lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20210407105252.30721-3-roberto.sassu@huawei.com>
Date:   Wed, 7 Apr 2021 12:52:42 +0200
From:   Roberto Sassu <roberto.sassu@...wei.com>
To:     <zohar@...ux.ibm.com>, <mjg59@...gle.com>
CC:     <linux-integrity@...r.kernel.org>,
        <linux-security-module@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Roberto Sassu <roberto.sassu@...wei.com>
Subject: [PATCH v5 02/12] evm: Load EVM key in ima_load_x509() to avoid appraisal

The public builtin keys do not need to be appraised by IMA as the
restriction on the IMA/EVM trusted keyrings ensures that a key can be
loaded only if it is signed with a key on the builtin or secondary
keyrings.

However, when evm_load_x509() is called, appraisal is already enabled and
a valid IMA signature must be added to the EVM key to pass verification.

Since the restriction is applied on both IMA and EVM trusted keyrings, it
is safe to disable appraisal also when the EVM key is loaded. This patch
calls evm_load_x509() inside ima_load_x509() if CONFIG_IMA_LOAD_X509 is
enabled, which crosses the normal IMA and EVM boundary.

Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
---
 security/integrity/iint.c         | 4 +++-
 security/integrity/ima/ima_init.c | 4 ++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 0ba01847e836..d66b94c7c8d5 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -208,7 +208,9 @@ int integrity_kernel_read(struct file *file, loff_t offset,
 void __init integrity_load_keys(void)
 {
 	ima_load_x509();
-	evm_load_x509();
+
+	if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
+		evm_load_x509();
 }
 
 static int __init integrity_fs_init(void)
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index 6e8742916d1d..5076a7d9d23e 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -108,6 +108,10 @@ void __init ima_load_x509(void)
 
 	ima_policy_flag &= ~unset_flags;
 	integrity_load_x509(INTEGRITY_KEYRING_IMA, CONFIG_IMA_X509_PATH);
+
+	/* load also EVM key to avoid appraisal */
+	evm_load_x509();
+
 	ima_policy_flag |= unset_flags;
 }
 #endif
-- 
2.26.2

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ