Contributors: 25
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Mimi Zohar |
839 |
44.82% |
10 |
16.39% |
| Dmitry Kasatkin |
461 |
24.63% |
14 |
22.95% |
| Matthew Garrett |
269 |
14.37% |
5 |
8.20% |
| Roberto Sassu |
99 |
5.29% |
7 |
11.48% |
| Xiu Jianfeng |
52 |
2.78% |
1 |
1.64% |
| Dan Carpenter |
25 |
1.34% |
1 |
1.64% |
| James Morris |
23 |
1.23% |
1 |
1.64% |
| Eric W. Biedermann |
13 |
0.69% |
2 |
3.28% |
| Andreas Gruenbacher |
11 |
0.59% |
1 |
1.64% |
| Al Viro |
10 |
0.53% |
1 |
1.64% |
| Seth Forshee |
9 |
0.48% |
1 |
1.64% |
| Tycho Andersen |
9 |
0.48% |
1 |
1.64% |
| David Howells |
9 |
0.48% |
2 |
3.28% |
| Paul Moore |
8 |
0.43% |
1 |
1.64% |
| Christoph Hellwig |
7 |
0.37% |
2 |
3.28% |
| Hernán Gonzalez |
6 |
0.32% |
1 |
1.64% |
| Andy Shevchenko |
5 |
0.27% |
1 |
1.64% |
| Christian Brauner |
5 |
0.27% |
2 |
3.28% |
| Eric Biggers |
3 |
0.16% |
1 |
1.64% |
| Eric Paris |
3 |
0.16% |
1 |
1.64% |
| Thomas Gleixner |
2 |
0.11% |
1 |
1.64% |
| Madhuparna Bhowmik |
1 |
0.05% |
1 |
1.64% |
| Stefan Berger |
1 |
0.05% |
1 |
1.64% |
| Paul Gortmaker |
1 |
0.05% |
1 |
1.64% |
| Joe Perches |
1 |
0.05% |
1 |
1.64% |
| Total |
1872 |
|
61 |
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2005-2010 IBM Corporation
*
* Authors:
* Mimi Zohar <zohar@us.ibm.com>
* Kylene Hall <kjhall@us.ibm.com>
*
* File: evm_crypto.c
* Using root's kernel master key (kmk), calculate the HMAC
*/
#define pr_fmt(fmt) "EVM: "fmt
#include <linux/export.h>
#include <linux/crypto.h>
#include <linux/xattr.h>
#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"
#define MAX_KEY_SIZE 128
static unsigned char evmkey[MAX_KEY_SIZE];
static const int evmkey_len = MAX_KEY_SIZE;
static struct crypto_shash *hmac_tfm;
static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
static DEFINE_MUTEX(mutex);
#define EVM_SET_KEY_BUSY 0
static unsigned long evm_set_key_flags;
static const char evm_hmac[] = "hmac(sha1)";
/**
* evm_set_key() - set EVM HMAC key from the kernel
* @key: pointer to a buffer with the key data
* @keylen: length of the key data
*
* This function allows setting the EVM HMAC key from the kernel
* without using the "encrypted" key subsystem keys. It can be used
* by the crypto HW kernel module which has its own way of managing
* keys.
*
* key length should be between 32 and 128 bytes long
*/
int evm_set_key(void *key, size_t keylen)
{
int rc;
rc = -EBUSY;
if (test_and_set_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags))
goto busy;
rc = -EINVAL;
if (keylen > MAX_KEY_SIZE)
goto inval;
memcpy(evmkey, key, keylen);
evm_initialized |= EVM_INIT_HMAC;
pr_info("key initialized\n");
return 0;
inval:
clear_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags);
busy:
pr_err("key initialization failed\n");
return rc;
}
EXPORT_SYMBOL_GPL(evm_set_key);
static struct shash_desc *init_desc(char type, uint8_t hash_algo)
{
long rc;
const char *algo;
struct crypto_shash **tfm, *tmp_tfm;
struct shash_desc *desc;
if (type == EVM_XATTR_HMAC) {
if (!(evm_initialized & EVM_INIT_HMAC)) {
pr_err_once("HMAC key is not set\n");
return ERR_PTR(-ENOKEY);
}
tfm = &hmac_tfm;
algo = evm_hmac;
} else {
if (hash_algo >= HASH_ALGO__LAST)
return ERR_PTR(-EINVAL);
tfm = &evm_tfm[hash_algo];
algo = hash_algo_name[hash_algo];
}
if (*tfm)
goto alloc;
mutex_lock(&mutex);
if (*tfm)
goto unlock;
tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
if (IS_ERR(tmp_tfm)) {
pr_err("Can not allocate %s (reason: %ld)\n", algo,
PTR_ERR(tmp_tfm));
mutex_unlock(&mutex);
return ERR_CAST(tmp_tfm);
}
if (type == EVM_XATTR_HMAC) {
rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len);
if (rc) {
crypto_free_shash(tmp_tfm);
mutex_unlock(&mutex);
return ERR_PTR(rc);
}
}
*tfm = tmp_tfm;
unlock:
mutex_unlock(&mutex);
alloc:
desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
GFP_KERNEL);
if (!desc)
return ERR_PTR(-ENOMEM);
desc->tfm = *tfm;
rc = crypto_shash_init(desc);
if (rc) {
kfree(desc);
return ERR_PTR(rc);
}
return desc;
}
/* Protect against 'cutting & pasting' security.evm xattr, include inode
* specific info.
*
* (Additional directory/file metadata needs to be added for more complete
* protection.)
*/
static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
char type, char *digest)
{
struct h_misc {
unsigned long ino;
__u32 generation;
uid_t uid;
gid_t gid;
umode_t mode;
} hmac_misc;
memset(&hmac_misc, 0, sizeof(hmac_misc));
/* Don't include the inode or generation number in portable
* signatures
*/
if (type != EVM_XATTR_PORTABLE_DIGSIG) {
hmac_misc.ino = inode->i_ino;
hmac_misc.generation = inode->i_generation;
}
/* The hmac uid and gid must be encoded in the initial user
* namespace (not the filesystems user namespace) as encoding
* them in the filesystems user namespace allows an attack
* where first they are written in an unprivileged fuse mount
* of a filesystem and then the system is tricked to mount the
* filesystem for real on next boot and trust it because
* everything is signed.
*/
hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
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_attrs & EVM_ATTR_FSUUID) &&
type != EVM_XATTR_PORTABLE_DIGSIG)
crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
crypto_shash_final(desc, digest);
pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
(int)sizeof(struct h_misc), &hmac_misc);
}
/*
* Dump large security xattr values as a continuous ascii hexademical string.
* (pr_debug is limited to 64 bytes.)
*/
static void dump_security_xattr_l(const char *prefix, const void *src,
size_t count)
{
#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
char *asciihex, *p;
p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
if (!asciihex)
return;
p = bin2hex(p, src, count);
*p = 0;
pr_debug("%s: (%zu) %.*s\n", prefix, count, (int)count * 2, asciihex);
kfree(asciihex);
#endif
}
static void dump_security_xattr(const char *name, const char *value,
size_t value_len)
{
if (value_len < 64)
pr_debug("%s: (%zu) [%*phN]\n", name, value_len,
(int)value_len, value);
else
dump_security_xattr_l(name, value, value_len);
}
/*
* Calculate the HMAC value across the set of protected security xattrs.
*
* Instead of retrieving the requested xattr, for performance, calculate
* the hmac using the requested xattr value. Don't alloc/free memory for
* 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,
uint8_t type, struct evm_digest *data)
{
struct inode *inode = d_backing_inode(dentry);
struct xattr_list *xattr;
struct shash_desc *desc;
size_t xattr_size = 0;
char *xattr_value = NULL;
int error;
int size, user_space_size;
bool ima_present = false;
if (!(inode->i_opflags & IOP_XATTR) ||
inode->i_sb->s_user_ns != &init_user_ns)
return -EOPNOTSUPP;
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;
list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
bool is_ima = false;
if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
is_ima = true;
/*
* Skip non-enabled xattrs for locally calculated
* signatures/HMACs.
*/
if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled)
continue;
if ((req_xattr_name && req_xattr_value)
&& !strcmp(xattr->name, req_xattr_name)) {
error = 0;
crypto_shash_update(desc, (const u8 *)req_xattr_value,
req_xattr_value_len);
if (is_ima)
ima_present = true;
dump_security_xattr(req_xattr_name,
req_xattr_value,
req_xattr_value_len);
continue;
}
size = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr->name,
&xattr_value, xattr_size, GFP_NOFS);
if (size == -ENOMEM) {
error = -ENOMEM;
goto out;
}
if (size < 0)
continue;
user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
xattr->name, NULL, 0);
if (user_space_size != size)
pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
dentry->d_name.name, xattr->name, size,
user_space_size);
error = 0;
xattr_size = size;
crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
if (is_ima)
ima_present = true;
dump_security_xattr(xattr->name, xattr_value, xattr_size);
}
hmac_add_misc(desc, inode, type, data->digest);
/* Portable EVM signatures must include an IMA hash */
if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
error = -EPERM;
out:
kfree(xattr_value);
kfree(desc);
return error;
}
int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
const char *req_xattr_value, size_t req_xattr_value_len,
struct evm_digest *data)
{
return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
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, struct evm_digest *data)
{
return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
req_xattr_value_len, type, data);
}
static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
{
const struct evm_ima_xattr_data *xattr_data = NULL;
struct evm_iint_cache *iint;
int rc = 0;
iint = evm_iint_inode(inode);
if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
return 1;
/* Do this the hard way */
rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_EVM,
(char **)&xattr_data, 0, GFP_NOFS);
if (rc <= 0) {
if (rc == -ENODATA)
rc = 0;
goto out;
}
if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
rc = 1;
else
rc = 0;
out:
kfree(xattr_data);
return rc;
}
/*
* Calculate the hmac and update security.evm xattr
*
* Expects to be called with i_mutex locked.
*/
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_digest data;
int rc = 0;
/*
* Don't permit any transformation of the EVM xattr if the signature
* is of an immutable type
*/
rc = evm_is_immutable(dentry, inode);
if (rc < 0)
return rc;
if (rc)
return -EPERM;
data.hdr.algo = HASH_ALGO_SHA1;
rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
xattr_value_len, &data);
if (rc == 0) {
data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry,
XATTR_NAME_EVM,
&data.hdr.xattr.data[1],
SHA1_DIGEST_SIZE + 1, 0);
} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
rc = __vfs_removexattr(&nop_mnt_idmap, dentry, XATTR_NAME_EVM);
}
return rc;
}
int evm_init_hmac(struct inode *inode, const struct xattr *xattrs,
char *hmac_val)
{
struct shash_desc *desc;
const struct xattr *xattr;
desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
if (IS_ERR(desc)) {
pr_info("init_desc failed\n");
return PTR_ERR(desc);
}
for (xattr = xattrs; xattr->name; xattr++) {
if (!evm_protected_xattr(xattr->name))
continue;
crypto_shash_update(desc, xattr->value, xattr->value_len);
}
hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
kfree(desc);
return 0;
}
/*
* Get the key from the TPM for the SHA1-HMAC
*/
int evm_init_key(void)
{
struct key *evm_key;
struct encrypted_key_payload *ekp;
int rc;
evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
if (IS_ERR(evm_key))
return -ENOENT;
down_read(&evm_key->sem);
ekp = evm_key->payload.data[0];
rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
/* burn the original key contents */
memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
up_read(&evm_key->sem);
key_put(evm_key);
return rc;
}