From d3b33679481d52ef02311119d4342a9a1f3d84db Mon Sep 17 00:00:00 2001
From: Dmitry Kasatkin <d.kasatkin@samsung.com>
Date: Fri, 28 Mar 2014 14:31:04 +0200
Subject: [PATCH] evm: replace HMAC version with attribute mask
Using HMAC version limits the posibility to arbitrarily add new
attributes such as SMACK64EXEC to the hmac calculation.
This patch replaces hmac version with attribute mask.
Desired attributes can be enabled with configuration parameter.
It allows to build kernels which works with previously labeled
filesystems.
Currently supported attribute is 'fsuuid' which is equivalent of
the former version 2.
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
---
security/integrity/evm/Kconfig | 25 +++++++++++++++++--------
security/integrity/evm/evm.h | 5 ++++-
security/integrity/evm/evm_crypto.c | 2 +-
security/integrity/evm/evm_main.c | 12 +++++++++++-
4 files changed, 33 insertions(+), 11 deletions(-)
diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
index d35b4915b00d47..0df4f7a2f1e9db 100644
--- a/security/integrity/evm/Kconfig
+++ b/security/integrity/evm/Kconfig
@@ -12,15 +12,24 @@ 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.
+
+endmenu
+
+endif
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index 37c88ddb3cfe45..88bfe77efa1cf1 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 6b540f1822e0b4..5e9687f02e1b14 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 6e0bd933b6a9a8..1dc09190a94801 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
@@ -57,6 +57,14 @@ 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;
@@ -432,6 +440,8 @@ static int __init init_evm(void)
{
int error;
+ evm_init_config();
+
error = evm_init_secfs();
if (error < 0) {
pr_info("Error registering secfs\n");
--
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