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bpf: Add setsockopt helper function to bpf 

Added support for calling a subset of socket setsockopts from
BPF_PROG_TYPE_SOCK_OPS programs. The code was duplicated rather
than making the changes to call the socket setsockopt function because
the changes required would have been larger.

The ops supported are:
  SO_RCVBUF
  SO_SNDBUF
  SO_MAX_PACING_RATE
  SO_PRIORITY
  SO_RCVLOWAT
  SO_MARK

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Lawrence Brakmo 2017-06-30 20:02:46 -07:00 committed by David S. Miller
parent c400296bf6
commit 8c4b4c7e9f
3 changed files with 94 additions and 2 deletions
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14
include/uapi/linux/bpf.h
View File

@ -520,6 +520,17 @@ union bpf_attr {
* Set full skb->hash.
* @skb: pointer to skb
* @hash: hash to set
*
* int bpf_setsockopt(bpf_socket, level, optname, optval, optlen)
* Calls setsockopt. Not all opts are available, only those with
* integer optvals plus TCP_CONGESTION.
* Supported levels: SOL_SOCKET and IPROTO_TCP
* @bpf_socket: pointer to bpf_socket
* @level: SOL_SOCKET or IPROTO_TCP
* @optname: option name
* @optval: pointer to option value
* @optlen: length of optval in byes
* Return: 0 or negative error
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -570,7 +581,8 @@ union bpf_attr {
FN(probe_read_str), \
FN(get_socket_cookie), \
FN(get_socket_uid), \
FN(set_hash),
FN(set_hash), \
FN(setsockopt),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call

79
net/core/filter.c
View File

@ -54,6 +54,7 @@
#include <net/dst.h>
#include <net/sock_reuseport.h>
#include <net/busy_poll.h>
#include <net/tcp.h>
/**
* sk_filter_trim_cap - run a packet through a socket filter
@ -2672,6 +2673,71 @@ static const struct bpf_func_proto bpf_get_socket_uid_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
int, level, int, optname, char *, optval, int, optlen)
{
struct sock *sk = bpf_sock->sk;
int ret = 0;
int val;
if (!sk_fullsock(sk))
return -EINVAL;
if (level == SOL_SOCKET) {
if (optlen != sizeof(int))
return -EINVAL;
val = *((int *)optval);
/* Only some socketops are supported */
switch (optname) {
case SO_RCVBUF:
sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
break;
case SO_SNDBUF:
sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
break;
case SO_MAX_PACING_RATE:
sk->sk_max_pacing_rate = val;
sk->sk_pacing_rate = min(sk->sk_pacing_rate,
sk->sk_max_pacing_rate);
break;
case SO_PRIORITY:
sk->sk_priority = val;
break;
case SO_RCVLOWAT:
if (val < 0)
val = INT_MAX;
sk->sk_rcvlowat = val ? : 1;
break;
case SO_MARK:
sk->sk_mark = val;
break;
default:
ret = -EINVAL;
}
} else if (level == SOL_TCP &&
sk->sk_prot->setsockopt == tcp_setsockopt) {
/* Place holder */
ret = -EINVAL;
} else {
ret = -EINVAL;
}
return ret;
}
static const struct bpf_func_proto bpf_setsockopt_proto = {
.func = bpf_setsockopt,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
.arg5_type = ARG_CONST_SIZE,
};
static const struct bpf_func_proto *
bpf_base_func_proto(enum bpf_func_id func_id)
{
@ -2822,6 +2888,17 @@ lwt_inout_func_proto(enum bpf_func_id func_id)
}
}
static const struct bpf_func_proto *
sock_ops_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
case BPF_FUNC_setsockopt:
return &bpf_setsockopt_proto;
default:
return bpf_base_func_proto(func_id);
}
}
static const struct bpf_func_proto *
lwt_xmit_func_proto(enum bpf_func_id func_id)
{
@ -3591,7 +3668,7 @@ const struct bpf_verifier_ops cg_sock_prog_ops = {
};
const struct bpf_verifier_ops sock_ops_prog_ops = {
.get_func_proto = bpf_base_func_proto,
.get_func_proto = sock_ops_func_proto,
.is_valid_access = sock_ops_is_valid_access,
.convert_ctx_access = sock_ops_convert_ctx_access,
};

3
samples/bpf/bpf_helpers.h
View File

@ -60,6 +60,9 @@ static unsigned long long (*bpf_get_prandom_u32)(void) =
(void *) BPF_FUNC_get_prandom_u32;
static int (*bpf_xdp_adjust_head)(void *ctx, int offset) =
(void *) BPF_FUNC_xdp_adjust_head;
static int (*bpf_setsockopt)(void *ctx, int level, int optname, void *optval,
int optlen) =
(void *) BPF_FUNC_setsockopt;
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions