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 Signed-off-by: Tycho Andersen <[email protected]> CC: David Howells <[email protected]> CC: James Morris <[email protected]> CC: "Serge E. Hallyn" <[email protected]> CC: Jason A. Donenfeld <[email protected]> CC: Eric Biggers <[email protected]> --- security/keys/big_key.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/security/keys/big_key.c b/security/keys/big_key.c index 933623784ccd..75c46786a166 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; @@ -109,7 +110,7 @@ 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[GCM_AES_IV_SIZE]; aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL); if (!aead_req) @@ -425,6 +426,12 @@ 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) != GCM_AES_IV_SIZE)) { + WARN(1, "big key algorithm changed?"); + return -EINVAL; + } + 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); -- 2.17.0
