[v2 PATCH] crypto: af_alg - Fix regression on empty requests

[Herbert Xu <herbert@gondor.apana.org.au>]

On Tue, Jun 30, 2020 at 02:18:11PM +0530, Naresh Kamboju wrote:
> 
> Since we are on this subject,
> LTP af_alg02  test case fails on stable 4.9 and stable 4.4
> This is not a regression because the test case has been failing from
> the beginning.
> 
> Is this test case expected to fail on stable 4.9 and 4.4 ?
> or any chance to fix this on these older branches ?
> 
> Test output:
> af_alg02.c:52: BROK: Timed out while reading from request socket.
> 
> ref:
> https://qa-reports.linaro.org/lkft/linux-stable-rc-4.9-oe/build/v4.9.228-191-g082e807235d7/testrun/2884917/suite/ltp-crypto-tests/test/af_alg02/history/
> https://qa-reports.linaro.org/lkft/linux-stable-rc-4.9-oe/build/v4.9.228-191-g082e807235d7/testrun/2884606/suite/ltp-crypto-tests/test/af_alg02/log

Actually this test really is broken.  Even though empty requests
are legal, they should never be done with no write(2) at all.
Because this fundamentally breaks the use of a blocking read(2)
to wait for more data.

Granted this has been broken since 2017 but I'm not going to
reintroduce this just because of a broken test case.

So please either remove af_alg02 or fix it by adding a control
message through sendmsg(2).

Thanks,

---8<---
Some user-space programs rely on crypto requests that have no
control metadata.  This broke when a check was added to require
the presence of control metadata with the ctx->init flag.

This patch fixes the regression by setting ctx->init as long as
one sendmsg(2) has been made, with or without a control message.

Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: f3c802a1f300 ("crypto: algif_aead - Only wake up when...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 9fcb91ea10c41..5882ed46f1adb 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -851,6 +851,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
 		err = -EINVAL;
 		goto unlock;
 	}
+	ctx->init = true;
 
 	if (init) {
 		ctx->enc = enc;
@@ -858,7 +859,6 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
 			memcpy(ctx->iv, con.iv->iv, ivsize);
 
 		ctx->aead_assoclen = con.aead_assoclen;
-		ctx->init = true;
 	}
 
 	while (size) {
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt