Messages in this thread Patch in this message | | | Date | Fri, 17 Jul 2020 13:11:33 -0500 | From | Tyler Hicks <> | Subject | Re: [PATCH v3 07/12] ima: Fail rule parsing when appraise_flag=blacklist is unsupportable |
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On 2020-07-17 13:40:22, Nayna wrote: > > On 7/9/20 2:19 AM, Tyler Hicks wrote: > > The "appraise_flag" option is only appropriate for appraise actions > > and its "blacklist" value is only appropriate when > > CONFIG_IMA_APPRAISE_MODSIG is enabled and "appraise_flag=blacklist" is > > only appropriate when "appraise_type=imasig|modsig" is also present. > > Make this clear at policy load so that IMA policy authors don't assume > > that other uses of "appraise_flag=blacklist" are supported. > > > > Fixes: 273df864cf74 ("ima: Check against blacklisted hashes for files with modsig") > > Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com> > > Cc: Nayna Jain <nayna@linux.ibm.com> > > --- > > > > * v3 > > - New patch > > > > security/integrity/ima/ima_policy.c | 13 ++++++++++++- > > 1 file changed, 12 insertions(+), 1 deletion(-) > > > > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c > > index 81da02071d41..9842e2e0bc6d 100644 > > --- a/security/integrity/ima/ima_policy.c > > +++ b/security/integrity/ima/ima_policy.c > > @@ -1035,6 +1035,11 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) > > return false; > > } > > + /* Ensure that combinations of flags are compatible with each other */ > > + if (entry->flags & IMA_CHECK_BLACKLIST && > > + !(entry->flags & IMA_MODSIG_ALLOWED)) > > + return false; > > + > > return true; > > } > > @@ -1371,8 +1376,14 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) > > result = -EINVAL; > > break; > > case Opt_appraise_flag: > > + if (entry->action != APPRAISE) { > > + result = -EINVAL; > > + break; > > + } > > + > > ima_log_string(ab, "appraise_flag", args[0].from); > > - if (strstr(args[0].from, "blacklist")) > > + if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) && > > + strstr(args[0].from, "blacklist")) > > entry->flags |= IMA_CHECK_BLACKLIST; > > If IMA_APPRAISE_MODSIG is disabled, it will allow the following rule to > load, which is not as expected. > > "appraise func=xxx_CHECK appraise_flag=blacklist appraise_type=imasig" > > Missing is the "else" condition to immediately reject the policy rule.
Thanks for the review. You're right. This change is needed:
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 9842e2e0bc6d..cf3ddb38dfa8 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -1385,6 +1385,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) && strstr(args[0].from, "blacklist")) entry->flags |= IMA_CHECK_BLACKLIST; + else + result = -EINVAL; break; case Opt_permit_directio: entry->flags |= IMA_PERMIT_DIRECTIO;
Making this change does not conflict with any later patches in the series.
Mimi, I've rebased and force pushed to my fixup branch with this change, for your comparison:
https://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/linux.git/log/?h=next-integrity-testing-fixup
Tyler
> > Thanks & Regards, > > - Nayna >
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