Re: [dpdk-dev] [PATCH v2 2/2] librte_ip_frag: add mbuf counter

[Alex Kiselev <alex@therouter.net>]

Hi Konstantin


> Hi Alex,

>> There might be situations (kind of attack when a lot of
>> fragmented packets are sent to a dpdk application in order
>> to flood the fragmentation table) when no additional mbufs
>> must be added to the fragmentations table since it already
>> contains to many of them. Currently there is no way to
>> determine the number of mbufs holded int the fragmentation
>> table. This patch allows to keep track of the number of mbufs
>> holded in the fragmentation table.

> I understand your intention, but still not sure it is worth it.
> My thought was that you can estimate by upper limit (num_entries * entries_per_bucket) or so.
No, I can't. The estimation error might be so big that there would be no difference at all.

> Probably another way to account number of mbufs without changes in the lib -
> apply something like that(assuming that your fragmets are not multisegs):

> uint32_t mbuf_in_frag_table = 0;
> ....

n= dr->>cnt;
> mb = rte_ipv4_frag_reassemble_packet(...);
> if (mb != NULL)
>    mbuf_in_frag_table += mb->nb_segs;
> mbuf_in_frag_table += dr->cnt - n + 1;

> In theory that could be applied even if fragments might be multisegs, but for that,
> we'll need to change rte_ip_frag_free_death_row() to return total number of freed segments.

That should be a little bit more complicated wrapper code:

uint32_t mbuf_in_frag_table = 0;
....

n= dr->cnt;
reassembled_mbuf = rte_ipv4_frag_reassemble_packet(..., fragmented_mbuf, ...);
if (reassembled_mbuf == NULL)
    mbuf_in_frag_table += fragmented_mbuf->nb_segs;
else
    mbuf_in_frag_table -= reassembled_mbuf->nb_segs;
mbuf_in_frag_table += dr->cnt - n;


Also, in that case every rte_ip_frag_free_death_row() needs a wrapper code too.

n= dr->cnt;
rte_ip_frag_free_death_row(..)
mbuf_in_frag_table += dr->cnt - n;


I think my approach is simplier.

> Konstantin


>> Signed-off-by: Alex Kiselev <alex@therouter.net>
>> ---
>>  lib/librte_ip_frag/ip_frag_common.h        | 16 +++++++++-------
>>  lib/librte_ip_frag/ip_frag_internal.c      | 16 +++++++++-------
>>  lib/librte_ip_frag/rte_ip_frag.h           | 18 +++++++++++++++++-
>>  lib/librte_ip_frag/rte_ip_frag_common.c    |  1 +
>>  lib/librte_ip_frag/rte_ip_frag_version.map |  1 +
>>  lib/librte_ip_frag/rte_ipv4_reassembly.c   |  2 +-
>>  lib/librte_ip_frag/rte_ipv6_reassembly.c   |  2 +-
>>  7 files changed, 39 insertions(+), 17 deletions(-)

>> diff --git a/lib/librte_ip_frag/ip_frag_common.h b/lib/librte_ip_frag/ip_frag_common.h
>> index 0fdcc7d0f..9fe5c0559 100644
>> --- a/lib/librte_ip_frag/ip_frag_common.h
>> +++ b/lib/librte_ip_frag/ip_frag_common.h
>> @@ -32,15 +32,15 @@
>>  #endif /* IP_FRAG_TBL_STAT */

>>  /* internal functions declarations */
>> -struct rte_mbuf * ip_frag_process(struct ip_frag_pkt *fp,
>> -             struct rte_ip_frag_death_row *dr, struct rte_mbuf *mb,
>> -             uint16_t ofs, uint16_t len, uint16_t more_frags);
>> +struct rte_mbuf *ip_frag_process(struct rte_ip_frag_tbl *tbl,
>> +     struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr,
>> +     struct rte_mbuf *mb, uint16_t ofs, uint16_t len, uint16_t more_frags);

>> -struct ip_frag_pkt * ip_frag_find(struct rte_ip_frag_tbl *tbl,
>> +struct ip_frag_pkt *ip_frag_find(struct rte_ip_frag_tbl *tbl,
>>               struct rte_ip_frag_death_row *dr,
>>               const struct ip_frag_key *key, uint64_t tms);

>> -struct ip_frag_pkt * ip_frag_lookup(struct rte_ip_frag_tbl *tbl,
>> +struct ip_frag_pkt *ip_frag_lookup(struct rte_ip_frag_tbl *tbl,
>>       const struct ip_frag_key *key, uint64_t tms,
>>       struct ip_frag_pkt **free, struct ip_frag_pkt **stale);

>> @@ -91,7 +91,8 @@ ip_frag_key_cmp(const struct ip_frag_key * k1, const struct ip_frag_key * k2)

>>  /* put fragment on death row */
>>  static inline void
>> -ip_frag_free(struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr)
>> +ip_frag_free(struct rte_ip_frag_tbl *tbl, struct ip_frag_pkt *fp,
>> +     struct rte_ip_frag_death_row *dr)
>>  {
>>       uint32_t i, k;

>> @@ -100,6 +101,7 @@ ip_frag_free(struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr)
>>               if (fp->frags[i].mb != NULL) {
>>                       dr->row[k++] = fp->frags[i].mb;
>>                       fp->frags[i].mb = NULL;
>> +                     tbl->nb_mbufs--;
>>               }
>>       }

>> @@ -160,7 +162,7 @@ static inline void
>>  ip_frag_tbl_del(struct rte_ip_frag_tbl *tbl, struct rte_ip_frag_death_row *dr,
>>       struct ip_frag_pkt *fp)
>>  {
>> -     ip_frag_free(fp, dr);
>> +     ip_frag_free(tbl, fp, dr);
>>       ip_frag_key_invalidate(&fp->key);
>>       TAILQ_REMOVE(&tbl->lru, fp, lru);
>>       tbl->use_entries--;
>> diff --git a/lib/librte_ip_frag/ip_frag_internal.c b/lib/librte_ip_frag/ip_frag_internal.c
>> index 97470a872..4c47d3fb4 100644
>> --- a/lib/librte_ip_frag/ip_frag_internal.c
>> +++ b/lib/librte_ip_frag/ip_frag_internal.c
>> @@ -29,14 +29,13 @@ static inline void
>>  ip_frag_tbl_reuse(struct rte_ip_frag_tbl *tbl, struct rte_ip_frag_death_row *dr,
>>       struct ip_frag_pkt *fp, uint64_t tms)
>>  {
>> -     ip_frag_free(fp, dr);
>> +     ip_frag_free(tbl, fp, dr);
>>       ip_frag_reset(fp, tms);
>>       TAILQ_REMOVE(&tbl->lru, fp, lru);
>>       TAILQ_INSERT_TAIL(&tbl->lru, fp, lru);
>>       IP_FRAG_TBL_STAT_UPDATE(&tbl->stat, reuse_num, 1);
>>  }

>> -
>>  static inline void
>>  ipv4_frag_hash(const struct ip_frag_key *key, uint32_t *v1, uint32_t *v2)
>>  {
>> @@ -88,8 +87,9 @@ ipv6_frag_hash(const struct ip_frag_key *key, uint32_t *v1, uint32_t *v2)
>>  }

>>  struct rte_mbuf *
>> -ip_frag_process(struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr,
>> -     struct rte_mbuf *mb, uint16_t ofs, uint16_t len, uint16_t more_frags)
>> +ip_frag_process(struct rte_ip_frag_tbl *tbl, struct ip_frag_pkt *fp,
>> +     struct rte_ip_frag_death_row *dr, struct rte_mbuf *mb, uint16_t ofs,
>> +     uint16_t len, uint16_t more_frags)
>>  {
>>       uint32_t idx;

>> @@ -147,7 +147,7 @@ ip_frag_process(struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr,
>>                               fp->frags[IP_LAST_FRAG_IDX].len);

>>               /* free all fragments, invalidate the entry. */
>> -             ip_frag_free(fp, dr);
>> +             ip_frag_free(tbl, fp, dr);
>>               ip_frag_key_invalidate(&fp->key);
>>               IP_FRAG_MBUF2DR(dr, mb);

>> @@ -157,6 +157,7 @@ ip_frag_process(struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr,
>>       fp->frags[idx].ofs = ofs;
>>       fp->frags[idx].len = len;
>>       fp->frags[idx].mb = mb;
>> +     tbl->nb_mbufs++;

>>       mb = NULL;

>> @@ -205,8 +206,9 @@ ip_frag_process(struct ip_frag_pkt *fp, struct rte_ip_frag_death_row *dr,
>>                               fp->frags[IP_LAST_FRAG_IDX].len);

>>               /* free associated resources. */
>> -             ip_frag_free(fp, dr);
>> -     }
>> +             ip_frag_free(tbl, fp, dr);
>> +     } else
>> +             tbl->nb_mbufs -= fp->last_idx;

>>       /* we are done with that entry, invalidate it. */
>>       ip_frag_key_invalidate(&fp->key);
>> diff --git a/lib/librte_ip_frag/rte_ip_frag.h b/lib/librte_ip_frag/rte_ip_frag.h
>> index 7f425f610..623934d87 100644
>> --- a/lib/librte_ip_frag/rte_ip_frag.h
>> +++ b/lib/librte_ip_frag/rte_ip_frag.h
>> @@ -96,6 +96,7 @@ struct rte_ip_frag_tbl {
>>       uint32_t             bucket_entries;  /**< hash associativity. */
>>       uint32_t             nb_entries;      /**< total size of the table. */
>>       uint32_t             nb_buckets;      /**< num of associativity lines. */
>> +     uint32_t             nb_mbufs;        /**< num of mbufs holded in the tbl. */
>>       struct ip_frag_pkt *last;         /**< last used entry. */
>>       struct ip_pkt_list lru;           /**< LRU list for table entries. */
>>       struct ip_frag_tbl_stat stat;     /**< statistics counters. */
>> @@ -329,8 +330,23 @@ void
>>  rte_ip_frag_table_statistics_dump(FILE * f, const struct rte_ip_frag_tbl *tbl);

>>  /**
>> - * Delete expired fragments
>> + * Number of mbufs holded in the fragmentation table.
>> + *
>> + * @param tbl
>> + *   Fragmentation table
>>   *
>> + * @return
>> + *   Number of mbufs holded in the fragmentation table.
>> + */
>> +static inline uint32_t __rte_experimental
>> +rte_frag_table_mbuf_count(const struct rte_ip_frag_tbl *tbl)
>> +{
>> +     return tbl->nb_mbufs;
>> +}
>> +
>> +/**
>> + * Delete expired fragments
>> + *
>>   * @param tbl
>>   *   Table to delete expired fragments from
>>   * @param dr
>> diff --git a/lib/librte_ip_frag/rte_ip_frag_common.c b/lib/librte_ip_frag/rte_ip_frag_common.c
>> index a23f6f24f..46c2df84a 100644
>> --- a/lib/librte_ip_frag/rte_ip_frag_common.c
>> +++ b/lib/librte_ip_frag/rte_ip_frag_common.c
>> @@ -75,6 +75,7 @@ rte_ip_frag_table_create(uint32_t bucket_num, uint32_t bucket_entries,
>>       tbl->nb_buckets = bucket_num;
>>       tbl->bucket_entries = bucket_entries;
>>       tbl->entry_mask = (tbl->nb_entries - 1) & ~(tbl->bucket_entries  - 1);
>> +     tbl->nb_mbufs = 0;

>>       TAILQ_INIT(&(tbl->lru));
>>       return tbl;
>> diff --git a/lib/librte_ip_frag/rte_ip_frag_version.map b/lib/librte_ip_frag/rte_ip_frag_version.map
>> index d40d5515f..f4700f460 100644
>> --- a/lib/librte_ip_frag/rte_ip_frag_version.map
>> +++ b/lib/librte_ip_frag/rte_ip_frag_version.map
>> @@ -23,4 +23,5 @@ EXPERIMENTAL {
>>       global:

>>       rte_frag_table_del_expired_entries;
>> +     rte_frag_table_mbuf_count;
>>  };
>> diff --git a/lib/librte_ip_frag/rte_ipv4_reassembly.c b/lib/librte_ip_frag/rte_ipv4_reassembly.c
>> index 4956b99ea..fbdfd860a 100644
>> --- a/lib/librte_ip_frag/rte_ipv4_reassembly.c
>> +++ b/lib/librte_ip_frag/rte_ipv4_reassembly.c
>> @@ -146,7 +146,7 @@ rte_ipv4_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,


>>       /* process the fragmented packet. */
>> -     mb = ip_frag_process(fp, dr, mb, ip_ofs, ip_len, ip_flag);
>> +     mb = ip_frag_process(tbl, fp, dr, mb, ip_ofs, ip_len, ip_flag);
>>       ip_frag_inuse(tbl, fp);

>>       IP_FRAG_LOG(DEBUG, "%s:%d:\n"
>> diff --git a/lib/librte_ip_frag/rte_ipv6_reassembly.c b/lib/librte_ip_frag/rte_ipv6_reassembly.c
>> index db249fe60..dda5a57b7 100644
>> --- a/lib/librte_ip_frag/rte_ipv6_reassembly.c
>> +++ b/lib/librte_ip_frag/rte_ipv6_reassembly.c
>> @@ -186,7 +186,7 @@ rte_ipv6_frag_reassemble_packet(struct rte_ip_frag_tbl *tbl,


>>       /* process the fragmented packet. */
>> -     mb = ip_frag_process(fp, dr, mb, ip_ofs, ip_len,
>> +     mb = ip_frag_process(tbl, fp, dr, mb, ip_ofs, ip_len,
>>                       MORE_FRAGS(frag_hdr->frag_data));
>>       ip_frag_inuse(tbl, fp);

>> --
>> 2.16.1.windows.1




-- 
Alex