1 files changed, 207 insertions, 72 deletions

diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 1d32cd20009a..a5e730ffda57 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2005-2010 IBM Corporation
  *
@@ -5,31 +6,28 @@
  * Mimi Zohar <zohar@us.ibm.com>
  * Kylene Hall <kjhall@us.ibm.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.
- *
  * File: evm_crypto.c
  *	 Using root's kernel master key (kmk), calculate the HMAC
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define pr_fmt(fmt) "EVM: "fmt
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/crypto.h>
 #include <linux/xattr.h>
 #include <linux/evm.h>
 #include <keys/encrypted-type.h>
 #include <crypto/hash.h>
+#include <crypto/hash_info.h>
 #include "evm.h"
 
 #define EVMKEY "evm-key"
 #define MAX_KEY_SIZE 128
 static unsigned char evmkey[MAX_KEY_SIZE];
-static int evmkey_len = MAX_KEY_SIZE;
+static const int evmkey_len = MAX_KEY_SIZE;
 
-struct crypto_shash *hmac_tfm;
-struct crypto_shash *hash_tfm;
+static struct crypto_shash *hmac_tfm;
+static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
 
 static DEFINE_MUTEX(mutex);
 
@@ -37,10 +35,12 @@ static DEFINE_MUTEX(mutex);
 
 static unsigned long evm_set_key_flags;
 
+static const char evm_hmac[] = "hmac(sha1)";
+
 /**
  * evm_set_key() - set EVM HMAC key from the kernel
  * @key: pointer to a buffer with the key data
- * @size: length of the key data
+ * @keylen: length of the key data
  *
  * This function allows setting the EVM HMAC key from the kernel
  * without using the "encrypted" key subsystem keys. It can be used
@@ -71,57 +71,59 @@ busy:
 }
 EXPORT_SYMBOL_GPL(evm_set_key);
 
-static struct shash_desc *init_desc(char type)
+static struct shash_desc *init_desc(char type, uint8_t hash_algo)
 {
 	long rc;
-	char *algo;
-	struct crypto_shash **tfm;
+	const char *algo;
+	struct crypto_shash **tfm, *tmp_tfm;
 	struct shash_desc *desc;
 
 	if (type == EVM_XATTR_HMAC) {
 		if (!(evm_initialized & EVM_INIT_HMAC)) {
-			pr_err("HMAC key is not set\n");
+			pr_err_once("HMAC key is not set\n");
 			return ERR_PTR(-ENOKEY);
 		}
 		tfm = &hmac_tfm;
 		algo = evm_hmac;
 	} else {
-		tfm = &hash_tfm;
-		algo = evm_hash;
+		if (hash_algo >= HASH_ALGO__LAST)
+			return ERR_PTR(-EINVAL);
+
+		tfm = &evm_tfm[hash_algo];
+		algo = hash_algo_name[hash_algo];
 	}
 
-	if (*tfm == NULL) {
-		mutex_lock(&mutex);
-		if (*tfm)
-			goto out;
-		*tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC);
-		if (IS_ERR(*tfm)) {
-			rc = PTR_ERR(*tfm);
-			pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);
-			*tfm = NULL;
+	if (*tfm)
+		goto alloc;
+	mutex_lock(&mutex);
+	if (*tfm)
+		goto unlock;
+
+	tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
+	if (IS_ERR(tmp_tfm)) {
+		pr_err("Can not allocate %s (reason: %ld)\n", algo,
+		       PTR_ERR(tmp_tfm));
+		mutex_unlock(&mutex);
+		return ERR_CAST(tmp_tfm);
+	}
+	if (type == EVM_XATTR_HMAC) {
+		rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len);
+		if (rc) {
+			crypto_free_shash(tmp_tfm);
 			mutex_unlock(&mutex);
 			return ERR_PTR(rc);
 		}
-		if (type == EVM_XATTR_HMAC) {
-			rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
-			if (rc) {
-				crypto_free_shash(*tfm);
-				*tfm = NULL;
-				mutex_unlock(&mutex);
-				return ERR_PTR(rc);
-			}
-		}
-out:
-		mutex_unlock(&mutex);
 	}
-
+	*tfm = tmp_tfm;
+unlock:
+	mutex_unlock(&mutex);
+alloc:
 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
 			GFP_KERNEL);
 	if (!desc)
 		return ERR_PTR(-ENOMEM);
 
 	desc->tfm = *tfm;
-	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
 	rc = crypto_shash_init(desc);
 	if (rc) {
@@ -138,7 +140,7 @@ out:
  * protection.)
  */
 static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
-			  char *digest)
+			  char type, char *digest)
 {
 	struct h_misc {
 		unsigned long ino;
@@ -149,8 +151,13 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
 	} hmac_misc;
 
 	memset(&hmac_misc, 0, sizeof(hmac_misc));
-	hmac_misc.ino = inode->i_ino;
-	hmac_misc.generation = inode->i_generation;
+	/* Don't include the inode or generation number in portable
+	 * signatures
+	 */
+	if (type != EVM_XATTR_PORTABLE_DIGSIG) {
+		hmac_misc.ino = inode->i_ino;
+		hmac_misc.generation = inode->i_generation;
+	}
 	/* The hmac uid and gid must be encoded in the initial user
 	 * namespace (not the filesystems user namespace) as encoding
 	 * them in the filesystems user namespace allows an attack
@@ -163,10 +170,44 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
 	hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
 	hmac_misc.mode = inode->i_mode;
 	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
-	if (evm_hmac_attrs & EVM_ATTR_FSUUID)
-		crypto_shash_update(desc, &inode->i_sb->s_uuid.b[0],
-				    sizeof(inode->i_sb->s_uuid));
+	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
+	    type != EVM_XATTR_PORTABLE_DIGSIG)
+		crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
 	crypto_shash_final(desc, digest);
+
+	pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
+		 (int)sizeof(struct h_misc), &hmac_misc);
+}
+
+/*
+ * Dump large security xattr values as a continuous ascii hexadecimal string.
+ * (pr_debug is limited to 64 bytes.)
+ */
+static void dump_security_xattr_l(const char *prefix, const void *src,
+				  size_t count)
+{
+#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
+	char *asciihex, *p;
+
+	p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
+	if (!asciihex)
+		return;
+
+	p = bin2hex(p, src, count);
+	*p = 0;
+	pr_debug("%s: (%zu) %.*s\n", prefix, count, (int)count * 2, asciihex);
+	kfree(asciihex);
+#endif
+}
+
+static void dump_security_xattr(const char *name, const char *value,
+				size_t value_len)
+{
+	if (value_len < 64)
+		pr_debug("%s: (%zu) [%*phN]\n", name, value_len,
+			 (int)value_len, value);
+	else
+		dump_security_xattr_l(name, value, value_len);
 }
 
 /*
@@ -177,36 +218,60 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
  * each xattr, but attempt to re-use the previously allocated memory.
  */
 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)
+				 const char *req_xattr_name,
+				 const char *req_xattr_value,
+				 size_t req_xattr_value_len,
+				 uint8_t type, struct evm_digest *data,
+				 struct evm_iint_cache *iint)
 {
-	struct inode *inode = d_backing_inode(dentry);
+	struct inode *inode = d_inode(d_real(dentry, D_REAL_METADATA));
+	struct xattr_list *xattr;
 	struct shash_desc *desc;
-	char **xattrname;
 	size_t xattr_size = 0;
 	char *xattr_value = NULL;
 	int error;
-	int size;
+	int size, user_space_size;
+	bool ima_present = false;
+	u64 i_version = 0;
 
-	if (!(inode->i_opflags & IOP_XATTR))
+	if (!(inode->i_opflags & IOP_XATTR) ||
+	    inode->i_sb->s_user_ns != &init_user_ns)
 		return -EOPNOTSUPP;
 
-	desc = init_desc(type);
+	desc = init_desc(type, data->hdr.algo);
 	if (IS_ERR(desc))
 		return PTR_ERR(desc);
 
+	data->hdr.length = crypto_shash_digestsize(desc->tfm);
+
 	error = -ENODATA;
-	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
+	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+		bool is_ima = false;
+
+		if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
+			is_ima = true;
+
+		/*
+		 * Skip non-enabled xattrs for locally calculated
+		 * signatures/HMACs.
+		 */
+		if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled)
+			continue;
+
 		if ((req_xattr_name && req_xattr_value)
-		    && !strcmp(*xattrname, req_xattr_name)) {
+		    && !strcmp(xattr->name, req_xattr_name)) {
 			error = 0;
 			crypto_shash_update(desc, (const u8 *)req_xattr_value,
 					     req_xattr_value_len);
+			if (is_ima)
+				ima_present = true;
+
+			dump_security_xattr(req_xattr_name,
+					    req_xattr_value,
+					    req_xattr_value_len);
 			continue;
 		}
-		size = vfs_getxattr_alloc(dentry, *xattrname,
+		size = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr->name,
 					  &xattr_value, xattr_size, GFP_NOFS);
 		if (size == -ENOMEM) {
 			error = -ENOMEM;
@@ -215,12 +280,32 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
 		if (size < 0)
 			continue;
 
+		user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
+					       xattr->name, NULL, 0);
+		if (user_space_size != size)
+			pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
+				 dentry->d_name.name, xattr->name, size,
+				 user_space_size);
 		error = 0;
 		xattr_size = size;
 		crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
+		if (is_ima)
+			ima_present = true;
+
+		dump_security_xattr(xattr->name, xattr_value, xattr_size);
 	}
-	hmac_add_misc(desc, inode, digest);
+	hmac_add_misc(desc, inode, type, data->digest);
 
+	if (inode != d_backing_inode(dentry) && iint) {
+		if (IS_I_VERSION(inode))
+			i_version = inode_query_iversion(inode);
+		integrity_inode_attrs_store(&iint->metadata_inode, i_version,
+					    inode);
+	}
+
+	/* Portable EVM signatures must include an IMA hash */
+	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
+		error = -EPERM;
 out:
 	kfree(xattr_value);
 	kfree(desc);
@@ -229,20 +314,50 @@ out:
 
 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)
+		  struct evm_digest *data, struct evm_iint_cache *iint)
 {
 	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
-				req_xattr_value_len, EVM_XATTR_HMAC, digest);
+				    req_xattr_value_len, EVM_XATTR_HMAC, data,
+				    iint);
 }
 
 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)
+		  char type, struct evm_digest *data, struct evm_iint_cache *iint)
 {
 	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
-				req_xattr_value_len, IMA_XATTR_DIGEST, digest);
+				     req_xattr_value_len, type, data, iint);
+}
+
+static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
+{
+	const struct evm_ima_xattr_data *xattr_data = NULL;
+	struct evm_iint_cache *iint;
+	int rc = 0;
+
+	iint = evm_iint_inode(inode);
+	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
+		return 1;
+
+	/* Do this the hard way */
+	rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_EVM,
+				(char **)&xattr_data, 0, GFP_NOFS);
+	if (rc <= 0) {
+		if (rc == -ENODATA)
+			rc = 0;
+		goto out;
+	}
+	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
+		rc = 1;
+	else
+		rc = 0;
+
+out:
+	kfree(xattr_data);
+	return rc;
 }
 
+
 /*
  * Calculate the hmac and update security.evm xattr
  *
@@ -252,35 +367,55 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
 			const char *xattr_value, size_t xattr_value_len)
 {
 	struct inode *inode = d_backing_inode(dentry);
-	struct evm_ima_xattr_data xattr_data;
+	struct evm_iint_cache *iint = evm_iint_inode(inode);
+	struct evm_digest data;
 	int rc = 0;
 
+	/*
+	 * Don't permit any transformation of the EVM xattr if the signature
+	 * is of an immutable type
+	 */
+	rc = evm_is_immutable(dentry, inode);
+	if (rc < 0)
+		return rc;
+	if (rc)
+		return -EPERM;
+
+	data.hdr.algo = HASH_ALGO_SHA1;
 	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
-			   xattr_value_len, xattr_data.digest);
+			   xattr_value_len, &data, iint);
 	if (rc == 0) {
-		xattr_data.type = EVM_XATTR_HMAC;
-		rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM,
-					   &xattr_data,
-					   sizeof(xattr_data), 0);
+		data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
+		rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry,
+					   XATTR_NAME_EVM,
+					   &data.hdr.xattr.data[1],
+					   SHA1_DIGEST_SIZE + 1, 0);
 	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
-		rc = __vfs_removexattr(dentry, XATTR_NAME_EVM);
+		rc = __vfs_removexattr(&nop_mnt_idmap, dentry, XATTR_NAME_EVM);
 	}
 	return rc;
 }
 
-int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
+int evm_init_hmac(struct inode *inode, const struct xattr *xattrs,
 		  char *hmac_val)
 {
 	struct shash_desc *desc;
+	const struct xattr *xattr;
 
-	desc = init_desc(EVM_XATTR_HMAC);
+	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
 	if (IS_ERR(desc)) {
 		pr_info("init_desc failed\n");
 		return PTR_ERR(desc);
 	}
 
-	crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
-	hmac_add_misc(desc, inode, hmac_val);
+	for (xattr = xattrs; xattr->name; xattr++) {
+		if (!evm_protected_xattr(xattr->name))
+			continue;
+
+		crypto_shash_update(desc, xattr->value, xattr->value_len);
+	}
+
+	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
 	kfree(desc);
 	return 0;
 }