[PATCH 5/7] ima: Introduce appraise_exec_immutable policy
From: Roberto Sassu <roberto.sassu@huawei.com>
Date: 2021-04-09 11:45:03
Also in:
linux-integrity, lkml
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
This patch modifies the existing "appraise_exec_tcb" policy, by adding the appraise_type=meta_immutable requirement for executed files. This policy can be selected by specifying ima_policy="appraise_exec_tcb|appraise_exec_immutable" in the kernel command line. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ security/integrity/ima/ima_policy.c | 8 +++++++- 2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 93c5f78905e2..265f7657f59d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt@@ -1780,6 +1780,10 @@ appraised (with imasig requirement) instead of files owned by root. + The "appraise_exec_immutable" policy requires immutable + metadata for executed files, if the "appraise_exec_tcb" + policy is selected. + The "appraise_tmpfs" policy excludes the dont_appraise rule for the tmpfs and ramfs filesystems for the "appraise_tcb" and "appraise_exec_tcb" policies.
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index a45e494e06e8..6249817ebd04 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c@@ -243,6 +243,7 @@ __setup("ima_tcb", default_measure_policy_setup); static unsigned int ima_measure_skip_flags __initdata; static unsigned int ima_appraise_skip_flags __initdata; static bool ima_use_appraise_tcb __initdata; +static bool ima_use_appraise_exec_immutable __initdata; static bool ima_use_secure_boot __initdata; static bool ima_use_critical_data __initdata; static bool ima_fail_unverifiable_sigs __ro_after_init;
@@ -267,7 +268,9 @@ static int __init policy_setup(char *str) else if (strcmp(p, "appraise_exec_tcb") == 0) { ima_use_appraise_tcb = true; ima_appraise_skip_flags |= IMA_SKIP_OPEN; - } else if (strcmp(p, "secure_boot") == 0) + } else if (strcmp(p, "appraise_exec_immutable") == 0) + ima_use_appraise_exec_immutable = 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;
@@ -913,6 +916,9 @@ void __init ima_init_policy(void) IMA_DEFAULT_POLICY, 0); } + if (ima_use_appraise_exec_immutable) + appraise_exec_rules[0].flags |= IMA_META_IMMUTABLE_REQUIRED; + if (ima_use_critical_data) add_rules(critical_data_rules, ARRAY_SIZE(critical_data_rules),
--
2.26.2