Fixed MTP to work with TWRP

security/integrity/evm/Kconfig

@@ -0,0 +1,44 @@
+config EVM
+	boolean "EVM support"
+	select KEYS
+	select ENCRYPTED_KEYS
+	select CRYPTO_HMAC
+	select CRYPTO_SHA1
+	default n
+	help
+	  EVM protects a file's security extended attributes against
+	  integrity attacks.
+
+	  If you are unsure how to answer this question, answer N.
+
+config EVM_ATTR_FSUUID
+	bool "FSUUID (version 2)"
+	default y
+	depends on EVM
+	help
+	  Include filesystem UUID for HMAC calculation.
+
+	  Default value is 'selected', which is former version 2.
+	  if 'not selected', it is former version 1
+
+	  WARNING: changing the HMAC calculation method or adding
+	  additional info to the calculation, requires existing EVM
+	  labeled file systems to be relabeled.
+
+config EVM_EXTRA_SMACK_XATTRS
+	bool "Additional SMACK xattrs"
+	depends on EVM && SECURITY_SMACK
+	default n
+	help
+	  Include additional SMACK xattrs for HMAC calculation.
+
+	  In addition to the original security xattrs (eg. security.selinux,
+	  security.SMACK64, security.capability, and security.ima) included
+	  in the HMAC calculation, enabling this option includes newly defined
+	  Smack xattrs: security.SMACK64EXEC, security.SMACK64TRANSMUTE and
+	  security.SMACK64MMAP.
+
+	  WARNING: changing the HMAC calculation method or adding
+	  additional info to the calculation, requires existing EVM
+	  labeled file systems to be relabeled.
+

security/integrity/evm/Makefile

@@ -0,0 +1,7 @@
+#
+# Makefile for building the Extended Verification Module(EVM)
+#
+obj-$(CONFIG_EVM) += evm.o
+
+evm-y := evm_main.o evm_crypto.o evm_secfs.o
+evm-$(CONFIG_FS_POSIX_ACL) += evm_posix_acl.o

security/integrity/evm/evm.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2005-2010 IBM Corporation
+ *
+ * Authors:
+ * 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.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;
+
+#define EVM_ATTR_FSUUID		0x0001
+
+extern int evm_hmac_attrs;
+
+extern struct crypto_shash *hmac_tfm;
+extern struct crypto_shash *hash_tfm;
+
+/* List of EVM protected security xattrs */
+extern char *evm_config_xattrnames[];
+
+int evm_init_key(void);
+int evm_update_evmxattr(struct dentry *dentry,
+			const char *req_xattr_name,
+			const char *req_xattr_value,
+			size_t req_xattr_value_len);
+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);
+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);
+int evm_init_hmac(struct inode *inode, const struct xattr *xattr,
+		  char *hmac_val);
+int evm_init_secfs(void);
+
+#endif

security/integrity/evm/evm_crypto.c

@@ -0,0 +1,262 @@
+/*
+ * Copyright (C) 2005-2010 IBM Corporation
+ *
+ * Authors:
+ * 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
+
+#include <linux/module.h>
+#include <linux/crypto.h>
+#include <linux/xattr.h>
+#include <keys/encrypted-type.h>
+#include <crypto/hash.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;
+
+struct crypto_shash *hmac_tfm;
+struct crypto_shash *hash_tfm;
+
+static DEFINE_MUTEX(mutex);
+
+static struct shash_desc *init_desc(char type)
+{
+	long rc;
+	char *algo;
+	struct crypto_shash **tfm;
+	struct shash_desc *desc;
+
+	if (type == EVM_XATTR_HMAC) {
+		tfm = &hmac_tfm;
+		algo = evm_hmac;
+	} else {
+		tfm = &hash_tfm;
+		algo = evm_hash;
+	}
+
+	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;
+			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);
+	}
+
+	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) {
+		kfree(desc);
+		return ERR_PTR(rc);
+	}
+	return desc;
+}
+
+/* Protect against 'cutting & pasting' security.evm xattr, include inode
+ * specific info.
+ *
+ * (Additional directory/file metadata needs to be added for more complete
+ * protection.)
+ */
+static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
+			  char *digest)
+{
+	struct h_misc {
+		unsigned long ino;
+		__u32 generation;
+		uid_t uid;
+		gid_t gid;
+		umode_t mode;
+	} hmac_misc;
+
+	memset(&hmac_misc, 0, sizeof(hmac_misc));
+	hmac_misc.ino = inode->i_ino;
+	hmac_misc.generation = inode->i_generation;
+	hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
+	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,
+				    sizeof(inode->i_sb->s_uuid));
+	crypto_shash_final(desc, digest);
+}
+
+/*
+ * Calculate the HMAC value across the set of protected security xattrs.
+ *
+ * Instead of retrieving the requested xattr, for performance, calculate
+ * the hmac using the requested xattr value. Don't alloc/free memory for
+ * 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)
+{
+	struct inode *inode = dentry->d_inode;
+	struct shash_desc *desc;
+	char **xattrname;
+	size_t xattr_size = 0;
+	char *xattr_value = NULL;
+	int error;
+	int size;
+
+	if (!inode->i_op->getxattr)
+		return -EOPNOTSUPP;
+	desc = init_desc(type);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	error = -ENODATA;
+	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
+		if ((req_xattr_name && req_xattr_value)
+		    && !strcmp(*xattrname, req_xattr_name)) {
+			error = 0;
+			crypto_shash_update(desc, (const u8 *)req_xattr_value,
+					     req_xattr_value_len);
+			continue;
+		}
+		size = vfs_getxattr_alloc(dentry, *xattrname,
+					  &xattr_value, xattr_size, GFP_NOFS);
+		if (size == -ENOMEM) {
+			error = -ENOMEM;
+			goto out;
+		}
+		if (size < 0)
+			continue;
+
+		error = 0;
+		xattr_size = size;
+		crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
+	}
+	hmac_add_misc(desc, inode, digest);
+
+out:
+	kfree(xattr_value);
+	kfree(desc);
+	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
+ *
+ * Expects to be called with i_mutex locked.
+ */
+int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
+			const char *xattr_value, size_t xattr_value_len)
+{
+	struct inode *inode = dentry->d_inode;
+	struct evm_ima_xattr_data xattr_data;
+	int rc = 0;
+
+	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
+			   xattr_value_len, xattr_data.digest);
+	if (rc == 0) {
+		xattr_data.type = EVM_XATTR_HMAC;
+		rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM,
+					   &xattr_data,
+					   sizeof(xattr_data), 0);
+	} else if (rc == -ENODATA && inode->i_op->removexattr) {
+		rc = inode->i_op->removexattr(dentry, XATTR_NAME_EVM);
+	}
+	return rc;
+}
+
+int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
+		  char *hmac_val)
+{
+	struct shash_desc *desc;
+
+	desc = init_desc(EVM_XATTR_HMAC);
+	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);
+	kfree(desc);
+	return 0;
+}
+
+/*
+ * Get the key from the TPM for the SHA1-HMAC
+ */
+int evm_init_key(void)
+{
+	struct key *evm_key;
+	struct encrypted_key_payload *ekp;
+	int rc = 0;
+
+	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
+	if (IS_ERR(evm_key))
+		return -ENOENT;
+
+	down_read(&evm_key->sem);
+	ekp = evm_key->payload.data;
+	if (ekp->decrypted_datalen > MAX_KEY_SIZE) {
+		rc = -EINVAL;
+		goto out;
+	}
+	memcpy(evmkey, ekp->decrypted_data, ekp->decrypted_datalen);
+out:
+	/* burn the original key contents */
+	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
+	up_read(&evm_key->sem);
+	key_put(evm_key);
+	return rc;
+}

security/integrity/evm/evm_main.c

@@ -0,0 +1,494 @@
+/*
+ * Copyright (C) 2005-2010 IBM Corporation
+ *
+ * Author:
+ * 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_main.c
+ *	implements evm_inode_setxattr, evm_inode_post_setxattr,
+ *	evm_inode_removexattr, and evm_verifyxattr
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/crypto.h>
+#include <linux/audit.h>
+#include <linux/xattr.h>
+#include <linux/integrity.h>
+#include <linux/evm.h>
+#include <crypto/hash.h>
+#include <crypto/algapi.h>
+#include "evm.h"
+
+int evm_initialized;
+
+static char *integrity_status_msg[] = {
+	"pass", "fail", "no_label", "no_xattrs", "unknown"
+};
+char *evm_hmac = "hmac(sha1)";
+char *evm_hash = "sha1";
+int evm_hmac_attrs;
+
+char *evm_config_xattrnames[] = {
+#ifdef CONFIG_SECURITY_SELINUX
+	XATTR_NAME_SELINUX,
+#endif
+#ifdef CONFIG_SECURITY_SMACK
+	XATTR_NAME_SMACK,
+#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS
+	XATTR_NAME_SMACKEXEC,
+	XATTR_NAME_SMACKTRANSMUTE,
+	XATTR_NAME_SMACKMMAP,
+#endif
+#endif
+#ifdef CONFIG_IMA_APPRAISE
+	XATTR_NAME_IMA,
+#endif
+	XATTR_NAME_CAPS,
+	NULL
+};
+
+static int evm_fixmode;
+static int __init evm_set_fixmode(char *str)
+{
+	if (strncmp(str, "fix", 3) == 0)
+		evm_fixmode = 1;
+	return 0;
+}
+__setup("evm=", evm_set_fixmode);
+
+static void __init evm_init_config(void)
+{
+#ifdef CONFIG_EVM_ATTR_FSUUID
+	evm_hmac_attrs |= EVM_ATTR_FSUUID;
+#endif
+	pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
+}
+
+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->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
+ *
+ * Compute the HMAC on the dentry's protected set of extended attributes
+ * and compare it against the stored security.evm xattr.
+ *
+ * For performance:
+ * - use the previoulsy retrieved xattr value and length to calculate the
+ *   HMAC.)
+ * - cache the verification result in the iint, when available.
+ *
+ * Returns integrity status
+ */
+static enum integrity_status evm_verify_hmac(struct dentry *dentry,
+					     const char *xattr_name,
+					     char *xattr_value,
+					     size_t xattr_value_len,
+					     struct integrity_iint_cache *iint)
+{
+	struct evm_ima_xattr_data *xattr_data = NULL;
+	struct evm_ima_xattr_data calc;
+	enum integrity_status evm_status = INTEGRITY_PASS;
+	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 */
+
+	/* first need to know the sig type */
+	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
+				GFP_NOFS);
+	if (rc <= 0) {
+		evm_status = INTEGRITY_FAIL;
+		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 */
+		} else if (rc == -EOPNOTSUPP) {
+			evm_status = INTEGRITY_UNKNOWN;
+		}
+		goto out;
+	}
+
+	xattr_len = rc;
+
+	/* 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 = crypto_memneq(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,
+					(const char *)xattr_data, 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;
+}
+
+static int evm_protected_xattr(const char *req_xattr_name)
+{
+	char **xattrname;
+	int namelen;
+	int found = 0;
+
+	namelen = strlen(req_xattr_name);
+	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
+		if ((strlen(*xattrname) == namelen)
+		    && (strncmp(req_xattr_name, *xattrname, namelen) == 0)) {
+			found = 1;
+			break;
+		}
+		if (strncmp(req_xattr_name,
+			    *xattrname + XATTR_SECURITY_PREFIX_LEN,
+			    strlen(req_xattr_name)) == 0) {
+			found = 1;
+			break;
+		}
+	}
+	return found;
+}
+
+/**
+ * evm_verifyxattr - verify the integrity of the requested xattr
+ * @dentry: object of the verify xattr
+ * @xattr_name: requested xattr
+ * @xattr_value: requested xattr value
+ * @xattr_value_len: requested xattr value length
+ *
+ * Calculate the HMAC for the given dentry and verify it against the stored
+ * security.evm xattr. For performance, use the xattr value and length
+ * previously retrieved to calculate the HMAC.
+ *
+ * Returns the xattr integrity status.
+ *
+ * This function requires the caller to lock the inode's i_mutex before it
+ * is executed.
+ */
+enum integrity_status evm_verifyxattr(struct dentry *dentry,
+				      const char *xattr_name,
+				      void *xattr_value, size_t xattr_value_len,
+				      struct integrity_iint_cache *iint)
+{
+	if (!evm_initialized || !evm_protected_xattr(xattr_name))
+		return INTEGRITY_UNKNOWN;
+
+	if (!iint) {
+		iint = integrity_iint_find(dentry->d_inode);
+		if (!iint)
+			return INTEGRITY_UNKNOWN;
+	}
+	return evm_verify_hmac(dentry, xattr_name, xattr_value,
+				 xattr_value_len, iint);
+}
+EXPORT_SYMBOL_GPL(evm_verifyxattr);
+
+/*
+ * evm_verify_current_integrity - verify the dentry's metadata integrity
+ * @dentry: pointer to the affected dentry
+ *
+ * Verify and return the dentry's metadata integrity. The exceptions are
+ * before EVM is initialized or in 'fix' mode.
+ */
+static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
+{
+	struct inode *inode = dentry->d_inode;
+
+	if (!evm_initialized || !S_ISREG(inode->i_mode) || evm_fixmode)
+		return 0;
+	return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
+}
+
+/*
+ * evm_protect_xattr - protect the EVM extended attribute
+ *
+ * Prevent security.evm from being modified or removed without the
+ * necessary permissions or when the existing value is invalid.
+ *
+ * The posix xattr acls are 'system' prefixed, which normally would not
+ * affect security.evm.  An interesting side affect of writing posix xattr
+ * acls is their modifying of the i_mode, which is included in security.evm.
+ * For posix xattr acls only, permit security.evm, even if it currently
+ * doesn't exist, to be updated.
+ */
+static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
+			     const void *xattr_value, size_t xattr_value_len)
+{
+	enum integrity_status evm_status;
+
+	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+	} else if (!evm_protected_xattr(xattr_name)) {
+		if (!posix_xattr_acl(xattr_name))
+			return 0;
+		evm_status = evm_verify_current_integrity(dentry);
+		if ((evm_status == INTEGRITY_PASS) ||
+		    (evm_status == INTEGRITY_NOXATTRS))
+			return 0;
+		goto out;
+	}
+	evm_status = evm_verify_current_integrity(dentry);
+	if (evm_status == INTEGRITY_NOXATTRS) {
+		struct integrity_iint_cache *iint;
+
+		iint = integrity_iint_find(dentry->d_inode);
+		if (iint && (iint->flags & IMA_NEW_FILE))
+			return 0;
+	}
+out:
+	if (evm_status != INTEGRITY_PASS)
+		integrity_audit_msg(AUDIT_INTEGRITY_METADATA, dentry->d_inode,
+				    dentry->d_name.name, "appraise_metadata",
+				    integrity_status_msg[evm_status],
+				    -EPERM, 0);
+	return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
+}
+
+/**
+ * evm_inode_setxattr - protect the EVM extended attribute
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ * @xattr_value: pointer to the new extended attribute value
+ * @xattr_value_len: pointer to the new extended attribute value length
+ *
+ * Before allowing the 'security.evm' protected xattr to be updated,
+ * verify the existing value is valid.  As only the kernel should have
+ * access to the EVM encrypted key needed to calculate the HMAC, prevent
+ * userspace from writing HMAC value.  Writing 'security.evm' requires
+ * requires CAP_SYS_ADMIN privileges.
+ */
+int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
+		       const void *xattr_value, size_t xattr_value_len)
+{
+	const struct evm_ima_xattr_data *xattr_data = xattr_value;
+
+	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+		if (!xattr_value_len)
+			return -EINVAL;
+		if (xattr_data->type != EVM_IMA_XATTR_DIGSIG)
+			return -EPERM;
+	}
+	return evm_protect_xattr(dentry, xattr_name, xattr_value,
+				 xattr_value_len);
+}
+
+/**
+ * evm_inode_removexattr - protect the EVM extended attribute
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ *
+ * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
+ * the current value is valid.
+ */
+int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
+{
+	return evm_protect_xattr(dentry, xattr_name, NULL, 0);
+}
+
+/**
+ * evm_inode_post_setxattr - update 'security.evm' to reflect the changes
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ * @xattr_value: pointer to the new extended attribute value
+ * @xattr_value_len: pointer to the new extended attribute value length
+ *
+ * Update the HMAC stored in 'security.evm' to reflect the change.
+ *
+ * No need to take the i_mutex lock here, as this function is called from
+ * __vfs_setxattr_noperm().  The caller of which has taken the inode's
+ * i_mutex lock.
+ */
+void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
+			     const void *xattr_value, size_t xattr_value_len)
+{
+	if (!evm_initialized || (!evm_protected_xattr(xattr_name)
+				 && !posix_xattr_acl(xattr_name)))
+		return;
+
+	evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
+}
+
+/**
+ * evm_inode_post_removexattr - update 'security.evm' after removing the xattr
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: pointer to the affected extended attribute name
+ *
+ * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
+ */
+void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
+{
+	struct inode *inode = dentry->d_inode;
+
+	if (!evm_initialized || !evm_protected_xattr(xattr_name))
+		return;
+
+	mutex_lock(&inode->i_mutex);
+	evm_update_evmxattr(dentry, xattr_name, NULL, 0);
+	mutex_unlock(&inode->i_mutex);
+}
+
+/**
+ * evm_inode_setattr - prevent updating an invalid EVM extended attribute
+ * @dentry: pointer to the affected dentry
+ */
+int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	unsigned int ia_valid = attr->ia_valid;
+	enum integrity_status evm_status;
+
+	if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
+		return 0;
+	evm_status = evm_verify_current_integrity(dentry);
+	if ((evm_status == INTEGRITY_PASS) ||
+	    (evm_status == INTEGRITY_NOXATTRS))
+		return 0;
+	integrity_audit_msg(AUDIT_INTEGRITY_METADATA, dentry->d_inode,
+			    dentry->d_name.name, "appraise_metadata",
+			    integrity_status_msg[evm_status], -EPERM, 0);
+	return -EPERM;
+}
+
+/**
+ * evm_inode_post_setattr - update 'security.evm' after modifying metadata
+ * @dentry: pointer to the affected dentry
+ * @ia_valid: for the UID and GID status
+ *
+ * For now, update the HMAC stored in 'security.evm' to reflect UID/GID
+ * changes.
+ *
+ * This function is called from notify_change(), which expects the caller
+ * to lock the inode's i_mutex.
+ */
+void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
+{
+	if (!evm_initialized)
+		return;
+
+	if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
+		evm_update_evmxattr(dentry, NULL, NULL, 0);
+}
+
+/*
+ * evm_inode_init_security - initializes security.evm
+ */
+int evm_inode_init_security(struct inode *inode,
+				 const struct xattr *lsm_xattr,
+				 struct xattr *evm_xattr)
+{
+	struct evm_ima_xattr_data *xattr_data;
+	int rc;
+
+	if (!evm_initialized || !evm_protected_xattr(lsm_xattr->name))
+		return 0;
+
+	xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
+	if (!xattr_data)
+		return -ENOMEM;
+
+	xattr_data->type = EVM_XATTR_HMAC;
+	rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest);
+	if (rc < 0)
+		goto out;
+
+	evm_xattr->value = xattr_data;
+	evm_xattr->value_len = sizeof(*xattr_data);
+	evm_xattr->name = XATTR_EVM_SUFFIX;
+	return 0;
+out:
+	kfree(xattr_data);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(evm_inode_init_security);
+
+static int __init init_evm(void)
+{
+	int error;
+
+	evm_init_config();
+
+	error = evm_init_secfs();
+	if (error < 0) {
+		pr_info("Error registering secfs\n");
+		goto err;
+	}
+
+	return 0;
+err:
+	return error;
+}
+
+/*
+ * evm_display_config - list the EVM protected security extended attributes
+ */
+static int __init evm_display_config(void)
+{
+	char **xattrname;
+
+	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++)
+		pr_info("%s\n", *xattrname);
+	return 0;
+}
+
+pure_initcall(evm_display_config);
+late_initcall(init_evm);
+
+MODULE_DESCRIPTION("Extended Verification Module");
+MODULE_LICENSE("GPL");

security/integrity/evm/evm_posix_acl.c

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2011 IBM Corporation
+ *
+ * Author:
+ * Mimi Zohar <zohar@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.
+ */
+
+#include <linux/module.h>
+#include <linux/xattr.h>
+#include <linux/evm.h>
+
+int posix_xattr_acl(const char *xattr)
+{
+	int xattr_len = strlen(xattr);
+
+	if ((strlen(XATTR_NAME_POSIX_ACL_ACCESS) == xattr_len)
+	     && (strncmp(XATTR_NAME_POSIX_ACL_ACCESS, xattr, xattr_len) == 0))
+		return 1;
+	if ((strlen(XATTR_NAME_POSIX_ACL_DEFAULT) == xattr_len)
+	     && (strncmp(XATTR_NAME_POSIX_ACL_DEFAULT, xattr, xattr_len) == 0))
+		return 1;
+	return 0;
+}

security/integrity/evm/evm_secfs.c

@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2010 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@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_secfs.c
+ *	- Used to signal when key is on keyring
+ *	- Get the key and enable EVM
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include "evm.h"
+
+static struct dentry *evm_init_tpm;
+
+/**
+ * evm_read_key - read() for <securityfs>/evm
+ *
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @count: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t evm_read_key(struct file *filp, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	char temp[80];
+	ssize_t rc;
+
+	if (*ppos != 0)
+		return 0;
+
+	sprintf(temp, "%d", evm_initialized);
+	rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+
+	return rc;
+}
+
+/**
+ * evm_write_key - write() for <securityfs>/evm
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Used to signal that key is on the kernel key ring.
+ * - get the integrity hmac key from the kernel key ring
+ * - create list of hmac protected extended attributes
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t evm_write_key(struct file *file, const char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	char temp[80];
+	int i, error;
+
+	if (!capable(CAP_SYS_ADMIN) || evm_initialized)
+		return -EPERM;
+
+	if (count >= sizeof(temp) || count == 0)
+		return -EINVAL;
+
+	if (copy_from_user(temp, buf, count) != 0)
+		return -EFAULT;
+
+	temp[count] = '\0';
+
+	if ((sscanf(temp, "%d", &i) != 1) || (i != 1))
+		return -EINVAL;
+
+	error = evm_init_key();
+	if (!error) {
+		evm_initialized = 1;
+		pr_info("initialized\n");
+	} else
+		pr_err("initialization failed\n");
+	return count;
+}
+
+static const struct file_operations evm_key_ops = {
+	.read		= evm_read_key,
+	.write		= evm_write_key,
+};
+
+int __init evm_init_secfs(void)
+{
+	int error = 0;
+
+	evm_init_tpm = securityfs_create_file("evm", S_IRUSR | S_IRGRP,
+					      NULL, NULL, &evm_key_ops);
+	if (!evm_init_tpm || IS_ERR(evm_init_tpm))
+		error = -EFAULT;
+	return error;
+}