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

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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: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-4-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Daan De Meyer 2023-10-11 20:51:05 +02:00 committed by Martin KaFai Lau
parent fefba7d1ae
commit 53e380d214
2 changed files with 35 additions and 1 deletions
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1
kernel/bpf/btf.c
View file

@ -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;

35
net/core/filter.c
View file

@ -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);