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Re: [RFC][PATCH] collect security labels on user processes generating audit messages



On Thu, 2006-02-16 at 09:56 -0500, Steve Grubb wrote:
> OK, I chased this down to make sure of what is happening. The audit working 
> group has a test kernel, lspp.8, that has all the future audit and lspp 
> patches in it for testing. (it can be found at 
> http://people.redhat.com/sgrubb/files/lspp). There is a patch 
> linux-2.6-audit-git.patch, which is not upstream, but should be in the next 
> kernel. That changes the code in audit_log_exit of auditsc.c to:
> 
>                 if (context->names[i].name)
>                         audit_log_untrustedstring(ab, context->names[i].name);
>                 else
>                         audit_log_format(ab, "(null)");
> 
> The code in audit_log_untrustedstring does this:
> 
>         while (*p) {
>                 if (*p == '"' || *p == '(' || *p < 0x21 || *p > 0x7f) {
>                         audit_log_hex(ab, string, strlen(string));
>                         return;
>                 }
>                 p++;
>         }
>         audit_log_format(ab, "\"%s\"", string);
> 
> This means that a real NULL will never have the double-quote marks around it, 
> where a file named \(null\) will always have double-quote marks around it. I 
> confirmed this by looking in the audit logs. 
> 
> However...ausearch does not make this distinction in its output. I will see 
> what I can do to make the necessary adjustments to ausearch so that its more 
> obvious. So, I think that puts this issue to bed...

Except for what other code should do about NULL pointers in output.  If
they defer it to vsnprintf, they will end up with <NULL> in the output.
So should Tim's code be checking for !ctx and outputting (null) there as
well?

-- 
Stephen Smalley
National Security Agency


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