9a20e67fa6
Packets captured and logged by the NFLOG target are unicast, so extend to catch and decode them. To avoid escaping issues, the raw contents are passed around as hex strings. Bug: 18335678 Change-Id: Ib7299500baa00080a1f000f9da843eb527363353
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/*
|
|
* 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 uid = -1;
|
|
return uevent_kernel_multicast_uid_recv(socket, buffer, length, &uid);
|
|
}
|
|
|
|
/**
|
|
* Like the above, but passes a uid_t in by pointer. 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 *uid)
|
|
{
|
|
return uevent_kernel_recv(socket, buffer, length, true, uid);
|
|
}
|
|
|
|
ssize_t uevent_kernel_recv(int socket, void *buffer, size_t length, bool require_group, uid_t *uid)
|
|
{
|
|
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,
|
|
};
|
|
|
|
*uid = -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);
|
|
*uid = cred->uid;
|
|
if (cred->uid != 0) {
|
|
/* ignoring netlink message from non-root user */
|
|
goto out;
|
|
}
|
|
|
|
if (addr.nl_pid != 0) {
|
|
/* ignore non-kernel */
|
|
goto out;
|
|
}
|
|
if (require_group && addr.nl_groups == 0) {
|
|
/* ignore unicast messages when requested */
|
|
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;
|
|
}
|