[PATCH 05/12] ima: Fail rule parsing when buffer hook functions have an invalid action
From: Tyler Hicks <hidden>
Date: 2020-06-23 00:34:25
Also in:
linux-integrity, lkml
Subsystem:
extended verification module (evm), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Mimi Zohar, Roberto Sassu, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
Buffer based hook functions, such as KEXEC_CMDLINE and KEY_CHECK, can
only measure. The process_buffer_measurement() function quietly ignores
all actions except measure so make this behavior clear at the time of
policy load.
The parsing of the keyrings conditional had a check to ensure that it
was only specified with measure actions but the check should be on the
hook function and not the keyrings conditional since
"appraise func=KEY_CHECK" is not a valid rule.
Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments")
Fixes: 5808611cccb2 ("IMA: Add KEY_CHECK func to measure keys")
Signed-off-by: Tyler Hicks <redacted>
---
security/integrity/ima/ima_policy.c | 36 +++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index ee5152ecd3d9..ecc234b956a2 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c@@ -979,6 +979,39 @@ static void check_template_modsig(const struct ima_template_desc *template) #undef MSG } +static bool ima_validate_rule(struct ima_rule_entry *entry) +{ + if (entry->action == UNKNOWN) + return false; + + if (entry->flags & IMA_FUNC) { + switch (entry->func) { + case NONE: + case FILE_CHECK: + case MMAP_CHECK: + case BPRM_CHECK: + case CREDS_CHECK: + case POST_SETATTR: + case MODULE_CHECK: + case FIRMWARE_CHECK: + case KEXEC_KERNEL_CHECK: + case KEXEC_INITRAMFS_CHECK: + case POLICY_CHECK: + break; + case KEXEC_CMDLINE: + case KEY_CHECK: + if (entry->action & ~(MEASURE | DONT_MEASURE)) + return false; + + break; + default: + return false; + } + } + + return true; +} + static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) { struct audit_buffer *ab;
@@ -1156,7 +1189,6 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) keyrings_len = strlen(args[0].from) + 1; if ((entry->keyrings) || - (entry->action != MEASURE) || (entry->func != KEY_CHECK) || (keyrings_len < 2)) { result = -EINVAL;
@@ -1362,7 +1394,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) break; } } - if (!result && (entry->action == UNKNOWN)) + if (!result && !ima_validate_rule(entry)) result = -EINVAL; else if (entry->action == APPRAISE) temp_ima_appraise |= ima_appraise_flag(entry->func);
--
2.25.1