linux-kernel - [PATCH v8 05/14] integrity: Introduce integrity_keyring_from

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Message-Id: <20181116200712.14154-6-bauerman@linux.ibm.com>
Date:   Fri, 16 Nov 2018 18:07:03 -0200
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        David Howells <dhowells@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Jessica Yu <jeyu@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Jonathan Corbet <corbet@....net>,
        "AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>
Subject: [PATCH v8 05/14] integrity: Introduce integrity_keyring_from_id()

IMA will need to obtain the keyring used to verify file signatures so that
it can verify the module-style signature appended to files.

Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
---
 security/integrity/digsig.c    | 28 +++++++++++++++++++++-------
 security/integrity/integrity.h |  6 ++++++
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 5eacba858e4b..bfa27f166184 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -43,11 +43,10 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
 #define restrict_link_to_ima restrict_link_by_builtin_trusted
 #endif
 
-int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
-			    const char *digest, int digestlen)
+struct key *integrity_keyring_from_id(const unsigned int id)
 {
-	if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
-		return -EINVAL;
+	if (id >= INTEGRITY_KEYRING_MAX)
+		return ERR_PTR(-EINVAL);
 
 	if (!keyring[id]) {
 		keyring[id] =
@@ -56,17 +55,32 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			int err = PTR_ERR(keyring[id]);
 			pr_err("no %s keyring: %d\n", keyring_name[id], err);
 			keyring[id] = NULL;
-			return err;
+			return ERR_PTR(err);
 		}
 	}
 
+	return keyring[id];
+}
+
+int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
+			    const char *digest, int digestlen)
+{
+	struct key *keyring;
+
+	if (siglen < 2)
+		return -EINVAL;
+
+	keyring = integrity_keyring_from_id(id);
+	if (IS_ERR(keyring))
+		return PTR_ERR(keyring);
+
 	switch (sig[1]) {
 	case 1:
 		/* v1 API expect signature without xattr type */
-		return digsig_verify(keyring[id], sig + 1, siglen - 1,
+		return digsig_verify(keyring, sig + 1, siglen - 1,
 				     digest, digestlen);
 	case 2:
-		return asymmetric_verify(keyring[id], sig, siglen,
+		return asymmetric_verify(keyring, sig, siglen,
 					 digest, digestlen);
 	}
 
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 20ac02bf1b84..91c41351e18a 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -153,6 +153,7 @@ extern struct dentry *integrity_dir;
 
 #ifdef CONFIG_INTEGRITY_SIGNATURE
 
+struct key *integrity_keyring_from_id(const unsigned int id);
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			    const char *digest, int digestlen);
 
@@ -160,6 +161,11 @@ int __init integrity_init_keyring(const unsigned int id);
 int __init integrity_load_x509(const unsigned int id, const char *path);
 #else
 
+static inline struct key *integrity_keyring_from_id(const unsigned int id)
+{
+	return ERR_PTR(-EINVAL);
+}
+
 static inline int integrity_digsig_verify(const unsigned int id,
 					  const char *sig, int siglen,
 					  const char *digest, int digestlen)