Oh bother - I think I see what's wrong. Does this version work better?
I'm afraid I only tested against signatures rather than HMACs, and I was
generating a raw SHA1 rather than an HMAC :(
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index 45c4a89c02ff..a8289fbf2f0c 100644
--- a/security/integrity/evm/evm.h
+++ b/security/integrity/evm/evm.h
@@ -42,6 +42,11 @@ extern struct crypto_shash *hash_tfm;
/* List of EVM protected security xattrs */
extern char *evm_config_xattrnames[];
+struct evm_digest {
+ struct ima_digest_data hdr;
+ char digest[IMA_MAX_DIGEST_SIZE];
+} __packed;
+
int evm_init_key(void);
int evm_update_evmxattr(struct dentry *dentry,
const char *req_xattr_name,
@@ -49,10 +54,11 @@ int evm_update_evmxattr(struct dentry *dentry,
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);
+ size_t req_xattr_value_len, struct evm_digest *data);
int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
const char *req_xattr_value,
- size_t req_xattr_value_len, char type, char *digest);
+ size_t req_xattr_value_len, char type,
+ struct evm_digest *data);
int evm_init_hmac(struct inode *inode, const struct xattr *xattr,
char *hmac_val);
int evm_init_secfs(void);
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index a46fba322340..eb87d40c62a5 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -21,6 +21,7 @@
#include <linux/evm.h>
#include <keys/encrypted-type.h>
#include <crypto/hash.h>
+#include <crypto/hash_info.h>
#include "evm.h"
#define EVMKEY "evm-key"
@@ -29,7 +30,7 @@ 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 struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
static DEFINE_MUTEX(mutex);
@@ -38,7 +39,6 @@ static DEFINE_MUTEX(mutex);
static unsigned long evm_set_key_flags;
static char * const evm_hmac = "hmac(sha1)";
-static char * const evm_hash = "sha1";
/**
* evm_set_key() - set EVM HMAC key from the kernel
@@ -74,10 +74,10 @@ int evm_set_key(void *key, size_t keylen)
}
EXPORT_SYMBOL_GPL(evm_set_key);
-static struct shash_desc *init_desc(char type)
+static struct shash_desc *init_desc(char type, uint8_t hash_algo)
{
long rc;
- char *algo;
+ const char *algo;
struct crypto_shash **tfm;
struct shash_desc *desc;
@@ -89,8 +89,8 @@ static struct shash_desc *init_desc(char type)
tfm = &hmac_tfm;
algo = evm_hmac;
} else {
- tfm = &hash_tfm;
- algo = evm_hash;
+ tfm = &evm_tfm[hash_algo];
+ algo = hash_algo_name[hash_algo];
}
if (*tfm == NULL) {
@@ -186,10 +186,10 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
* 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)
+ const char *req_xattr_name,
+ const char *req_xattr_value,
+ size_t req_xattr_value_len,
+ uint8_t type, struct evm_digest *data)
{
struct inode *inode = d_backing_inode(dentry);
struct shash_desc *desc;
@@ -203,10 +203,12 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
if (!(inode->i_opflags & IOP_XATTR))
return -EOPNOTSUPP;
- desc = init_desc(type);
+ desc = init_desc(type, data->hdr.algo);
if (IS_ERR(desc))
return PTR_ERR(desc);
+ data->hdr.length = crypto_shash_digestsize(desc->tfm);
+
error = -ENODATA;
for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
bool is_ima = false;
@@ -238,7 +240,7 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
if (is_ima)
ima_present = true;
}
- hmac_add_misc(desc, inode, type, digest);
+ hmac_add_misc(desc, inode, type, data->digest);
/* Portable EVM signatures must include an IMA hash */
if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
@@ -251,18 +253,18 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
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)
+ struct evm_digest *data)
{
return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
- req_xattr_value_len, EVM_XATTR_HMAC, digest);
+ req_xattr_value_len, EVM_XATTR_HMAC, data);
}
int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
const char *req_xattr_value, size_t req_xattr_value_len,
- char type, char *digest)
+ char type, struct evm_digest *data)
{
return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
- req_xattr_value_len, type, digest);
+ req_xattr_value_len, type, data);
}
static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
@@ -302,7 +304,7 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
const char *xattr_value, size_t xattr_value_len)
{
struct inode *inode = d_backing_inode(dentry);
- struct evm_ima_xattr_data xattr_data;
+ struct evm_digest data;
int rc = 0;
/*
@@ -315,13 +317,14 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
if (rc)
return -EPERM;
+ data.hdr.algo = HASH_ALGO_SHA1;
rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
- xattr_value_len, xattr_data.digest);
+ xattr_value_len, &data);
if (rc == 0) {
- xattr_data.type = EVM_XATTR_HMAC;
+ data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM,
- &xattr_data,
- sizeof(xattr_data), 0);
+ &data.hdr.xattr.data[1],
+ SHA1_DIGEST_SIZE + 1, 0);
} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
rc = __vfs_removexattr(dentry, XATTR_NAME_EVM);
}
@@ -333,7 +336,7 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
{
struct shash_desc *desc;
- desc = init_desc(EVM_XATTR_HMAC);
+ desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
if (IS_ERR(desc)) {
pr_info("init_desc failed\n");
return PTR_ERR(desc);
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 9ea9c19a545c..88ea9c1962d6 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -25,6 +25,7 @@
#include <linux/magic.h>
#include <crypto/hash.h>
+#include <crypto/hash_info.h>
#include <crypto/algapi.h>
#include "evm.h"
@@ -122,8 +123,9 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
struct integrity_iint_cache *iint)
{
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;
+ struct evm_digest digest;
struct inode *inode;
int rc, xattr_len;
@@ -159,25 +161,28 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
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);
if (rc)
break;
- rc = crypto_memneq(xattr_data->digest, calc.digest,
- sizeof(calc.digest));
+ rc = crypto_memneq(xattr_data->digest, digest.digest,
+ SHA1_DIGEST_SIZE);
if (rc)
rc = -EINVAL;
break;
case EVM_IMA_XATTR_DIGSIG:
case EVM_XATTR_PORTABLE_DIGSIG:
+ 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,
- calc.digest);
+ xattr_value_len, xattr_data->type, &digest);
if (rc)
break;
rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
(const char *)xattr_data, xattr_len,
- calc.digest, sizeof(calc.digest));
+ digest.digest, digest.hdr.length);
if (!rc) {
inode = d_backing_inode(dentry);
--
2.17.0.441.gb46fe60e1d-goog
