libudev: monitor - use simpler hash

[elogind.git] / udev / lib / libudev-monitor.c

diff --git a/udev/lib/libudev-monitor.c b/udev/lib/libudev-monitor.c
index 570fcafbb42406f1246bb673ec8f36a788493965..a0f93546f7f8fb7c035c01f3ee03a49a3e88d26d 100644 (file)
--- a/udev/lib/libudev-monitor.c
+++ b/udev/lib/libudev-monitor.c
@@ -56,8 +56,9 @@ struct udev_monitor_netlink_header {
        unsigned short properties_off;
        unsigned short properties_len;
        /*
-        * crc32 of some common device properties to filter with socket filters in the client
-        * used in the kernel from socket filter rules; needs to be stored in network order
+        * hashes of some common device propertie strings to filter with socket filters in
+        * the client used in the kernel from socket filter rules; needs to be stored in
+        * network order
         */
        unsigned int filter_subsystem;
 };
@@ -247,11 +248,11 @@ static int filter_apply(struct udev_monitor *udev_monitor)
        /* add all subsystem match values */
        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);
-               unsigned int crc;
+               unsigned int hash;
 
-               crc = util_crc32((unsigned char *)subsys, strlen(subsys));
+               hash = util_string_hash32(subsys);
                /* jump if value does not match */
-               bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, crc, 0, 1);
+               bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
                /* matched, pass packet */
                bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
 
@@ -414,8 +415,9 @@ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monito
        struct cmsghdr *cmsg;
        struct sockaddr_nl snl;
        struct ucred *cred;
-       char buf[4096];
-       size_t bufpos;
+       char buf[8192];
+       ssize_t buflen;
+       ssize_t bufpos;
        struct udev_monitor_netlink_header *nlh;
        int devpath_set = 0;
        int subsystem_set = 0;
@@ -440,12 +442,18 @@ retry:
                smsg.msg_namelen = sizeof(snl);
        }
 
-       if (recvmsg(udev_monitor->sock, &smsg, 0) < 0) {
+       buflen = recvmsg(udev_monitor->sock, &smsg, 0);
+       if (buflen < 0) {
                if (errno != EINTR)
                        info(udev_monitor->udev, "unable to receive message\n");
                return NULL;
        }
 
+       if (buflen < 32 || (size_t)buflen >= sizeof(buf)) {
+               info(udev_monitor->udev, "invalid message length\n");
+               return NULL;
+       }
+
        if (udev_monitor->snl.nl_family != 0) {
                if (snl.nl_groups == 0) {
                        info(udev_monitor->udev, "unicast netlink message ignored\n");
@@ -469,18 +477,20 @@ retry:
                return NULL;
        }
 
-       nlh = (struct udev_monitor_netlink_header *) buf;
-       if (nlh->magic == ntohl(UDEV_MONITOR_MAGIC)) {
-               /* udev message with version magic */
+       if (strncmp(buf, "udev-", 5) == 0) {
+               /* udev message needs proper version magic */
+               nlh = (struct udev_monitor_netlink_header *) buf;
+               if (nlh->magic != htonl(UDEV_MONITOR_MAGIC))
+                       return NULL;
                if (nlh->properties_off < sizeof(struct udev_monitor_netlink_header))
                        return NULL;
-               if (nlh->properties_off+32U > sizeof(buf))
+               if (nlh->properties_off+32U > buflen)
                        return NULL;
                bufpos = nlh->properties_off;
        } else {
                /* kernel message with header */
                bufpos = strlen(buf) + 1;
-               if (bufpos < sizeof("a@/d") || bufpos >= sizeof(buf)) {
+               if ((size_t)bufpos < sizeof("a@/d") || bufpos >= buflen) {
                        info(udev_monitor->udev, "invalid message length\n");
                        return NULL;
                }
@@ -497,7 +507,7 @@ retry:
                return NULL;
        }
 
-       while (bufpos < sizeof(buf)) {
+       while (bufpos < buflen) {
                char *key;
                size_t keylen;
 
@@ -629,7 +639,6 @@ int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_devi
                smsg.msg_namelen = udev_monitor->addrlen;
        } else if (udev_monitor->snl.nl_family != 0) {
                const char *val;
-               size_t vlen;
                struct udev_monitor_netlink_header nlh;
 
 
@@ -638,8 +647,7 @@ int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_devi
                util_strlcpy(nlh.version, "udev-" VERSION, sizeof(nlh.version));
                nlh.magic = htonl(UDEV_MONITOR_MAGIC);
                val = udev_device_get_subsystem(udev_device);
-               vlen = strlen(val);
-               nlh.filter_subsystem = htonl(util_crc32((unsigned char *)val, vlen));
+               nlh.filter_subsystem = htonl(util_string_hash32(val));
                iov[0].iov_base = &nlh;
                iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);