Merge remote-tracking branch 'integrity/next-with-keys' into keys-next

Signed-off-by: David Howells <[e-mail]>

Documentation/kernel-parameters.txt

···
 			possible to determine what the correct size should be.
 			This option provides an override for these situations.
 
+	ca_keys=	[KEYS] This parameter identifies a specific key(s) on
+			the system trusted keyring to be used for certificate
+			trust validation.
+			format: { id:<keyid> | builtin }
+
 	ccw_timeout_log [S390]
 			See Documentation/s390/CommonIO for details.
 

crypto/asymmetric_keys/asymmetric_keys.h

···
  * 2 of the Licence, or (at your option) any later version.
  */
 
+int asymmetric_keyid_match(const char *kid, const char *id);
+
 static inline const char *asymmetric_key_id(const struct key *key)
 {
 	return key->type_data.p[1];

crypto/asymmetric_keys/asymmetric_type.c

···
 static DECLARE_RWSEM(asymmetric_key_parsers_sem);
 
 /*
+ * Match asymmetric key id with partial match
+ * @id:		key id to match in a form "id:<id>"
+ */
+int asymmetric_keyid_match(const char *kid, const char *id)
+{
+	size_t idlen, kidlen;
+
+	if (!kid || !id)
+		return 0;
+
+	/* make it possible to use id as in the request: "id:<id>" */
+	if (strncmp(id, "id:", 3) == 0)
+		id += 3;
+
+	/* Anything after here requires a partial match on the ID string */
+	idlen = strlen(id);
+	kidlen = strlen(kid);
+	if (idlen > kidlen)
+		return 0;
+
+	kid += kidlen - idlen;
+	if (strcasecmp(id, kid) != 0)
+		return 0;
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(asymmetric_keyid_match);
+
+/*
  * Match asymmetric keys on (part of) their name
  * We have some shorthand methods for matching keys.  We allow:
  *
···
 {
 	const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
 	const char *spec = description;
-	const char *id, *kid;
+	const char *id;
 	ptrdiff_t speclen;
-	size_t idlen, kidlen;
 
 	if (!subtype || !spec || !*spec)
 		return 0;
···
 	speclen = id - spec;
 	id++;
 
-	/* Anything after here requires a partial match on the ID string */
-	kid = asymmetric_key_id(key);
-	if (!kid)
-		return 0;
-
-	idlen = strlen(id);
-	kidlen = strlen(kid);
-	if (idlen > kidlen)
-		return 0;
-
-	kid += kidlen - idlen;
-	if (strcasecmp(id, kid) != 0)
-		return 0;
-
-	if (speclen == 2 &&
-	    memcmp(spec, "id", 2) == 0)
-		return 1;
+	if (speclen == 2 && memcmp(spec, "id", 2) == 0)
+		return asymmetric_keyid_match(asymmetric_key_id(key), id);
 
 	if (speclen == subtype->name_len &&
 	    memcmp(spec, subtype->name, speclen) == 0)

crypto/asymmetric_keys/x509_public_key.c

···
 #include <linux/asn1_decoder.h>
 #include <keys/asymmetric-subtype.h>
 #include <keys/asymmetric-parser.h>
+#include <keys/system_keyring.h>
 #include <crypto/hash.h>
 #include "asymmetric_keys.h"
 #include "public_key.h"
 #include "x509_parser.h"
+
+static bool use_builtin_keys;
+static char *ca_keyid;
+
+#ifndef MODULE
+static int __init ca_keys_setup(char *str)
+{
+	if (!str)		/* default system keyring */
+		return 1;
+
+	if (strncmp(str, "id:", 3) == 0)
+		ca_keyid = str;	/* owner key 'id:xxxxxx' */
+	else if (strcmp(str, "builtin") == 0)
+		use_builtin_keys = true;
+
+	return 1;
+}
+__setup("ca_keys=", ca_keys_setup);
+#endif
+
+/*
+ * Find a key in the given keyring by issuer and authority.
+ */
+static struct key *x509_request_asymmetric_key(struct key *keyring,
+					       const char *signer,
+					       size_t signer_len,
+					       const char *authority,
+					       size_t auth_len)
+{
+	key_ref_t key;
+	char *id;
+
+	/* Construct an identifier. */
+	id = kmalloc(signer_len + 2 + auth_len + 1, GFP_KERNEL);
+	if (!id)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(id, signer, signer_len);
+	id[signer_len + 0] = ':';
+	id[signer_len + 1] = ' ';
+	memcpy(id + signer_len + 2, authority, auth_len);
+	id[signer_len + 2 + auth_len] = 0;
+
+	pr_debug("Look up: \"%s\"\n", id);
+
+	key = keyring_search(make_key_ref(keyring, 1),
+			     &key_type_asymmetric, id);
+	if (IS_ERR(key))
+		pr_debug("Request for module key '%s' err %ld\n",
+			 id, PTR_ERR(key));
+	kfree(id);
+
+	if (IS_ERR(key)) {
+		switch (PTR_ERR(key)) {
+			/* Hide some search errors */
+		case -EACCES:
+		case -ENOTDIR:
+		case -EAGAIN:
+			return ERR_PTR(-ENOKEY);
+		default:
+			return ERR_CAST(key);
+		}
+	}
+
+	pr_devel("<==%s() = 0 [%x]\n", __func__,
+		 key_serial(key_ref_to_ptr(key)));
+	return key_ref_to_ptr(key);
+}
 
 /*
  * Set up the signature parameters in an X.509 certificate.  This involves
···
 EXPORT_SYMBOL_GPL(x509_check_signature);
 
 /*
+ * Check the new certificate against the ones in the trust keyring.  If one of
+ * those is the signing key and validates the new certificate, then mark the
+ * new certificate as being trusted.
+ *
+ * Return 0 if the new certificate was successfully validated, 1 if we couldn't
+ * find a matching parent certificate in the trusted list and an error if there
+ * is a matching certificate but the signature check fails.
+ */
+static int x509_validate_trust(struct x509_certificate *cert,
+			       struct key *trust_keyring)
+{
+	struct key *key;
+	int ret = 1;
+
+	if (!trust_keyring)
+		return -EOPNOTSUPP;
+
+	if (ca_keyid && !asymmetric_keyid_match(cert->authority, ca_keyid))
+		return -EPERM;
+
+	key = x509_request_asymmetric_key(trust_keyring,
+					  cert->issuer, strlen(cert->issuer),
+					  cert->authority,
+					  strlen(cert->authority));
+	if (!IS_ERR(key))  {
+		if (!use_builtin_keys
+		    || test_bit(KEY_FLAG_BUILTIN, &key->flags))
+			ret = x509_check_signature(key->payload.data, cert);
+		key_put(key);
+	}
+	return ret;
+}
+
+/*
  * Attempt to parse a data blob for a key as an X509 certificate.
  */
 static int x509_key_preparse(struct key_preparsed_payload *prep)
···
 	/* Check the signature on the key if it appears to be self-signed */
 	if (!cert->authority ||
 	    strcmp(cert->fingerprint, cert->authority) == 0) {
-		ret = x509_check_signature(cert->pub, cert);
+		ret = x509_check_signature(cert->pub, cert); /* self-signed */
 		if (ret < 0)
 			goto error_free_cert;
+	} else if (!prep->trusted) {
+		ret = x509_validate_trust(cert, get_system_trusted_keyring());
+		if (!ret)
+			prep->trusted = 1;
 	}
 
 	/* Propose a description */

include/keys/system_keyring.h

···
 #include <linux/key.h>
 
 extern struct key *system_trusted_keyring;
-
+static inline struct key *get_system_trusted_keyring(void)
+{
+	return system_trusted_keyring;
+}
+#else
+static inline struct key *get_system_trusted_keyring(void)
+{
+	return NULL;
+}
 #endif
 
 #endif /* _KEYS_SYSTEM_KEYRING_H */

include/linux/key.h

···
 #define KEY_FLAG_INVALIDATED	7	/* set if key has been invalidated */
 #define KEY_FLAG_TRUSTED	8	/* set if key is trusted */
 #define KEY_FLAG_TRUSTED_ONLY	9	/* set if keyring only accepts links to trusted keys */
+#define KEY_FLAG_BUILTIN	10	/* set if key is builtin */
 
 	/* the key type and key description string
 	 * - the desc is used to match a key against search criteria

kernel/system_keyring.c

···
 			pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
 			       PTR_ERR(key));
 		} else {
+			set_bit(KEY_FLAG_BUILTIN, &key_ref_to_ptr(key)->flags);
 			pr_notice("Loaded X.509 cert '%s'\n",
 				  key_ref_to_ptr(key)->description);
 			key_ref_put(key);

security/integrity/digsig.c

···
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/err.h>
+#include <linux/sched.h>
 #include <linux/rbtree.h>
+#include <linux/cred.h>
 #include <linux/key-type.h>
 #include <linux/digsig.h>
 
···
 static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
 	"_evm",
 	"_module",
+#ifndef CONFIG_IMA_TRUSTED_KEYRING
 	"_ima",
+#else
+	".ima",
+#endif
 };
 
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
···
 	}
 
 	return -EOPNOTSUPP;
+}
+
+int integrity_init_keyring(const unsigned int id)
+{
+	const struct cred *cred = current_cred();
+	int err = 0;
+
+	keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
+				    KGIDT_INIT(0), cred,
+				    ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+				     KEY_USR_VIEW | KEY_USR_READ |
+				     KEY_USR_WRITE | KEY_USR_SEARCH),
+				    KEY_ALLOC_NOT_IN_QUOTA, NULL);
+	if (!IS_ERR(keyring[id]))
+		set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags);
+	else {
+		err = PTR_ERR(keyring[id]);
+		pr_info("Can't allocate %s keyring (%d)\n",
+			keyring_name[id], err);
+		keyring[id] = NULL;
+	}
+	return err;
 }

security/integrity/ima/Kconfig

···
 	  For more information on integrity appraisal refer to:
 	  <http://linux-ima.sourceforge.net>
 	  If unsure, say N.
+
+config IMA_TRUSTED_KEYRING
+	bool "Require all keys on the .ima keyring be signed"
+	depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING
+	depends on INTEGRITY_ASYMMETRIC_KEYS
+	select KEYS_DEBUG_PROC_KEYS
+	default y
+	help
+	   This option requires that all keys added to the .ima
+	   keyring be signed by a key on the system trusted keyring.

security/integrity/ima/ima.h

···
 	return -EINVAL;
 }
 #endif /* CONFIG_IMA_LSM_RULES */
+
+#ifdef CONFIG_IMA_TRUSTED_KEYRING
+static inline int ima_init_keyring(const unsigned int id)
+{
+	return integrity_init_keyring(id);
+}
+#else
+static inline int ima_init_keyring(const unsigned int id)
+{
+	return 0;
+}
+#endif /* CONFIG_IMA_TRUSTED_KEYRING */
 #endif

security/integrity/ima/ima_main.c

···
 
 	hash_setup(CONFIG_IMA_DEFAULT_HASH);
 	error = ima_init();
-	if (!error)
-		ima_initialized = 1;
+	if (error)
+		goto out;
+
+	error = ima_init_keyring(INTEGRITY_KEYRING_IMA);
+	if (error)
+		goto out;
+	ima_initialized = 1;
+out:
 	return error;
 }
 

security/integrity/integrity.h

···
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			    const char *digest, int digestlen);
 
+int integrity_init_keyring(const unsigned int id);
 #else
 
 static inline int integrity_digsig_verify(const unsigned int id,
···
 	return -EOPNOTSUPP;
 }
 
+static inline int integrity_init_keyring(const unsigned int id)
+{
+	return 0;
+}
 #endif /* CONFIG_INTEGRITY_SIGNATURE */
 
 #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS

security/keys/keyctl.c

···
 		return ret;
 	if (ret == 0 || ret >= len)
 		return -EINVAL;
-	if (type[0] == '.')
-		return -EPERM;
 	type[len - 1] = '\0';
 	return 0;
 }
···
 		if (!*description) {
 			kfree(description);
 			description = NULL;
+		} else if ((description[0] == '.') &&
+			   (strncmp(type, "keyring", 7) == 0)) {
+			ret = -EPERM;
+			goto error2;
 		}
 	}