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

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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>
This commit is contained in:
Eric Dumazet 2018-03-31 12:58:53 -07:00 committed by David S. Miller
parent 2d44ed22e6
commit 3e67f106f6
8 changed files with 32 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/networking/ip-sysctl.txt
View File

@ -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.

20
include/net/inet_frag.h
View File

@ -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 :

10
net/ieee802154/6lowpan/reassembly.c
View File

@ -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
},

10
net/ipv4/ip_fragment.c
View File

@ -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
},

2
net/ipv4/proc.c
View File

@ -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;

10
net/ipv6/netfilter/nf_conntrack_reasm.c
View File

@ -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
},
{ }

2
net/ipv6/proc.c
View File

@ -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;

6
net/ipv6/reassembly.c
View File

@ -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,