A process must have search permission on the key for this function to be
successful.
+ (*) Compute a Diffie-Hellman shared secret or public key
+
+ long keyctl(KEYCTL_DH_COMPUTE, struct keyctl_dh_params *params,
+ char *buffer, size_t buflen);
+
+ The params struct contains serial numbers for three keys:
+
+ - The prime, p, known to both parties
+ - The local private key
+ - The base integer, which is either a shared generator or the
+ remote public key
+
+ The value computed is:
+
+ result = base ^ private (mod prime)
+
+ If the base is the shared generator, the result is the local
+ public key. If the base is the remote public key, the result is
+ the shared secret.
+
+ The buffer length must be at least the length of the prime, or zero.
+
+ If the buffer length is nonzero, the length of the result is
+ returned when it is successfully calculated and copied in to the
+ buffer. When the buffer length is zero, the minimum required
+ buffer length is returned.
+
+ This function will return error EOPNOTSUPP if the key type is not
+ supported, error ENOKEY if the key could not be found, or error
+ EACCES if the key is not readable by the caller.
===============
KERNEL SERVICES
struct list_head tun_dev_attach_queue;
struct list_head tun_dev_attach;
struct list_head tun_dev_open;
- struct list_head skb_owned_by;
#endif /* CONFIG_SECURITY_NETWORK */
#ifdef CONFIG_SECURITY_NETWORK_XFRM
struct list_head xfrm_policy_alloc_security;
#ifndef _LINUX_KEYCTL_H
#define _LINUX_KEYCTL_H
+#include <linux/types.h>
+
/* special process keyring shortcut IDs */
#define KEY_SPEC_THREAD_KEYRING -1 /* - key ID for thread-specific keyring */
#define KEY_SPEC_PROCESS_KEYRING -2 /* - key ID for process-specific keyring */
#define KEYCTL_INSTANTIATE_IOV 20 /* instantiate a partially constructed key */
#define KEYCTL_INVALIDATE 21 /* invalidate a key */
#define KEYCTL_GET_PERSISTENT 22 /* get a user's persistent keyring */
+#define KEYCTL_DH_COMPUTE 23 /* Compute Diffie-Hellman values */
+
+/* keyctl structures */
+struct keyctl_dh_params {
+ __s32 private;
+ __s32 prime;
+ __s32 base;
+};
#endif /* _LINUX_KEYCTL_H */
default n
select ASYMMETRIC_KEY_TYPE
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
- select PUBLIC_KEY_ALGO_RSA
select CRYPTO_RSA
select X509_CERTIFICATE_PARSER
help
bool "Large payload keys"
depends on KEYS
depends on TMPFS
+ select CRYPTO
+ select CRYPTO_AES
+ select CRYPTO_ECB
+ select CRYPTO_RNG
help
This option provides support for holding large keys within the kernel
(for example Kerberos ticket caches). The data may be stored out to
Userspace only ever sees/stores encrypted blobs.
If you are unsure as to whether this is required, answer N.
+
+config KEY_DH_OPERATIONS
+ bool "Diffie-Hellman operations on retained keys"
+ depends on KEYS
+ select MPILIB
+ help
+ This option provides support for calculating Diffie-Hellman
+ public keys and shared secrets using values stored as keys
+ in the kernel.
+
+ If you are unsure as to whether this is required, answer N.
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SYSCTL) += sysctl.o
obj-$(CONFIG_PERSISTENT_KEYRINGS) += persistent.o
+obj-$(CONFIG_KEY_DH_OPERATIONS) += dh.o
#
# Key types
#include <linux/file.h>
#include <linux/shmem_fs.h>
#include <linux/err.h>
+#include <linux/scatterlist.h>
#include <keys/user-type.h>
#include <keys/big_key-type.h>
+#include <crypto/rng.h>
/*
* Layout of key payload words.
big_key_len,
};
+/*
+ * Crypto operation with big_key data
+ */
+enum big_key_op {
+ BIG_KEY_ENC,
+ BIG_KEY_DEC,
+};
+
/*
* If the data is under this limit, there's no point creating a shm file to
* hold it as the permanently resident metadata for the shmem fs will be at
*/
#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))
+/*
+ * Key size for big_key data encryption
+ */
+#define ENC_KEY_SIZE 16
+
/*
* big_key defined keys take an arbitrary string as the description and an
* arbitrary blob of data as the payload
.read = big_key_read,
};
+/*
+ * Crypto names for big_key data encryption
+ */
+static const char big_key_rng_name[] = "stdrng";
+static const char big_key_alg_name[] = "ecb(aes)";
+
+/*
+ * Crypto algorithms for big_key data encryption
+ */
+static struct crypto_rng *big_key_rng;
+static struct crypto_blkcipher *big_key_blkcipher;
+
+/*
+ * Generate random key to encrypt big_key data
+ */
+static inline int big_key_gen_enckey(u8 *key)
+{
+ return crypto_rng_get_bytes(big_key_rng, key, ENC_KEY_SIZE);
+}
+
+/*
+ * Encrypt/decrypt big_key data
+ */
+static int big_key_crypt(enum big_key_op op, u8 *data, size_t datalen, u8 *key)
+{
+ int ret = -EINVAL;
+ struct scatterlist sgio;
+ struct blkcipher_desc desc;
+
+ if (crypto_blkcipher_setkey(big_key_blkcipher, key, ENC_KEY_SIZE)) {
+ ret = -EAGAIN;
+ goto error;
+ }
+
+ desc.flags = 0;
+ desc.tfm = big_key_blkcipher;
+
+ sg_init_one(&sgio, data, datalen);
+
+ if (op == BIG_KEY_ENC)
+ ret = crypto_blkcipher_encrypt(&desc, &sgio, &sgio, datalen);
+ else
+ ret = crypto_blkcipher_decrypt(&desc, &sgio, &sgio, datalen);
+
+error:
+ return ret;
+}
+
/*
* Preparse a big key
*/
{
struct path *path = (struct path *)&prep->payload.data[big_key_path];
struct file *file;
+ u8 *enckey;
+ u8 *data = NULL;
ssize_t written;
size_t datalen = prep->datalen;
int ret;
/* Create a shmem file to store the data in. This will permit the data
* to be swapped out if needed.
*
- * TODO: Encrypt the stored data with a temporary key.
+ * File content is stored encrypted with randomly generated key.
*/
- file = shmem_kernel_file_setup("", datalen, 0);
+ size_t enclen = ALIGN(datalen, crypto_blkcipher_blocksize(big_key_blkcipher));
+
+ /* prepare aligned data to encrypt */
+ data = kmalloc(enclen, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ memcpy(data, prep->data, datalen);
+ memset(data + datalen, 0x00, enclen - datalen);
+
+ /* generate random key */
+ enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL);
+ if (!enckey) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ ret = big_key_gen_enckey(enckey);
+ if (ret)
+ goto err_enckey;
+
+ /* encrypt aligned data */
+ ret = big_key_crypt(BIG_KEY_ENC, data, enclen, enckey);
+ if (ret)
+ goto err_enckey;
+
+ /* save aligned data to file */
+ file = shmem_kernel_file_setup("", enclen, 0);
if (IS_ERR(file)) {
ret = PTR_ERR(file);
- goto error;
+ goto err_enckey;
}
- written = kernel_write(file, prep->data, prep->datalen, 0);
- if (written != datalen) {
+ written = kernel_write(file, data, enclen, 0);
+ if (written != enclen) {
ret = written;
if (written >= 0)
ret = -ENOMEM;
/* Pin the mount and dentry to the key so that we can open it again
* later
*/
+ prep->payload.data[big_key_data] = enckey;
*path = file->f_path;
path_get(path);
fput(file);
+ kfree(data);
} else {
/* Just store the data in a buffer */
void *data = kmalloc(datalen, GFP_KERNEL);
+
if (!data)
return -ENOMEM;
err_fput:
fput(file);
+err_enckey:
+ kfree(enckey);
error:
+ kfree(data);
return ret;
}
{
if (prep->datalen > BIG_KEY_FILE_THRESHOLD) {
struct path *path = (struct path *)&prep->payload.data[big_key_path];
+
path_put(path);
- } else {
- kfree(prep->payload.data[big_key_data]);
}
+ kfree(prep->payload.data[big_key_data]);
}
/*
{
size_t datalen = (size_t)key->payload.data[big_key_len];
- if (datalen) {
+ if (datalen > BIG_KEY_FILE_THRESHOLD) {
struct path *path = (struct path *)&key->payload.data[big_key_path];
+
path_put(path);
path->mnt = NULL;
path->dentry = NULL;
- } else {
- kfree(key->payload.data[big_key_data]);
- key->payload.data[big_key_data] = NULL;
}
+ kfree(key->payload.data[big_key_data]);
+ key->payload.data[big_key_data] = NULL;
}
/*
if (datalen > BIG_KEY_FILE_THRESHOLD) {
struct path *path = (struct path *)&key->payload.data[big_key_path];
struct file *file;
- loff_t pos;
+ u8 *data;
+ u8 *enckey = (u8 *)key->payload.data[big_key_data];
+ size_t enclen = ALIGN(datalen, crypto_blkcipher_blocksize(big_key_blkcipher));
+
+ data = kmalloc(enclen, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
file = dentry_open(path, O_RDONLY, current_cred());
- if (IS_ERR(file))
- return PTR_ERR(file);
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto error;
+ }
- pos = 0;
- ret = vfs_read(file, buffer, datalen, &pos);
- fput(file);
- if (ret >= 0 && ret != datalen)
+ /* read file to kernel and decrypt */
+ ret = kernel_read(file, 0, data, enclen);
+ if (ret >= 0 && ret != enclen) {
ret = -EIO;
+ goto err_fput;
+ }
+
+ ret = big_key_crypt(BIG_KEY_DEC, data, enclen, enckey);
+ if (ret)
+ goto err_fput;
+
+ ret = datalen;
+
+ /* copy decrypted data to user */
+ if (copy_to_user(buffer, data, datalen) != 0)
+ ret = -EFAULT;
+
+err_fput:
+ fput(file);
+error:
+ kfree(data);
} else {
ret = datalen;
if (copy_to_user(buffer, key->payload.data[big_key_data],
return ret;
}
+/*
+ * Register key type
+ */
static int __init big_key_init(void)
{
return register_key_type(&key_type_big_key);
}
+
+/*
+ * Initialize big_key crypto and RNG algorithms
+ */
+static int __init big_key_crypto_init(void)
+{
+ int ret = -EINVAL;
+
+ /* init RNG */
+ big_key_rng = crypto_alloc_rng(big_key_rng_name, 0, 0);
+ if (IS_ERR(big_key_rng)) {
+ big_key_rng = NULL;
+ return -EFAULT;
+ }
+
+ /* seed RNG */
+ ret = crypto_rng_reset(big_key_rng, NULL, crypto_rng_seedsize(big_key_rng));
+ if (ret)
+ goto error;
+
+ /* init block cipher */
+ big_key_blkcipher = crypto_alloc_blkcipher(big_key_alg_name, 0, 0);
+ if (IS_ERR(big_key_blkcipher)) {
+ big_key_blkcipher = NULL;
+ ret = -EFAULT;
+ goto error;
+ }
+
+ return 0;
+
+error:
+ crypto_free_rng(big_key_rng);
+ big_key_rng = NULL;
+ return ret;
+}
+
device_initcall(big_key_init);
+late_initcall(big_key_crypto_init);
case KEYCTL_GET_PERSISTENT:
return keyctl_get_persistent(arg2, arg3);
+ case KEYCTL_DH_COMPUTE:
+ return keyctl_dh_compute(compat_ptr(arg2), compat_ptr(arg3),
+ arg4);
+
default:
return -EOPNOTSUPP;
}
--- /dev/null
+/* Crypto operations using stored keys
+ *
+ * Copyright (c) 2016, Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/mpi.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <keys/user-type.h>
+#include "internal.h"
+
+/*
+ * Public key or shared secret generation function [RFC2631 sec 2.1.1]
+ *
+ * ya = g^xa mod p;
+ * or
+ * ZZ = yb^xa mod p;
+ *
+ * where xa is the local private key, ya is the local public key, g is
+ * the generator, p is the prime, yb is the remote public key, and ZZ
+ * is the shared secret.
+ *
+ * Both are the same calculation, so g or yb are the "base" and ya or
+ * ZZ are the "result".
+ */
+static int do_dh(MPI result, MPI base, MPI xa, MPI p)
+{
+ return mpi_powm(result, base, xa, p);
+}
+
+static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi)
+{
+ struct key *key;
+ key_ref_t key_ref;
+ long status;
+ ssize_t ret;
+
+ key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
+ if (IS_ERR(key_ref)) {
+ ret = -ENOKEY;
+ goto error;
+ }
+
+ key = key_ref_to_ptr(key_ref);
+
+ ret = -EOPNOTSUPP;
+ if (key->type == &key_type_user) {
+ down_read(&key->sem);
+ status = key_validate(key);
+ if (status == 0) {
+ const struct user_key_payload *payload;
+
+ payload = user_key_payload(key);
+
+ if (maxlen == 0) {
+ *mpi = NULL;
+ ret = payload->datalen;
+ } else if (payload->datalen <= maxlen) {
+ *mpi = mpi_read_raw_data(payload->data,
+ payload->datalen);
+ if (*mpi)
+ ret = payload->datalen;
+ } else {
+ ret = -EINVAL;
+ }
+ }
+ up_read(&key->sem);
+ }
+
+ key_put(key);
+error:
+ return ret;
+}
+
+long keyctl_dh_compute(struct keyctl_dh_params __user *params,
+ char __user *buffer, size_t buflen)
+{
+ long ret;
+ MPI base, private, prime, result;
+ unsigned nbytes;
+ struct keyctl_dh_params pcopy;
+ uint8_t *kbuf;
+ ssize_t keylen;
+ size_t resultlen;
+
+ if (!params || (!buffer && buflen)) {
+ ret = -EINVAL;
+ goto out;
+ }
+ if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ keylen = mpi_from_key(pcopy.prime, buflen, &prime);
+ if (keylen < 0 || !prime) {
+ /* buflen == 0 may be used to query the required buffer size,
+ * which is the prime key length.
+ */
+ ret = keylen;
+ goto out;
+ }
+
+ /* The result is never longer than the prime */
+ resultlen = keylen;
+
+ keylen = mpi_from_key(pcopy.base, SIZE_MAX, &base);
+ if (keylen < 0 || !base) {
+ ret = keylen;
+ goto error1;
+ }
+
+ keylen = mpi_from_key(pcopy.private, SIZE_MAX, &private);
+ if (keylen < 0 || !private) {
+ ret = keylen;
+ goto error2;
+ }
+
+ result = mpi_alloc(0);
+ if (!result) {
+ ret = -ENOMEM;
+ goto error3;
+ }
+
+ kbuf = kmalloc(resultlen, GFP_KERNEL);
+ if (!kbuf) {
+ ret = -ENOMEM;
+ goto error4;
+ }
+
+ ret = do_dh(result, base, private, prime);
+ if (ret)
+ goto error5;
+
+ ret = mpi_read_buffer(result, kbuf, resultlen, &nbytes, NULL);
+ if (ret != 0)
+ goto error5;
+
+ ret = nbytes;
+ if (copy_to_user(buffer, kbuf, nbytes) != 0)
+ ret = -EFAULT;
+
+error5:
+ kfree(kbuf);
+error4:
+ mpi_free(result);
+error3:
+ mpi_free(private);
+error2:
+ mpi_free(base);
+error1:
+ mpi_free(prime);
+out:
+ return ret;
+}
#include <linux/sched.h>
#include <linux/key-type.h>
#include <linux/task_work.h>
+#include <linux/keyctl.h>
struct iovec;
}
#endif
+#ifdef CONFIG_KEY_DH_OPERATIONS
+extern long keyctl_dh_compute(struct keyctl_dh_params __user *, char __user *,
+ size_t);
+#else
+static inline long keyctl_dh_compute(struct keyctl_dh_params __user *params,
+ char __user *buffer, size_t buflen)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
/*
* Debugging key validation
*/
case KEYCTL_GET_PERSISTENT:
return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
+ case KEYCTL_DH_COMPUTE:
+ return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2,
+ (char __user *) arg3,
+ (size_t) arg4);
+
default:
return -EOPNOTSUPP;
}
*/
int user_update(struct key *key, struct key_preparsed_payload *prep)
{
- struct user_key_payload *upayload, *zap;
- size_t datalen = prep->datalen;
+ struct user_key_payload *zap = NULL;
int ret;
- ret = -EINVAL;
- if (datalen <= 0 || datalen > 32767 || !prep->data)
- goto error;
-
- /* construct a replacement payload */
- ret = -ENOMEM;
- upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
- if (!upayload)
- goto error;
-
- upayload->datalen = datalen;
- memcpy(upayload->data, prep->data, datalen);
-
/* check the quota and attach the new data */
- zap = upayload;
-
- ret = key_payload_reserve(key, datalen);
-
- if (ret == 0) {
- /* attach the new data, displacing the old */
- if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags))
- zap = key->payload.data[0];
- else
- zap = NULL;
- rcu_assign_keypointer(key, upayload);
- key->expiry = 0;
- }
+ ret = key_payload_reserve(key, prep->datalen);
+ if (ret < 0)
+ return ret;
+
+ /* attach the new data, displacing the old */
+ key->expiry = prep->expiry;
+ if (!test_bit(KEY_FLAG_NEGATIVE, &key->flags))
+ zap = rcu_dereference_key(key);
+ rcu_assign_keypointer(key, prep->payload.data[0]);
+ prep->payload.data[0] = NULL;
if (zap)
kfree_rcu(zap, rcu);
-
-error:
return ret;
}
-
EXPORT_SYMBOL_GPL(user_update);
/*
.tun_dev_attach =
LIST_HEAD_INIT(security_hook_heads.tun_dev_attach),
.tun_dev_open = LIST_HEAD_INIT(security_hook_heads.tun_dev_open),
- .skb_owned_by = LIST_HEAD_INIT(security_hook_heads.skb_owned_by),
#endif /* CONFIG_SECURITY_NETWORK */
#ifdef CONFIG_SECURITY_NETWORK_XFRM
.xfrm_policy_alloc_security =
projects / deliverable / linux.git / commitdiff
