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 6f2a3670e44b6662ce53c16cb7ca1e4f61274c15..5dc1a040a2f1db610873de26c2d79bc57ac5a1a2 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 95e353e3305b43253084d972e32538138bcc5454..a52e7273e7a59bc8ce47b21d29235a740add8db0 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 1aec71a3f90478a29065e6559a78aec2e930ceab..44f148a6bb57bb737c35a07e3f070472e209ea23 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 b0366224f314ae521d8c1f8fe04c53e419292b4c..053869f2c49b9fd7a87316f1ef1416568b1bf508 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 aacfce0d7d82cf59269a69ef4d6ac8d9955b0bdc..a058de677e947846eb93020e0788148827c8f3cd 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 d866412b8f6c432f04c0968f08f820fdc561262b..603a395928593a071aff28105578d3bfdbf1b31e 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 8befeb91e0712ecc4d05c4c0a6ecca1808dcbcac..a85f7e0b14b10f59fdd2ea6901f8e9a95c13654f 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 2a77fda5e3bca1b6ce8c24df11e741653a15c665..905a8aee2671fd76b47d9cc6b6b0c17c9691d224 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,