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Commit 41aa2c37 authored by Daniel Mentz's avatar Daniel Mentz
Browse files

Increase netlink uevent rcvbuf size to 16M 

Increase size of the NETLINK_KOBJECT_UEVENT socket receive buffer to
16M.  Also, use SO_RCVBUFFORCE to override any limits set by
/proc/sys/net/core/rmem_max.

We had a couple of instances, where we lost critical uevent messages due
to receive buffer overflows.

Bug: 119933843
Change-Id: I6aab183aa0194e173f9175b47c6beb0835cf6675
parent 67fe6f09

init/uevent_listener.cpp

+2 −2
Original line number Diff line number Diff line
@@ -87,8 +87,8 @@ static void ParseEvent(const char* msg, Uevent* uevent) { 
}



UeventListener::UeventListener() {

    // is 2MB enough? udev uses 128MB!

    device_fd_.reset(uevent_open_socket(2 * 1024 * 1024, true));

    // is 16MB enough? udev uses 128MB!

    device_fd_.reset(uevent_open_socket(16 * 1024 * 1024, true));

    if (device_fd_ == -1) {

        LOG(FATAL) << "Could not open uevent socket";

    }

libcutils/uevent.cpp

+14 −2
Original line number Diff line number Diff line
@@ -95,6 +95,8 @@ out: 
int uevent_open_socket(int buf_sz, bool passcred) {

    struct sockaddr_nl addr;

    int on = passcred;

    int buf_sz_readback = 0;

    socklen_t optlen = sizeof(buf_sz_readback);

    int s;



    memset(&addr, 0, sizeof(addr));
@@ -105,11 +107,21 @@ int uevent_open_socket(int buf_sz, bool passcred) { 
    s = socket(PF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_KOBJECT_UEVENT);

    if (s < 0) return -1;



    /* buf_sz should be less than net.core.rmem_max for this to succeed */

    if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, &buf_sz, sizeof(buf_sz)) < 0) {

    if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, &buf_sz, sizeof(buf_sz)) < 0 ||

          getsockopt(s, SOL_SOCKET, SO_RCVBUF, &buf_sz_readback, &optlen) < 0) {

        close(s);

        return -1;

    }

    /* Only if SO_RCVBUF was not effective, try SO_RCVBUFFORCE. Generally, we

     * want to avoid SO_RCVBUFFORCE, because it generates SELinux denials in

     * case we don't have CAP_NET_ADMIN. This is the case, for example, for

     * healthd. */

    if (buf_sz_readback < 2 * buf_sz) {

        if (setsockopt(s, SOL_SOCKET, SO_RCVBUFFORCE, &buf_sz, sizeof(buf_sz)) < 0) {

            close(s);

            return -1;

        }

    }



    setsockopt(s, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));