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."

include/linux/key.h

@@ -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);

security/keys/Kconfig

@@ -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

security/keys/big_key.c

 /* 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);
+	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)];
 
-	if (crypto_skcipher_setkey(big_key_skcipher, key, ENC_KEY_SIZE)) {
+	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;
 }
 

security/keys/internal.h

@@ -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 *);

security/keys/key.c

@@ -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;

security/keys/keyctl.c

@@ -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;
-	key_put(authkey);
-
+	if (ret == 0)
 		ret = authkey->serial;
+	key_put(authkey);
 error:
 	return ret;
 }

security/keys/keyring.c

@@ -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),
+			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'

security/keys/proc.c

@@ -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;

security/keys/process_keys.c

@@ -77,6 +77,7 @@ 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_UID_KEYRING |
 							KEY_ALLOC_IN_QUOTA,
 						    NULL, NULL);
 			if (IS_ERR(uid_keyring)) {
@@ -94,6 +95,7 @@ int install_user_keyrings(void)
 			session_keyring =
 				keyring_alloc(buf, user->uid, INVALID_GID,
 					      cred, user_keyring_perm,
+					      KEY_ALLOC_UID_KEYRING |
 						  KEY_ALLOC_IN_QUOTA,
 					      NULL, NULL);
 			if (IS_ERR(session_keyring)) {

security/keys/request_key_auth.c

@@ -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);
 }