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authorTycho Andersen <tycho@tycho.ws>2018-04-24 14:26:37 -0600
committerJames Morris <james.morris@microsoft.com>2018-05-11 13:07:45 -0700
commita964f395614af195cf5c5caa84a9c487b86d5ba5 (patch)
tree4f816e0c843c2aa721e58ae9f9693054dc1b5396 /security
parent5859cdf55063943192f316b3d6c673fd6fcbee46 (diff)
big key: get rid of stack array allocation
We're interested in getting rid of all of the stack allocated arrays in the kernel [1]. This patch simply hardcodes the iv length to match that of the hardcoded cipher. [1]: https://lkml.org/lkml/2018/3/7/621 v2: hardcode the length of the nonce to be the GCM AES IV length, and do a sanity check in init(), Eric Biggers v3: * remember to free big_key_aead when sanity check fails * define a constant for big key IV size so it can be changed along side the algorithm in the code Signed-off-by: Tycho Andersen <tycho@tycho.ws> Reviewed-by: Kees Cook <keescook@chromium.org> CC: David Howells <dhowells@redhat.com> CC: James Morris <jmorris@namei.org> CC: "Serge E. Hallyn" <serge@hallyn.com> CC: Jason A. Donenfeld <Jason@zx2c4.com> CC: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: James Morris <james.morris@microsoft.com>
Diffstat (limited to 'security')
-rw-r--r--security/keys/big_key.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/security/keys/big_key.c b/security/keys/big_key.c
index 933623784ccd..2806e70d7f8f 100644
--- a/security/keys/big_key.c
+++ b/security/keys/big_key.c
@@ -22,6 +22,7 @@
#include <keys/user-type.h>
#include <keys/big_key-type.h>
#include <crypto/aead.h>
+#include <crypto/gcm.h>
struct big_key_buf {
unsigned int nr_pages;
@@ -85,6 +86,7 @@ struct key_type key_type_big_key = {
* Crypto names for big_key data authenticated encryption
*/
static const char big_key_alg_name[] = "gcm(aes)";
+#define BIG_KEY_IV_SIZE GCM_AES_IV_SIZE
/*
* Crypto algorithms for big_key data authenticated encryption
@@ -109,7 +111,7 @@ static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t dat
* 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)];
+ u8 zero_nonce[BIG_KEY_IV_SIZE];
aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
if (!aead_req)
@@ -425,6 +427,13 @@ static int __init big_key_init(void)
pr_err("Can't alloc crypto: %d\n", ret);
return ret;
}
+
+ if (unlikely(crypto_aead_ivsize(big_key_aead) != BIG_KEY_IV_SIZE)) {
+ WARN(1, "big key algorithm changed?");
+ ret = -EINVAL;
+ goto free_aead;
+ }
+
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);