Re: [PATCH] examples/ipsec-secgw: fix SPD no-match is misinterpreted

[Akhil Goyal <akhil.goyal@nxp.com>]

Hi Konstantin,

On 3/28/2019 6:17 PM, Konstantin Ananyev wrote:
> acl_classify() returns zero value when no matching rule was found.
> Currently ipsec-secgw treats it as a valid SPI value, though it has
> to discard such packets.
> Error could be easily observed by sending outbound unmatched packets,
> user will see something like that in the log:
> IPSEC: No cryptodev: core 7, cipher_algo 0, auth_algo 0, aead_algo 0
>
> To fix it we need to treat packets with zero result from acl_classify()
> as invalid ones. Also we can change DISCARD and BYPASS values to
> simplify checks and save some extra space for valid SPI values.
spi value =0 is invalid but zero result may have a valid packet.
consider a case:
SPI = 128 or 256 or 512 and so on  => sa_idx = 0 and result will come as 
zero, and this would be a valid packet.

I see that the sa_idx  calculation logic is not correct in first place. 
There will be multiple spi values for same sa_idx which is not correct.
So we have 2 issues here:
1. result = 0, means sa_idx =0 which may be correct, but as you said if 
acl_classify fails, it also return 0.
2. SPI values which are IPSEC_SA_MAX_ENTRIES apart will have same sa_idx 
and will keep on overwriting the previous ones.

So I believe the fix in this patch is not enough to resolve these 
issues. It will work on some values and will break on other values of spi.

-Akhil

>
> Fixes: 906257e965b7 ("examples/ipsec-secgw: support IPv6")
> Fixes: 2a5106af132b ("examples/ipsec-secgw: fix corner case for SPI value")
> Cc: stable@dpdk.org
>
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> ---
>   examples/ipsec-secgw/ipsec-secgw.c | 12 ++++++------
>   examples/ipsec-secgw/ipsec.h       |  6 ++----
>   examples/ipsec-secgw/sp4.c         | 11 ++++++++---
>   examples/ipsec-secgw/sp6.c         | 11 ++++++++---
>   4 files changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/examples/ipsec-secgw/ipsec-secgw.c b/examples/ipsec-secgw/ipsec-secgw.c
> index ffbd00b08..59e084234 100644
> --- a/examples/ipsec-secgw/ipsec-secgw.c
> +++ b/examples/ipsec-secgw/ipsec-secgw.c
> @@ -438,11 +438,11 @@ inbound_sp_sa(struct sp_ctx *sp, struct sa_ctx *sa, struct traffic_type *ip,
>   	for (i = 0; i < ip->num; i++) {
>   		m = ip->pkts[i];
>   		res = ip->res[i];
> -		if (res & BYPASS) {
> +		if (res == BYPASS) {
>   			ip->pkts[j++] = m;
>   			continue;
>   		}
> -		if (res & DISCARD) {
> +		if (res == DISCARD) {
>   			rte_pktmbuf_free(m);
>   			continue;
>   		}
> @@ -453,7 +453,7 @@ inbound_sp_sa(struct sp_ctx *sp, struct sa_ctx *sa, struct traffic_type *ip,
>   			continue;
>   		}
>   
> -		sa_idx = ip->res[i] & PROTECT_MASK;
> +		sa_idx = ip->res[i];
>   		if (sa_idx >= IPSEC_SA_MAX_ENTRIES ||
>   				!inbound_sa_check(sa, m, sa_idx)) {
>   			rte_pktmbuf_free(m);
> @@ -541,10 +541,10 @@ outbound_sp(struct sp_ctx *sp, struct traffic_type *ip,
>   	j = 0;
>   	for (i = 0; i < ip->num; i++) {
>   		m = ip->pkts[i];
> -		sa_idx = ip->res[i] & PROTECT_MASK;
> -		if (ip->res[i] & DISCARD)
> +		sa_idx = ip->res[i];
> +		if (sa_idx == DISCARD)
>   			rte_pktmbuf_free(m);
> -		else if (ip->res[i] & BYPASS)
> +		else if (sa_idx == BYPASS)
>   			ip->pkts[j++] = m;
>   		else if (sa_idx < IPSEC_SA_MAX_ENTRIES) {
>   			ipsec->res[ipsec->num] = sa_idx;
> diff --git a/examples/ipsec-secgw/ipsec.h b/examples/ipsec-secgw/ipsec.h
> index 99f49d65f..44daf384b 100644
> --- a/examples/ipsec-secgw/ipsec.h
> +++ b/examples/ipsec-secgw/ipsec.h
> @@ -41,10 +41,8 @@
>   #define SPI2IDX(spi) (spi & (IPSEC_SA_MAX_ENTRIES - 1))
>   #define INVALID_SPI (0)
>   
> -#define DISCARD (0x80000000)
> -#define BYPASS (0x40000000)
> -#define PROTECT_MASK (0x3fffffff)
> -#define PROTECT(sa_idx) (SPI2IDX(sa_idx) & PROTECT_MASK) /* SA idx 30 bits */
> +#define DISCARD	INVALID_SPI
> +#define BYPASS	UINT32_MAX
>   
>   #define IPSEC_XFORM_MAX 2
>   
> diff --git a/examples/ipsec-secgw/sp4.c b/examples/ipsec-secgw/sp4.c
> index d1dc64bad..bfaddc52e 100644
> --- a/examples/ipsec-secgw/sp4.c
> +++ b/examples/ipsec-secgw/sp4.c
> @@ -99,6 +99,7 @@ parse_sp4_tokens(char **tokens, uint32_t n_tokens,
>   
>   	uint32_t *ri = NULL; /* rule index */
>   	uint32_t ti = 0; /* token index */
> +	uint32_t tv;
>   
>   	uint32_t esp_p = 0;
>   	uint32_t protect_p = 0;
> @@ -169,8 +170,12 @@ parse_sp4_tokens(char **tokens, uint32_t n_tokens,
>   			if (status->status < 0)
>   				return;
>   
> -			rule_ipv4->data.userdata =
> -				PROTECT(atoi(tokens[ti]));
> +			tv = atoi(tokens[ti]);
> +			APP_CHECK(tv != DISCARD && tv != BYPASS, status,
> +				"invalid SPI: %s", tokens[ti]);
> +			if (status->status < 0)
> +				return;
> +			rule_ipv4->data.userdata = tv;
>   
>   			protect_p = 1;
>   			continue;
> @@ -523,7 +528,7 @@ sp4_spi_present(uint32_t spi, int inbound)
>   	}
>   
>   	for (i = 0; i != num; i++) {
> -		if (acr[i].data.userdata == PROTECT(spi))
> +		if (acr[i].data.userdata == spi)
>   			return i;
>   	}
>   
> diff --git a/examples/ipsec-secgw/sp6.c b/examples/ipsec-secgw/sp6.c
> index e67d85aaf..b7fcf7c16 100644
> --- a/examples/ipsec-secgw/sp6.c
> +++ b/examples/ipsec-secgw/sp6.c
> @@ -130,6 +130,7 @@ parse_sp6_tokens(char **tokens, uint32_t n_tokens,
>   
>   	uint32_t *ri = NULL; /* rule index */
>   	uint32_t ti = 0; /* token index */
> +	uint32_t tv;
>   
>   	uint32_t esp_p = 0;
>   	uint32_t protect_p = 0;
> @@ -202,8 +203,12 @@ parse_sp6_tokens(char **tokens, uint32_t n_tokens,
>   			if (status->status < 0)
>   				return;
>   
> -			rule_ipv6->data.userdata =
> -				PROTECT(atoi(tokens[ti]));
> +			tv = atoi(tokens[ti]);
> +			APP_CHECK(tv != DISCARD && tv != BYPASS, status,
> +				"invalid SPI: %s", tokens[ti]);
> +			if (status->status < 0)
> +				return;
> +			rule_ipv6->data.userdata = tv;
>   
>   			protect_p = 1;
>   			continue;
> @@ -637,7 +642,7 @@ sp6_spi_present(uint32_t spi, int inbound)
>   	}
>   
>   	for (i = 0; i != num; i++) {
> -		if (acr[i].data.userdata == PROTECT(spi))
> +		if (acr[i].data.userdata == spi)
>   			return i;
>   	}
>