1 files changed, 851 insertions, 128 deletions

diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index df0fa451a871..73d500a375cb 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2005-2010 IBM Corporation
  *
@@ -5,68 +6,140 @@
  * 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
+ *	evm_inode_removexattr, evm_verifyxattr, and evm_inode_set_acl.
  */
 
-#include <linux/module.h>
-#include <linux/crypto.h>
+#define pr_fmt(fmt) "EVM: "fmt
+
+#include <linux/init.h>
 #include <linux/audit.h>
 #include <linux/xattr.h>
 #include <linux/integrity.h>
 #include <linux/evm.h>
+#include <linux/magic.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/lsm_hooks.h>
+
 #include <crypto/hash.h>
+#include <crypto/hash_info.h>
+#include <crypto/utils.h>
 #include "evm.h"
 
 int evm_initialized;
 
-static char *integrity_status_msg[] = {
-	"pass", "fail", "no_label", "no_xattrs", "unknown"
+static const char * const integrity_status_msg[] = {
+	"pass", "pass_immutable", "fail", "fail_immutable", "no_label",
+	"no_xattrs", "unknown"
 };
-char *evm_hmac = "hmac(sha1)";
-char *evm_hash = "sha1";
-int evm_hmac_version = CONFIG_EVM_HMAC_VERSION;
+int evm_hmac_attrs;
 
-char *evm_config_xattrnames[] = {
-#ifdef CONFIG_SECURITY_SELINUX
-	XATTR_NAME_SELINUX,
-#endif
-#ifdef CONFIG_SECURITY_SMACK
-	XATTR_NAME_SMACK,
-#endif
-#ifdef CONFIG_IMA_APPRAISE
-	XATTR_NAME_IMA,
-#endif
-	XATTR_NAME_CAPS,
-	NULL
+static struct xattr_list evm_config_default_xattrnames[] = {
+	{
+	 .name = XATTR_NAME_SELINUX,
+	 .enabled = IS_ENABLED(CONFIG_SECURITY_SELINUX)
+	},
+	{
+	 .name = XATTR_NAME_SMACK,
+	 .enabled = IS_ENABLED(CONFIG_SECURITY_SMACK)
+	},
+	{
+	 .name = XATTR_NAME_SMACKEXEC,
+	 .enabled = IS_ENABLED(CONFIG_EVM_EXTRA_SMACK_XATTRS)
+	},
+	{
+	 .name = XATTR_NAME_SMACKTRANSMUTE,
+	 .enabled = IS_ENABLED(CONFIG_EVM_EXTRA_SMACK_XATTRS)
+	},
+	{
+	 .name = XATTR_NAME_SMACKMMAP,
+	 .enabled = IS_ENABLED(CONFIG_EVM_EXTRA_SMACK_XATTRS)
+	},
+	{
+	 .name = XATTR_NAME_APPARMOR,
+	 .enabled = IS_ENABLED(CONFIG_SECURITY_APPARMOR)
+	},
+	{
+	 .name = XATTR_NAME_IMA,
+	 .enabled = IS_ENABLED(CONFIG_IMA_APPRAISE)
+	},
+	{
+	 .name = XATTR_NAME_CAPS,
+	 .enabled = true
+	},
 };
 
-static int evm_fixmode;
+LIST_HEAD(evm_config_xattrnames);
+
+static int evm_fixmode __ro_after_init;
 static int __init evm_set_fixmode(char *str)
 {
 	if (strncmp(str, "fix", 3) == 0)
 		evm_fixmode = 1;
-	return 0;
+	else
+		pr_err("invalid \"%s\" mode", str);
+
+	return 1;
 }
 __setup("evm=", evm_set_fixmode);
 
+static void __init evm_init_config(void)
+{
+	int i, xattrs;
+
+	xattrs = ARRAY_SIZE(evm_config_default_xattrnames);
+
+	pr_info("Initialising EVM extended attributes:\n");
+	for (i = 0; i < xattrs; i++) {
+		pr_info("%s%s\n", evm_config_default_xattrnames[i].name,
+			!evm_config_default_xattrnames[i].enabled ?
+			" (disabled)" : "");
+		list_add_tail(&evm_config_default_xattrnames[i].list,
+			      &evm_config_xattrnames);
+	}
+
+#ifdef CONFIG_EVM_ATTR_FSUUID
+	evm_hmac_attrs |= EVM_ATTR_FSUUID;
+#endif
+	pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
+}
+
+static bool evm_key_loaded(void)
+{
+	return (bool)(evm_initialized & EVM_KEY_MASK);
+}
+
+/*
+ * This function determines whether or not it is safe to ignore verification
+ * errors, based on the ability of EVM to calculate HMACs. If the HMAC key
+ * is not loaded, and it cannot be loaded in the future due to the
+ * EVM_SETUP_COMPLETE initialization flag, allowing an operation despite the
+ * attrs/xattrs being found invalid will not make them valid.
+ */
+static bool evm_hmac_disabled(void)
+{
+	if (evm_initialized & EVM_INIT_HMAC)
+		return false;
+
+	if (!(evm_initialized & EVM_SETUP_COMPLETE))
+		return false;
+
+	return true;
+}
+
 static int evm_find_protected_xattrs(struct dentry *dentry)
 {
-	struct inode *inode = dentry->d_inode;
-	char **xattr;
+	struct inode *inode = d_backing_inode(dentry);
+	struct xattr_list *xattr;
 	int error;
 	int count = 0;
 
-	if (!inode->i_op || !inode->i_op->getxattr)
+	if (!(inode->i_opflags & IOP_XATTR))
 		return -EOPNOTSUPP;
 
-	for (xattr = evm_config_xattrnames; *xattr != NULL; xattr++) {
-		error = inode->i_op->getxattr(dentry, *xattr, NULL, 0);
+	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+		error = __vfs_getxattr(dentry, inode, xattr->name, NULL, 0);
 		if (error < 0) {
 			if (error == -ENODATA)
 				continue;
@@ -78,6 +151,17 @@ static int evm_find_protected_xattrs(struct dentry *dentry)
 	return count;
 }
 
+static int is_unsupported_hmac_fs(struct dentry *dentry)
+{
+	struct inode *inode = d_backing_inode(dentry);
+
+	if (inode->i_sb->s_iflags & SB_I_EVM_HMAC_UNSUPPORTED) {
+		pr_info_once("%s not supported\n", inode->i_sb->s_type->name);
+		return 1;
+	}
+	return 0;
+}
+
 /*
  * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
  *
@@ -85,7 +169,7 @@ static int evm_find_protected_xattrs(struct dentry *dentry)
  * and compare it against the stored security.evm xattr.
  *
  * For performance:
- * - use the previoulsy retrieved xattr value and length to calculate the
+ * - use the previously retrieved xattr value and length to calculate the
  *   HMAC.)
  * - cache the verification result in the iint, when available.
  *
@@ -94,61 +178,100 @@ static int evm_find_protected_xattrs(struct dentry *dentry)
 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)
+					     size_t xattr_value_len)
 {
 	struct evm_ima_xattr_data *xattr_data = NULL;
-	struct evm_ima_xattr_data calc;
+	struct signature_v2_hdr *hdr;
 	enum integrity_status evm_status = INTEGRITY_PASS;
-	int rc, xattr_len;
+	struct evm_digest digest;
+	struct inode *inode = d_backing_inode(dentry);
+	struct evm_iint_cache *iint = evm_iint_inode(inode);
+	int rc, xattr_len, evm_immutable = 0;
 
-	if (iint && iint->evm_status == INTEGRITY_PASS)
+	if (iint && (iint->evm_status == INTEGRITY_PASS ||
+		     iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
 		return iint->evm_status;
 
+	/*
+	 * On unsupported filesystems without EVM_INIT_X509 enabled, skip
+	 * signature verification.
+	 */
+	if (!(evm_initialized & EVM_INIT_X509) &&
+	    is_unsupported_hmac_fs(dentry))
+		return INTEGRITY_UNKNOWN;
+
 	/* 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);
+	rc = vfs_getxattr_alloc(&nop_mnt_idmap, 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) {
+		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 - 1;
+	xattr_len = rc;
 
 	/* check value type */
 	switch (xattr_data->type) {
 	case EVM_XATTR_HMAC:
+		if (xattr_len != sizeof(struct evm_xattr)) {
+			evm_status = INTEGRITY_FAIL;
+			goto out;
+		}
+
+		digest.hdr.algo = HASH_ALGO_SHA1;
 		rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
-				   xattr_value_len, calc.digest);
+				   xattr_value_len, &digest, iint);
 		if (rc)
 			break;
-		rc = memcmp(xattr_data->digest, calc.digest,
-			    sizeof(calc.digest));
+		rc = crypto_memneq(xattr_data->data, digest.digest,
+				   SHA1_DIGEST_SIZE);
 		if (rc)
 			rc = -EINVAL;
 		break;
+	case EVM_XATTR_PORTABLE_DIGSIG:
+		evm_immutable = 1;
+		fallthrough;
 	case EVM_IMA_XATTR_DIGSIG:
+		/* accept xattr with non-empty signature field */
+		if (xattr_len <= sizeof(struct signature_v2_hdr)) {
+			evm_status = INTEGRITY_FAIL;
+			goto out;
+		}
+
+		hdr = (struct signature_v2_hdr *)xattr_data;
+		digest.hdr.algo = hdr->hash_algo;
 		rc = evm_calc_hash(dentry, xattr_name, xattr_value,
-				xattr_value_len, calc.digest);
+				   xattr_value_len, xattr_data->type, &digest,
+				   iint);
 		if (rc)
 			break;
 		rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
-					xattr_data->digest, xattr_len,
-					calc.digest, sizeof(calc.digest));
+					(const char *)xattr_data, xattr_len,
+					digest.digest, digest.hdr.length);
 		if (!rc) {
-			/* we probably want to replace rsa with hmac here */
-			evm_update_evmxattr(dentry, xattr_name, xattr_value,
-				   xattr_value_len);
+			if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG) {
+				if (iint)
+					iint->flags |= EVM_IMMUTABLE_DIGSIG;
+				evm_status = INTEGRITY_PASS_IMMUTABLE;
+			} else if (!IS_RDONLY(inode) &&
+				   !(inode->i_sb->s_readonly_remount) &&
+				   !IS_IMMUTABLE(inode) &&
+				   !is_unsupported_hmac_fs(dentry)) {
+				evm_update_evmxattr(dentry, xattr_name,
+						    xattr_value,
+						    xattr_value_len);
+			}
 		}
 		break;
 	default:
@@ -156,9 +279,16 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 		break;
 	}
 
-	if (rc)
-		evm_status = (rc == -ENODATA) ?
-				INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
+	if (rc) {
+		if (rc == -ENODATA)
+			evm_status = INTEGRITY_NOXATTRS;
+		else if (evm_immutable)
+			evm_status = INTEGRITY_FAIL_IMMUTABLE;
+		else
+			evm_status = INTEGRITY_FAIL;
+	}
+	pr_debug("digest: (%d) [%*phN]\n", digest.hdr.length, digest.hdr.length,
+		  digest.digest);
 out:
 	if (iint)
 		iint->evm_status = evm_status;
@@ -166,29 +296,112 @@ out:
 	return evm_status;
 }
 
-static int evm_protected_xattr(const char *req_xattr_name)
+static int evm_protected_xattr_common(const char *req_xattr_name,
+				      bool all_xattrs)
 {
-	char **xattrname;
 	int namelen;
 	int found = 0;
+	struct xattr_list *xattr;
 
 	namelen = strlen(req_xattr_name);
-	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
-		if ((strlen(*xattrname) == namelen)
-		    && (strncmp(req_xattr_name, *xattrname, namelen) == 0)) {
+	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+		if (!all_xattrs && !xattr->enabled)
+			continue;
+
+		if ((strlen(xattr->name) == namelen)
+		    && (strncmp(req_xattr_name, xattr->name, namelen) == 0)) {
 			found = 1;
 			break;
 		}
 		if (strncmp(req_xattr_name,
-			    *xattrname + XATTR_SECURITY_PREFIX_LEN,
+			    xattr->name + XATTR_SECURITY_PREFIX_LEN,
 			    strlen(req_xattr_name)) == 0) {
 			found = 1;
 			break;
 		}
 	}
+
 	return found;
 }
 
+int evm_protected_xattr(const char *req_xattr_name)
+{
+	return evm_protected_xattr_common(req_xattr_name, false);
+}
+
+int evm_protected_xattr_if_enabled(const char *req_xattr_name)
+{
+	return evm_protected_xattr_common(req_xattr_name, true);
+}
+
+/**
+ * evm_read_protected_xattrs - read EVM protected xattr names, lengths, values
+ * @dentry: dentry of the read xattrs
+ * @buffer: buffer xattr names, lengths or values are copied to
+ * @buffer_size: size of buffer
+ * @type: n: names, l: lengths, v: values
+ * @canonical_fmt: data format (true: little endian, false: native format)
+ *
+ * Read protected xattr names (separated by |), lengths (u32) or values for a
+ * given dentry and return the total size of copied data. If buffer is NULL,
+ * just return the total size.
+ *
+ * Returns the total size on success, a negative value on error.
+ */
+int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
+			      int buffer_size, char type, bool canonical_fmt)
+{
+	struct xattr_list *xattr;
+	int rc, size, total_size = 0;
+
+	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
+		rc = __vfs_getxattr(dentry, d_backing_inode(dentry),
+				    xattr->name, NULL, 0);
+		if (rc < 0 && rc == -ENODATA)
+			continue;
+		else if (rc < 0)
+			return rc;
+
+		switch (type) {
+		case 'n':
+			size = strlen(xattr->name) + 1;
+			if (buffer) {
+				if (total_size)
+					*(buffer + total_size - 1) = '|';
+
+				memcpy(buffer + total_size, xattr->name, size);
+			}
+			break;
+		case 'l':
+			size = sizeof(u32);
+			if (buffer) {
+				if (canonical_fmt)
+					rc = (__force int)cpu_to_le32(rc);
+
+				*(u32 *)(buffer + total_size) = rc;
+			}
+			break;
+		case 'v':
+			size = rc;
+			if (buffer) {
+				rc = __vfs_getxattr(dentry,
+					d_backing_inode(dentry), xattr->name,
+					buffer + total_size,
+					buffer_size - total_size);
+				if (rc < 0)
+					return rc;
+			}
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		total_size += size;
+	}
+
+	return total_size;
+}
+
 /**
  * evm_verifyxattr - verify the integrity of the requested xattr
  * @dentry: object of the verify xattr
@@ -207,19 +420,13 @@ static int evm_protected_xattr(const char *req_xattr_name)
  */
 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)
+				      void *xattr_value, size_t xattr_value_len)
 {
-	if (!evm_initialized || !evm_protected_xattr(xattr_name))
+	if (!evm_key_loaded() || !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);
+				 xattr_value_len);
 }
 EXPORT_SYMBOL_GPL(evm_verifyxattr);
 
@@ -232,11 +439,47 @@ EXPORT_SYMBOL_GPL(evm_verifyxattr);
  */
 static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
 {
-	struct inode *inode = dentry->d_inode;
+	struct inode *inode = d_backing_inode(dentry);
 
-	if (!evm_initialized || !S_ISREG(inode->i_mode) || evm_fixmode)
-		return 0;
-	return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
+	if (!evm_key_loaded() || !S_ISREG(inode->i_mode) || evm_fixmode)
+		return INTEGRITY_PASS;
+	return evm_verify_hmac(dentry, NULL, NULL, 0);
+}
+
+/*
+ * evm_xattr_change - check if passed xattr value differs from current value
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @xattr_name: requested xattr
+ * @xattr_value: requested xattr value
+ * @xattr_value_len: requested xattr value length
+ *
+ * Check if passed xattr value differs from current value.
+ *
+ * Returns 1 if passed xattr value differs from current value, 0 otherwise.
+ */
+static int evm_xattr_change(struct mnt_idmap *idmap,
+			    struct dentry *dentry, const char *xattr_name,
+			    const void *xattr_value, size_t xattr_value_len)
+{
+	char *xattr_data = NULL;
+	int rc = 0;
+
+	rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr_name, &xattr_data,
+				0, GFP_NOFS);
+	if (rc < 0) {
+		rc = 1;
+		goto out;
+	}
+
+	if (rc == xattr_value_len)
+		rc = !!memcmp(xattr_value, xattr_data, rc);
+	else
+		rc = 1;
+
+out:
+	kfree(xattr_data);
+	return rc;
 }
 
 /*
@@ -249,9 +492,10 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
  * 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.
+ * doesn't exist, to be updated unless the EVM signature is immutable.
  */
-static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
+static int evm_protect_xattr(struct mnt_idmap *idmap,
+			     struct dentry *dentry, const char *xattr_name,
 			     const void *xattr_value, size_t xattr_value_len)
 {
 	enum integrity_status evm_status;
@@ -259,19 +503,66 @@ static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
 	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
+		if (is_unsupported_hmac_fs(dentry))
+			return -EPERM;
 	} else if (!evm_protected_xattr(xattr_name)) {
 		if (!posix_xattr_acl(xattr_name))
 			return 0;
+		if (is_unsupported_hmac_fs(dentry))
+			return 0;
+
 		evm_status = evm_verify_current_integrity(dentry);
 		if ((evm_status == INTEGRITY_PASS) ||
 		    (evm_status == INTEGRITY_NOXATTRS))
 			return 0;
 		goto out;
-	}
+	} else if (is_unsupported_hmac_fs(dentry))
+		return 0;
+
 	evm_status = evm_verify_current_integrity(dentry);
+	if (evm_status == INTEGRITY_NOXATTRS) {
+		struct evm_iint_cache *iint;
+
+		/* Exception if the HMAC is not going to be calculated. */
+		if (evm_hmac_disabled())
+			return 0;
+
+		iint = evm_iint_inode(d_backing_inode(dentry));
+		if (iint && (iint->flags & EVM_NEW_FILE))
+			return 0;
+
+		/* exception for pseudo filesystems */
+		if (dentry->d_sb->s_magic == TMPFS_MAGIC
+		    || dentry->d_sb->s_magic == SYSFS_MAGIC)
+			return 0;
+
+		integrity_audit_msg(AUDIT_INTEGRITY_METADATA,
+				    dentry->d_inode, dentry->d_name.name,
+				    "update_metadata",
+				    integrity_status_msg[evm_status],
+				    -EPERM, 0);
+	}
 out:
-	if (evm_status != INTEGRITY_PASS)
-		integrity_audit_msg(AUDIT_INTEGRITY_METADATA, dentry->d_inode,
+	/* Exception if the HMAC is not going to be calculated. */
+	if (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
+	    evm_status == INTEGRITY_UNKNOWN))
+		return 0;
+
+	/*
+	 * Writing other xattrs is safe for portable signatures, as portable
+	 * signatures are immutable and can never be updated.
+	 */
+	if (evm_status == INTEGRITY_FAIL_IMMUTABLE)
+		return 0;
+
+	if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
+	    !evm_xattr_change(idmap, dentry, xattr_name, xattr_value,
+			      xattr_value_len))
+		return 0;
+
+	if (evm_status != INTEGRITY_PASS &&
+	    evm_status != INTEGRITY_PASS_IMMUTABLE)
+		integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
 				    dentry->d_name.name, "appraise_metadata",
 				    integrity_status_msg[evm_status],
 				    -EPERM, 0);
@@ -280,32 +571,220 @@ out:
 
 /**
  * evm_inode_setxattr - protect the EVM extended attribute
+ * @idmap: idmap of the mount
  * @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
+ * @flags: flags to pass into filesystem operations
  *
- * Updating 'security.evm' requires CAP_SYS_ADMIN privileges and that
- * the current value is valid.
+ * 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)
+static int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
+			      const char *xattr_name, const void *xattr_value,
+			      size_t xattr_value_len, int flags)
 {
-	return evm_protect_xattr(dentry, xattr_name, xattr_value,
+	const struct evm_ima_xattr_data *xattr_data = xattr_value;
+
+	/* Policy permits modification of the protected xattrs even though
+	 * there's no HMAC key loaded
+	 */
+	if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+		return 0;
+
+	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+		if (!xattr_value_len)
+			return -EINVAL;
+		if (xattr_data->type != EVM_IMA_XATTR_DIGSIG &&
+		    xattr_data->type != EVM_XATTR_PORTABLE_DIGSIG)
+			return -EPERM;
+	}
+	return evm_protect_xattr(idmap, dentry, xattr_name, xattr_value,
 				 xattr_value_len);
 }
 
 /**
  * evm_inode_removexattr - protect the EVM extended attribute
+ * @idmap: idmap of the mount
  * @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)
+static int evm_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
+				 const char *xattr_name)
 {
-	return evm_protect_xattr(dentry, xattr_name, NULL, 0);
+	/* Policy permits modification of the protected xattrs even though
+	 * there's no HMAC key loaded
+	 */
+	if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+		return 0;
+
+	return evm_protect_xattr(idmap, dentry, xattr_name, NULL, 0);
+}
+
+#ifdef CONFIG_FS_POSIX_ACL
+static int evm_inode_set_acl_change(struct mnt_idmap *idmap,
+				    struct dentry *dentry, const char *name,
+				    struct posix_acl *kacl)
+{
+	int rc;
+
+	umode_t mode;
+	struct inode *inode = d_backing_inode(dentry);
+
+	if (!kacl)
+		return 1;
+
+	rc = posix_acl_update_mode(idmap, inode, &mode, &kacl);
+	if (rc || (inode->i_mode != mode))
+		return 1;
+
+	return 0;
+}
+#else
+static inline int evm_inode_set_acl_change(struct mnt_idmap *idmap,
+					   struct dentry *dentry,
+					   const char *name,
+					   struct posix_acl *kacl)
+{
+	return 0;
+}
+#endif
+
+/**
+ * evm_inode_set_acl - protect the EVM extended attribute from posix acls
+ * @idmap: idmap of the idmapped mount
+ * @dentry: pointer to the affected dentry
+ * @acl_name: name of the posix acl
+ * @kacl: pointer to the posix acls
+ *
+ * Prevent modifying posix acls causing the EVM HMAC to be re-calculated
+ * and 'security.evm' xattr updated, unless the existing 'security.evm' is
+ * valid.
+ *
+ * Return: zero on success, -EPERM on failure.
+ */
+static int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+			     const char *acl_name, struct posix_acl *kacl)
+{
+	enum integrity_status evm_status;
+
+	/* Policy permits modification of the protected xattrs even though
+	 * there's no HMAC key loaded
+	 */
+	if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+		return 0;
+
+	evm_status = evm_verify_current_integrity(dentry);
+	if ((evm_status == INTEGRITY_PASS) ||
+	    (evm_status == INTEGRITY_NOXATTRS))
+		return 0;
+
+	/* Exception if the HMAC is not going to be calculated. */
+	if (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
+	    evm_status == INTEGRITY_UNKNOWN))
+		return 0;
+
+	/*
+	 * Writing other xattrs is safe for portable signatures, as portable
+	 * signatures are immutable and can never be updated.
+	 */
+	if (evm_status == INTEGRITY_FAIL_IMMUTABLE)
+		return 0;
+
+	if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
+	    !evm_inode_set_acl_change(idmap, dentry, acl_name, kacl))
+		return 0;
+
+	if (evm_status != INTEGRITY_PASS_IMMUTABLE)
+		integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
+				    dentry->d_name.name, "appraise_metadata",
+				    integrity_status_msg[evm_status],
+				    -EPERM, 0);
+	return -EPERM;
+}
+
+/**
+ * evm_inode_remove_acl - Protect the EVM extended attribute from posix acls
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @acl_name: name of the posix acl
+ *
+ * Prevent removing posix acls causing the EVM HMAC to be re-calculated
+ * and 'security.evm' xattr updated, unless the existing 'security.evm' is
+ * valid.
+ *
+ * Return: zero on success, -EPERM on failure.
+ */
+static int evm_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+				const char *acl_name)
+{
+	return evm_inode_set_acl(idmap, dentry, acl_name, NULL);
+}
+
+static void evm_reset_status(struct inode *inode)
+{
+	struct evm_iint_cache *iint;
+
+	iint = evm_iint_inode(inode);
+	if (iint)
+		iint->evm_status = INTEGRITY_UNKNOWN;
+}
+
+/**
+ * evm_metadata_changed: Detect changes to the metadata
+ * @inode: a file's inode
+ * @metadata_inode: metadata inode
+ *
+ * On a stacked filesystem detect whether the metadata has changed. If this is
+ * the case reset the evm_status associated with the inode that represents the
+ * file.
+ */
+bool evm_metadata_changed(struct inode *inode, struct inode *metadata_inode)
+{
+	struct evm_iint_cache *iint = evm_iint_inode(inode);
+	bool ret = false;
+
+	if (iint) {
+		ret = (!IS_I_VERSION(metadata_inode) ||
+		       integrity_inode_attrs_changed(&iint->metadata_inode,
+						     metadata_inode));
+		if (ret)
+			iint->evm_status = INTEGRITY_UNKNOWN;
+	}
+
+	return ret;
+}
+
+/**
+ * evm_revalidate_status - report whether EVM status re-validation is necessary
+ * @xattr_name: pointer to the affected extended attribute name
+ *
+ * Report whether callers of evm_verifyxattr() should re-validate the
+ * EVM status.
+ *
+ * Return true if re-validation is necessary, false otherwise.
+ */
+bool evm_revalidate_status(const char *xattr_name)
+{
+	if (!evm_key_loaded())
+		return false;
+
+	/* evm_inode_post_setattr() passes NULL */
+	if (!xattr_name)
+		return true;
+
+	if (!evm_protected_xattr(xattr_name) && !posix_xattr_acl(xattr_name) &&
+	    strcmp(xattr_name, XATTR_NAME_EVM))
+		return false;
+
+	return true;
 }
 
 /**
@@ -314,6 +793,7 @@ int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
  * @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
+ * @flags: flags to pass into filesystem operations
  *
  * Update the HMAC stored in 'security.evm' to reflect the change.
  *
@@ -321,15 +801,42 @@ int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
  * __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)
+static void evm_inode_post_setxattr(struct dentry *dentry,
+				    const char *xattr_name,
+				    const void *xattr_value,
+				    size_t xattr_value_len,
+				    int flags)
 {
-	if (!evm_initialized || (!evm_protected_xattr(xattr_name)
-				 && !posix_xattr_acl(xattr_name)))
+	if (!evm_revalidate_status(xattr_name))
+		return;
+
+	evm_reset_status(dentry->d_inode);
+
+	if (!strcmp(xattr_name, XATTR_NAME_EVM))
+		return;
+
+	if (!(evm_initialized & EVM_INIT_HMAC))
+		return;
+
+	if (is_unsupported_hmac_fs(dentry))
 		return;
 
 	evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
-	return;
+}
+
+/**
+ * evm_inode_post_set_acl - Update the EVM extended attribute from posix acls
+ * @dentry: pointer to the affected dentry
+ * @acl_name: name of the posix acl
+ * @kacl: pointer to the posix acls
+ *
+ * Update the 'security.evm' xattr with the EVM HMAC re-calculated after setting
+ * posix acls.
+ */
+static void evm_inode_post_set_acl(struct dentry *dentry, const char *acl_name,
+				   struct posix_acl *kacl)
+{
+	return evm_inode_post_setxattr(dentry, acl_name, NULL, 0, 0);
 }
 
 /**
@@ -338,36 +845,101 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
  * @xattr_name: pointer to the affected extended attribute name
  *
  * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
+ *
+ * No need to take the i_mutex lock here, as this function is called from
+ * vfs_removexattr() which takes the i_mutex.
  */
-void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
+static void evm_inode_post_removexattr(struct dentry *dentry,
+				       const char *xattr_name)
 {
-	struct inode *inode = dentry->d_inode;
+	if (!evm_revalidate_status(xattr_name))
+		return;
+
+	evm_reset_status(dentry->d_inode);
+
+	if (!strcmp(xattr_name, XATTR_NAME_EVM))
+		return;
 
-	if (!evm_initialized || !evm_protected_xattr(xattr_name))
+	if (!(evm_initialized & EVM_INIT_HMAC))
 		return;
 
-	mutex_lock(&inode->i_mutex);
 	evm_update_evmxattr(dentry, xattr_name, NULL, 0);
-	mutex_unlock(&inode->i_mutex);
-	return;
+}
+
+/**
+ * evm_inode_post_remove_acl - Update the EVM extended attribute from posix acls
+ * @idmap: idmap of the mount
+ * @dentry: pointer to the affected dentry
+ * @acl_name: name of the posix acl
+ *
+ * Update the 'security.evm' xattr with the EVM HMAC re-calculated after
+ * removing posix acls.
+ */
+static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap,
+					     struct dentry *dentry,
+					     const char *acl_name)
+{
+	evm_inode_post_removexattr(dentry, acl_name);
+}
+
+static int evm_attr_change(struct mnt_idmap *idmap,
+			   struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = d_backing_inode(dentry);
+	unsigned int ia_valid = attr->ia_valid;
+
+	if (!i_uid_needs_update(idmap, attr, inode) &&
+	    !i_gid_needs_update(idmap, attr, inode) &&
+	    (!(ia_valid & ATTR_MODE) || attr->ia_mode == inode->i_mode))
+		return 0;
+
+	return 1;
 }
 
 /**
  * evm_inode_setattr - prevent updating an invalid EVM extended attribute
+ * @idmap: idmap of the mount
  * @dentry: pointer to the affected dentry
+ * @attr: iattr structure containing the new file attributes
+ *
+ * Permit update of file attributes when files have a valid EVM signature,
+ * except in the case of them having an immutable portable signature.
  */
-int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
+static int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+			     struct iattr *attr)
 {
 	unsigned int ia_valid = attr->ia_valid;
 	enum integrity_status evm_status;
 
+	/* Policy permits modification of the protected attrs even though
+	 * there's no HMAC key loaded
+	 */
+	if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
+		return 0;
+
+	if (is_unsupported_hmac_fs(dentry))
+		return 0;
+
 	if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
 		return 0;
+
 	evm_status = evm_verify_current_integrity(dentry);
+	/*
+	 * Writing attrs is safe for portable signatures, as portable signatures
+	 * are immutable and can never be updated.
+	 */
 	if ((evm_status == INTEGRITY_PASS) ||
-	    (evm_status == INTEGRITY_NOXATTRS))
+	    (evm_status == INTEGRITY_NOXATTRS) ||
+	    (evm_status == INTEGRITY_FAIL_IMMUTABLE) ||
+	    (evm_hmac_disabled() && (evm_status == INTEGRITY_NOLABEL ||
+	     evm_status == INTEGRITY_UNKNOWN)))
+		return 0;
+
+	if (evm_status == INTEGRITY_PASS_IMMUTABLE &&
+	    !evm_attr_change(idmap, dentry, attr))
 		return 0;
-	integrity_audit_msg(AUDIT_INTEGRITY_METADATA, dentry->d_inode,
+
+	integrity_audit_msg(AUDIT_INTEGRITY_METADATA, d_backing_inode(dentry),
 			    dentry->d_name.name, "appraise_metadata",
 			    integrity_status_msg[evm_status], -EPERM, 0);
 	return -EPERM;
@@ -375,6 +947,7 @@ int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
 
 /**
  * evm_inode_post_setattr - update 'security.evm' after modifying metadata
+ * @idmap: idmap of the idmapped mount
  * @dentry: pointer to the affected dentry
  * @ia_valid: for the UID and GID status
  *
@@ -384,41 +957,106 @@ int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
  * 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)
+static void evm_inode_post_setattr(struct mnt_idmap *idmap,
+				   struct dentry *dentry, int ia_valid)
 {
-	if (!evm_initialized)
+	if (!evm_revalidate_status(NULL))
+		return;
+
+	evm_reset_status(dentry->d_inode);
+
+	if (!(evm_initialized & EVM_INIT_HMAC))
+		return;
+
+	if (is_unsupported_hmac_fs(dentry))
 		return;
 
 	if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
 		evm_update_evmxattr(dentry, NULL, NULL, 0);
-	return;
+}
+
+static int evm_inode_copy_up_xattr(struct dentry *src, const char *name)
+{
+	struct evm_ima_xattr_data *xattr_data = NULL;
+	int rc;
+
+	if (strcmp(name, XATTR_NAME_EVM) != 0)
+		return -EOPNOTSUPP;
+
+	/* first need to know the sig type */
+	rc = vfs_getxattr_alloc(&nop_mnt_idmap, src, XATTR_NAME_EVM,
+				(char **)&xattr_data, 0, GFP_NOFS);
+	if (rc <= 0)
+		return -EPERM;
+
+	if (rc < offsetof(struct evm_ima_xattr_data, type) +
+		 sizeof(xattr_data->type))
+		return -EPERM;
+
+	switch (xattr_data->type) {
+	case EVM_XATTR_PORTABLE_DIGSIG:
+		rc = 0; /* allow copy-up */
+		break;
+	case EVM_XATTR_HMAC:
+	case EVM_IMA_XATTR_DIGSIG:
+	default:
+		rc = -ECANCELED; /* discard */
+	}
+
+	kfree(xattr_data);
+	return rc;
 }
 
 /*
- * evm_inode_init_security - initializes security.evm
+ * evm_inode_init_security - initializes security.evm HMAC value
  */
-int evm_inode_init_security(struct inode *inode,
-				 const struct xattr *lsm_xattr,
-				 struct xattr *evm_xattr)
+int evm_inode_init_security(struct inode *inode, struct inode *dir,
+			    const struct qstr *qstr, struct xattr *xattrs,
+			    int *xattr_count)
 {
-	struct evm_ima_xattr_data *xattr_data;
+	struct evm_xattr *xattr_data;
+	struct xattr *xattr, *evm_xattr;
+	bool evm_protected_xattrs = false;
 	int rc;
 
-	if (!evm_initialized || !evm_protected_xattr(lsm_xattr->name))
+	if (!(evm_initialized & EVM_INIT_HMAC) || !xattrs)
 		return 0;
 
+	/*
+	 * security_inode_init_security() makes sure that the xattrs array is
+	 * contiguous, there is enough space for security.evm, and that there is
+	 * a terminator at the end of the array.
+	 */
+	for (xattr = xattrs; xattr->name; xattr++) {
+		if (evm_protected_xattr(xattr->name))
+			evm_protected_xattrs = true;
+	}
+
+	/* EVM xattr not needed. */
+	if (!evm_protected_xattrs)
+		return 0;
+
+	evm_xattr = lsm_get_xattr_slot(xattrs, xattr_count);
+	/*
+	 * Array terminator (xattr name = NULL) must be the first non-filled
+	 * xattr slot.
+	 */
+	WARN_ONCE(evm_xattr != xattr,
+		  "%s: xattrs terminator is not the first non-filled slot\n",
+		  __func__);
+
 	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);
+	xattr_data->data.type = EVM_XATTR_HMAC;
+	rc = evm_init_hmac(inode, xattrs, xattr_data->digest);
 	if (rc < 0)
 		goto out;
 
 	evm_xattr->value = xattr_data;
 	evm_xattr->value_len = sizeof(*xattr_data);
-	evm_xattr->name = kstrdup(XATTR_EVM_SUFFIX, GFP_NOFS);
+	evm_xattr->name = XATTR_EVM_SUFFIX;
 	return 0;
 out:
 	kfree(xattr_data);
@@ -426,35 +1064,120 @@ out:
 }
 EXPORT_SYMBOL_GPL(evm_inode_init_security);
 
+static int evm_inode_alloc_security(struct inode *inode)
+{
+	struct evm_iint_cache *iint = evm_iint_inode(inode);
+
+	/* Called by security_inode_alloc(), it cannot be NULL. */
+	iint->flags = 0UL;
+	iint->evm_status = INTEGRITY_UNKNOWN;
+
+	return 0;
+}
+
+static void evm_file_release(struct file *file)
+{
+	struct inode *inode = file_inode(file);
+	struct evm_iint_cache *iint = evm_iint_inode(inode);
+	fmode_t mode = file->f_mode;
+
+	if (!S_ISREG(inode->i_mode) || !(mode & FMODE_WRITE))
+		return;
+
+	if (iint && iint->flags & EVM_NEW_FILE &&
+	    atomic_read(&inode->i_writecount) == 1)
+		iint->flags &= ~EVM_NEW_FILE;
+}
+
+static void evm_post_path_mknod(struct mnt_idmap *idmap, struct dentry *dentry)
+{
+	struct inode *inode = d_backing_inode(dentry);
+	struct evm_iint_cache *iint = evm_iint_inode(inode);
+
+	if (!S_ISREG(inode->i_mode))
+		return;
+
+	if (iint)
+		iint->flags |= EVM_NEW_FILE;
+}
+
+#ifdef CONFIG_EVM_LOAD_X509
+void __init evm_load_x509(void)
+{
+	int rc;
+
+	rc = integrity_load_x509(INTEGRITY_KEYRING_EVM, CONFIG_EVM_X509_PATH);
+	if (!rc)
+		evm_initialized |= EVM_INIT_X509;
+}
+#endif
+
 static int __init init_evm(void)
 {
 	int error;
+	struct list_head *pos, *q;
+
+	evm_init_config();
+
+	error = integrity_init_keyring(INTEGRITY_KEYRING_EVM);
+	if (error)
+		goto error;
 
 	error = evm_init_secfs();
 	if (error < 0) {
-		printk(KERN_INFO "EVM: Error registering secfs\n");
-		goto err;
+		pr_info("Error registering secfs\n");
+		goto error;
+	}
+
+error:
+	if (error != 0) {
+		if (!list_empty(&evm_config_xattrnames)) {
+			list_for_each_safe(pos, q, &evm_config_xattrnames)
+				list_del(pos);
+		}
 	}
 
-	return 0;
-err:
 	return error;
 }
 
-/*
- * evm_display_config - list the EVM protected security extended attributes
- */
-static int __init evm_display_config(void)
-{
-	char **xattrname;
+static struct security_hook_list evm_hooks[] __ro_after_init = {
+	LSM_HOOK_INIT(inode_setattr, evm_inode_setattr),
+	LSM_HOOK_INIT(inode_post_setattr, evm_inode_post_setattr),
+	LSM_HOOK_INIT(inode_copy_up_xattr, evm_inode_copy_up_xattr),
+	LSM_HOOK_INIT(inode_setxattr, evm_inode_setxattr),
+	LSM_HOOK_INIT(inode_post_setxattr, evm_inode_post_setxattr),
+	LSM_HOOK_INIT(inode_set_acl, evm_inode_set_acl),
+	LSM_HOOK_INIT(inode_post_set_acl, evm_inode_post_set_acl),
+	LSM_HOOK_INIT(inode_remove_acl, evm_inode_remove_acl),
+	LSM_HOOK_INIT(inode_post_remove_acl, evm_inode_post_remove_acl),
+	LSM_HOOK_INIT(inode_removexattr, evm_inode_removexattr),
+	LSM_HOOK_INIT(inode_post_removexattr, evm_inode_post_removexattr),
+	LSM_HOOK_INIT(inode_init_security, evm_inode_init_security),
+	LSM_HOOK_INIT(inode_alloc_security, evm_inode_alloc_security),
+	LSM_HOOK_INIT(file_release, evm_file_release),
+	LSM_HOOK_INIT(path_post_mknod, evm_post_path_mknod),
+};
 
-	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++)
-		printk(KERN_INFO "EVM: %s\n", *xattrname);
+static const struct lsm_id evm_lsmid = {
+	.name = "evm",
+	.id = LSM_ID_EVM,
+};
+
+static int __init init_evm_lsm(void)
+{
+	security_add_hooks(evm_hooks, ARRAY_SIZE(evm_hooks), &evm_lsmid);
 	return 0;
 }
 
-pure_initcall(evm_display_config);
-late_initcall(init_evm);
+struct lsm_blob_sizes evm_blob_sizes __ro_after_init = {
+	.lbs_inode = sizeof(struct evm_iint_cache),
+	.lbs_xattr_count = 1,
+};
 
-MODULE_DESCRIPTION("Extended Verification Module");
-MODULE_LICENSE("GPL");
+DEFINE_LSM(evm) = {
+	.id = &evm_lsmid,
+	.init = init_evm_lsm,
+	.order = LSM_ORDER_LAST,
+	.blobs = &evm_blob_sizes,
+	.initcall_late = init_evm,
+};