Re: [PATCH bpf-next v3 09/10] selftests/bpf: Add tests for cgroup unix socket address hooks

[Martin KaFai Lau <martin.lau@linux.dev>]

On 4/21/23 9:27 AM, Daan De Meyer wrote:
> The unix socket address hooks do not support modifying the source
> address so we skip source address checks when we're running a unix
> socket address hook test.
> 
> Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
> ---
>   tools/testing/selftests/bpf/bpf_kfuncs.h      |  13 ++
>   .../selftests/bpf/prog_tests/section_names.c  |  30 ++++
>   .../testing/selftests/bpf/progs/bindun_prog.c |  59 ++++++++
>   .../selftests/bpf/progs/connectun_prog.c      |  53 +++++++
>   .../selftests/bpf/progs/recvmsgun_prog.c      |  59 ++++++++
>   .../selftests/bpf/progs/sendmsgun_prog.c      |  53 +++++++
>   tools/testing/selftests/bpf/test_sock_addr.c  | 137 +++++++++++++++++-
>   7 files changed, 397 insertions(+), 7 deletions(-)
>   create mode 100644 tools/testing/selftests/bpf/progs/bindun_prog.c
>   create mode 100644 tools/testing/selftests/bpf/progs/connectun_prog.c
>   create mode 100644 tools/testing/selftests/bpf/progs/recvmsgun_prog.c
>   create mode 100644 tools/testing/selftests/bpf/progs/sendmsgun_prog.c
> 
> diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h
> index 8c993ec8ceea..dbdec3d5152e 100644
> --- a/tools/testing/selftests/bpf/bpf_kfuncs.h
> +++ b/tools/testing/selftests/bpf/bpf_kfuncs.h
> @@ -1,6 +1,8 @@
>   #ifndef __BPF_KFUNCS__
>   #define __BPF_KFUNCS__
>   
> +struct bpf_sock_addr_kern;
> +
>   /* Description
>    *  Initializes an skb-type dynptr
>    * Returns
> @@ -35,4 +37,15 @@ extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, __u32 offset,
>   extern void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *ptr, __u32 offset,
>   			      void *buffer, __u32 buffer__szk) __ksym;
>   
> +/* Description
> + *  Modify the contents of a sockaddr.
> + * Returns__bpf_kfunc
> + *  -EINVAL if the sockaddr family does not match, the sockaddr is too small or
> + *  too big, 0 if the sockaddr was successfully modified.
> + */
> +extern int bpf_sock_addr_set(struct bpf_sock_addr_kern *sa_kern,
> +			     const void *addr, __u32 addrlen__sz) __ksym;


It needs some negative tests, like
- addrlen__sz > UNIX_PATH_MAX for AF_UNIX test.
- addrlen__sz is larger than the size of addr in the stack.

> diff --git a/tools/testing/selftests/bpf/progs/bindun_prog.c b/tools/testing/selftests/bpf/progs/bindun_prog.c
> new file mode 100644
> index 000000000000..60addb5a9c96
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bindun_prog.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
> +
> +#include "vmlinux.h"
> +
> +#include <string.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_core_read.h>
> +#include "bpf_kfuncs.h"
> +
> +#ifndef AF_UNIX
> +#define AF_UNIX 1

Move it to bpf_tracing_net.h. AF_INET[6] is already there.

> +#endif
> +
> +#define DST_REWRITE_PATH	"\0bpf_cgroup_unix_test_rewrite"
> +
> +void *bpf_cast_to_kern_ctx(void *) __ksym;
> +
> +SEC("cgroup/bindun")
> +int bind_un_prog(struct bpf_sock_addr *ctx)
> +{
> +	struct bpf_sock *sk = ctx->sk;
> +	struct bpf_sock_addr_kern *sa_kern = bpf_cast_to_kern_ctx(ctx);
> +	struct sockaddr_un *sa_kern_unaddr;
> +	struct sockaddr_un unaddr = {
> +		.sun_family = AF_UNIX,
> +	};
> +	__u32 unaddrlen = offsetof(struct sockaddr_un, sun_path) +
> +			  sizeof(DST_REWRITE_PATH) - 1;
> +	int ret;
> +
> +	if (!sk)
> +		return 0;
> +
> +	if (sk->family != AF_UNIX)
> +		return 0;
> +
> +	if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
> +		return 0;
> +
> +	memcpy(unaddr.sun_path, DST_REWRITE_PATH, sizeof(DST_REWRITE_PATH) - 1);
> +
> +	ret = bpf_sock_addr_set(sa_kern, (struct sockaddr *) &unaddr, unaddrlen);
> +	if (ret)
> +		return 0;
> +
> +	if (sa_kern->uaddrlen != unaddrlen)
> +		return 0;
> +
> +	sa_kern_unaddr = bpf_rdonly_cast(sa_kern->uaddr,
> +					 bpf_core_type_id_kernel(struct sockaddr_un));
> +	if (memcmp(sa_kern_unaddr->sun_path, DST_REWRITE_PATH,
> +		   sizeof(DST_REWRITE_PATH) - 1) != 0)
> +		return 0;
> +
> +	return 1;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/progs/connectun_prog.c b/tools/testing/selftests/bpf/progs/connectun_prog.c
> new file mode 100644
> index 000000000000..ac7209bd326f
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/connectun_prog.c
> @@ -0,0 +1,53 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
> +
> +#include "vmlinux.h"
> +
> +#include <string.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_core_read.h>
> +#include "bpf_kfuncs.h"
> +
> +#ifndef AF_UNIX
> +#define AF_UNIX 1
> +#endif
> +
> +#define DST_REWRITE_PATH	"\0bpf_cgroup_unix_test_rewrite"
> +
> +void *bpf_cast_to_kern_ctx(void *) __ksym;

Move it to bpf_kfuncs.h also?