From: nicolas.iooss@m4x.org (Nicolas Iooss)
Date: Sat, 12 Aug 2017 11:52:18 +0200
Subject: [refpolicy] [PATCH 1/1] audit: allow reading /etc/localtime
Message-ID: <20170812095218.23124-1-nicolas.iooss@m4x.org>
To: refpolicy@oss.tresys.com
List-Id: refpolicy.oss.tresys.com

When auditctl logs a message to syslog, it needs to read /etc/localtime.
This is currently denied:

    avc:  denied  { read } for  pid=191 comm="auditctl" name="UTC"
    dev="vda1" ino=394043 scontext=system_u:system_r:auditctl_t
    tcontext=system_u:object_r:locale_t tclass=file permissive=1
    avc:  denied  { open } for  pid=191 comm="auditctl"
    path="/usr/share/zoneinfo/UTC" dev="vda1" ino=394043
    scontext=system_u:system_r:auditctl_t
    tcontext=system_u:object_r:locale_t tclass=file permissive=1

This occurs for example at boot time when "/usr/bin/augenrules --load"
is run [1]. Here is an extract of "strace -s 256 -f /usr/bin/augenrules
--load":

    [pid   635] execve("/sbin/auditctl", ["/sbin/auditctl", "-R",
    "/etc/audit/audit.rules"], 0x1e77d80 /* 16 vars */) = 0
    ...
    [pid   635] open("/etc/audit/audit.rules", O_RDONLY) = -1 ENOENT (No
    such file or directory)
    [pid   635] open("/etc/localtime", O_RDONLY|O_CLOEXEC) = 4
    [pid   635] fstat(4, {st_mode=S_IFREG|0644, st_size=127, ...}) = 0
    [pid   635] fstat(4, {st_mode=S_IFREG|0644, st_size=127, ...}) = 0
    [pid   635] read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 127
    [pid   635] lseek(4, -71, SEEK_CUR)     = 56
    [pid   635] read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0", 4096) = 71
    [pid   635] close(4)                    = 0
    [pid   635] socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 4
    [pid   635] connect(4, {sa_family=AF_UNIX, sun_path="/dev/log"}, 110) = 0
    [pid   635] sendto(4, "<14>Aug 12 08:59:53 auditctl: file
    /etc/audit/audit.rules doesn't exist, skipping", 81, MSG_NOSIGNAL,
    NULL, 0) = 81
    [pid   635] exit_group(0)               = ?

More precisely, auditctl uses vsyslog() from glibc, which uses
localtime_r() to fetch the time is in local timezone.

[1] On a systemd system, this command is automatically run by
auditd.service unit, cf.
https://github.com/linux-audit/audit-userspace/blob/v2.7.7/init.d/auditd.service#L21
---
 policy/modules/system/logging.te | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/policy/modules/system/logging.te b/policy/modules/system/logging.te
index d87581360e2d..b9bebb56aba1 100644
--- a/policy/modules/system/logging.te
+++ b/policy/modules/system/logging.te
@@ -118,6 +118,8 @@ kernel_setsched(auditctl_t)
 domain_read_all_domains_state(auditctl_t)
 domain_use_interactive_fds(auditctl_t)
 
+miscfiles_read_localization(auditctl_t)
+
 mls_file_read_all_levels(auditctl_t)
 
 term_use_all_terms(auditctl_t)
-- 
2.14.1