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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

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.
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.

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