Remove socket deletion from epoll

[albertomn86]

Description

The file descriptor deletion from the epoll has been removed from the HandleSecure() function.

wazuh/src/remoted/secure.c

Lines 198 to 200 in 090986e

	if (wnotify_delete(notify, sock_client) < 0) {
	merror("wnotify_delete(%d): %s (%d)", sock_client, strerror(errno), errno);
	}

This deletion is not necessary because the file descriptor is removed from it after all the file descriptors referring to the socket have been closed. It is described here:

• epoll documentation:

Will closing a file descriptor cause it to be removed from all epoll interest lists?

Yes, but be aware of the following point. A file descriptor is a reference to an open file description (see open(2)). Whenever a file descriptor is duplicated via dup(2), dup2(2), fcntl(2) F_DUPFD, or fork(2), a new file descriptor referring to the same open file description is created. An open file description con‐ tinues to exist until all file descriptors referring to it have been closed.

• kqueue manual:

Calling close() on a file descriptor will remove any kevents that reference the descriptor.

In high load environments, this deletion might cause a race condition and the following error could appear:

2019/05/20 05:33:12 ossec-remoted: ERROR: wnotify_delete(130): Bad file descriptor (9)

Tests

• Compilation without warnings in every supported platform
  • Linux
• Source installation
• Source upgrade
• Memory tests
  • Valgrind report for affected components
  • CPU impact
  • RAM usage impact
• Retrocompatibility with older Wazuh versions
• Working on cluster environments

[vikman90]

LGTM!

[albertomn86]

Valgrind report

 ==27534== Memcheck, a memory error detector
==27534== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==27534== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==27534== Command: /var/ossec/bin/ossec-remoted -fdd
==27534== Parent PID: 3948
==27534==
==27534==
==27534== HEAP SUMMARY:
==27534==     in use at exit: 55 bytes in 6 blocks
==27534==   total heap usage: 12,016 allocs, 12,010 frees, 5,171,311 bytes allocated
==27534==
==27534== LEAK SUMMARY:
==27534==    definitely lost: 0 bytes in 0 blocks
==27534==    indirectly lost: 0 bytes in 0 blocks
==27534==      possibly lost: 0 bytes in 0 blocks
==27534==    still reachable: 55 bytes in 6 blocks
==27534==         suppressed: 0 bytes in 0 blocks
==27534== Reachable blocks (those to which a pointer was found) are not shown.
==27534== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==27534==
==27534== For counts of detected and suppressed errors, rerun with: -v
==27534== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
==27534== could not unlink /tmp/vgdb-pipe-from-vgdb-to-27534-by-root-on-???
==27534== could not unlink /tmp/vgdb-pipe-to-vgdb-from-27534-by-root-on-???
==27534== could not unlink /tmp/vgdb-pipe-shared-mem-vgdb-27534-by-root-on-???