Merge branch 'next-evm-digsig' of git://git.kernel.org/pub/scm/linux/kernel/git/kasatkin/linux-digsig into next

7 files changed, 226 insertions, 30 deletions

diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index 4bf00ac..d87fa2a 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -3,5 +3,19 @@ config INTEGRITY
 	def_bool y
 	depends on IMA || EVM
 
+config INTEGRITY_DIGSIG
+	boolean "Digital signature verification using multiple keyrings"
+	depends on INTEGRITY
+	default n
+	select DIGSIG
+	help
+	  This option enables digital signature verification support
+	  using multiple keyrings. It defines separate keyrings for each
+	  of the different use cases - evm, ima, and modules.
+	  Different keyrings improves search performance, but also allow
+	  to "lock" certain keyring to prevent adding new keys.
+	  This is useful for evm and module keyrings, when keys are
+	  usually only added from initramfs.
+
 source security/integrity/ima/Kconfig
 source security/integrity/evm/Kconfig
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 0ae44ae..bece056 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_INTEGRITY) += integrity.o
+obj-$(CONFIG_INTEGRITY_DIGSIG) += digsig.o
 
 integrity-y := iint.o
 
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
new file mode 100644
index 0000000..2dc167d
--- /dev/null
+++ b/security/integrity/digsig.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2011 Intel Corporation
+ *
+ * Author:
+ * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/err.h>
+#include <linux/rbtree.h>
+#include <linux/key-type.h>
+#include <linux/digsig.h>
+
+#include "integrity.h"
+
+static struct key *keyring[INTEGRITY_KEYRING_MAX];
+
+static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
+	"_evm",
+	"_module",
+	"_ima",
+};
+
+int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
+					const char *digest, int digestlen)
+{
+	if (id >= INTEGRITY_KEYRING_MAX)
+		return -EINVAL;
+
+	if (!keyring[id]) {
+		keyring[id] =
+			request_key(&key_type_keyring, keyring_name[id], NULL);
+		if (IS_ERR(keyring[id])) {
+			int err = PTR_ERR(keyring[id]);
+			pr_err("no %s keyring: %d\n", keyring_name[id], err);
+			keyring[id] = NULL;
+			return err;
+		}
+	}
+
+	return digsig_verify(keyring[id], sig, siglen, digest, digestlen);
+}
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index d320f51..c885247 100644
--- a/security/integrity/evm/evm.h
+++ b/security/integrity/evm/evm.h
@@ -12,14 +12,21 @@
  * File: evm.h
  *
  */
+
+#ifndef __INTEGRITY_EVM_H
+#define __INTEGRITY_EVM_H
+
 #include <linux/xattr.h>
 #include <linux/security.h>
+
 #include "../integrity.h"
 
 extern int evm_initialized;
 extern char *evm_hmac;
+extern char *evm_hash;
 
 extern struct crypto_shash *hmac_tfm;
+extern struct crypto_shash *hash_tfm;
 
 /* List of EVM protected security xattrs */
 extern char *evm_config_xattrnames[];
@@ -32,7 +39,12 @@ extern int evm_update_evmxattr(struct dentry *dentry,
 extern int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
 			 const char *req_xattr_value,
 			 size_t req_xattr_value_len, char *digest);
+extern int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
+			 const char *req_xattr_value,
+			 size_t req_xattr_value_len, char *digest);
 extern int evm_init_hmac(struct inode *inode, const struct xattr *xattr,
 			 char *hmac_val);
 extern int evm_init_secfs(void);
 extern void evm_cleanup_secfs(void);
+
+#endif
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 5dd5b140..847a2d7 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -26,34 +26,48 @@ static unsigned char evmkey[MAX_KEY_SIZE];
 static int evmkey_len = MAX_KEY_SIZE;
 
 struct crypto_shash *hmac_tfm;
+struct crypto_shash *hash_tfm;
 
-static struct shash_desc *init_desc(void)
+static struct shash_desc *init_desc(const char type)
 {
 	int rc;
+	char *algo;
+	struct crypto_shash **tfm;
 	struct shash_desc *desc;
 
-	if (hmac_tfm == NULL) {
-		hmac_tfm = crypto_alloc_shash(evm_hmac, 0, CRYPTO_ALG_ASYNC);
-		if (IS_ERR(hmac_tfm)) {
+	if (type == EVM_XATTR_HMAC) {
+		tfm = &hmac_tfm;
+		algo = evm_hmac;
+	} else {
+		tfm = &hash_tfm;
+		algo = evm_hash;
+	}
+
+	if (*tfm == NULL) {
+		*tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC);
+		if (IS_ERR(*tfm)) {
 			pr_err("Can not allocate %s (reason: %ld)\n",
-			       evm_hmac, PTR_ERR(hmac_tfm));
-			rc = PTR_ERR(hmac_tfm);
-			hmac_tfm = NULL;
+			       algo, PTR_ERR(*tfm));
+			rc = PTR_ERR(*tfm);
+			*tfm = NULL;
 			return ERR_PTR(rc);
 		}
 	}
 
-	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac_tfm),
+	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
 			GFP_KERNEL);
 	if (!desc)
 		return ERR_PTR(-ENOMEM);
 
-	desc->tfm = hmac_tfm;
+	desc->tfm = *tfm;
 	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	rc = crypto_shash_setkey(hmac_tfm, evmkey, evmkey_len);
-	if (rc)
-		goto out;
+	if (type == EVM_XATTR_HMAC) {
+		rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
+		if (rc)
+			goto out;
+	}
+
 	rc = crypto_shash_init(desc);
 out:
 	if (rc) {
@@ -97,9 +111,11 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
  * the hmac using the requested xattr value. Don't alloc/free memory for
  * each xattr, but attempt to re-use the previously allocated memory.
  */
-int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
-		  const char *req_xattr_value, size_t req_xattr_value_len,
-		  char *digest)
+static int evm_calc_hmac_or_hash(struct dentry *dentry,
+				const char *req_xattr_name,
+				const char *req_xattr_value,
+				size_t req_xattr_value_len,
+				char type, char *digest)
 {
 	struct inode *inode = dentry->d_inode;
 	struct shash_desc *desc;
@@ -111,7 +127,7 @@ int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
 
 	if (!inode->i_op || !inode->i_op->getxattr)
 		return -EOPNOTSUPP;
-	desc = init_desc();
+	desc = init_desc(type);
 	if (IS_ERR(desc))
 		return PTR_ERR(desc);
 
@@ -145,6 +161,22 @@ out:
 	return error;
 }
 
+int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
+		  const char *req_xattr_value, size_t req_xattr_value_len,
+		  char *digest)
+{
+	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
+				req_xattr_value_len, EVM_XATTR_HMAC, digest);
+}
+
+int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
+		  const char *req_xattr_value, size_t req_xattr_value_len,
+		  char *digest)
+{
+	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
+				req_xattr_value_len, IMA_XATTR_DIGEST, digest);
+}
+
 /*
  * Calculate the hmac and update security.evm xattr
  *
@@ -175,7 +207,7 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
 {
 	struct shash_desc *desc;
 
-	desc = init_desc();
+	desc = init_desc(EVM_XATTR_HMAC);
 	if (IS_ERR(desc)) {
 		printk(KERN_INFO "init_desc failed\n");
 		return PTR_ERR(desc);
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 92d3d99..8901501 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -25,6 +25,7 @@
 int evm_initialized;
 
 char *evm_hmac = "hmac(sha1)";
+char *evm_hash = "sha1";
 
 char *evm_config_xattrnames[] = {
 #ifdef CONFIG_SECURITY_SELINUX
@@ -46,6 +47,29 @@ static int __init evm_set_fixmode(char *str)
 }
 __setup("evm=", evm_set_fixmode);
 
+static int evm_find_protected_xattrs(struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+	char **xattr;
+	int error;
+	int count = 0;
+
+	if (!inode->i_op || !inode->i_op->getxattr)
+		return -EOPNOTSUPP;
+
+	for (xattr = evm_config_xattrnames; *xattr != NULL; xattr++) {
+		error = inode->i_op->getxattr(dentry, *xattr, NULL, 0);
+		if (error < 0) {
+			if (error == -ENODATA)
+				continue;
+			return error;
+		}
+		count++;
+	}
+
+	return count;
+}
+
 /*
  * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
  *
@@ -65,32 +89,72 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 					     size_t xattr_value_len,
 					     struct integrity_iint_cache *iint)
 {
-	struct evm_ima_xattr_data xattr_data;
+	struct evm_ima_xattr_data *xattr_data = NULL;
+	struct evm_ima_xattr_data calc;
 	enum integrity_status evm_status = INTEGRITY_PASS;
-	int rc;
+	int rc, xattr_len;
 
 	if (iint && iint->evm_status == INTEGRITY_PASS)
 		return iint->evm_status;
 
 	/* if status is not PASS, try to check again - against -ENOMEM */
 
-	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
-			   xattr_value_len, xattr_data.digest);
-	if (rc < 0) {
-		evm_status = (rc == -ENODATA)
-		    ? INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
+	/* first need to know the sig type */
+	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
+				GFP_NOFS);
+	if (rc <= 0) {
+		if (rc == 0)
+			evm_status = INTEGRITY_FAIL; /* empty */
+		else if (rc == -ENODATA) {
+			rc = evm_find_protected_xattrs(dentry);
+			if (rc > 0)
+				evm_status = INTEGRITY_NOLABEL;
+			else if (rc == 0)
+				evm_status = INTEGRITY_NOXATTRS; /* new file */
+		}
 		goto out;
 	}
 
-	xattr_data.type = EVM_XATTR_HMAC;
-	rc = vfs_xattr_cmp(dentry, XATTR_NAME_EVM, (u8 *)&xattr_data,
-			   sizeof xattr_data, GFP_NOFS);
-	if (rc < 0)
-		evm_status = (rc == -ENODATA)
-		    ? INTEGRITY_NOLABEL : INTEGRITY_FAIL;
+	xattr_len = rc - 1;
+
+	/* check value type */
+	switch (xattr_data->type) {
+	case EVM_XATTR_HMAC:
+		rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
+				   xattr_value_len, calc.digest);
+		if (rc)
+			break;
+		rc = memcmp(xattr_data->digest, calc.digest,
+			    sizeof(calc.digest));
+		if (rc)
+			rc = -EINVAL;
+		break;
+	case EVM_IMA_XATTR_DIGSIG:
+		rc = evm_calc_hash(dentry, xattr_name, xattr_value,
+				xattr_value_len, calc.digest);
+		if (rc)
+			break;
+		rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
+					xattr_data->digest, xattr_len,
+					calc.digest, sizeof(calc.digest));
+		if (!rc) {
+			/* we probably want to replace rsa with hmac here */
+			evm_update_evmxattr(dentry, xattr_name, xattr_value,
+				   xattr_value_len);
+		}
+		break;
+	default:
+		rc = -EINVAL;
+		break;
+	}
+
+	if (rc)
+		evm_status = (rc == -ENODATA) ?
+				INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
 out:
 	if (iint)
 		iint->evm_status = evm_status;
+	kfree(xattr_data);
 	return evm_status;
 }
 
@@ -354,6 +418,8 @@ static int __init init_evm(void)
 		printk(KERN_INFO "EVM: Error registering secfs\n");
 		goto err;
 	}
+
+	return 0;
 err:
 	return error;
 }
@@ -363,6 +429,8 @@ static void __exit cleanup_evm(void)
 	evm_cleanup_secfs();
 	if (hmac_tfm)
 		crypto_free_shash(hmac_tfm);
+	if (hash_tfm)
+		crypto_free_shash(hash_tfm);
 }
 
 /*
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 3143a3c..4da6ba8 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -46,5 +46,26 @@ struct integrity_iint_cache {
 struct integrity_iint_cache *integrity_iint_insert(struct inode *inode);
 struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
 
+#define INTEGRITY_KEYRING_EVM		0
+#define INTEGRITY_KEYRING_MODULE	1
+#define INTEGRITY_KEYRING_IMA		2
+#define INTEGRITY_KEYRING_MAX		3
+
+#ifdef CONFIG_INTEGRITY_DIGSIG
+
+int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
+					const char *digest, int digestlen);
+
+#else
+
+static inline int integrity_digsig_verify(const unsigned int id,
+					  const char *sig, int siglen,
+					  const char *digest, int digestlen)
+{
+	return -EOPNOTSUPP;
+}
+
+#endif /* CONFIG_INTEGRITY_DIGSIG */
+
 /* set during initialization */
 extern int iint_initialized;