udevd: listen for netlink events

After the first valid netlink-event all event with a serial number
received on the udevsend socket will be ignored.

Signed-off-by: Kay Sievers <kay.sievers@suse.de>

diff --git a/udev.c b/udev.c
index ce9b42f30db510519cc6c0d9f7f8883cbd15e4cb..2be4c357408d7f266da37a3b4303071f7822bfff 100644 (file)
--- a/udev.c
+++ b/udev.c
@@ -54,8 +54,10 @@ void log_message(int priority, const char *format, ...)
 }
 #endif
 
-/* decide if we should manage the whole hotplug event
- * for now look if the kernel calls udevsend instead of /sbin/hotplug
+/* Decide if we should manage the whole uevent, including multiplexing
+ * of the hotplug directories.
+ * For now look if the kernel calls udevsend instead of /sbin/hotplug,
+ * or the uevent-helper in /proc/sys/kernel/hotplug is empty.
  */
 static int manage_hotplug_event(void) {
        char helper[256];
@@ -70,13 +72,15 @@ static int manage_hotplug_event(void) {
        if (fd < 0)
                return 0;
 
-       len = read(fd, helper, 256);
+       len = read(fd, helper, sizeof(helper)-1);
        close(fd);
 
        if (len < 0)
                return 0;
        helper[len] = '\0';
 
+       if (helper[0] == '\0' || helper[0] == '\n')
+               return 1;
        if (strstr(helper, "udevsend"))
                return 1;
 

diff --git a/udevd.c b/udevd.c
index 91033b068844a42965d48d46db91dc2c6b2558da..68e3a75f33358b2a66c4f14cb8eabd3efe0a226e 100644 (file)
--- a/udevd.c
+++ b/udevd.c
@@ -38,6 +38,7 @@
 #include <sys/un.h>
 #include <sys/sysinfo.h>
 #include <sys/stat.h>
+#include <linux/netlink.h>
 
 #include "list.h"
 #include "udev_libc_wrapper.h"
@@ -49,6 +50,7 @@
 
 /* global variables*/
 static int udevsendsock;
+static int ueventsock;
 static pid_t sid;
 
 static int pipefds[2];
@@ -126,7 +128,8 @@ static void msg_queue_insert(struct hotplug_msg *msg)
                        break;
 
                if (loop_msg->seqnum == msg->seqnum) {
-                       info("ignoring duplicate message seq %llu", msg->seqnum);
+                       dbg("ignoring duplicate message seq %llu", msg->seqnum);
+                       free(msg);
                        return;
                }
        }
@@ -154,6 +157,8 @@ static void execute_udev(struct hotplug_msg *msg)
        switch (pid) {
        case 0:
                /* child */
+               if (ueventsock != -1)
+                       close(ueventsock);
                close(udevsendsock);
                logging_close();
 
@@ -416,13 +421,60 @@ recheck:
        }
 }
 
+static struct hotplug_msg *get_msg_from_envbuf(const char *buf, int buf_size)
+{
+       int bufpos;
+       int i;
+       struct hotplug_msg *msg;
+
+       msg = malloc(sizeof(struct hotplug_msg) + buf_size);
+       if (msg == NULL)
+               return NULL;
+       memset(msg, 0x00, sizeof(struct hotplug_msg) + buf_size);
+
+       /* copy environment buffer and reconstruct envp */
+       memcpy(msg->envbuf, buf, buf_size);
+       bufpos = 0;
+       for (i = 0; (bufpos < buf_size) && (i < HOTPLUG_NUM_ENVP-2); i++) {
+               int keylen;
+               char *key;
+
+               key = &msg->envbuf[bufpos];
+               keylen = strlen(key);
+               msg->envp[i] = key;
+               bufpos += keylen + 1;
+               dbg("add '%s' to msg.envp[%i]", msg->envp[i], i);
+
+               /* remember some keys for further processing */
+               if (strncmp(key, "ACTION=", 7) == 0)
+                       msg->action = &key[7];
+
+               if (strncmp(key, "DEVPATH=", 8) == 0)
+                       msg->devpath = &key[8];
+
+               if (strncmp(key, "SUBSYSTEM=", 10) == 0)
+                       msg->subsystem = &key[10];
+
+               if (strncmp(key, "SEQNUM=", 7) == 0)
+                       msg->seqnum = strtoull(&key[7], NULL, 10);
+
+               if (strncmp(key, "PHYSDEVPATH=", 12) == 0)
+                       msg->physdevpath = &key[12];
+
+               if (strncmp(key, "TIMEOUT=", 8) == 0)
+                       msg->timeout = strtoull(&key[8], NULL, 10);
+       }
+       msg->envp[i++] = "UDEVD_EVENT=1";
+       msg->envp[i] = NULL;
+
+       return msg;
+}
+
 /* receive the udevsend message and do some sanity checks */
 static struct hotplug_msg *get_udevsend_msg(void)
 {
        static struct udevsend_msg usend_msg;
        struct hotplug_msg *msg;
-       int bufpos;
-       int i;
        ssize_t size;
        struct msghdr smsg;
        struct cmsghdr *cmsg;
@@ -467,46 +519,60 @@ static struct hotplug_msg *get_udevsend_msg(void)
 
        envbuf_size = size - offsetof(struct udevsend_msg, envbuf);
        dbg("envbuf_size=%i", envbuf_size);
-       msg = malloc(sizeof(struct hotplug_msg) + envbuf_size);
+       msg = get_msg_from_envbuf(usend_msg.envbuf, envbuf_size);
        if (msg == NULL)
                return NULL;
 
-       memset(msg, 0x00, sizeof(struct hotplug_msg) + envbuf_size);
-
-       /* copy environment buffer and reconstruct envp */
-       memcpy(msg->envbuf, usend_msg.envbuf, envbuf_size);
-       bufpos = 0;
-       for (i = 0; (bufpos < envbuf_size) && (i < HOTPLUG_NUM_ENVP-2); i++) {
-               int keylen;
-               char *key;
+       return msg;
+}
 
-               key = &msg->envbuf[bufpos];
-               keylen = strlen(key);
-               msg->envp[i] = key;
-               bufpos += keylen + 1;
-               dbg("add '%s' to msg.envp[%i]", msg->envp[i], i);
+/* receive the kernel user event message and do some sanity checks */
+static struct hotplug_msg *get_uevent_msg(void)
+{
+       struct hotplug_msg *msg;
+       int bufpos;
+       ssize_t size;
+       static char buffer[HOTPLUG_BUFFER_SIZE + 512];
+       char *pos;
 
-               /* remember some keys for further processing */
-               if (strncmp(key, "ACTION=", 7) == 0)
-                       msg->action = &key[7];
+       size = recv(ueventsock, &buffer, sizeof(buffer), 0);
+       if (size <  0) {
+               if (errno != EINTR)
+                       dbg("unable to receive udevsend message");
+               return NULL;
+       }
 
-               if (strncmp(key, "DEVPATH=", 8) == 0)
-                       msg->devpath = &key[8];
+       if ((size_t)size > sizeof(buffer)-1)
+               size = sizeof(buffer)-1;
+       buffer[size] = '\0';
+       dbg("uevent_size=%i", size);
 
-               if (strncmp(key, "SUBSYSTEM=", 10) == 0)
-                       msg->subsystem = &key[10];
+       /* start of event payload */
+       bufpos = strlen(buffer)+1;
+       msg = get_msg_from_envbuf(&buffer[bufpos], size-bufpos);
+       if (msg == NULL)
+               return NULL;
 
-               if (strncmp(key, "SEQNUM=", 7) == 0)
-                       msg->seqnum = strtoull(&key[7], NULL, 10);
+       /* validate message */
+       pos = strchr(buffer, '@');
+       if (pos == NULL) {
+               dbg("invalid uevent '%s'", buffer);
+               free(msg);
+               return NULL;
+       }
+       pos[0] = '\0';
 
-               if (strncmp(key, "PHYSDEVPATH=", 12) == 0)
-                       msg->physdevpath = &key[12];
+       if (msg->action == NULL) {
+               dbg("no ACTION in payload found, skip event '%s'", buffer);
+               free(msg);
+               return NULL;
+       }
 
-               if (strncmp(key, "TIMEOUT=", 8) == 0)
-                       msg->timeout = strtoull(&key[8], NULL, 10);
+       if (strcmp(msg->action, buffer) != 0) {
+               dbg("ACTION in payload does not match uevent, skip event '%s'", buffer);
+               free(msg);
+               return NULL;
        }
-       msg->envp[i++] = "UDEVD_EVENT=1";
-       msg->envp[i] = NULL;
 
        return msg;
 }
@@ -622,6 +688,34 @@ static int init_udevsend_socket(void)
        return 0;
 }
 
+static int init_uevent_socket(void)
+{
+       struct sockaddr_nl snl;
+       int retval;
+
+       memset(&snl, 0x00, sizeof(struct sockaddr_nl));
+       snl.nl_family = AF_NETLINK;
+       snl.nl_pid = getpid();
+       snl.nl_groups = 0xffffffff;
+
+       ueventsock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
+       if (ueventsock == -1) {
+               dbg("error getting socket, %s", strerror(errno));
+               return -1;
+       }
+
+       retval = bind(ueventsock, (struct sockaddr *) &snl,
+                     sizeof(struct sockaddr_nl));
+       if (retval < 0) {
+               dbg("bind failed, %s", strerror(errno));
+               close(ueventsock);
+               ueventsock = -1;
+               return -1;
+       }
+
+       return 0;
+}
+
 int main(int argc, char *argv[], char *envp[])
 {
        struct sysinfo info;
@@ -631,6 +725,7 @@ int main(int argc, char *argv[], char *envp[])
        struct sigaction act;
        fd_set readfds;
        const char *udevd_expected_seqnum;
+       int uevent_active = 0;
 
        logging_init("udevd");
        udev_init_config();
@@ -716,6 +811,10 @@ int main(int argc, char *argv[], char *envp[])
        sigaction(SIGALRM, &act, NULL);
        sigaction(SIGCHLD, &act, NULL);
 
+       if (init_uevent_socket() < 0) {
+               dbg("uevent socket not available");
+       }
+
        if (init_udevsend_socket() < 0) {
                if (errno == EADDRINUSE)
                        dbg("another udevd running, exit");
@@ -745,6 +844,8 @@ int main(int argc, char *argv[], char *envp[])
 
        FD_ZERO(&readfds);
        FD_SET(udevsendsock, &readfds);
+       if (ueventsock != -1)
+               FD_SET(ueventsock, &readfds);
        FD_SET(pipefds[0], &readfds);
        maxsockplus = udevsendsock+1;
        while (1) {
@@ -761,8 +862,27 @@ int main(int argc, char *argv[], char *envp[])
 
                if (FD_ISSET(udevsendsock, &workreadfds)) {
                        msg = get_udevsend_msg();
-                       if (msg)
+                       if (msg) {
+                               /* discard kernel messages if netlink is active */
+                               if (uevent_active && msg->seqnum != 0) {
+                                       dbg("skip kernel udevsend message, netlink is active");
+                                       free(msg);
+                                       continue;
+                               }
+                               msg_queue_insert(msg);
+                       }
+               }
+
+               if (FD_ISSET(ueventsock, &workreadfds)) {
+                       msg = get_uevent_msg();
+                       if (msg) {
                                msg_queue_insert(msg);
+                               /* disable udevsend with first netlink message */
+                               if (!uevent_active) {
+                                       info("netlink message received, disable kernel udevsend messages");
+                                       uevent_active = 1;
+                               }
+                       }
                }
 
                if (FD_ISSET(pipefds[0], &workreadfds))