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| author | Tycho Andersen <tycho@tycho.ws> | 2018-04-24 23:26:37 +0300 |
|---|---|---|
| committer | James Morris <james.morris@microsoft.com> | 2018-05-11 23:07:45 +0300 |
| commit | a964f395614af195cf5c5caa84a9c487b86d5ba5 (patch) | |
| tree | 4f816e0c843c2aa721e58ae9f9693054dc1b5396 | |
| parent | 5859cdf55063943192f316b3d6c673fd6fcbee46 (diff) | |
| download | linux-a964f395614af195cf5c5caa84a9c487b86d5ba5.tar.xz | |
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>
| -rw-r--r-- | security/keys/big_key.c | 11 |
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); |