generic: 5.15: fix panic on tcp_no_window_check set with interface up

The current reworked version cause kernel panic when the value is changes and
an interface is up. Following the tcp_be_liberal impelementation,
reimplement this to permit a safe change of this value without any
panic.
This has been tested with a QSDK package where tcp_no_window_check is used.

Fixes: 92fb51bc9881 ("generic: 5.15: standardize tcp_no_window_check pending patch")
Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>

diff --git a/target/linux/generic/pending-5.15/613-netfilter_optional_tcp_window_check.patch b/target/linux/generic/pending-5.15/613-netfilter_optional_tcp_window_check.patch
index b9919ae4754a46447fbd0a0db536be4ff2374c1e..1ddfc8e0148631df18ae100a46ff340bd300f786 100644 (file)
--- a/target/linux/generic/pending-5.15/613-netfilter_optional_tcp_window_check.patch
+++ b/target/linux/generic/pending-5.15/613-netfilter_optional_tcp_window_check.patch
@@ -2,6 +2,7 @@ From: Felix Fietkau <nbd@nbd.name>
 Subject: netfilter: optional tcp window check
 
 Signed-off-by: Felix Fietkau <nbd@nbd.name>
+Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>
 ---
  net/netfilter/nf_conntrack_proto_tcp.c | 13 +++++++++++++
  1 file changed, 13 insertions(+)
@@ -12,68 +13,71 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
        s32 receiver_offset;
        bool res, in_recv_win;
  
-+      if (net->ct.sysctl_no_window_check)
++      if (tn->tcp_no_window_check)
 +              return true;
 +
        /*
         * Get the required data from the packet.
         */
-@@ -1160,7 +1163,7 @@ int nf_conntrack_tcp_packet(struct nf_co
+@@ -1151,7 +1154,7 @@ int nf_conntrack_tcp_packet(struct nf_co
                 IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED &&
                 timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK])
                timeout = timeouts[TCP_CONNTRACK_UNACK];
 -      else if (ct->proto.tcp.last_win == 0 &&
-+      else if (!net->ct.sysctl_no_window_check && ct->proto.tcp.last_win == 0 &&
++      else if (!tn->tcp_no_window_check && ct->proto.tcp.last_win == 0 &&
                 timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
                timeout = timeouts[TCP_CONNTRACK_RETRANS];
        else
+@@ -1451,6 +1454,9 @@ int nf_conntrack_tcp_packet(struct nf_co
+        * If it's non-zero, we mark only out of window RST segments as INVALID.
+        */
+       tn->tcp_be_liberal = 0;
++
++      /* Skip Windows Check */
++      tn->tcp_no_window_check = 0;
+ 
+       /* If it's non-zero, we turn off RST sequence number check */
+       tn->tcp_ignore_invalid_rst = 0;
 --- a/net/netfilter/nf_conntrack_standalone.c
 +++ b/net/netfilter/nf_conntrack_standalone.c
 @@ -671,6 +671,7 @@ enum nf_ct_sysctl_index {
-       NF_SYSCTL_CT_LWTUNNEL,
  #endif
- 
+       NF_SYSCTL_CT_PROTO_TCP_LOOSE,
+       NF_SYSCTL_CT_PROTO_TCP_LIBERAL,
 +      NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK,
-       __NF_SYSCTL_CT_LAST_SYSCTL,
- };
- 
-@@ -1026,6 +1027,13 @@ static struct ctl_table nf_ct_sysctl_tab
-               .proc_handler   = nf_hooks_lwtunnel_sysctl_handler,
+       NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST,
+       NF_SYSCTL_CT_PROTO_TCP_MAX_RETRANS,
+       NF_SYSCTL_CT_PROTO_TIMEOUT_UDP,
+@@ -800,6 +800,14 @@ static struct ctl_table nf_ct_sysctl_tab
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = SYSCTL_ONE,
        },
- #endif
 +      [NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK] = {
 +              .procname       = "nf_conntrack_tcp_no_window_check",
-+              .data           = &init_net.ct.sysctl_no_window_check,
-+              .maxlen         = sizeof(unsigned int),
++              .maxlen         = sizeof(u8),
 +              .mode           = 0644,
-+              .proc_handler   = proc_dointvec,
++              .proc_handler   = proc_dou8vec_minmax,
++              .extra1         = SYSCTL_ZERO,
++              .extra2         = SYSCTL_ONE,
 +      },
-       {}
- };
+       [NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST] = {
+               .procname       = "nf_conntrack_tcp_ignore_invalid_rst",
+               .maxlen         = sizeof(u8),
+@@ -900,6 +900,7 @@ static int nf_conntrack_standalone_init_
  
-@@ -1153,6 +1161,7 @@ static int nf_conntrack_standalone_init_
- #ifdef CONFIG_NF_CONNTRACK_EVENTS
-       table[NF_SYSCTL_CT_EVENTS].data = &net->ct.sysctl_events;
- #endif
-+      table[NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK].data = &net->ct.sysctl_no_window_check;
- #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
-       table[NF_SYSCTL_CT_TIMESTAMP].data = &net->ct.sysctl_tstamp;
- #endif
-@@ -1222,6 +1231,7 @@ static int nf_conntrack_pernet_init(stru
-       int ret;
- 
-       net->ct.sysctl_checksum = 1;
-+      net->ct.sysctl_no_window_check = 1;
- 
-       ret = nf_conntrack_standalone_init_sysctl(net);
-       if (ret < 0)
+       XASSIGN(LOOSE, &tn->tcp_loose);
+       XASSIGN(LIBERAL, &tn->tcp_be_liberal);
++      XASSIGN(NO_WINDOW_CHECK, &tn->tcp_no_window_check);
+       XASSIGN(MAX_RETRANS, &tn->tcp_max_retrans);
+       XASSIGN(IGNORE_INVALID_RST, &tn->tcp_ignore_invalid_rst);
+ #undef XASSIGN
 --- a/include/net/netns/conntrack.h
 +++ b/include/net/netns/conntrack.h
 @@ -109,6 +109,7 @@ struct netns_ct {
-       u8                      sysctl_auto_assign_helper;
-       u8                      sysctl_tstamp;
-       u8                      sysctl_checksum;
-+      u8                      sysctl_no_window_check;
- 
-       struct ct_pcpu __percpu *pcpu_lists;
-       struct ip_conntrack_stat __percpu *stat;
+       unsigned int timeouts[TCP_CONNTRACK_TIMEOUT_MAX];
+       u8 tcp_loose;
+       u8 tcp_be_liberal;
++      u8 tcp_no_window_check;
+       u8 tcp_max_retrans;
+       u8 tcp_ignore_invalid_rst;
+ #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)