Messages in this thread | | | Subject | Re: [PATCH v7 4/8] IMA: add policy rule to measure critical data | From | Tushar Sugandhi <> | Date | Thu, 10 Dec 2020 19:28:15 -0800 |
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On 2020-12-10 3:10 p.m., Tyler Hicks wrote: > On 2020-12-09 11:42:08, Tushar Sugandhi wrote: >> A new IMA policy rule is needed for the IMA hook >> ima_measure_critical_data() and the corresponding func CRITICAL_DATA for >> measuring the input buffer. The policy rule should ensure the buffer >> would get measured only when the policy rule allows the action. The >> policy rule should also support the necessary constraints (flags etc.) >> for integrity critical buffer data measurements. >> >> Add a policy rule to define the constraints for restricting integrity >> critical data measurements. >> >> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com> >> --- >> security/integrity/ima/ima_policy.c | 35 +++++++++++++++++++++++++---- >> 1 file changed, 31 insertions(+), 4 deletions(-) >> >> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c >> index 2a0c0603626e..9a8ee80a3128 100644 >> --- a/security/integrity/ima/ima_policy.c >> +++ b/security/integrity/ima/ima_policy.c >> @@ -34,6 +34,7 @@ >> #define IMA_PCR 0x0100 >> #define IMA_FSNAME 0x0200 >> #define IMA_KEYRINGS 0x0400 >> +#define IMA_DATA_SOURCE 0x0800 > > You introduce data_source= in the next patch. This macro shouldn't be > added until the next patch. > Ok I will move IMA_DATA_SOURCE to the next patch.
>> >> #define UNKNOWN 0 >> #define MEASURE 0x0001 /* same as IMA_MEASURE */ >> @@ -85,6 +86,7 @@ struct ima_rule_entry { >> } lsm[MAX_LSM_RULES]; >> char *fsname; >> struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */ >> + struct ima_rule_opt_list *data_source; /* Measure data from this source */ >> struct ima_template_desc *template; >> }; >> >> @@ -479,6 +481,12 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule, >> else >> opt_list = rule->keyrings; >> break; >> + case CRITICAL_DATA: >> + if (!rule->data_source) >> + return true; >> + else >> + opt_list = rule->data_source; > > If you take my suggestions on patch #1, remove the else and simply > assign opt_list here, too. > Yup. Will do. >> + break; >> default: >> break; >> } >> @@ -518,13 +526,19 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, >> { >> int i; >> >> - if (func == KEY_CHECK) { >> - return (rule->flags & IMA_FUNC) && (rule->func == func) && >> - ima_match_rule_data(rule, func_data, cred); >> - } >> if ((rule->flags & IMA_FUNC) && >> (rule->func != func && func != POST_SETATTR)) >> return false; >> + >> + switch (func) { >> + case KEY_CHECK: >> + case CRITICAL_DATA: >> + return ((rule->func == func) && >> + ima_match_rule_data(rule, func_data, cred)); >> + default: >> + break; >> + } >> + >> if ((rule->flags & IMA_MASK) && >> (rule->mask != mask && func != POST_SETATTR)) >> return false; >> @@ -1119,6 +1133,19 @@ static bool ima_validate_rule(struct ima_rule_entry *entry) >> if (ima_rule_contains_lsm_cond(entry)) >> return false; >> >> + break; >> + case CRITICAL_DATA: >> + if (entry->action & ~(MEASURE | DONT_MEASURE)) >> + return false; >> + >> + if (!(entry->flags & IMA_DATA_SOURCE) || >> + (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR | >> + IMA_DATA_SOURCE))) > > IMA_DATA_SOURCE shouldn't exist in this patch. This isn't the right > indentation, either. See how IMA_KEYRINGS is indented in the KEY_CHECK > case above. > Will do. ~Tushar > Tyler > >> + return false; >> + >> + if (ima_rule_contains_lsm_cond(entry)) >> + return false; >> + >> break; >> default: >> return false; >> -- >> 2.17.1 >>
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