev_device_unref(udev_device);
return NULL;
}
if (nlh->properties_off+32 > (size_t)buflen) {
udev_device_unref(udev_device);
return NULL;
}
bufpos = nlh->properties_off;
udev_device_set_is_initialized(udev_device);
} else {
bufpos = strlen(buf) + 1;
if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
udev_dbg(udev_monitor->udev, "invalid message length\n");
udev_device_unref(udev_device);
return NULL;
}
if (strstr(buf, "@/") == NULL) {
udev_dbg(udev_monitor->udev, "unrecognized message header\n");
udev_device_unref(udev_device);
return NULL;
}
}
udev_device_set_info_loaded(udev_device);
while (bufpos < buflen) {
char *key;
size_t keylen;
key = &buf[bufpos];
keylen = strlen(key);
if (keylen == 0)
break;
bufpos += keylen + 1;
udev_device_add_property_from_string_parse(udev_device, key);
}
if (udev_device_add_property_from_string_parse_finish(udev_device) < 0) {
udev_dbg(udev_monitor->udev, "missing values, invalid device\n");
udev_device_unref(udev_device);
return NULL;
}
if (!passes_filter(udev_monitor, udev_device)) {
struct pollfd pfd[1];
int rc;
udev_device_unref(udev_device);
pfd[0].fd = udev_monitor->sock;
pfd[0].events = POLLIN;
rc = poll(pfd, 1, 0);
if (rc > 0)
goto retry;
return NULL;
}
return udev_device;
}
int udev_monitor_send_device(struct udev_monitor *udev_monitor,
struct udev_monitor *destination, struct udev_device *udev_device)
{
const char *buf;
ssize_t blen;
ssize_t count;
struct msghdr smsg;
struct iovec iov[2];
const char *val;
struct udev_monitor_netlink_header nlh;
struct udev_list_entry *list_entry;
uint64_t tag_bloom_bits;
blen = udev_device_get_properties_monitor_buf(udev_device, &buf);
if (blen < 32)
return -EINVAL;
memzero(&nlh, sizeof(struct udev_monitor_netlink_header));
memcpy(nlh.prefix, "libudev", 8);
nlh.magic = htonl(UDEV_MONITOR_MAGIC);
nlh.header_size = sizeof(struct udev_monitor_netlink_header);
val = udev_device_get_subsystem(udev_device);
nlh.filter_subsystem_hash = htonl(util_string_hash32(val));
val = udev_device_get_devtype(udev_device);
if (val != NULL)
nlh.filter_devtype_hash = htonl(util_string_hash32(val));
iov[0].iov_base = &nlh;
iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
tag_bloom_bits = 0;
udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
tag_bloom_bits |= util_string_bloom64(udev_list_entry_get_name(list_entry));
if (tag_bloom_bits > 0) {
nlh.filter_tag_bloom_hi = htonl(tag_bloom_bits >> 32);
nlh.filter_tag_bloom_lo = htonl(tag_bloom_bits & 0xffffffff);
}
nlh.properties_off = iov[0].iov_len;
nlh.properties_len = blen;
iov[1].iov_base = (char *)buf;
iov[1].iov_len = blen;
memzero(&smsg, sizeof(struct msghdr));
smsg.msg_iov = iov;
smsg.msg_iovlen = 2;
if (destination != NULL)
smsg.msg_name = &destination->snl;
else
smsg.msg_name = &udev_monitor->snl_destination;
smsg.msg_namelen = sizeof(struct sockaddr_nl);
count = sendmsg(udev_monitor->sock, &smsg, 0);
udev_dbg(udev_monitor->udev, "passed %zi bytes to netlink monitor %p\n", count, udev_monitor);
return count;
}
_public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype)
{
if (udev_monitor == NULL)
return -EINVAL;
if (subsystem == NULL)
return -EINVAL;
if (udev_list_entry_add(&udev_monitor->filter_subsystem_list, subsystem, devtype) == NULL)
return -ENOMEM;
return 0;
}
_public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag)
{
if (udev_monitor == NULL)
return -EINVAL;
if (tag == NULL)
return -EINVAL;
if (udev_list_entry_add(&udev_monitor->filter_tag_list, tag, NULL) == NULL)
return -ENOMEM;
return 0;
}
_public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor)
{
static struct sock_fprog filter = { 0, NULL };
udev_list_cleanup(&udev_monitor->filter_subsystem_list);
return setsockopt(udev_monitor->sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter));
}