On Tue, Jul 7, 2020 at 2:45 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> On 7/7/20 1:01 AM, Stanislav Fomichev wrote:
> > Simple test that enforces a single SOCK_DGRAM socker per cgroup.
> >
> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> > ---
> > .../selftests/bpf/prog_tests/udp_limit.c | 75 +++++++++++++++++++
> > tools/testing/selftests/bpf/progs/udp_limit.c | 42 +++++++++++
> > 2 files changed, 117 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/udp_limit.c
> > create mode 100644 tools/testing/selftests/bpf/progs/udp_limit.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/udp_limit.c b/tools/testing/selftests/bpf/prog_tests/udp_limit.c
> > new file mode 100644
> > index 000000000000..2aba09d4d01b
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/udp_limit.c
> > @@ -0,0 +1,75 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include <test_progs.h>
> > +#include "udp_limit.skel.h"
> > +
> > +#include <sys/types.h>
> > +#include <sys/socket.h>
> > +
> > +static int duration;
> > +
> > +void test_udp_limit(void)
> > +{
> > + struct udp_limit *skel;
> > + int fd1 = -1, fd2 = -1;
> > + int cgroup_fd;
> > +
> > + cgroup_fd = test__join_cgroup("/udp_limit");
> > + if (CHECK(cgroup_fd < 0, "cg-join", "errno %d", errno))
> > + return;
> > +
> > + skel = udp_limit__open_and_load();
> > + if (CHECK(!skel, "skel-load", "errno %d", errno))
> > + goto close_cgroup_fd;
> > +
> > + skel->links.sock = bpf_program__attach_cgroup(skel->progs.sock, cgroup_fd);
> > + skel->links.sock_release = bpf_program__attach_cgroup(skel->progs.sock_release, cgroup_fd);
> > + if (CHECK(IS_ERR(skel->links.sock) || IS_ERR(skel->links.sock_release),
> > + "cg-attach", "sock %ld sock_release %ld",
> > + PTR_ERR(skel->links.sock),
> > + PTR_ERR(skel->links.sock_release)))
> > + goto close_skeleton;
> > +
> > + /* BPF program enforces a single UDP socket per cgroup,
> > + * verify that.
> > + */
> > + fd1 = socket(AF_INET, SOCK_DGRAM, 0);
> > + if (CHECK(fd1 < 0, "fd1", "errno %d", errno))
> > + goto close_skeleton;
> > +
> > + fd2 = socket(AF_INET, SOCK_DGRAM, 0);
> > + if (CHECK(fd2 >= 0, "fd2", "errno %d", errno))
> > + goto close_skeleton;
> > +
> > + /* We can reopen again after close. */
> > + close(fd1);
> > + fd1 = -1;
> > +
> > + fd1 = socket(AF_INET, SOCK_DGRAM, 0);
> > + if (CHECK(fd1 < 0, "fd1-again", "errno %d", errno))
> > + goto close_skeleton;
> > +
> > + /* Make sure the program was invoked the expected
> > + * number of times:
> > + * - open fd1 - BPF_CGROUP_INET_SOCK_CREATE
> > + * - attempt to openfd2 - BPF_CGROUP_INET_SOCK_CREATE
> > + * - close fd1 - BPF_CGROUP_INET_SOCK_RELEASE
> > + * - open fd1 again - BPF_CGROUP_INET_SOCK_CREATE
> > + */
> > + if (CHECK(skel->bss->invocations != 4, "bss-invocations",
> > + "invocations=%d", skel->bss->invocations))
> > + goto close_skeleton;
> > +
> > + /* We should still have a single socket in use */
> > + if (CHECK(skel->bss->in_use != 1, "bss-in_use",
> > + "in_use=%d", skel->bss->in_use))
> > + goto close_skeleton;
> > +
> > +close_skeleton:
> > + if (fd1 >= 0)
> > + close(fd1);
> > + if (fd2 >= 0)
> > + close(fd2);
> > + udp_limit__destroy(skel);
> > +close_cgroup_fd:
> > + close(cgroup_fd);
> > +}
> > diff --git a/tools/testing/selftests/bpf/progs/udp_limit.c b/tools/testing/selftests/bpf/progs/udp_limit.c
> > new file mode 100644
> > index 000000000000..edbb30a27e63
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/udp_limit.c
> > @@ -0,0 +1,42 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +
> > +#include <sys/socket.h>
> > +#include <linux/bpf.h>
> > +#include <bpf/bpf_helpers.h>
> > +
> > +int invocations = 0, in_use = 0;
> > +
> > +SEC("cgroup/sock")
>
> nit: Doesn't matter overly much, but given you've added `cgroup/sock_create`
> earlier in patch 2/4 intention was probably to use it as well. But either is
> fine as it resolved to the same.
heh, had the same thought, but didn't want to be too nitpicky :)
>
> > +int sock(struct bpf_sock *ctx)
> > +{
> > + __u32 key;
> > +
> > + if (ctx->type != SOCK_DGRAM)
> > + return 1;
> > +
> > + __sync_fetch_and_add(&invocations, 1);
> > +
> > + if (in_use > 0) {
> > + /* BPF_CGROUP_INET_SOCK_RELEASE is _not_ called
> > + * when we return an error from the BPF
> > + * program!
> > + */
> > + return 0;
> > + }
> > +
> > + __sync_fetch_and_add(&in_use, 1);
> > + return 1;
> > +}
> > +
> > +SEC("cgroup/sock_release")
> > +int sock_release(struct bpf_sock *ctx)
> > +{
> > + __u32 key;
> > +
> > + if (ctx->type != SOCK_DGRAM)
> > + return 1;
> > +
> > + __sync_fetch_and_add(&invocations, 1);
> > + __sync_fetch_and_add(&in_use, -1);
> > + return 1;
> > +}
> >
>
