ASR_BASE
Change-Id: Icf3719cc0afe3eeb3edc7fa80a2eb5199ca9dda1
diff --git a/package/utils/adbd/src/libcutils/uevent.c b/package/utils/adbd/src/libcutils/uevent.c
new file mode 100644
index 0000000..97a81e3
--- /dev/null
+++ b/package/utils/adbd/src/libcutils/uevent.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <cutils/uevent.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include <linux/netlink.h>
+
+/**
+ * Like recv(), but checks that messages actually originate from the kernel.
+ */
+ssize_t uevent_kernel_multicast_recv(int socket, void *buffer, size_t length)
+{
+ uid_t user = -1;
+ return uevent_kernel_multicast_uid_recv(socket, buffer, length, &user);
+}
+
+/**
+ * Like the above, but passes a uid_t in by reference. In the event that this
+ * fails due to a bad uid check, the uid_t will be set to the uid of the
+ * socket's peer.
+ *
+ * If this method rejects a netlink message from outside the kernel, it
+ * returns -1, sets errno to EIO, and sets "user" to the UID associated with the
+ * message. If the peer UID cannot be determined, "user" is set to -1."
+ */
+ssize_t uevent_kernel_multicast_uid_recv(int socket, void *buffer,
+ size_t length, uid_t *user)
+{
+ struct iovec iov = { buffer, length };
+ struct sockaddr_nl addr;
+ char control[CMSG_SPACE(sizeof(struct ucred))];
+ struct msghdr hdr = {
+ &addr,
+ sizeof(addr),
+ &iov,
+ 1,
+ control,
+ sizeof(control),
+ 0,
+ };
+
+ *user = -1;
+ ssize_t n = recvmsg(socket, &hdr, 0);
+ if (n <= 0) {
+ return n;
+ }
+
+ struct cmsghdr *cmsg = CMSG_FIRSTHDR(&hdr);
+ if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
+ /* ignoring netlink message with no sender credentials */
+ goto out;
+ }
+
+ struct ucred *cred = (struct ucred *)CMSG_DATA(cmsg);
+ *user = cred->uid;
+ if (cred->uid != 0) {
+ /* ignoring netlink message from non-root user */
+ goto out;
+ }
+
+ if (addr.nl_groups == 0 || addr.nl_pid != 0) {
+ /* ignoring non-kernel or unicast netlink message */
+ goto out;
+ }
+
+ return n;
+
+out:
+ /* clear residual potentially malicious data */
+ bzero(buffer, length);
+ errno = EIO;
+ return -1;
+}
+
+int uevent_open_socket(int buf_sz, bool passcred)
+{
+ struct sockaddr_nl addr;
+ int on = passcred;
+ int s;
+
+ memset(&addr, 0, sizeof(addr));
+ addr.nl_family = AF_NETLINK;
+ addr.nl_pid = getpid();
+ addr.nl_groups = 0xffffffff;
+
+ s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
+ if(s < 0)
+ return -1;
+
+ setsockopt(s, SOL_SOCKET, SO_RCVBUFFORCE, &buf_sz, sizeof(buf_sz));
+ setsockopt(s, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
+
+ if(bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+ close(s);
+ return -1;
+ }
+
+ return s;
+}