[PATCH v3 2/2] IMA: Add audit log for failure conditions

[Mimi Zohar]

On Thu, 2020-06-18 at 14:10 -0700, Lakshmi Ramasubramanian wrote:
> process_buffer_measurement() and ima_alloc_key_entry() functions need to
> log an audit message for auditing integrity measurement failures.
> 
> Add audit message in these two functions. Remove "pr_devel" log message
> in process_buffer_measurement().
> 
> Sample audit messages:
> 
> [    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0
> auid=4294967295 ses=4294967295 subj=kernel op=measuring_key
> cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0
> errno=-12

My only concern is that auditing -ENOMEM will put additional memory
pressure on the system.  I'm not sure if this is a concern and, if so,
how it should be handled.

> 
> [    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1
> uid=0 auid=4294967295 ses=4294967295
> subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline
> cause=hashing_error comm="systemd" name="kexec-cmdline" res=0
> errno=-22
> 
> Signed-off-by: Lakshmi Ramasubramanian <nramas at linux.microsoft.com>

Reviewed-by: Mimi Zohar <zohar at linux.ibm.com>