From: Martin KaFai Lau <martin.lau@linux.dev>
To: Daan De Meyer <daan.j.demeyer@gmail.com>
Cc: kernel-team@meta.com, bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v3 2/9] bpf: Propagate modified uaddrlen from cgroup sockaddr programs
Date: Tue, 29 Aug 2023 23:21:04 -0700 [thread overview]
Message-ID: <b48c25fd-6c4e-d04f-aea8-65acf6a9fe2a@linux.dev> (raw)
In-Reply-To: <20230829101838.851350-3-daan.j.demeyer@gmail.com>
On 8/29/23 3:18 AM, Daan De Meyer wrote:
> @@ -1482,11 +1485,22 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
> if (!ctx.uaddr) {
> memset(&unspec, 0, sizeof(unspec));
> ctx.uaddr = (struct sockaddr *)&unspec;
> - }
> + ctx.uaddrlen = sizeof(unspec);
ctx.uaddr could be NULL during BPF_CGROUP_RUN_PROG_UDP[46]_SENDMSG_LOCK(). There
is nothing from the sa_kern->uaddr that is useful to read, so ctx.uaddrlen
should be 0. The new kfunc bpf_sock_addr_set_addr() can do better than the
current sa->user_ip[46] uapi and should return error in this case because the
kernel will eventually ignore it.
> + } else if (uaddrlen)
> + ctx.uaddrlen = *uaddrlen;
> + else if (sk->sk_family == AF_INET)
> + ctx.uaddrlen = sizeof(struct sockaddr_in);
> + else if (sk->sk_family == AF_INET6)
> + ctx.uaddrlen = sizeof(struct sockaddr_in6);
>
> cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
> - return bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run,
> - 0, flags);
> + ret = bpf_prog_run_array_cg(&cgrp->bpf, atype, &ctx, bpf_prog_run,
> + 0, flags);
> +
> + if (!ret && uaddrlen)
> + *uaddrlen = ctx.uaddrlen;
> +
> + return ret;
> }
> EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);
>
[ ... ]
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index 3a88545a265d..255b02d98404 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -135,7 +135,7 @@ static int tcp_v6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
>
> sock_owned_by_me(sk);
>
> - return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr);
> + return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr, NULL);
For IPv6, there is a minimum SIN6_LEN_RFC2133 which excludes the last '__u32
sin6_scope_id'. Meaning the last 4 bytes in 'struct sockaddr_in6' is optional.
It has been a few months since v2, so my memory faded a bit. I recalled one of
the concerns on passing addrlen to BPF_CGROUP_RUN_PROG is the bpf prog can
change it for AF_INET[6] and the addrlen change could be ignored by the kernel.
The bpf_sock_addr_set_addr() in v3 does not allow addrlen changes in AF_INET[6].
I think it now makes sense to pass addrlen (of AF_INET[6]) to BPF_CGROUP_RUN_*
whenever it is available such that the newly added sa_kern->uaddrlen can better
reflect what is in the sa_kern->uaddr.
I think the only addrlen missing case is in the inet[6]_getname(). Either NULL
can be passed or create a local addrlen var. afaict, the addrlen must be 'struct
sockaddr_in[6]' in those cases.
next prev parent reply other threads:[~2023-08-30 6:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-29 10:18 [PATCH bpf-next v3 0/9] Add cgroup sockaddr hooks for unix sockets Daan De Meyer
2023-08-29 10:18 ` [PATCH bpf-next v3 1/9] selftests/bpf: Add missing section name tests for getpeername/getsockname Daan De Meyer
2023-08-29 10:18 ` [PATCH bpf-next v3 2/9] bpf: Propagate modified uaddrlen from cgroup sockaddr programs Daan De Meyer
2023-08-30 6:21 ` Martin KaFai Lau [this message]
2023-08-29 10:18 ` [PATCH bpf-next v3 3/9] bpf: Add bpf_sock_addr_set() to allow writing sockaddr len from bpf Daan De Meyer
2023-08-29 17:42 ` Alexei Starovoitov
2023-08-30 6:28 ` Martin KaFai Lau
2023-08-29 10:18 ` [PATCH bpf-next v3 4/9] bpf: Implement cgroup sockaddr hooks for unix sockets Daan De Meyer
2023-08-29 10:18 ` [PATCH bpf-next v3 5/9] libbpf: Add support for cgroup unix socket address hooks Daan De Meyer
2023-08-29 10:18 ` [PATCH bpf-next v3 6/9] bpftool: " Daan De Meyer
2023-08-29 16:27 ` Quentin Monnet
2023-08-29 10:18 ` [PATCH bpf-next v3 7/9] documentation/bpf: Document " Daan De Meyer
2023-08-29 10:18 ` [PATCH bpf-next v3 8/9] selftests/bpf: Make sure mount directory exists Daan De Meyer
2023-08-30 6:32 ` Martin KaFai Lau
2023-08-29 10:18 ` [PATCH bpf-next v3 9/9] selftests/bpf: Add tests for cgroup unix socket address hooks Daan De Meyer
2023-08-30 6:51 ` Martin KaFai Lau
-- strict thread matches above, loose matches on Subject: below --
2023-08-31 15:34 [PATCH bpf-next v4 0/9] Add cgroup sockaddr hooks for unix sockets Daan De Meyer
2023-08-31 15:34 ` [PATCH bpf-next v3 2/9] bpf: Propagate modified uaddrlen from cgroup sockaddr programs Daan De Meyer
2023-09-05 21:21 ` Martin KaFai Lau
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