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Message-ID: <67e1810e3b460_2f662329482@willemb.c.googlers.com.notmuch>
Date: Mon, 24 Mar 2025 11:58:06 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Kuniyuki Iwashima <kuniyu@...zon.com>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>,
"David S. Miller" <davem@...emloft.net>,
David Ahern <dsahern@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>,
Kuniyuki Iwashima <kuniyu@...zon.com>,
Kuniyuki Iwashima <kuni1840@...il.com>,
netdev@...r.kernel.org
Subject: Re: [PATCH v1 net 3/3] selftest: net: Check wraparounds for
sk->sk_rmem_alloc.
Kuniyuki Iwashima wrote:
> The test creates client and server sockets and sets INT_MAX to the
> server's SO_RCVBUFFORCE.
>
> Then, the client floods packets to the server until the UDP memory
> usage reaches (INT_MAX + 1) >> PAGE_SHIFT.
>
> Finally, both sockets are close()d, and the last assert makes sure
> that the memory usage drops to 0.
>
> If needed, we can extend the test later for other protocols.
>
> Without patch 1:
>
> # RUN so_rcvbuf.udp_ipv4.rmem_max ...
> # so_rcvbuf.c:160:rmem_max:Expected pages (524800) <= *variant->max_pages (524288)
> # rmem_max: Test terminated by assertion
> # FAIL so_rcvbuf.udp_ipv4.rmem_max
> not ok 1 so_rcvbuf.udp_ipv4.rmem_max
>
> Without patch 2:
>
> # RUN so_rcvbuf.udp_ipv4.rmem_max ...
> # so_rcvbuf.c:167:rmem_max:max_pages: 524288
> # so_rcvbuf.c:175:rmem_max:Expected get_prot_pages(_metadata, variant) (524288) == 0 (0)
> # rmem_max: Test terminated by assertion
> # FAIL so_rcvbuf.udp_ipv4.rmem_max
> not ok 1 so_rcvbuf.udp_ipv4.rmem_max
>
> Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
> ---
> tools/testing/selftests/net/.gitignore | 1 +
> tools/testing/selftests/net/Makefile | 2 +-
> tools/testing/selftests/net/so_rcvbuf.c | 178 ++++++++++++++++++++++++
> 3 files changed, 180 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/net/so_rcvbuf.c
>
> diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
> index 28a715a8ef2b..befbdfb26581 100644
> --- a/tools/testing/selftests/net/.gitignore
> +++ b/tools/testing/selftests/net/.gitignore
> @@ -41,6 +41,7 @@ sk_so_peek_off
> socket
> so_incoming_cpu
> so_netns_cookie
> +so_rcvbuf
> so_txtime
> stress_reuseport_listen
> tap
> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index 8f32b4f01aee..d04428eaa819 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -83,7 +83,7 @@ TEST_GEN_PROGS += sk_bind_sendto_listen
> TEST_GEN_PROGS += sk_connect_zero_addr
> TEST_GEN_PROGS += sk_so_peek_off
> TEST_PROGS += test_ingress_egress_chaining.sh
> -TEST_GEN_PROGS += so_incoming_cpu
> +TEST_GEN_PROGS += so_incoming_cpu so_rcvbuf
> TEST_PROGS += sctp_vrf.sh
> TEST_GEN_FILES += sctp_hello
> TEST_GEN_FILES += ip_local_port_range
> diff --git a/tools/testing/selftests/net/so_rcvbuf.c b/tools/testing/selftests/net/so_rcvbuf.c
> new file mode 100644
> index 000000000000..6e20bafce32e
> --- /dev/null
> +++ b/tools/testing/selftests/net/so_rcvbuf.c
> @@ -0,0 +1,178 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright Amazon.com Inc. or its affiliates. */
> +
> +#include <limits.h>
> +#include <netinet/in.h>
> +#include <sys/socket.h>
> +#include <unistd.h>
> +
> +#include "../kselftest_harness.h"
> +
> +static int udp_max_pages;
> +
> +static int udp_parse_pages(struct __test_metadata *_metadata,
> + char *line, int *pages)
> +{
> + int ret, unused;
> +
> + if (strncmp(line, "UDP:", 4))
> + return -1;
> +
> + ret = sscanf(line + 4, " inuse %d mem %d", &unused, pages);
> + ASSERT_EQ(2, ret);
> +
> + return 0;
> +}
> +
> +FIXTURE(so_rcvbuf)
> +{
> + union {
> + struct sockaddr addr;
> + struct sockaddr_in addr4;
> + struct sockaddr_in6 addr6;
> + };
> + socklen_t addrlen;
> + int server;
> + int client;
> +};
> +
> +FIXTURE_VARIANT(so_rcvbuf)
> +{
> + int family;
> + int type;
> + int protocol;
> + int *max_pages;
> + int (*parse_pages)(struct __test_metadata *_metadata,
> + char *line, int *pages);
> +};
> +
> +FIXTURE_VARIANT_ADD(so_rcvbuf, udp_ipv4)
> +{
> + .family = AF_INET,
> + .type = SOCK_DGRAM,
> + .protocol = 0,
> + .max_pages = &udp_max_pages,
> + .parse_pages = udp_parse_pages,
> +};
> +
> +FIXTURE_VARIANT_ADD(so_rcvbuf, udp_ipv6)
> +{
> + .family = AF_INET6,
> + .type = SOCK_DGRAM,
> + .protocol = 0,
> + .max_pages = &udp_max_pages,
> + .parse_pages = udp_parse_pages,
> +};
> +
> +static int get_page_shift(void)
> +{
> + int page_size = getpagesize();
> + int page_shift = 0;
> +
> + while (page_size > 1) {
> + page_size >>= 1;
> + page_shift++;
> + }
> +
> + return page_shift;
> +}
> +
> +FIXTURE_SETUP(so_rcvbuf)
> +{
> + self->addr.sa_family = variant->family;
> +
> + if (variant->family == AF_INET)
> + self->addrlen = sizeof(struct sockaddr_in);
> + else
> + self->addrlen = sizeof(struct sockaddr_in6);
> +
> + udp_max_pages = (INT_MAX + 1L) >> get_page_shift();
> +}
> +
> +FIXTURE_TEARDOWN(so_rcvbuf)
> +{
> +}
> +
> +static void create_socketpair(struct __test_metadata *_metadata,
> + FIXTURE_DATA(so_rcvbuf) *self,
> + const FIXTURE_VARIANT(so_rcvbuf) *variant)
> +{
> + int ret;
> +
> + self->server = socket(variant->family, variant->type, variant->protocol);
> + ASSERT_NE(self->server, -1);
> +
> + self->client = socket(variant->family, variant->type, variant->protocol);
> + ASSERT_NE(self->client, -1);
> +
> + ret = bind(self->server, &self->addr, self->addrlen);
> + ASSERT_EQ(ret, 0);
> +
> + ret = getsockname(self->server, &self->addr, &self->addrlen);
> + ASSERT_EQ(ret, 0);
> +
> + ret = connect(self->client, &self->addr, self->addrlen);
> + ASSERT_EQ(ret, 0);
> +}
> +
> +static int get_prot_pages(struct __test_metadata *_metadata,
> + const FIXTURE_VARIANT(so_rcvbuf) *variant)
> +{
> + char *line = NULL;
> + size_t unused;
> + int pages = 0;
> + FILE *f;
> +
> + f = fopen("/proc/net/sockstat", "r");
> + ASSERT_NE(NULL, f);
> +
> + while (getline(&line, &unused, f) != -1)
> + if (!variant->parse_pages(_metadata, line, &pages))
> + break;
> +
> + free(line);
> + fclose(f);
> +
> + return pages;
> +}
> +
> +TEST_F(so_rcvbuf, rmem_max)
> +{
> + char buf[16] = {};
> + int ret, i;
> +
> + create_socketpair(_metadata, self, variant);
> +
> + ret = setsockopt(self->server, SOL_SOCKET, SO_RCVBUFFORCE,
> + &(int){INT_MAX}, sizeof(int));
> + ASSERT_EQ(ret, 0);
> +
> + ASSERT_EQ(get_prot_pages(_metadata, variant), 0);
> +
> + for (i = 1; ; i++) {
> + ret = send(self->client, buf, sizeof(buf), 0);
> + ASSERT_EQ(ret, sizeof(buf));
> +
> + if (i % 10000 == 0) {
> + int pages = get_prot_pages(_metadata, variant);
> +
> + /* sk_rmem_alloc wrapped around too much ? */
> + ASSERT_LE(pages, *variant->max_pages);
> +
> + if (pages == *variant->max_pages)
> + break;
Does correctness depend here on max_pages being a multiple of 10K?
> + }
> + }
> +
> + TH_LOG("max_pages: %d", get_prot_pages(_metadata, variant));
> +
> + close(self->client);
> + close(self->server);
> +
> + /* Give RCU a chance to call udp_destruct_common() */
> + sleep(5);
> +
> + ASSERT_EQ(get_prot_pages(_metadata, variant), 0);
> +}
> +
> +TEST_HARNESS_MAIN
> --
> 2.48.1
>
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