libudev: monitor - do not filter messages with wrong magic

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

diff --git a/udev/lib/libudev-monitor.c b/udev/lib/libudev-monitor.c
index a0f93546f7f8fb7c035c01f3ee03a49a3e88d26d..211aa12f62b1b770aa09edff05acfdda525ff202 100644 (file)
--- a/udev/lib/libudev-monitor.c
+++ b/udev/lib/libudev-monitor.c
@@ -56,11 +56,12 @@ struct udev_monitor_netlink_header {
        unsigned short properties_off;
        unsigned short properties_len;
        /*
-        * hashes of some common device propertie strings to filter with socket filters in
+        * hashes of some common device properties 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;
+       unsigned int filter_devtype;
 };
 
 static struct udev_monitor *udev_monitor_new(struct udev *udev)
@@ -236,23 +237,34 @@ static int filter_apply(struct udev_monitor *udev_monitor)
        memset(ins, 0x00, sizeof(ins));
        i = 0;
 
-       /* load magic in accu */
+       /* load magic in A */
        bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, magic));
        /* jump if magic matches */
        bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, UDEV_MONITOR_MAGIC, 1, 0);
-       /* wrong magic, drop packet */
-       bpf_stmt(ins, &i, BPF_RET|BPF_K, 0);
+       /* wrong magic, pass packet */
+       bpf_stmt(ins, &i, BPF_RET|BPF_K, 0xffffffff);
 
-       /* load filter_subsystem value in accu */
-       bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem));
        /* 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 hash;
 
-               hash = util_string_hash32(subsys);
-               /* jump if value does not match */
-               bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
+               /* load filter_subsystem value in A */
+               bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_subsystem));
+               hash = util_string_hash32(udev_list_entry_get_name(list_entry));
+               if (udev_list_entry_get_value(list_entry) == NULL) {
+                       /* jump if subsystem does not match */
+                       bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 1);
+               } else {
+                       /* jump if subsystem does not match */
+                       bpf_jmp(ins, &i, BPF_JMP|BPF_JEQ|BPF_K, hash, 0, 3);
+
+                       /* load filter_devtype value in A */
+                       bpf_stmt(ins, &i, BPF_LD|BPF_W|BPF_ABS, offsetof(struct udev_monitor_netlink_header, filter_devtype));
+                       /* jump if value does not match */
+                       hash = util_string_hash32(udev_list_entry_get_value(list_entry));
+                       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);
 
@@ -374,20 +386,29 @@ int udev_monitor_get_fd(struct udev_monitor *udev_monitor)
 static int passes_filter(struct udev_monitor *udev_monitor, struct udev_device *udev_device)
 {
        struct udev_list_entry *list_entry;
-       int pass = 0;
 
        if (udev_list_get_entry(&udev_monitor->filter_subsystem_list) == NULL)
                return 1;
 
        udev_list_entry_foreach(list_entry, udev_list_get_entry(&udev_monitor->filter_subsystem_list)) {
-               const char *subsys = udev_device_get_subsystem(udev_device);
+               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 (strcmp(udev_list_entry_get_name(list_entry), subsys) == 0) {
-                       pass= 1;
-                       break;
-               }
+               if (strcmp(dsubsys, subsys) != 0)
+                       continue;
+
+               devtype = udev_list_entry_get_value(list_entry);
+               if (devtype == NULL)
+                       return 1;
+               ddevtype = udev_device_get_devtype(udev_device);
+               if (ddevtype == NULL)
+                       continue;
+               if (strcmp(ddevtype, devtype) == 0)
+                       return 1;
        }
-       return pass;
+       return 0;
 }
 
 /**
@@ -648,6 +669,9 @@ int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_devi
                nlh.magic = htonl(UDEV_MONITOR_MAGIC);
                val = udev_device_get_subsystem(udev_device);
                nlh.filter_subsystem = htonl(util_string_hash32(val));
+               val = udev_device_get_devtype(udev_device);
+               if (val != NULL)
+                       nlh.filter_devtype = htonl(util_string_hash32(val));
                iov[0].iov_base = &nlh;
                iov[0].iov_len = sizeof(struct udev_monitor_netlink_header);
 
@@ -672,14 +696,14 @@ int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_devi
        return count;
 }
 
-int udev_monitor_filter_add_match_subsystem(struct udev_monitor *udev_monitor, const char *subsystem)
+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 0;
        if (udev_list_entry_add(udev_monitor->udev,
-                               &udev_monitor->filter_subsystem_list, subsystem, NULL, 1, 0) == NULL)
+                               &udev_monitor->filter_subsystem_list, subsystem, devtype, 0, 0) == NULL)
                return -ENOMEM;
        return 0;
 }