mnl: fix --echo buffer size again

If restart is triggered with --echo, it causes rules to be duplicated
which is not correct. Remove restart logic.

1. If user passes --echo, use a default 4mb buffer.
2. assume each element in the batch will result in a 1k
   notification.

This passes tests both in x86_64 and s390.

Joint work with Florian Westphal.

Fixes: 877baf9538f6 ("src: mnl: retry when we hit -ENOBUFS")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/mnl.c b/src/mnl.c
index 9c1f5356c9b96fe50a4fd2c1df1446a1aeae0168..8031bd6add800faf5a0c7efaebea88596d8aa906 100644 (file)
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -304,6 +304,8 @@ static ssize_t mnl_nft_socket_sendmsg(struct netlink_ctx *ctx,
        return sendmsg(mnl_socket_get_fd(ctx->nft->nf_sock), msg, 0);
 }
 
+#define NFT_MNL_ECHO_RCVBUFF_DEFAULT   (MNL_SOCKET_BUFFER_SIZE * 1024)
+
 int mnl_batch_talk(struct netlink_ctx *ctx, struct list_head *err_list,
                   uint32_t num_cmds)
 {
@@ -311,8 +313,6 @@ int mnl_batch_talk(struct netlink_ctx *ctx, struct list_head *err_list,
        int ret, fd = mnl_socket_get_fd(nl), portid = mnl_socket_get_portid(nl);
        uint32_t iov_len = nftnl_batch_iovec_len(ctx->batch);
        char rcv_buf[MNL_SOCKET_BUFFER_SIZE];
-       unsigned int enobuf_restarts = 0;
-       size_t avg_msg_size, batch_size;
        const struct sockaddr_nl snl = {
                .nl_family = AF_NETLINK
        };
@@ -321,17 +321,24 @@ int mnl_batch_talk(struct netlink_ctx *ctx, struct list_head *err_list,
                .tv_usec        = 0
        };
        struct iovec iov[iov_len];
-       unsigned int scale = 4;
        struct msghdr msg = {};
+       unsigned int rcvbufsiz;
+       size_t batch_size;
        fd_set readfds;
 
        mnl_set_sndbuffer(ctx->nft->nf_sock, ctx->batch);
 
        batch_size = mnl_nft_batch_to_msg(ctx, &msg, &snl, iov, iov_len);
-       avg_msg_size = div_round_up(batch_size, num_cmds);
 
-restart:
-       mnl_set_rcvbuffer(ctx->nft->nf_sock, num_cmds * avg_msg_size * scale);
+       if (nft_output_echo(&ctx->nft->output)) {
+               rcvbufsiz = num_cmds * 1024;
+               if (rcvbufsiz < NFT_MNL_ECHO_RCVBUFF_DEFAULT)
+                       rcvbufsiz = NFT_MNL_ECHO_RCVBUFF_DEFAULT;
+       } else {
+               rcvbufsiz = num_cmds * div_round_up(batch_size, num_cmds) * 4;
+       }
+
+       mnl_set_rcvbuffer(ctx->nft->nf_sock, rcvbufsiz);
 
        ret = mnl_nft_socket_sendmsg(ctx, &msg);
        if (ret == -1)
@@ -350,13 +357,8 @@ restart:
                        break;
 
                ret = mnl_socket_recvfrom(nl, rcv_buf, sizeof(rcv_buf));
-               if (ret == -1) {
-                       if (errno == ENOBUFS && enobuf_restarts++ < 3) {
-                               scale *= 2;
-                               goto restart;
-                       }
+               if (ret == -1)
                        return -1;
-               }
 
                ret = mnl_cb_run(rcv_buf, ret, 0, portid, &netlink_echo_callback, ctx);
                /* Continue on error, make sure we get all acknowledgments */