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author | Nick Kralevich <nnk@google.com> | 2011-04-18 15:55:59 -0700 |
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committer | Nick Kralevich <nnk@google.com> | 2011-04-19 12:33:44 -0700 |
commit | 6bc08280108d020edfceff039f3955eebdc1e45c (patch) | |
tree | daefe1fa1cb80f28ed17c2291af071170eb7f5f5 /libsysutils/src/NetlinkListener.cpp | |
parent | 71ead1835317af5305f9ef87ce06ebdf9cff92e6 (diff) | |
download | system_core-6bc08280108d020edfceff039f3955eebdc1e45c.zip system_core-6bc08280108d020edfceff039f3955eebdc1e45c.tar.gz system_core-6bc08280108d020edfceff039f3955eebdc1e45c.tar.bz2 |
Validate sender credentials on netlink msg receive
Verify that netlink messages are actually from the kernel,
and not from a userspace program.
This is a manual cherry-pick from b620a0b1c7ae486e979826200e8e441605b0a5d6
Change-Id: I237f0a5cb56393bb3aab64a7ae5898f2bdc95cef
Diffstat (limited to 'libsysutils/src/NetlinkListener.cpp')
-rw-r--r-- | libsysutils/src/NetlinkListener.cpp | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/libsysutils/src/NetlinkListener.cpp b/libsysutils/src/NetlinkListener.cpp index a4f62c6..ddf6537 100644 --- a/libsysutils/src/NetlinkListener.cpp +++ b/libsysutils/src/NetlinkListener.cpp @@ -17,6 +17,7 @@ #include <sys/types.h> #include <sys/socket.h> +#include <linux/netlink.h> #include <string.h> #define LOG_TAG "NetlinkListener" @@ -32,11 +33,33 @@ NetlinkListener::NetlinkListener(int socket) : bool NetlinkListener::onDataAvailable(SocketClient *cli) { int socket = cli->getSocket(); - int count; + ssize_t count; + char cred_msg[CMSG_SPACE(sizeof(struct ucred))]; + struct sockaddr_nl snl; + struct iovec iov = {mBuffer, sizeof(mBuffer)}; + struct msghdr hdr = {&snl, sizeof(snl), &iov, 1, cred_msg, sizeof(cred_msg), 0}; - count = TEMP_FAILURE_RETRY(recv(socket, mBuffer, sizeof(mBuffer), 0)); + count = TEMP_FAILURE_RETRY(recvmsg(socket, &hdr, 0)); if (count < 0) { - SLOGE("recv failed (%s)", strerror(errno)); + SLOGE("recvmsg failed (%s)", strerror(errno)); + return false; + } + + if ((snl.nl_groups != 1) || (snl.nl_pid != 0)) { + SLOGE("ignoring non-kernel netlink multicast message"); + return false; + } + + struct cmsghdr * cmsg = CMSG_FIRSTHDR(&hdr); + + if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) { + SLOGE("ignoring message with no sender credentials"); + return false; + } + + struct ucred * cred = (struct ucred *)CMSG_DATA(cmsg); + if (cred->uid != 0) { + SLOGE("ignoring message from non-root UID %d", cred->uid); return false; } |