am de35f274: am 03752be0: am 0c297f5e: Merge "Revert "Fold uevent message origin checking from init into libcutils.""

* commit 'de35f2741c4e32e331a92be99f7c04b92b94beb2':
  Revert "Fold uevent message origin checking from init into libcutils."

1 files changed, 29 insertions, 5 deletions

diff --git a/init/devices.c b/init/devices.c
index a200c95e..bc36ac15 100644
--- a/init/devices.c
+++ b/init/devices.c
@@ -34,8 +34,6 @@
 #include <asm/page.h>
 #include <sys/wait.h>
 
-#include <cutils/uevent.h>
-
 #include "devices.h"
 #include "util.h"
 #include "log.h"
@@ -772,9 +770,35 @@ static void handle_firmware_event(struct uevent *uevent)
 #define UEVENT_MSG_LEN  1024
 void handle_device_fd()
 {
-    char msg[UEVENT_MSG_LEN+2];
-    int n;
-    while ((n = uevent_checked_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
+    for(;;) {
+        char msg[UEVENT_MSG_LEN+2];
+        char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+        struct iovec iov = {msg, sizeof(msg)};
+        struct sockaddr_nl snl;
+        struct msghdr hdr = {&snl, sizeof(snl), &iov, 1, cred_msg, sizeof(cred_msg), 0};
+
+        ssize_t n = recvmsg(device_fd, &hdr, 0);
+        if (n <= 0) {
+            break;
+        }
+
+        if ((snl.nl_groups != 1) || (snl.nl_pid != 0)) {
+            /* ignoring non-kernel netlink multicast message */
+            continue;
+        }
+
+        struct cmsghdr * cmsg = CMSG_FIRSTHDR(&hdr);
+        if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
+            /* no sender credentials received, ignore message */
+            continue;
+        }
+
+        struct ucred * cred = (struct ucred *)CMSG_DATA(cmsg);
+        if (cred->uid != 0) {
+            /* message from non-root user, ignore */
+            continue;
+        }
+
         if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
             continue;