Merge branch 'serge-next-2' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux-security

Pull more security layer updates from Serge Hallyn:
 "A few more commits had previously failed to make it through
  security-next into linux-next but this week made it into linux-next.
  At least commit "ima: introduce ima_kernel_read()" was deemed critical
  by Mimi to make this merge window.

  This is a temporary tree just for this request.  Mimi has pointed me
  to some previous threads about keeping maintainer trees at the
  previous release, which I'll certainly do for anything long-term,
  after talking with James"

* 'serge-next-2' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux-security:
  ima: introduce ima_kernel_read()
  evm: prohibit userspace writing 'security.evm' HMAC value
  ima: check inode integrity cache in violation check
  ima: prevent unnecessary policy checking
  evm: provide option to protect additional SMACK xattrs
  evm: replace HMAC version with attribute mask
  ima: prevent new digsig xattr from being replaced

4 files changed, 65 insertions, 13 deletions

diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
index d35b4915b00d..d606f3d12d6b 100644
--- a/security/integrity/evm/Kconfig
+++ b/security/integrity/evm/Kconfig
@@ -12,15 +12,41 @@ config EVM
 
 	  If you are unsure how to answer this question, answer N.
 
-config EVM_HMAC_VERSION
-	int "EVM HMAC version"
+if EVM
+
+menu "EVM options"
+
+config EVM_ATTR_FSUUID
+	bool "FSUUID (version 2)"
+	default y
 	depends on EVM
-	default 2
 	help
-	  This options adds EVM HMAC version support.
-	  1 - original version
-	  2 - add per filesystem unique identifier (UUID) (default)
+	  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 
+	  WARNING: changing the HMAC calculation method or adding
 	  additional info to the calculation, requires existing EVM
-	  labeled file systems to be relabeled.  
+	  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.
+
+endmenu
+
+endif
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index 37c88ddb3cfe..88bfe77efa1c 100644
--- a/security/integrity/evm/evm.h
+++ b/security/integrity/evm/evm.h
@@ -24,7 +24,10 @@
 extern int evm_initialized;
 extern char *evm_hmac;
 extern char *evm_hash;
-extern int evm_hmac_version;
+
+#define EVM_ATTR_FSUUID		0x0001
+
+extern int evm_hmac_attrs;
 
 extern struct crypto_shash *hmac_tfm;
 extern struct crypto_shash *hash_tfm;
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 6b540f1822e0..5e9687f02e1b 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -112,7 +112,7 @@ 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_version > 1)
+	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);
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 6e0bd933b6a9..3bcb80df4d01 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -32,7 +32,7 @@ static char *integrity_status_msg[] = {
 };
 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
@@ -40,6 +40,11 @@ char *evm_config_xattrnames[] = {
 #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,
@@ -57,6 +62,14 @@ static int __init evm_set_fixmode(char *str)
 }
 __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;
@@ -287,12 +300,20 @@ out:
  * @xattr_value: pointer to the new extended attribute value
  * @xattr_value_len: pointer to the new extended attribute value length
  *
- * 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)
 {
+	const struct evm_ima_xattr_data *xattr_data = xattr_value;
+
+	if ((strcmp(xattr_name, XATTR_NAME_EVM) == 0)
+	    && (xattr_data->type == EVM_XATTR_HMAC))
+		return -EPERM;
 	return evm_protect_xattr(dentry, xattr_name, xattr_value,
 				 xattr_value_len);
 }
@@ -432,6 +453,8 @@ static int __init init_evm(void)
 {
 	int error;
 
+	evm_init_config();
+
 	error = evm_init_secfs();
 	if (error < 0) {
 		pr_info("Error registering secfs\n");