Re: [PATCH RFC] tests: check decoding of libudev netlink header

[Harsha S. <har...@gm...>]

On Sun, Feb 18, 2018 at 9:08 AM, Chen Jingpiao <che...@gm...> wrote:
> On 02/16 02:19, Harsha Sharma wrote:
>> * tests/netlink_kobject_uevent_libudev.c: New file.
>> * tests/gen_tests.in (netlink_kobject_uevent_libudev): New entry.
>> * tests/pure_executables.list: Add netlink_kobject_uevent_libudev.
>> * tests/.gitignore: Likewise.
>>
>> Signed-off-by: Harsha Sharma <har...@gm...>
>> ---
>>  tests/.gitignore                       |  1 +
>>  tests/gen_tests.in                     |  1 +
>>  tests/netlink_kobject_uevent_libudev.c | 88 ++++++++++++++++++++++++++++++++++
>>  tests/pure_executables.list            |  1 +
>>  4 files changed, 91 insertions(+)
>>  create mode 100644 tests/netlink_kobject_uevent_libudev.c
>>
>> diff --git a/tests/.gitignore b/tests/.gitignore
>> index 2541ec24..623b98f8 100644
>> --- a/tests/.gitignore
>> +++ b/tests/.gitignore
>> @@ -215,6 +215,7 @@ netlink_crypto
>>  netlink_generic
>>  netlink_inet_diag
>>  netlink_kobject_uevent
>> +netlink_kobject_uevent_libudev
>>  netlink_netfilter
>>  netlink_netlink_diag
>>  netlink_protocol
>> diff --git a/tests/gen_tests.in b/tests/gen_tests.in
>> index 18f36408..263479a5 100644
>> --- a/tests/gen_tests.in
>> +++ b/tests/gen_tests.in
>> @@ -199,6 +199,7 @@ netlink_audit     +netlink_sock_diag.test
>>  netlink_crypto       +netlink_sock_diag.test
>>  netlink_generic      +netlink_sock_diag.test
>>  netlink_kobject_uevent       +netlink_sock_diag.test
>> +netlink_kobject_uevent_libudev  +netlink_sock_diag.test
>>  netlink_netfilter    +netlink_sock_diag.test
>>  netlink_protocol     -e trace=sendto
>>  netlink_route        +netlink_sock_diag.test
>> diff --git a/tests/netlink_kobject_uevent_libudev.c b/tests/netlink_kobject_uevent_libudev.c
>> new file mode 100644
>> index 00000000..8f0b2bfa
>> --- /dev/null
>> +++ b/tests/netlink_kobject_uevent_libudev.c
>> @@ -0,0 +1,88 @@
>> +/*
>> + * Copyright (c) 2017 JingPiao Chen <che...@gm...>
>> + * Copyright (c) 2017 The strace developers.
>> + * All rights reserved.
>> + *
>> + * Redistribution and use in source and binary forms, with or without
>> + * modification, are permitted provided that the following conditions
>> + * are met:
>> + * 1. Redistributions of source code must retain the above copyright
>> + *    notice, this list of conditions and the following disclaimer.
>> + * 2. Redistributions in binary form must reproduce the above copyright
>> + *    notice, this list of conditions and the following disclaimer in the
>> + *    documentation and/or other materials provided with the distribution.
>> + * 3. The name of the author may not be used to endorse or promote products
>> + *    derived from this software without specific prior written permission.
>> + *
>> + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
>> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
>> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
>> + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
>> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
>> + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
>> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
>> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
>> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
>> + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>> + */
>> +
>> +#include "tests.h"
>> +#include <stdio.h>
>> +#include <string.h>
>> +#include <sys/socket.h>
>> +#include "netlink.h"
>> +#include "netlink_kobject_uevent.h"
>> +#include <sys/types.h>
>> +#include <unistd.h>
>> +#include <arpa/inet.h>
>> +#include <fcntl.h>
>> +
>> +int
>> +main(void)
>> +{
>> +     skip_if_unavailable("/proc/self/fd/");
>> +
>> +     int fd, ret;
>> +     struct sockaddr_nl nls;
>> +     struct udev_monitor_netlink_header uh;
>> +
>> +     memset(&nls, 0, sizeof(nls));
>> +     nls.nl_family = AF_NETLINK;
>> +     nls.nl_pid = getpid();
>> +     nls.nl_groups = -1;
>> +
>> +     fd = socket(AF_NETLINK, (SOCK_DGRAM | SOCK_CLOEXEC),
>> +                 NETLINK_KOBJECT_UEVENT);
>> +     if (fd < 0)
>> +             perror_msg_and_skip("socket AF_NETLINK");
>> +
>> +     ret = bind(fd, (struct sockaddr *) &nls, sizeof(nls));
>> +     if (ret)
>> +             perror_msg_and_skip("bind AF_NETLINK");
>
> Replace with create_nl_socket().

I need to set nls.nl_pid = getpid();
and nls.nl_groups = -1; to recieve from kernel broadcast so using
create_nl_socket in place of this doesn't work.

>> +
>> +     printf("Waiting for events now...\n");
>
> Why print this message?

This is a RFC patch so to clear what's happening I left this.

>> +     while (1) {
>> +             int r = recv(fd, &uh, sizeof(uh), MSG_ERRQUEUE);
>> +             if (r <= 0)
>> +                     perror_msg_and_skip("recv");
>> +             if (!strcmp(uh.prefix, "libudev"))
>> +                     printf("recvfrom(%i, {{prefix=\"%s\""
>> +                            ", magic=htonl(%#x), header_size=%u"
>> +                            ", properties_off=%u, properties_len=%u"
>> +                            ", filter_subsystem_hash=htonl(%#x)"
>> +                            ", filter_devtype_hash=htonl(%#x)"
>> +                            ", filter_tag_bloom_hi=htonl(%#x)"
>> +                            ", filter_tag_bloom_lo=htonl(%#x)}}, %li"
>> +                            ", MSG_ERRQUEUE, NULL, NULL)\n",
>> +                            fd, uh.prefix, ntohl(uh.magic), uh.header_size,
>> +                            uh.properties_off, uh.properties_len,
>> +                            ntohl(uh.filter_subsystem_hash),
>> +                            ntohl(uh.filter_devtype_hash),
>> +                            ntohl(uh.filter_tag_bloom_hi),
>> +                            ntohl(uh.filter_tag_bloom_lo), sizeof(uh));
>> +     }
>
> I do not understand how this work. travis-ci is fail.

This actually waits for kernel uevents and prints decoding of
udev_monitor_netlink_header.
On strace -e trace=network ./tests/netlink_kobject_uvent_libudev, it
shows decoding of libudev header along with printf output which is
exactly same.

> netlink_kobject_uevent_libudev.gen.test source netlink_sock_diag.test,
> which only trace sendto syscall.

strace -e trace=sendto udevadm monitor > /dev/null shows no output.
NETLINK_KOBJECT_UEVENT protocol is used to receive kernel messages to
userspace so sendto syscall is never used in this process. So make
check for this test is supposed to fail.
Please let me know if I'm wrong somewhere or any other way this test
can be improved.
Thanks a lot for your review.


>> +
>> +     close(fd);
>> +     puts("+++ exited with 0 +++");
>> +     return 0;
>> +}
>> diff --git a/tests/pure_executables.list b/tests/pure_executables.list
>> index 2f602a93..1ed40d1f 100755
>> --- a/tests/pure_executables.list
>> +++ b/tests/pure_executables.list
>> @@ -175,6 +175,7 @@ netlink_audit
>>  netlink_crypto
>>  netlink_generic
>>  netlink_kobject_uevent
>> +netlink_kobject_uevent_libudev
>>  netlink_netfilter
>>  netlink_protocol
>>  netlink_route
>> --
>> 2.14.1
>>
>
> --

Regards,
Harsha Sharma