Commit 2569e7e1 authored by James Morris's avatar James Morris

Merge commit 'keys-fixes-20170927' into fixes-v4.14-rc3

From David Howells:

"There are two sets of patches here:
 (1) A bunch of core keyrings bug fixes from Eric Biggers.

 (2) Fixing big_key to use safe crypto from Jason A. Donenfeld."
parents 9cd6681c 428490e3
......@@ -187,6 +187,7 @@ struct key {
#define KEY_FLAG_BUILTIN 8 /* set if key is built in to the kernel */
#define KEY_FLAG_ROOT_CAN_INVAL 9 /* set if key can be invalidated by root without permission */
#define KEY_FLAG_KEEP 10 /* set if key should not be removed */
#define KEY_FLAG_UID_KEYRING 11 /* set if key is a user or user session keyring */
/* the key type and key description string
* - the desc is used to match a key against search criteria
......@@ -243,6 +244,7 @@ extern struct key *key_alloc(struct key_type *type,
#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
#define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
#define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
#define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
extern void key_revoke(struct key *key);
extern void key_invalidate(struct key *key);
......
......@@ -45,10 +45,8 @@ config BIG_KEYS
bool "Large payload keys"
depends on KEYS
depends on TMPFS
depends on (CRYPTO_ANSI_CPRNG = y || CRYPTO_DRBG = y)
select CRYPTO_AES
select CRYPTO_ECB
select CRYPTO_RNG
select CRYPTO_GCM
help
This option provides support for holding large keys within the kernel
(for example Kerberos ticket caches). The data may be stored out to
......
/* Large capacity key type
*
* Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
......@@ -16,10 +17,10 @@
#include <linux/shmem_fs.h>
#include <linux/err.h>
#include <linux/scatterlist.h>
#include <linux/random.h>
#include <keys/user-type.h>
#include <keys/big_key-type.h>
#include <crypto/rng.h>
#include <crypto/skcipher.h>
#include <crypto/aead.h>
/*
* Layout of key payload words.
......@@ -49,7 +50,12 @@ enum big_key_op {
/*
* Key size for big_key data encryption
*/
#define ENC_KEY_SIZE 16
#define ENC_KEY_SIZE 32
/*
* Authentication tag length
*/
#define ENC_AUTHTAG_SIZE 16
/*
* big_key defined keys take an arbitrary string as the description and an
......@@ -64,57 +70,62 @@ struct key_type key_type_big_key = {
.destroy = big_key_destroy,
.describe = big_key_describe,
.read = big_key_read,
/* no ->update(); don't add it without changing big_key_crypt() nonce */
};
/*
* Crypto names for big_key data encryption
* Crypto names for big_key data authenticated encryption
*/
static const char big_key_rng_name[] = "stdrng";
static const char big_key_alg_name[] = "ecb(aes)";
static const char big_key_alg_name[] = "gcm(aes)";
/*
* Crypto algorithms for big_key data encryption
* Crypto algorithms for big_key data authenticated encryption
*/
static struct crypto_rng *big_key_rng;
static struct crypto_skcipher *big_key_skcipher;
static struct crypto_aead *big_key_aead;
/*
* Generate random key to encrypt big_key data
* Since changing the key affects the entire object, we need a mutex.
*/
static inline int big_key_gen_enckey(u8 *key)
{
return crypto_rng_get_bytes(big_key_rng, key, ENC_KEY_SIZE);
}
static DEFINE_MUTEX(big_key_aead_lock);
/*
* 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;
int ret;
struct scatterlist sgio;
SKCIPHER_REQUEST_ON_STACK(req, big_key_skcipher);
if (crypto_skcipher_setkey(big_key_skcipher, key, ENC_KEY_SIZE)) {
struct aead_request *aead_req;
/* We always use a zero nonce. The reason we can get away with this is
* because we're using a different randomly generated key for every
* different encryption. Notably, too, key_type_big_key doesn't define
* an .update function, so there's no chance we'll wind up reusing the
* key to encrypt updated data. Simply put: one key, one encryption.
*/
u8 zero_nonce[crypto_aead_ivsize(big_key_aead)];
aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
if (!aead_req)
return -ENOMEM;
memset(zero_nonce, 0, sizeof(zero_nonce));
sg_init_one(&sgio, data, datalen + (op == BIG_KEY_ENC ? ENC_AUTHTAG_SIZE : 0));
aead_request_set_crypt(aead_req, &sgio, &sgio, datalen, zero_nonce);
aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
aead_request_set_ad(aead_req, 0);
mutex_lock(&big_key_aead_lock);
if (crypto_aead_setkey(big_key_aead, key, ENC_KEY_SIZE)) {
ret = -EAGAIN;
goto error;
}
skcipher_request_set_tfm(req, big_key_skcipher);
skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
NULL, NULL);
sg_init_one(&sgio, data, datalen);
skcipher_request_set_crypt(req, &sgio, &sgio, datalen, NULL);
if (op == BIG_KEY_ENC)
ret = crypto_skcipher_encrypt(req);
ret = crypto_aead_encrypt(aead_req);
else
ret = crypto_skcipher_decrypt(req);
skcipher_request_zero(req);
ret = crypto_aead_decrypt(aead_req);
error:
mutex_unlock(&big_key_aead_lock);
aead_request_free(aead_req);
return ret;
}
......@@ -146,16 +157,13 @@ int big_key_preparse(struct key_preparsed_payload *prep)
*
* File content is stored encrypted with randomly generated key.
*/
size_t enclen = ALIGN(datalen, crypto_skcipher_blocksize(big_key_skcipher));
size_t enclen = datalen + ENC_AUTHTAG_SIZE;
loff_t pos = 0;
/* 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);
......@@ -163,13 +171,12 @@ int big_key_preparse(struct key_preparsed_payload *prep)
ret = -ENOMEM;
goto error;
}
ret = big_key_gen_enckey(enckey);
if (ret)
ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE);
if (unlikely(ret))
goto err_enckey;
/* encrypt aligned data */
ret = big_key_crypt(BIG_KEY_ENC, data, enclen, enckey);
ret = big_key_crypt(BIG_KEY_ENC, data, datalen, enckey);
if (ret)
goto err_enckey;
......@@ -195,7 +202,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
*path = file->f_path;
path_get(path);
fput(file);
kfree(data);
kzfree(data);
} else {
/* Just store the data in a buffer */
void *data = kmalloc(datalen, GFP_KERNEL);
......@@ -211,9 +218,9 @@ int big_key_preparse(struct key_preparsed_payload *prep)
err_fput:
fput(file);
err_enckey:
kfree(enckey);
kzfree(enckey);
error:
kfree(data);
kzfree(data);
return ret;
}
......@@ -227,7 +234,7 @@ void big_key_free_preparse(struct key_preparsed_payload *prep)
path_put(path);
}
kfree(prep->payload.data[big_key_data]);
kzfree(prep->payload.data[big_key_data]);
}
/*
......@@ -259,7 +266,7 @@ void big_key_destroy(struct key *key)
path->mnt = NULL;
path->dentry = NULL;
}
kfree(key->payload.data[big_key_data]);
kzfree(key->payload.data[big_key_data]);
key->payload.data[big_key_data] = NULL;
}
......@@ -295,7 +302,7 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
struct file *file;
u8 *data;
u8 *enckey = (u8 *)key->payload.data[big_key_data];
size_t enclen = ALIGN(datalen, crypto_skcipher_blocksize(big_key_skcipher));
size_t enclen = datalen + ENC_AUTHTAG_SIZE;
loff_t pos = 0;
data = kmalloc(enclen, GFP_KERNEL);
......@@ -328,7 +335,7 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
err_fput:
fput(file);
error:
kfree(data);
kzfree(data);
} else {
ret = datalen;
if (copy_to_user(buffer, key->payload.data[big_key_data],
......@@ -344,47 +351,31 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
*/
static int __init big_key_init(void)
{
struct crypto_skcipher *cipher;
struct crypto_rng *rng;
int ret;
rng = crypto_alloc_rng(big_key_rng_name, 0, 0);
if (IS_ERR(rng)) {
pr_err("Can't alloc rng: %ld\n", PTR_ERR(rng));
return PTR_ERR(rng);
}
big_key_rng = rng;
/* seed RNG */
ret = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
if (ret) {
pr_err("Can't reset rng: %d\n", ret);
goto error_rng;
}
/* init block cipher */
cipher = crypto_alloc_skcipher(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(cipher)) {
ret = PTR_ERR(cipher);
big_key_aead = crypto_alloc_aead(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(big_key_aead)) {
ret = PTR_ERR(big_key_aead);
pr_err("Can't alloc crypto: %d\n", ret);
goto error_rng;
return ret;
}
ret = crypto_aead_setauthsize(big_key_aead, ENC_AUTHTAG_SIZE);
if (ret < 0) {
pr_err("Can't set crypto auth tag len: %d\n", ret);
goto free_aead;
}
big_key_skcipher = cipher;
ret = register_key_type(&key_type_big_key);
if (ret < 0) {
pr_err("Can't register type: %d\n", ret);
goto error_cipher;
goto free_aead;
}
return 0;
error_cipher:
crypto_free_skcipher(big_key_skcipher);
error_rng:
crypto_free_rng(big_key_rng);
free_aead:
crypto_free_aead(big_key_aead);
return ret;
}
......
......@@ -141,7 +141,7 @@ extern key_ref_t keyring_search_aux(key_ref_t keyring_ref,
extern key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx);
extern key_ref_t search_process_keyrings(struct keyring_search_context *ctx);
extern struct key *find_keyring_by_name(const char *name, bool skip_perm_check);
extern struct key *find_keyring_by_name(const char *name, bool uid_keyring);
extern int install_user_keyrings(void);
extern int install_thread_keyring_to_cred(struct cred *);
......
......@@ -54,10 +54,10 @@ void __key_check(const struct key *key)
struct key_user *key_user_lookup(kuid_t uid)
{
struct key_user *candidate = NULL, *user;
struct rb_node *parent = NULL;
struct rb_node **p;
struct rb_node *parent, **p;
try_again:
parent = NULL;
p = &key_user_tree.rb_node;
spin_lock(&key_user_lock);
......@@ -302,6 +302,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
key->flags |= 1 << KEY_FLAG_IN_QUOTA;
if (flags & KEY_ALLOC_BUILT_IN)
key->flags |= 1 << KEY_FLAG_BUILTIN;
if (flags & KEY_ALLOC_UID_KEYRING)
key->flags |= 1 << KEY_FLAG_UID_KEYRING;
#ifdef KEY_DEBUGGING
key->magic = KEY_DEBUG_MAGIC;
......
......@@ -766,12 +766,17 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
key = key_ref_to_ptr(key_ref);
if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
ret = -ENOKEY;
goto error2;
}
/* see if we can read it directly */
ret = key_permission(key_ref, KEY_NEED_READ);
if (ret == 0)
goto can_read_key;
if (ret != -EACCES)
goto error;
goto error2;
/* we can't; see if it's searchable from this process's keyrings
* - we automatically take account of the fact that it may be
......@@ -1406,11 +1411,9 @@ long keyctl_assume_authority(key_serial_t id)
}
ret = keyctl_change_reqkey_auth(authkey);
if (ret < 0)
goto error;
if (ret == 0)
ret = authkey->serial;
key_put(authkey);
ret = authkey->serial;
error:
return ret;
}
......
......@@ -423,7 +423,7 @@ static void keyring_describe(const struct key *keyring, struct seq_file *m)
}
struct keyring_read_iterator_context {
size_t qty;
size_t buflen;
size_t count;
key_serial_t __user *buffer;
};
......@@ -435,9 +435,9 @@ static int keyring_read_iterator(const void *object, void *data)
int ret;
kenter("{%s,%d},,{%zu/%zu}",
key->type->name, key->serial, ctx->count, ctx->qty);
key->type->name, key->serial, ctx->count, ctx->buflen);
if (ctx->count >= ctx->qty)
if (ctx->count >= ctx->buflen)
return 1;
ret = put_user(key->serial, ctx->buffer);
......@@ -472,16 +472,12 @@ static long keyring_read(const struct key *keyring,
return 0;
/* Calculate how much data we could return */
ctx.qty = nr_keys * sizeof(key_serial_t);
if (!buffer || !buflen)
return ctx.qty;
if (buflen > ctx.qty)
ctx.qty = buflen;
return nr_keys * sizeof(key_serial_t);
/* Copy the IDs of the subscribed keys into the buffer */
ctx.buffer = (key_serial_t __user *)buffer;
ctx.buflen = buflen;
ctx.count = 0;
ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
if (ret < 0) {
......@@ -1101,15 +1097,15 @@ key_ref_t find_key_to_update(key_ref_t keyring_ref,
/*
* Find a keyring with the specified name.
*
* All named keyrings in the current user namespace are searched, provided they
* grant Search permission directly to the caller (unless this check is
* skipped). Keyrings whose usage points have reached zero or who have been
* revoked are skipped.
* Only keyrings that have nonzero refcount, are not revoked, and are owned by a
* user in the current user namespace are considered. If @uid_keyring is %true,
* the keyring additionally must have been allocated as a user or user session
* keyring; otherwise, it must grant Search permission directly to the caller.
*
* Returns a pointer to the keyring with the keyring's refcount having being
* incremented on success. -ENOKEY is returned if a key could not be found.
*/
struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
struct key *find_keyring_by_name(const char *name, bool uid_keyring)
{
struct key *keyring;
int bucket;
......@@ -1137,10 +1133,15 @@ struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
if (strcmp(keyring->description, name) != 0)
continue;
if (!skip_perm_check &&
key_permission(make_key_ref(keyring, 0),
KEY_NEED_SEARCH) < 0)
continue;
if (uid_keyring) {
if (!test_bit(KEY_FLAG_UID_KEYRING,
&keyring->flags))
continue;
} else {
if (key_permission(make_key_ref(keyring, 0),
KEY_NEED_SEARCH) < 0)
continue;
}
/* we've got a match but we might end up racing with
* key_cleanup() if the keyring is currently 'dead'
......
......@@ -187,7 +187,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
struct keyring_search_context ctx = {
.index_key.type = key->type,
.index_key.description = key->description,
.cred = current_cred(),
.cred = m->file->f_cred,
.match_data.cmp = lookup_user_key_possessed,
.match_data.raw_data = key,
.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
......@@ -207,11 +207,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
}
}
/* check whether the current task is allowed to view the key (assuming
* non-possession)
* - the caller holds a spinlock, and thus the RCU read lock, making our
* access to __current_cred() safe
*/
/* check whether the current task is allowed to view the key */
rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
if (rc < 0)
return 0;
......
......@@ -77,7 +77,8 @@ int install_user_keyrings(void)
if (IS_ERR(uid_keyring)) {
uid_keyring = keyring_alloc(buf, user->uid, INVALID_GID,
cred, user_keyring_perm,
KEY_ALLOC_IN_QUOTA,
KEY_ALLOC_UID_KEYRING |
KEY_ALLOC_IN_QUOTA,
NULL, NULL);
if (IS_ERR(uid_keyring)) {
ret = PTR_ERR(uid_keyring);
......@@ -94,7 +95,8 @@ int install_user_keyrings(void)
session_keyring =
keyring_alloc(buf, user->uid, INVALID_GID,
cred, user_keyring_perm,
KEY_ALLOC_IN_QUOTA,
KEY_ALLOC_UID_KEYRING |
KEY_ALLOC_IN_QUOTA,
NULL, NULL);
if (IS_ERR(session_keyring)) {
ret = PTR_ERR(session_keyring);
......
......@@ -120,6 +120,18 @@ static void request_key_auth_revoke(struct key *key)
}
}
static void free_request_key_auth(struct request_key_auth *rka)
{
if (!rka)
return;
key_put(rka->target_key);
key_put(rka->dest_keyring);
if (rka->cred)
put_cred(rka->cred);
kfree(rka->callout_info);
kfree(rka);
}
/*
* Destroy an instantiation authorisation token key.
*/
......@@ -129,15 +141,7 @@ static void request_key_auth_destroy(struct key *key)
kenter("{%d}", key->serial);
if (rka->cred) {
put_cred(rka->cred);
rka->cred = NULL;
}
key_put(rka->target_key);
key_put(rka->dest_keyring);
kfree(rka->callout_info);
kfree(rka);
free_request_key_auth(rka);
}
/*
......@@ -151,22 +155,18 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
const struct cred *cred = current->cred;
struct key *authkey = NULL;
char desc[20];
int ret;
int ret = -ENOMEM;
kenter("%d,", target->serial);
/* allocate a auth record */
rka = kmalloc(sizeof(*rka), GFP_KERNEL);
if (!rka) {
kleave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
rka->callout_info = kmalloc(callout_len, GFP_KERNEL);
if (!rka->callout_info) {
kleave(" = -ENOMEM");
kfree(rka);
return ERR_PTR(-ENOMEM);
}
rka = kzalloc(sizeof(*rka), GFP_KERNEL);
if (!rka)
goto error;
rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
if (!rka->callout_info)
goto error_free_rka;
rka->callout_len = callout_len;
/* see if the calling process is already servicing the key request of
* another process */
......@@ -176,8 +176,12 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
/* if the auth key has been revoked, then the key we're
* servicing is already instantiated */
if (test_bit(KEY_FLAG_REVOKED, &cred->request_key_auth->flags))
goto auth_key_revoked;
if (test_bit(KEY_FLAG_REVOKED,
&cred->request_key_auth->flags)) {
up_read(&cred->request_key_auth->sem);
ret = -EKEYREVOKED;
goto error_free_rka;
}
irka = cred->request_key_auth->payload.data[0];
rka->cred = get_cred(irka->cred);
......@@ -193,8 +197,6 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
rka->target_key = key_get(target);
rka->dest_keyring = key_get(dest_keyring);
memcpy(rka->callout_info, callout_info, callout_len);
rka->callout_len = callout_len;
/* allocate the auth key */
sprintf(desc, "%x", target->serial);
......@@ -205,32 +207,22 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL);
if (IS_ERR(authkey)) {
ret = PTR_ERR(authkey);
goto error_alloc;
goto error_free_rka;
}
/* construct the auth key */
ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
if (ret < 0)
goto error_inst;
goto error_put_authkey;
kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage));
return authkey;
auth_key_revoked:
up_read(&cred->request_key_auth->sem);
kfree(rka->callout_info);
kfree(rka);
kleave("= -EKEYREVOKED");
return ERR_PTR(-EKEYREVOKED);
error_inst:
key_revoke(authkey);
error_put_authkey:
key_put(authkey);
error_alloc:
key_put(rka->target_key);
key_put(rka->dest_keyring);
kfree(rka->callout_info);
kfree(rka);
error_free_rka:
free_request_key_auth(rka);
error:
kleave("= %d", ret);
return ERR_PTR(ret);
}
......
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