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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
Download Patch File Download Diff File Expand all files Collapse all files

20
include/net/inet_frag.h
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@@ -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 :