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>

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 94d7ded1a6cf95d0c9435d20f8de3f0ead450a15..dd43b22758d65ce98adf8f18e8a570b5b6a01145 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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

diff --git a/net/core/filter.c b/net/core/filter.c
index 1f6a26c4f8b960d3fc1aada364b24891bd5945aa..ca033e15d35e7a7e956c4c8a5ae6eafed3ab16fb 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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,
 };

diff --git a/samples/bpf/bpf_helpers.h b/samples/bpf/bpf_helpers.h
index f4840b8bb8f90af32a5af01a489fbe076452afc9..d50ac342dc92762eba4dcbafb27dd24ab27b4729 100644 (file)
--- a/samples/bpf/bpf_helpers.h
+++ b/samples/bpf/bpf_helpers.h
@@ -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