6.6-stable review patch. If anyone has any objections, please let me know.
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From: Zhao Yipeng zhaoyipeng5@huawei.com
[ Upstream commit 738c9738e690f5cea24a3ad6fd2d9a323cf614f6 ]
In ima_match_rules(), if ima_filter_rule_match() returns -ENOENT due to the rule being NULL, the function incorrectly skips the 'if (!rc)' check and sets 'result = true'. The LSM rule is considered a match, causing extra files to be measured by IMA.
This issue can be reproduced in the following scenario: After unloading the SELinux policy module via 'semodule -d', if an IMA measurement is triggered before ima_lsm_rules is updated, in ima_match_rules(), the first call to ima_filter_rule_match() returns -ESTALE. This causes the code to enter the 'if (rc == -ESTALE && !rule_reinitialized)' block, perform ima_lsm_copy_rule() and retry. In ima_lsm_copy_rule(), since the SELinux module has been removed, the rule becomes NULL, and the second call to ima_filter_rule_match() returns -ENOENT. This bypasses the 'if (!rc)' check and results in a false match.
Call trace: selinux_audit_rule_match+0x310/0x3b8 security_audit_rule_match+0x60/0xa0 ima_match_rules+0x2e4/0x4a0 ima_match_policy+0x9c/0x1e8 ima_get_action+0x48/0x60 process_measurement+0xf8/0xa98 ima_bprm_check+0x98/0xd8 security_bprm_check+0x5c/0x78 search_binary_handler+0x6c/0x318 exec_binprm+0x58/0x1b8 bprm_execve+0xb8/0x130 do_execveat_common.isra.0+0x1a8/0x258 __arm64_sys_execve+0x48/0x68 invoke_syscall+0x50/0x128 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x44/0x200 el0t_64_sync_handler+0x100/0x130 el0t_64_sync+0x3c8/0x3d0
Fix this by changing 'if (!rc)' to 'if (rc <= 0)' to ensure that error codes like -ENOENT do not bypass the check and accidentally result in a successful match.
Fixes: 4af4662fa4a9d ("integrity: IMA policy") Signed-off-by: Zhao Yipeng zhaoyipeng5@huawei.com Reviewed-by: Roberto Sassu roberto.sassu@huawei.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- security/integrity/ima/ima_policy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index f3f46c6186c08..afbf963cb7483 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -672,7 +672,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, goto retry; } } - if (!rc) { + if (rc <= 0) { result = false; goto out; }