Messages in this thread | | | Subject | Re: [PATCH v6 7/8] IMA: add a built-in policy rule for critical data measurement | From | Lakshmi Ramasubramanian <> | Date | Fri, 20 Nov 2020 15:33:36 -0800 |
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On 11/20/20 6:30 AM, Mimi Zohar wrote:
Hi Mimi,
> > On Thu, 2020-11-19 at 15:26 -0800, Tushar Sugandhi wrote: >> From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> >> >> The IMA hook to measure kernel critical data, namely >> ima_measure_critical_data(), could be called before a custom IMA policy >> is loaded. >> Define a new critical data builtin policy to allow measuring >> early kernel integrity critical data before a custom IMA policy is >> loaded. > > Everything needing to be said seems to be included in the second > sentence. Does the first sentence add anything? "Define a new > critical data builtin policy" makes for a good Subject line.
Agreed - will update.
> >> >> Add critical data to built-in IMA rules if the kernel command line >> contains "ima_policy=critical_data". > > The boot command line parameters are defined in Documentation/admin- > guide/kernel-parameters.txt. Please update "ima_policy".
Will do.
> >> >> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com> >> --- >> security/integrity/ima/ima_policy.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c >> index c9e52dab0638..119604a3efa0 100644 >> --- a/security/integrity/ima/ima_policy.c >> +++ b/security/integrity/ima/ima_policy.c >> @@ -206,6 +206,10 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { >> .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, >> }; >> >> +static struct ima_rule_entry critical_data_rules[] __ro_after_init = { >> + {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC}, >> +}; >> + >> /* An array of architecture specific rules */ >> static struct ima_rule_entry *arch_policy_entry __ro_after_init; >> >> @@ -228,6 +232,7 @@ __setup("ima_tcb", default_measure_policy_setup); >> >> static bool ima_use_appraise_tcb __initdata; >> static bool ima_use_secure_boot __initdata; >> +static bool ima_use_critical_data __ro_after_init; > > Unlike ima_fail_unverifiable_sigs, ima_use_critical_data is only used > during __init. Please change "__ro_after_init" to "__initdata". (The > critical data policy itself is defined properly as __ro_after_init.)
Will do.
> >> static bool ima_fail_unverifiable_sigs __ro_after_init; >> static int __init policy_setup(char *str) >> { >> @@ -242,6 +247,8 @@ static int __init policy_setup(char *str) >> ima_use_appraise_tcb = true; >> else if (strcmp(p, "secure_boot") == 0) >> ima_use_secure_boot = true; >> + else if (strcmp(p, "critical_data") == 0) >> + ima_use_critical_data = true; >> else if (strcmp(p, "fail_securely") == 0) >> ima_fail_unverifiable_sigs = true; >> else >> @@ -875,6 +882,11 @@ void __init ima_init_policy(void) >> ARRAY_SIZE(default_appraise_rules), >> IMA_DEFAULT_POLICY); >> >> + if (ima_use_critical_data) >> + add_rules(critical_data_rules, >> + ARRAY_SIZE(critical_data_rules), >> + IMA_DEFAULT_POLICY); >> + >> ima_update_policy_flag(); >> } >> >
thanks, -lakshmi
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