[PATCH v9 7/8] IMA: define a builtin critical data measurement policy
From: Tushar Sugandhi <hidden>
Date: 2020-12-12 18:06:56
Also in:
dm-devel, linux-integrity, lkml, selinux
Subsystem:
documentation, extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Jonathan Corbet, Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
From: Lakshmi Ramasubramanian <redacted> Define a new critical data builtin policy to allow measuring early kernel integrity critical data before a custom IMA policy is loaded. Add critical data to built-in IMA rules if the kernel command line contains "ima_policy=critical_data". Update the documentation on kernel parameters to document the new critical data builtin policy. Signed-off-by: Lakshmi Ramasubramanian <redacted> Reviewed-by: Tyler Hicks <redacted> --- Documentation/admin-guide/kernel-parameters.txt | 5 ++++- security/integrity/ima/ima_policy.c | 12 ++++++++++++ 2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 526d65d8573a..6034d75c3ca0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt@@ -1746,7 +1746,7 @@ ima_policy= [IMA] The builtin policies to load during IMA setup. Format: "tcb | appraise_tcb | secure_boot | - fail_securely" + fail_securely | critical_data" The "tcb" policy measures all programs exec'd, files mmap'd for exec, and all files opened with the read
@@ -1765,6 +1765,9 @@ filesystems with the SB_I_UNVERIFIABLE_SIGNATURE flag. + The "critical_data" policy measures kernel integrity + critical data. + ima_tcb [IMA] Deprecated. Use ima_policy= instead. Load a policy which meets the needs of the Trusted Computing Base. This means IMA will measure all
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index fea996a9e26c..376b625acc72 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 __initdata; 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
@@ -872,6 +879,11 @@ 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(); }
--
2.17.1