1 files changed, 233 insertions, 52 deletions

diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index cc7956d787..62fe66dd53 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -151,11 +151,11 @@ static int evm_find_protected_xattrs(struct dentry *dentry)
 	return count;
 }
 
-static int is_unsupported_fs(struct dentry *dentry)
+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_UNSUPPORTED) {
+	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;
 	}
@@ -178,21 +178,26 @@ static int is_unsupported_fs(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 signature_v2_hdr *hdr;
 	enum integrity_status evm_status = INTEGRITY_PASS;
 	struct evm_digest digest;
-	struct inode *inode;
+	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 ||
 		     iint->evm_status == INTEGRITY_PASS_IMMUTABLE))
 		return iint->evm_status;
 
-	if (is_unsupported_fs(dentry))
+	/*
+	 * 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 */
@@ -226,7 +231,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 
 		digest.hdr.algo = HASH_ALGO_SHA1;
 		rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
-				   xattr_value_len, &digest);
+				   xattr_value_len, &digest, iint);
 		if (rc)
 			break;
 		rc = crypto_memneq(xattr_data->data, digest.digest,
@@ -247,22 +252,22 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
 		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, xattr_data->type, &digest);
+				   xattr_value_len, xattr_data->type, &digest,
+				   iint);
 		if (rc)
 			break;
 		rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
 					(const char *)xattr_data, xattr_len,
 					digest.digest, digest.hdr.length);
 		if (!rc) {
-			inode = d_backing_inode(dentry);
-
 			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_IMMUTABLE(inode) &&
+				   !is_unsupported_hmac_fs(dentry)) {
 				evm_update_evmxattr(dentry, xattr_name,
 						    xattr_value,
 						    xattr_value_len);
@@ -403,7 +408,6 @@ int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
  * @xattr_name: requested xattr
  * @xattr_value: requested xattr value
  * @xattr_value_len: requested xattr value length
- * @iint: inode integrity metadata
  *
  * Calculate the HMAC for the given dentry and verify it against the stored
  * security.evm xattr. For performance, use the xattr value and length
@@ -416,22 +420,13 @@ int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
  */
 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_key_loaded() || !evm_protected_xattr(xattr_name))
 		return INTEGRITY_UNKNOWN;
 
-	if (is_unsupported_fs(dentry))
-		return INTEGRITY_UNKNOWN;
-
-	if (!iint) {
-		iint = integrity_iint_find(d_backing_inode(dentry));
-		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);
 
@@ -448,7 +443,7 @@ static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
 
 	if (!evm_key_loaded() || !S_ISREG(inode->i_mode) || evm_fixmode)
 		return INTEGRITY_PASS;
-	return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
+	return evm_verify_hmac(dentry, NULL, NULL, 0);
 }
 
 /*
@@ -508,12 +503,12 @@ static int evm_protect_xattr(struct mnt_idmap *idmap,
 	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		if (is_unsupported_fs(dentry))
+		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_fs(dentry))
+		if (is_unsupported_hmac_fs(dentry))
 			return 0;
 
 		evm_status = evm_verify_current_integrity(dentry);
@@ -521,19 +516,19 @@ static int evm_protect_xattr(struct mnt_idmap *idmap,
 		    (evm_status == INTEGRITY_NOXATTRS))
 			return 0;
 		goto out;
-	} else if (is_unsupported_fs(dentry))
+	} else if (is_unsupported_hmac_fs(dentry))
 		return 0;
 
 	evm_status = evm_verify_current_integrity(dentry);
 	if (evm_status == INTEGRITY_NOXATTRS) {
-		struct integrity_iint_cache *iint;
+		struct evm_iint_cache *iint;
 
 		/* Exception if the HMAC is not going to be calculated. */
 		if (evm_hmac_disabled())
 			return 0;
 
-		iint = integrity_iint_find(d_backing_inode(dentry));
-		if (iint && (iint->flags & IMA_NEW_FILE))
+		iint = evm_iint_inode(d_backing_inode(dentry));
+		if (iint && (iint->flags & EVM_NEW_FILE))
 			return 0;
 
 		/* exception for pseudo filesystems */
@@ -581,6 +576,7 @@ out:
  * @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
  *
  * Before allowing the 'security.evm' protected xattr to be updated,
  * verify the existing value is valid.  As only the kernel should have
@@ -588,9 +584,9 @@ out:
  * userspace from writing HMAC value.  Writing 'security.evm' requires
  * requires CAP_SYS_ADMIN privileges.
  */
-int evm_inode_setxattr(struct mnt_idmap *idmap, 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)
 {
 	const struct evm_ima_xattr_data *xattr_data = xattr_value;
 
@@ -620,8 +616,8 @@ int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
  * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
  * the current value is valid.
  */
-int evm_inode_removexattr(struct mnt_idmap *idmap,
-			  struct dentry *dentry, const char *xattr_name)
+static int evm_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
+				 const char *xattr_name)
 {
 	/* Policy permits modification of the protected xattrs even though
 	 * there's no HMAC key loaded
@@ -671,9 +667,11 @@ static inline int evm_inode_set_acl_change(struct mnt_idmap *idmap,
  * 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.
  */
-int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
-		      const char *acl_name, struct posix_acl *kacl)
+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;
 
@@ -712,16 +710,59 @@ int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	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 integrity_iint_cache *iint;
+	struct evm_iint_cache *iint;
 
-	iint = integrity_iint_find(inode);
+	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
  *
@@ -752,6 +793,7 @@ bool evm_revalidate_status(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.
  *
@@ -759,8 +801,11 @@ bool evm_revalidate_status(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_revalidate_status(xattr_name))
 		return;
@@ -773,13 +818,28 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
 	if (!(evm_initialized & EVM_INIT_HMAC))
 		return;
 
-	if (is_unsupported_fs(dentry))
+	if (is_unsupported_hmac_fs(dentry))
 		return;
 
 	evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
 }
 
 /**
+ * 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);
+}
+
+/**
  * 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
@@ -789,7 +849,8 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
  * 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)
 {
 	if (!evm_revalidate_status(xattr_name))
 		return;
@@ -805,6 +866,22 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
 	evm_update_evmxattr(dentry, xattr_name, NULL, 0);
 }
 
+/**
+ * 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)
 {
@@ -828,8 +905,8 @@ static int evm_attr_change(struct mnt_idmap *idmap,
  * 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 mnt_idmap *idmap, 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;
@@ -840,7 +917,7 @@ int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	if (evm_initialized & EVM_ALLOW_METADATA_WRITES)
 		return 0;
 
-	if (is_unsupported_fs(dentry))
+	if (is_unsupported_hmac_fs(dentry))
 		return 0;
 
 	if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
@@ -870,6 +947,7 @@ int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 
 /**
  * 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
  *
@@ -879,7 +957,8 @@ int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
  * 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_revalidate_status(NULL))
 		return;
@@ -889,18 +968,43 @@ void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
 	if (!(evm_initialized & EVM_INIT_HMAC))
 		return;
 
-	if (is_unsupported_fs(dentry))
+	if (is_unsupported_hmac_fs(dentry))
 		return;
 
 	if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
 		evm_update_evmxattr(dentry, NULL, NULL, 0);
 }
 
-int evm_inode_copy_up_xattr(const char *name)
+static int evm_inode_copy_up_xattr(struct dentry *src, const char *name)
 {
-	if (strcmp(name, XATTR_NAME_EVM) == 0)
-		return 1; /* Discard */
-	return -EOPNOTSUPP;
+	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 = 1; /* discard */
+	}
+
+	kfree(xattr_data);
+	return rc;
 }
 
 /*
@@ -960,6 +1064,42 @@ 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 && 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)
 {
@@ -999,4 +1139,45 @@ error:
 	return error;
 }
 
+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),
+};
+
+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;
+}
+
+struct lsm_blob_sizes evm_blob_sizes __ro_after_init = {
+	.lbs_inode = sizeof(struct evm_iint_cache),
+	.lbs_xattr_count = 1,
+};
+
+DEFINE_LSM(evm) = {
+	.name = "evm",
+	.init = init_evm_lsm,
+	.order = LSM_ORDER_LAST,
+	.blobs = &evm_blob_sizes,
+};
+
 late_initcall(init_evm);