From 70957a10e1dbc72382994a8c630b7a0c0b55b515 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 27 Aug 2020 17:14:36 +1000 Subject: [PATCH] crypto: af_alg - Work around empty control messages without MSG_MORE commit c195d66a8a75c60515819b101975f38b7ec6577f upstream. The iwd daemon uses libell which sets up the skcipher operation with two separate control messages. As the first control message is sent without MSG_MORE, it is interpreted as an empty request. While libell should be fixed to use MSG_MORE where appropriate, this patch works around the bug in the kernel so that existing binaries continue to work. We will print a warning however. A separate issue is that the new kernel code no longer allows the control message to be sent twice within the same request. This restriction is obviously incompatible with what iwd was doing (first setting an IV and then sending the real control message). This patch changes the kernel so that this is explicitly allowed. Reported-by: Caleb Jorden Fixes: f3c802a1f300 ("crypto: algif_aead - Only wake up when...") Cc: Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- crypto/af_alg.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/crypto/af_alg.c b/crypto/af_alg.c index 35e026ba2c7e..1d4b0157ee5d 100644 --- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -847,9 +848,15 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size, } lock_sock(sk); - if (ctx->init && (init || !ctx->more)) { - err = -EINVAL; - goto unlock; + if (ctx->init && !ctx->more) { + if (ctx->used) { + err = -EINVAL; + goto unlock; + } + + pr_info_once( + "%s sent an empty control message without MSG_MORE.\n", + current->comm); } ctx->init = true;