This is a note to let you know that I've just added the patch titled
KEYS: encrypted: avoid encrypting/decrypting stack buffers
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
keys-encrypted-avoid-encrypting-decrypting-stack-buffers.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e9ff56ac352446f55141aaef1553cee662b2e310 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@xxxxxxxxxx>
Date: Thu, 8 Jun 2017 14:48:10 +0100
Subject: KEYS: encrypted: avoid encrypting/decrypting stack buffers
From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit e9ff56ac352446f55141aaef1553cee662b2e310 upstream.
Since v4.9, the crypto API cannot (normally) be used to encrypt/decrypt
stack buffers because the stack may be virtually mapped. Fix this for
the padding buffers in encrypted-keys by using ZERO_PAGE for the
encryption padding and by allocating a temporary heap buffer for the
decryption padding.
Tested with CONFIG_DEBUG_SG=y:
keyctl new_session
keyctl add user master "abcdefghijklmnop" @s
keyid=$(keyctl add encrypted desc "new user:master 25" @s)
datablob="$(keyctl pipe $keyid)"
keyctl unlink $keyid
keyid=$(keyctl add encrypted desc "load $datablob" @s)
datablob2="$(keyctl pipe $keyid)"
[ "$datablob" = "$datablob2" ] && echo "Success!"
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: James Morris <james.l.morris@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
security/keys/encrypted-keys/encrypted.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
--- a/security/keys/encrypted-keys/encrypted.c
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -480,12 +480,9 @@ static int derived_key_encrypt(struct en
struct skcipher_request *req;
unsigned int encrypted_datalen;
u8 iv[AES_BLOCK_SIZE];
- unsigned int padlen;
- char pad[16];
int ret;
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
- padlen = encrypted_datalen - epayload->decrypted_datalen;
req = init_skcipher_req(derived_key, derived_keylen);
ret = PTR_ERR(req);
@@ -493,11 +490,10 @@ static int derived_key_encrypt(struct en
goto out;
dump_decrypted_data(epayload);
- memset(pad, 0, sizeof pad);
sg_init_table(sg_in, 2);
sg_set_buf(&sg_in[0], epayload->decrypted_data,
epayload->decrypted_datalen);
- sg_set_buf(&sg_in[1], pad, padlen);
+ sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
sg_init_table(sg_out, 1);
sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
@@ -584,9 +580,14 @@ static int derived_key_decrypt(struct en
struct skcipher_request *req;
unsigned int encrypted_datalen;
u8 iv[AES_BLOCK_SIZE];
- char pad[16];
+ u8 *pad;
int ret;
+ /* Throwaway buffer to hold the unused zero padding at the end */
+ pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
+ if (!pad)
+ return -ENOMEM;
+
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
req = init_skcipher_req(derived_key, derived_keylen);
ret = PTR_ERR(req);
@@ -594,13 +595,12 @@ static int derived_key_decrypt(struct en
goto out;
dump_encrypted_data(epayload, encrypted_datalen);
- memset(pad, 0, sizeof pad);
sg_init_table(sg_in, 1);
sg_init_table(sg_out, 2);
sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
sg_set_buf(&sg_out[0], epayload->decrypted_data,
epayload->decrypted_datalen);
- sg_set_buf(&sg_out[1], pad, sizeof pad);
+ sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
memcpy(iv, epayload->iv, sizeof(iv));
skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
@@ -612,6 +612,7 @@ static int derived_key_decrypt(struct en
goto out;
dump_decrypted_data(epayload);
out:
+ kfree(pad);
return ret;
}
Patches currently in stable-queue which might be from ebiggers@xxxxxxxxxx are
queue-4.9/keys-encrypted-avoid-encrypting-decrypting-stack-buffers.patch
queue-4.9/keys-fix-freeing-uninitialized-memory-in-key_update.patch
queue-4.9/keys-fix-dereferencing-null-payload-with-nonzero-length.patch