[v2,06/11] tls/sw: tls_sw_splice_read: always request non-blocking I/O

Commit Message

Ahelenia Ziemiańska Dec. 21, 2023, 3:09 a.m. UTC

Otherwise we risk sleeping with the pipe locked for indeterminate
lengths of time ‒ given
	cat > tls_sw.c <<^D
	#define _GNU_SOURCE
	#include <fcntl.h>
	#include <unistd.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <netinet/tcp.h>
	#include <linux/tls.h>
	int main()
	{
		int s = socket(AF_INET, SOCK_STREAM, 0);
		struct sockaddr_in addr = {
			.sin_family = AF_INET,
			.sin_addr = { htonl(INADDR_LOOPBACK) },
			.sin_port = htons(getpid() % (0xFFFF - 1000) + 1000)
		};
		bind(s, &addr, sizeof(addr));
		listen(s, 1);
		if (!fork()) {
			connect(socket(AF_INET, SOCK_STREAM, 0), &addr, sizeof(addr));
			sleep(100);
			return 0;
		}

		s = accept(s, NULL, NULL);
		setsockopt(s, SOL_TCP, TCP_ULP, "tls", sizeof("tls"));
		setsockopt(s, SOL_TLS, TLS_RX,
			   &(struct tls12_crypto_info_aes_gcm_128){
				   .info.version = TLS_1_2_VERSION,
				   .info.cipher_type = TLS_CIPHER_AES_GCM_128 },
			   sizeof(struct tls12_crypto_info_aes_gcm_128));

		for (;;)
			splice(s, 0, 1, 0, 128 * 1024 * 1024, 0);
	}
	^D
	cc tls_sw.c -o tls_sw
	mkfifo fifo
	./tls_sw > fifo &
	read -r _ < fifo &
	sleep 0.1
	echo zupa > fifo
tls_sw used to sleep in splice and the shell used to enter an
uninterruptible sleep in open("fifo");
now the splice returns -EAGAIN and the whole program completes.

Signed-off-by: Ahelenia Ziemiańska <[e-mail]>
---
 net/tls/tls_sw.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Patch

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index e37b4d2e2acd..3f474deed94d 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2157,7 +2157,7 @@  ssize_t tls_sw_splice_read(struct socket *sock,  loff_t *ppos,
 	int chunk;
 	int err;
 
-	err = tls_rx_reader_lock(sk, ctx, flags & SPLICE_F_NONBLOCK);
+	err = tls_rx_reader_lock(sk, ctx, true);
 	if (err < 0)
 		return err;
 
@@ -2166,8 +2166,7 @@  ssize_t tls_sw_splice_read(struct socket *sock,  loff_t *ppos,
 	} else {
 		struct tls_decrypt_arg darg;
 
-		err = tls_rx_rec_wait(sk, NULL, flags & SPLICE_F_NONBLOCK,
-				      true);
+		err = tls_rx_rec_wait(sk, NULL, true, true);
 		if (err <= 0)
 			goto splice_read_end;