[PATCH] busybox: fix fwmark and add fwmask support to ip rule

[Yousong Zhou]

On Tue, 4 Aug 2020 at 06:58, Rui Salvaterra <rsalvaterra at gmail.com> wrote:
>
> BusyBox ip (rule) applet supports fwmark for policy routing (albeit through the
> old and deprecated RTA_PROTOINFO message attribute), but fwmask is completely
> unsupported. For this reason, mwan3 depends on ip(-tiny), which compiles to
> over 280 kiB on MIPS32 (-mips16 -mtune=74kc -O2).
>
> This pending [1] BusyBox patch modernises the fwmark implementation (using the
> FRA_FWMARK attribute) and also implements fwmask (FRA_FWMASK) required by mwan3,
> allowing it to drop its dependecy on ip.
>
> Other potential candidates for dropping their ip dependency (relying only on
> BusyBox ip) are shadowsocks-libev, strongswan and vpn-policy-routing.

As far as shadowsocks-libev is concerned, busybox ip command should
work just fine.  Maybe we could let buxybox PROVIDES "ip"

Regards,
                yousong

>
> [1] http://lists.busybox.net/pipermail/busybox/2020-July/088164.html
>
> Signed-off-by: Rui Salvaterra <rsalvaterra at gmail.com>
> ---
>  .../302-ip-rule-add-support-for-fwmask.patch  | 90 +++++++++++++++++++
>  1 file changed, 90 insertions(+)
>  create mode 100644 package/utils/busybox/patches/302-ip-rule-add-support-for-fwmask.patch
>
> diff --git a/package/utils/busybox/patches/302-ip-rule-add-support-for-fwmask.patch b/package/utils/busybox/patches/302-ip-rule-add-support-for-fwmask.patch
> new file mode 100644
> index 0000000000..abdc309068
> --- /dev/null
> +++ b/package/utils/busybox/patches/302-ip-rule-add-support-for-fwmask.patch
> @@ -0,0 +1,90 @@
> +From f06ac1e49b4a5a57660c7b370a7ebd436981bd89 Mon Sep 17 00:00:00 2001
> +From: Rui Salvaterra <rsalvaterra at gmail.com>
> +Date: Fri, 31 Jul 2020 09:59:40 +0100
> +Subject: [PATCH] ip rule: add support for fwmark/fwmask for policy routing
> +
> +This adds support for fwmark/fwmask in ip rule which is needed, for example, in
> +OpenWrt's mwan3. Masks are supported since Linux 2.6.19.
> +
> +Fixes: https://bugs.busybox.net/show_bug.cgi?id=11621
> +
> +Signed-off-by: Rui Salvaterra <rsalvaterra at gmail.com>
> +---
> + networking/ip.c                |  2 +-
> + networking/libiproute/iprule.c | 31 +++++++++++++++++++++++++------
> + 2 files changed, 26 insertions(+), 7 deletions(-)
> +
> +diff --git a/networking/ip.c b/networking/ip.c
> +index 034ee4fc8..bade93e62 100644
> +--- a/networking/ip.c
> ++++ b/networking/ip.c
> +@@ -257,7 +257,7 @@
> + //usage:#define iprule_trivial_usage
> + //usage:       "[list] | add|del SELECTOR ACTION"
> + //usage:#define iprule_full_usage "\n\n"
> +-//usage:       "      SELECTOR := [from PREFIX] [to PREFIX] [tos TOS] [fwmark FWMARK]\n"
> ++//usage:       "      SELECTOR := [from PREFIX] [to PREFIX] [tos TOS] [fwmark FWMARK[/MASK] ]\n"
> + //usage:       "                      [dev IFACE] [pref NUMBER]\n"
> + //usage:       "      ACTION := [table TABLE_ID] [nat ADDR]\n"
> + //usage:       "                      [prohibit|reject|unreachable]\n"
> +diff --git a/networking/libiproute/iprule.c b/networking/libiproute/iprule.c
> +index 0ce0dfeef..40a09a4ab 100644
> +--- a/networking/libiproute/iprule.c
> ++++ b/networking/libiproute/iprule.c
> +@@ -17,8 +17,10 @@
> + #include <arpa/inet.h>
> +
> + /* from <linux/fib_rules.h>: */
> +-#define FRA_SUPPRESS_IFGROUP   13
> +-#define FRA_SUPPRESS_PREFIXLEN 14
> ++#define FRA_FWMARK            10
> ++#define FRA_SUPPRESS_IFGROUP  13
> ++#define FRA_SUPPRESS_PREFIXLEN        14
> ++#define FRA_FWMASK            16
> +
> + #include "ip_common.h"  /* #include "libbb.h" is inside */
> + #include "rt_names.h"
> +@@ -117,8 +119,18 @@ static int FAST_FUNC print_rule(const struct sockaddr_nl *who UNUSED_PARAM,
> +       if (r->rtm_tos) {
> +               printf("tos %s ", rtnl_dsfield_n2a(r->rtm_tos));
> +       }
> +-      if (tb[RTA_PROTOINFO]) {
> +-              printf("fwmark %#x ", *(uint32_t*)RTA_DATA(tb[RTA_PROTOINFO]));
> ++
> ++      if (tb[FRA_FWMARK] || tb[FRA_FWMASK]) {
> ++              uint32_t mark = 0, mask = 0;
> ++
> ++              if (tb[FRA_FWMARK])
> ++                      mark = *(uint32_t*)RTA_DATA(tb[FRA_FWMARK]);
> ++
> ++              if (tb[FRA_FWMASK] &&
> ++                  (mask = *(uint32_t*)RTA_DATA(tb[FRA_FWMASK])) != 0xFFFFFFFF)
> ++                      printf("fwmark %#x/%#x ", mark, mask);
> ++              else
> ++                      printf("fwmark %#x ", mark);
> +       }
> +
> +       if (tb[RTA_IIF]) {
> +@@ -257,10 +269,17 @@ static int iprule_modify(int cmd, char **argv)
> +                               invarg_1_to_2(*argv, "TOS");
> +                       req.r.rtm_tos = tos;
> +               } else if (key == ARG_fwmark) {
> +-                      uint32_t fwmark;
> ++                      char *slash;
> ++                      uint32_t fwmark, fwmask;
> +                       NEXT_ARG();
> ++                      if ((slash = strchr(*argv, '/')) != NULL)
> ++                              *slash = '\0';
> +                       fwmark = get_u32(*argv, keyword_fwmark);
> +-                      addattr32(&req.n, sizeof(req), RTA_PROTOINFO, fwmark);
> ++                      addattr32(&req.n, sizeof(req), FRA_FWMARK, fwmark);
> ++                      if (slash) {
> ++                              fwmask = get_u32(slash + 1, "fwmask");
> ++                              addattr32(&req.n, sizeof(req), FRA_FWMASK, fwmask);
> ++                      }
> +               } else if (key == ARG_realms) {
> +                       uint32_t realm;
> +                       NEXT_ARG();
> +--
> +2.28.0
> +
> --
> 2.28.0
>
>
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