Commit 53e380d2 authored by Daan De Meyer's avatar Daan De Meyer Committed by Martin KaFai Lau
Browse files

bpf: Add bpf_sock_addr_set_sun_path() to allow writing unix sockaddr from bpf 



As prep for adding unix socket support to the cgroup sockaddr hooks,
let's add a kfunc bpf_sock_addr_set_sun_path() that allows modifying a unix
sockaddr from bpf. While this is already possible for AF_INET and AF_INET6,
we'll need this kfunc when we add unix socket support since modifying the
address for those requires modifying both the address and the sockaddr
length.

Signed-off-by: default avatarDaan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-4-daan.j.demeyer@gmail.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent fefba7d1

kernel/bpf/btf.c

+1 −0
Original line number Diff line number Diff line
@@ -7850,6 +7850,7 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type) 
	case BPF_PROG_TYPE_SYSCALL:

		return BTF_KFUNC_HOOK_SYSCALL;

	case BPF_PROG_TYPE_CGROUP_SKB:

	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:

		return BTF_KFUNC_HOOK_CGROUP_SKB;

	case BPF_PROG_TYPE_SCHED_ACT:

		return BTF_KFUNC_HOOK_SCHED_ACT;

net/core/filter.c

+34 −1
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ 
#include <net/xdp.h>

#include <net/mptcp.h>

#include <net/netfilter/nf_conntrack_bpf.h>

#include <linux/un.h>



static const struct bpf_func_proto *

bpf_sk_base_func_proto(enum bpf_func_id func_id);
@@ -11768,6 +11769,27 @@ __bpf_kfunc int bpf_dynptr_from_xdp(struct xdp_buff *xdp, u64 flags, 


	return 0;

}



__bpf_kfunc int bpf_sock_addr_set_sun_path(struct bpf_sock_addr_kern *sa_kern,

					   const u8 *sun_path, u32 sun_path__sz)

{

	struct sockaddr_un *un;



	if (sa_kern->sk->sk_family != AF_UNIX)

		return -EINVAL;



	/* We do not allow changing the address to unnamed or larger than the

	 * maximum allowed address size for a unix sockaddr.

	 */

	if (sun_path__sz == 0 || sun_path__sz > UNIX_PATH_MAX)

		return -EINVAL;



	un = (struct sockaddr_un *)sa_kern->uaddr;

	memcpy(un->sun_path, sun_path, sun_path__sz);

	sa_kern->uaddrlen = offsetof(struct sockaddr_un, sun_path) + sun_path__sz;



	return 0;

}

__diag_pop();



int bpf_dynptr_from_skb_rdonly(struct sk_buff *skb, u64 flags,
@@ -11792,6 +11814,10 @@ BTF_SET8_START(bpf_kfunc_check_set_xdp) 
BTF_ID_FLAGS(func, bpf_dynptr_from_xdp)

BTF_SET8_END(bpf_kfunc_check_set_xdp)



BTF_SET8_START(bpf_kfunc_check_set_sock_addr)

BTF_ID_FLAGS(func, bpf_sock_addr_set_sun_path)

BTF_SET8_END(bpf_kfunc_check_set_sock_addr)



static const struct btf_kfunc_id_set bpf_kfunc_set_skb = {

	.owner = THIS_MODULE,

	.set = &bpf_kfunc_check_set_skb,
@@ -11802,6 +11828,11 @@ static const struct btf_kfunc_id_set bpf_kfunc_set_xdp = { 
	.set = &bpf_kfunc_check_set_xdp,

};



static const struct btf_kfunc_id_set bpf_kfunc_set_sock_addr = {

	.owner = THIS_MODULE,

	.set = &bpf_kfunc_check_set_sock_addr,

};



static int __init bpf_kfunc_init(void)

{

	int ret;
@@ -11816,7 +11847,9 @@ static int __init bpf_kfunc_init(void) 
	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_XMIT, &bpf_kfunc_set_skb);

	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_LWT_SEG6LOCAL, &bpf_kfunc_set_skb);

	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_NETFILTER, &bpf_kfunc_set_skb);

	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);

	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);

	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_CGROUP_SOCK_ADDR,

						&bpf_kfunc_set_sock_addr);

}

late_initcall(bpf_kfunc_init);