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>

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 6f2a367..5dc1a04 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -133,10 +133,10 @@ 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 95e353e..a52e727 100644 (file)
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -8,11 +8,11 @@ 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;
 };
@@ -102,7 +102,7 @@ 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);
@@ -119,19 +119,19 @@ 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 1aec71a..44f148a 100644 (file)
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -411,23 +411,23 @@ 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 b036622..053869f 100644 (file)
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -678,23 +678,23 @@ 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 aacfce0..a058de6 100644 (file)
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -71,7 +71,7 @@ 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 d866412..603a395 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 8befeb9..a85f7e0 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 2a77fda..905a8ae 100644 (file)
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -552,15 +552,15 @@ 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,