Revert "net: Remove low_thresh in ip defrag"

This reverts commit b2cbac9b9b28730e9e53be20b6cdf979d3b9f27e.

We have multiple reports of obvious breakage from this patch.

Reported-by: Ido Schimmel <idosch@idosch.org>
Link: https://lore.kernel.org/all/ZGIRWjNcfqI8yY8W@shredder/
Link: https://lore.kernel.org/all/CADJHv_sDK=0RrMA2FTZQV5fw7UQ+qY=HG21Wu5qb0V9vvx5w6A@mail.gmail.com/
Reported-by: syzbot+a5e719ac7c268e414c95@syzkaller.appspotmail.com
Reported-by: syzbot+a03fd670838d927d9cd8@syzkaller.appspotmail.com
Fixes: b2cbac9b9b28 ("net: Remove low_thresh in ip defrag")
Link: https://lore.kernel.org/r/20230517034112.1261835-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/networking/nf_conntrack-sysctl.rst b/Documentation/networking/nf_conntrack-sysctl.rst
index 9ca356b..8b1045c 100644 (file)
--- a/Documentation/networking/nf_conntrack-sysctl.rst
+++ b/Documentation/networking/nf_conntrack-sysctl.rst
@@ -55,7 +55,6 @@ nf_conntrack_frag6_high_thresh - INTEGER
        nf_conntrack_frag6_low_thresh is reached.
 
 nf_conntrack_frag6_low_thresh - INTEGER
-       (Obsolete since linux-4.17)
        default 196608
 
        See nf_conntrack_frag6_low_thresh

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 8543e74..325ad89 100644 (file)
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -13,6 +13,7 @@
 struct fqdir {
        /* sysctls */
        long                    high_thresh;
+       long                    low_thresh;
        int                     timeout;
        int                     max_dist;
        struct inet_frags       *f;

diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index 3ba4c0f..a91283d 100644 (file)
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -318,7 +318,7 @@ err:
 }
 
 #ifdef CONFIG_SYSCTL
-static unsigned long lowpanfrag_low_thresh_unuesd = IPV6_FRAG_LOW_THRESH;
+
 static struct ctl_table lowpan_frags_ns_ctl_table[] = {
        {
                .procname       = "6lowpanfrag_high_thresh",
@@ -374,9 +374,9 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
        }
 
        table[0].data   = &ieee802154_lowpan->fqdir->high_thresh;
-       table[0].extra1 = &lowpanfrag_low_thresh_unuesd;
-       table[1].data   = &lowpanfrag_low_thresh_unuesd;
-       table[1].extra2 = &ieee802154_lowpan->fqdir->high_thresh;
+       table[0].extra1 = &ieee802154_lowpan->fqdir->low_thresh;
+       table[1].data   = &ieee802154_lowpan->fqdir->low_thresh;
+       table[1].extra2 = &ieee802154_lowpan->fqdir->high_thresh;
        table[2].data   = &ieee802154_lowpan->fqdir->timeout;
 
        hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
@@ -451,6 +451,7 @@ static int __net_init lowpan_frags_init_net(struct net *net)
                return res;
 
        ieee802154_lowpan->fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+       ieee802154_lowpan->fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
        ieee802154_lowpan->fqdir->timeout = IPV6_FRAG_TIMEOUT;
 
        res = lowpan_frags_ns_sysctl_register(net);

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 0db5eb3..69c00ff 100644 (file)
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -553,7 +553,7 @@ EXPORT_SYMBOL(ip_check_defrag);
 
 #ifdef CONFIG_SYSCTL
 static int dist_min;
-static unsigned long ipfrag_low_thresh_unused;
+
 static struct ctl_table ip4_frags_ns_ctl_table[] = {
        {
                .procname       = "ipfrag_high_thresh",
@@ -609,9 +609,9 @@ static int __net_init ip4_frags_ns_ctl_register(struct net *net)
 
        }
        table[0].data   = &net->ipv4.fqdir->high_thresh;
-       table[0].extra1 = &ipfrag_low_thresh_unused;
-       table[1].data   = &ipfrag_low_thresh_unused;
-       table[1].extra2 = &net->ipv4.fqdir->high_thresh;
+       table[0].extra1 = &net->ipv4.fqdir->low_thresh;
+       table[1].data   = &net->ipv4.fqdir->low_thresh;
+       table[1].extra2 = &net->ipv4.fqdir->high_thresh;
        table[2].data   = &net->ipv4.fqdir->timeout;
        table[3].data   = &net->ipv4.fqdir->max_dist;
 
@@ -674,9 +674,12 @@ static int __net_init ipv4_frags_init_net(struct net *net)
         * A 64K fragment consumes 129736 bytes (44*2944)+200
         * (1500 truesize == 2944, sizeof(struct ipq) == 200)
         *
-        * We will commit 4MB at one time. Should we cross that limit.
+        * We will commit 4MB at one time. Should we cross that limit
+        * we will prune down to 3MB, making room for approx 8 big 64K
+        * fragments 8x128k.
         */
        net->ipv4.fqdir->high_thresh = 4 * 1024 * 1024;
+       net->ipv4.fqdir->low_thresh  = 3 * 1024 * 1024;
        /*
         * Important NOTE! Fragment queue must be destroyed before MSL expires.
         * RFC791 is wrong proposing to prolongate timer each fragment arrival

diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index dc8a285..d13240f 100644 (file)
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -42,7 +42,7 @@ static struct nft_ct_frag6_pernet *nf_frag_pernet(struct net *net)
 }
 
 #ifdef CONFIG_SYSCTL
-static unsigned long nf_conntrack_frag6_low_thresh_unused = IPV6_FRAG_LOW_THRESH;
+
 static struct ctl_table nf_ct_frag6_sysctl_table[] = {
        {
                .procname       = "nf_conntrack_frag6_timeout",
@@ -82,10 +82,10 @@ static int nf_ct_frag6_sysctl_register(struct net *net)
        nf_frag = nf_frag_pernet(net);
 
        table[0].data   = &nf_frag->fqdir->timeout;
-       table[1].data   = &nf_conntrack_frag6_low_thresh_unused;
-       table[1].extra2 = &nf_frag->fqdir->high_thresh;
+       table[1].data   = &nf_frag->fqdir->low_thresh;
+       table[1].extra2 = &nf_frag->fqdir->high_thresh;
        table[2].data   = &nf_frag->fqdir->high_thresh;
-       table[2].extra1 = &nf_conntrack_frag6_low_thresh_unused;
+       table[2].extra1 = &nf_frag->fqdir->low_thresh;
 
        hdr = register_net_sysctl(net, "net/netfilter", table);
        if (hdr == NULL)
@@ -500,6 +500,7 @@ static int nf_ct_net_init(struct net *net)
                return res;
 
        nf_frag->fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+       nf_frag->fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
        nf_frag->fqdir->timeout = IPV6_FRAG_TIMEOUT;
 
        res = nf_ct_frag6_sysctl_register(net);

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index eb8373c..5bc8a28 100644 (file)
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -416,7 +416,7 @@ static const struct inet6_protocol frag_protocol = {
 };
 
 #ifdef CONFIG_SYSCTL
-static unsigned long ip6_frags_low_thresh_unused = IPV6_FRAG_LOW_THRESH;
+
 static struct ctl_table ip6_frags_ns_ctl_table[] = {
        {
                .procname       = "ip6frag_high_thresh",
@@ -465,9 +465,9 @@ static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
 
        }
        table[0].data   = &net->ipv6.fqdir->high_thresh;
-       table[0].extra1 = &ip6_frags_low_thresh_unused;
-       table[1].data   = &ip6_frags_low_thresh_unused;
-       table[1].extra2 = &net->ipv6.fqdir->high_thresh;
+       table[0].extra1 = &net->ipv6.fqdir->low_thresh;
+       table[1].data   = &net->ipv6.fqdir->low_thresh;
+       table[1].extra2 = &net->ipv6.fqdir->high_thresh;
        table[2].data   = &net->ipv6.fqdir->timeout;
 
        hdr = register_net_sysctl(net, "net/ipv6", table);
@@ -536,6 +536,7 @@ static int __net_init ipv6_frags_init_net(struct net *net)
                return res;
 
        net->ipv6.fqdir->high_thresh = IPV6_FRAG_HIGH_THRESH;
+       net->ipv6.fqdir->low_thresh = IPV6_FRAG_LOW_THRESH;
        net->ipv6.fqdir->timeout = IPV6_FRAG_TIMEOUT;
 
        res = ip6_frags_ns_sysctl_register(net);