| Message ID | 20200709061911.954326-8-tyhicks@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support | expand |
On Thu, 2020-07-09 at 01:19 -0500, 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. The code looks correct, but this patch description could be written at a higher level. Perhaps it just needs to be prefixed with something like this: Verifying that a file hash is not blacklisted is currently only supported for files with appended signatures (modsig). In the future, this might change. For now, ... Mimi > > 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; > break; > case Opt_permit_directio:
On 2020-07-16 14:14:50, Mimi Zohar wrote: > On Thu, 2020-07-09 at 01:19 -0500, 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. > > The code looks correct, but this patch description could be written at > a higher level. Perhaps it just needs to be prefixed with something > like this: > > Verifying that a file hash is not blacklisted is currently only > supported for files with appended signatures (modsig). In the future, > this might change. For now, ... That makes sense. I'm not up to speed on the intent behind the blacklist feature or where it may go in the future so I didn't think to add anything along those lines. If you are happy with the rest of the series, please feel free to append this to the commit message. Otherwise, I can add it if I need to submit a new revision of the series. Tyler > > Mimi > > > > > 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; > > break; > > case Opt_permit_directio:
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 >
On 7/17/20 2:11 PM, Tyler Hicks wrote: > 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; > Reviewed-by: Nayna Jain<nayna@linux.ibm.com> Tested-by: Nayna Jain<nayna@linux.ibm.com> Thanks & Regards, - Nayna
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; break; case Opt_permit_directio:
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(-)