From e9ff56ac352446f55141aaef1553cee662b2e310 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 8 Jun 2017 14:48:10 +0100 Subject: KEYS: encrypted: avoid encrypting/decrypting stack buffers 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 Cc: Herbert Xu Cc: Mimi Zohar Cc: stable@vger.kernel.org # 4.9+ Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris --- security/keys/encrypted-keys/encrypted.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'security') diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c index 2ab48eab29a1..d14f1a47a130 100644 --- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -479,12 +479,9 @@ static int derived_key_encrypt(struct encrypted_key_payload *epayload, 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); @@ -492,11 +489,10 @@ static int derived_key_encrypt(struct encrypted_key_payload *epayload, 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); @@ -583,9 +579,14 @@ static int derived_key_decrypt(struct encrypted_key_payload *epayload, 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); @@ -593,13 +594,12 @@ static int derived_key_decrypt(struct encrypted_key_payload *epayload, 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); @@ -611,6 +611,7 @@ static int derived_key_decrypt(struct encrypted_key_payload *epayload, goto out; dump_decrypted_data(epayload); out: + kfree(pad); return ret; } -- cgit v1.2.1