inet: frags: break the 2GB limit for frags storage

Some users are willing to provision huge amounts of memory to be able
to perform reassembly reasonnably well under pressure.

Current memory tracking is using one atomic_t and integers.

Switch to atomic_long_t so that 64bit arches can use more than 2GB,
without any cost for 32bit arches.

Note that this patch avoids an overflow error, if high_thresh was set
to ~2GB, since this test in inet_frag_alloc() was never true :

if (... || frag_mem_limit(nf) > nf->high_thresh)

Tested:

$ echo 16000000000 >/proc/sys/net/ipv4/ipfrag_high_thresh

<frag DDOS>

$ grep FRAG /proc/net/sockstat
FRAG: inuse 14705885 memory 16000002880

$ nstat -n ; sleep 1 ; nstat | grep Reas
IpReasmReqds                    3317150            0.0
IpReasmFails                    3317112            0.0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 3e67f106f619dcfaf6f4e2039599bdb69848c714)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 6cd6325..dbdc413 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -122,10 +122,10 @@ min_adv_mss - INTEGER
 
 IP Fragmentation:
 
-ipfrag_high_thresh - INTEGER
+ipfrag_high_thresh - LONG INTEGER
        Maximum memory used to reassemble IP fragments.
 
-ipfrag_low_thresh - INTEGER
+ipfrag_low_thresh - LONG INTEGER
        (Obsolete since linux-4.17)
        Maximum memory used to reassemble IP fragments before the kernel
        begins to remove incomplete fragment queues to free up resources.

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 23161bf..dea175f 100644 (file)
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -7,11 +7,11 @@ struct netns_frags {
        struct rhashtable       rhashtable ____cacheline_aligned_in_smp;
 
        /* Keep atomic mem on separate cachelines in structs that include it */
-       atomic_t                mem ____cacheline_aligned_in_smp;
+       atomic_long_t           mem ____cacheline_aligned_in_smp;
        /* sysctls */
+       long                    high_thresh;
+       long                    low_thresh;
        int                     timeout;
-       int                     high_thresh;
-       int                     low_thresh;
        int                     max_dist;
        struct inet_frags       *f;
 };
@@ -101,7 +101,7 @@ void inet_frags_fini(struct inet_frags *);
 
 static inline int inet_frags_init_net(struct netns_frags *nf)
 {
-       atomic_set(&nf->mem, 0);
+       atomic_long_set(&nf->mem, 0);
        return rhashtable_init(&nf->rhashtable, &nf->f->rhash_params);
 }
 void inet_frags_exit_net(struct netns_frags *nf);
@@ -118,19 +118,19 @@ static inline void inet_frag_put(struct inet_frag_queue *q)
 
 /* Memory Tracking Functions. */
 
-static inline int frag_mem_limit(struct netns_frags *nf)
+static inline long frag_mem_limit(const struct netns_frags *nf)
 {
-       return atomic_read(&nf->mem);
+       return atomic_long_read(&nf->mem);
 }
 
-static inline void sub_frag_mem_limit(struct netns_frags *nf, int i)
+static inline void sub_frag_mem_limit(struct netns_frags *nf, long val)
 {
-       atomic_sub(i, &nf->mem);
+       atomic_long_sub(val, &nf->mem);
 }
 
-static inline void add_frag_mem_limit(struct netns_frags *nf, int i)
+static inline void add_frag_mem_limit(struct netns_frags *nf, long val)
 {
-       atomic_add(i, &nf->mem);
+       atomic_long_add(val, &nf->mem);
 }
 
 /* RFC 3168 support :

diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index b540159..122a625 100644 (file)
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -410,23 +410,23 @@ err:
 }
 
 #ifdef CONFIG_SYSCTL
-static int zero;
+static long zero;
 
 static struct ctl_table lowpan_frags_ns_ctl_table[] = {
        {
                .procname       = "6lowpanfrag_high_thresh",
                .data           = &init_net.ieee802154_lowpan.frags.high_thresh,
-               .maxlen         = sizeof(int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &init_net.ieee802154_lowpan.frags.low_thresh
        },
        {
                .procname       = "6lowpanfrag_low_thresh",
                .data           = &init_net.ieee802154_lowpan.frags.low_thresh,
-               .maxlen         = sizeof(int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &zero,
                .extra2         = &init_net.ieee802154_lowpan.frags.high_thresh
        },

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 696bfef..3dd19be 100644 (file)
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -681,23 +681,23 @@ struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
 EXPORT_SYMBOL(ip_check_defrag);
 
 #ifdef CONFIG_SYSCTL
-static int zero;
+static long zero;
 
 static struct ctl_table ip4_frags_ns_ctl_table[] = {
        {
                .procname       = "ipfrag_high_thresh",
                .data           = &init_net.ipv4.frags.high_thresh,
-               .maxlen         = sizeof(int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &init_net.ipv4.frags.low_thresh
        },
        {
                .procname       = "ipfrag_low_thresh",
                .data           = &init_net.ipv4.frags.low_thresh,
-               .maxlen         = sizeof(int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &zero,
                .extra2         = &init_net.ipv4.frags.high_thresh
        },

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index b7a2d00..aa1e525 100644 (file)
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -73,7 +73,7 @@ static int sockstat_seq_show(struct seq_file *seq, void *v)
                   sock_prot_inuse_get(net, &udplite_prot));
        seq_printf(seq, "RAW: inuse %d\n",
                   sock_prot_inuse_get(net, &raw_prot));
-       seq_printf(seq,  "FRAG: inuse %u memory %u\n",
+       seq_printf(seq,  "FRAG: inuse %u memory %lu\n",
                   atomic_read(&net->ipv4.frags.rhashtable.nelems),
                   frag_mem_limit(&net->ipv4.frags));
        return 0;

diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 267f2ae..8bc0df9 100644 (file)
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -63,7 +63,7 @@ struct nf_ct_frag6_skb_cb
 static struct inet_frags nf_frags;
 
 #ifdef CONFIG_SYSCTL
-static int zero;
+static long zero;
 
 static struct ctl_table nf_ct_frag6_sysctl_table[] = {
        {
@@ -76,18 +76,18 @@ static struct ctl_table nf_ct_frag6_sysctl_table[] = {
        {
                .procname       = "nf_conntrack_frag6_low_thresh",
                .data           = &init_net.nf_frag.frags.low_thresh,
-               .maxlen         = sizeof(unsigned int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &zero,
                .extra2         = &init_net.nf_frag.frags.high_thresh
        },
        {
                .procname       = "nf_conntrack_frag6_high_thresh",
                .data           = &init_net.nf_frag.frags.high_thresh,
-               .maxlen         = sizeof(unsigned int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &init_net.nf_frag.frags.low_thresh
        },
        { }

diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index 5704ec3..dc04c02 100644 (file)
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -47,7 +47,7 @@ static int sockstat6_seq_show(struct seq_file *seq, void *v)
                        sock_prot_inuse_get(net, &udplitev6_prot));
        seq_printf(seq, "RAW6: inuse %d\n",
                       sock_prot_inuse_get(net, &rawv6_prot));
-       seq_printf(seq, "FRAG6: inuse %u memory %u\n",
+       seq_printf(seq, "FRAG6: inuse %u memory %lu\n",
                   atomic_read(&net->ipv6.frags.rhashtable.nelems),
                   frag_mem_limit(&net->ipv6.frags));
        return 0;

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 6de4cec..8a4ece3 100644 (file)
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -546,15 +546,15 @@ static struct ctl_table ip6_frags_ns_ctl_table[] = {
        {
                .procname       = "ip6frag_high_thresh",
                .data           = &init_net.ipv6.frags.high_thresh,
-               .maxlen         = sizeof(int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
+               .proc_handler   = proc_doulongvec_minmax,
                .extra1         = &init_net.ipv6.frags.low_thresh
        },
        {
                .procname       = "ip6frag_low_thresh",
                .data           = &init_net.ipv6.frags.low_thresh,
-               .maxlen         = sizeof(int),
+               .maxlen         = sizeof(unsigned long),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &zero,