Hello, On Wednesday, August 11, 2021 3:40:51 PM EDT Mimi Zohar wrote: > On Wed, 2021-08-11 at 11:40 +0000, THOBY Simon wrote: > Other than the two questions on " IMA: add a policy option to restrict > xattr hash algorithms on appraisal" patch, the patch set is looking > good. > > thanks, > > Mimi > > > Here is also a short description of the new audit messages, but I can > > send it in a followup mail if that is not the proper place: > > > > When writing the xattr with an algorithm not built in the kernel (here > > the > > kernel was built with CONFIG_CRYPTO_MD5 unset), e.g. with > > > > "evmctl ima_hash -a md5 /usr/bin/strace": > > audit(1628066120.418:121): pid=1344 uid=0 auid=0 ses=1 > > subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 op=set_data > > cause=unavailable-hash-algorithm comm="evmctl" name="/usr/bin/strace" > > dev="dm-0" ino=2632657 res=0 errno=0> Is this audit event accurate? I seem to be seeing name=value=value. I'm hoping this is a copy/paste/mail client issue. -Steve > > With the same command and the policy rule > > > > "appraise func=SETXATTR_CHECK appraise_algos=sha256,sha384,sha512", we get: > > audit(1628066210.141:127): pid=1362 uid=0 auid=0 ses=1 > > subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 op=set_data > > cause=denied-hash-algorithm comm="evmctl" name="/usr/bin/strace" > > dev="dm-0" ino=2632657 res=0 errno=0> > > Note that the cause is now 'denied-hash-algorithm' instead of > > 'unavailable-hash-algorithm'. We get that audit message for any algorithm > > outside of sha256/384/512 (including algorithms not compiled in the > > kernel > > like MD5). In a sense, 'denied-hash-algorithm' takes predecence over > > 'unavailable-hash-algorithm'. > > > > When appraising files, e.g. trying to execute a file whose xattr was > > hashed with sha1 while the policy rule > > > > "appraise func=BPRM_CHECK fowner=0 appraise_algos=sha256" is enabled: > > audit(1628066349.230:130): pid=1369 uid=0 auid=0 ses=1 > > subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 > > op=collect_data cause=denied-hash-algorithm comm="bash" > > name="/usr/bin/strace" dev="dm-0" ino=2632657 res=0 errno=0> > > This series is based on the following repo/branch: > > repo: > > https://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.g > > it branch: next-integrity-testing > > commit e37be5343ae2b9419aea1442b07e5d2428b437b4 ("Merge branch > > 'ima-buffer-measurement-changes-v4' into next-integrity") > -- > Linux-audit mailing list > Linux-audit@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/linux-audit
