Use a lookup table of algorithm flags for alg_is_* helpers.

[jhb]

Summary

This makes it easier to maintain these functions as algorithms are
added or removed.

Test Plan

• used test program I'll post in a bit to verify identical behavior before/after

[jhb]

Test program:

#include <sys/param.h>
#include "sys/opencrypto/cryptodev.h"
#include <stdbool.h>
#include <stdio.h>

#define	ALG_COMPRESSION		0x1
#define	ALG_CIPHER		0x2
#define	ALG_DIGEST		0x4
#define	ALG_KEYED_DIGEST	0x8
#define	ALG_AEAD		0x10

static int alg_flags[] = {
	[CRYPTO_DES_CBC] = ALG_CIPHER,
	[CRYPTO_3DES_CBC] = ALG_CIPHER,
	[CRYPTO_BLF_CBC] = ALG_CIPHER,
	[CRYPTO_CAST_CBC] = ALG_CIPHER,
	[CRYPTO_SKIPJACK_CBC] = ALG_CIPHER,
	[CRYPTO_MD5_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_SHA1_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_RIPEMD160_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_MD5_KPDK] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_SHA1_KPDK] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_AES_CBC] = ALG_CIPHER,
	[CRYPTO_ARC4] = ALG_CIPHER,
	[CRYPTO_MD5] = ALG_DIGEST,
	[CRYPTO_SHA1] = ALG_DIGEST,
	[CRYPTO_NULL_HMAC] = ALG_DIGEST,
	[CRYPTO_NULL_CBC] = ALG_CIPHER,
	[CRYPTO_DEFLATE_COMP] = ALG_COMPRESSION,
	[CRYPTO_SHA2_256_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_SHA2_384_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_SHA2_512_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_CAMELLIA_CBC] = ALG_CIPHER,
	[CRYPTO_AES_XTS] = ALG_CIPHER,
	[CRYPTO_AES_ICM] = ALG_CIPHER,
	[CRYPTO_AES_NIST_GMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_AES_NIST_GCM_16] = ALG_AEAD,
	[CRYPTO_BLAKE2B] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_BLAKE2S] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_CHACHA20] = ALG_CIPHER,
	[CRYPTO_SHA2_224_HMAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_RIPEMD160] = ALG_DIGEST,
	[CRYPTO_SHA2_224] = ALG_DIGEST,
	[CRYPTO_SHA2_256] = ALG_DIGEST,
	[CRYPTO_SHA2_384] = ALG_DIGEST,
	[CRYPTO_SHA2_512] = ALG_DIGEST,
	[CRYPTO_POLY1305] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_AES_CCM_CBC_MAC] = ALG_DIGEST | ALG_KEYED_DIGEST,
	[CRYPTO_AES_CCM_16] = ALG_AEAD,
};

static bool
alg_is_compression(int alg)
{

	if (alg == CRYPTO_DEFLATE_COMP)
		return (true);
	return (false);
}

static bool
alg_is_cipher(int alg)
{

	if (alg >= CRYPTO_DES_CBC && alg <= CRYPTO_SKIPJACK_CBC)
		return (true);
	if (alg >= CRYPTO_AES_CBC && alg <= CRYPTO_ARC4)
		return (true);
	if (alg == CRYPTO_NULL_CBC)
		return (true);
	if (alg >= CRYPTO_CAMELLIA_CBC && alg <= CRYPTO_AES_ICM)
		return (true);
	if (alg == CRYPTO_CHACHA20)
		return (true);
	return (false);
}

static bool
alg_is_digest(int alg)
{

	if (alg >= CRYPTO_MD5_HMAC && alg <= CRYPTO_SHA1_KPDK)
		return (true);
	if (alg >= CRYPTO_MD5 && alg <= CRYPTO_SHA1)
		return (true);
	if (alg == CRYPTO_NULL_HMAC)
		return (true);
	if (alg >= CRYPTO_SHA2_256_HMAC && alg <= CRYPTO_SHA2_512_HMAC)
		return (true);
	if (alg == CRYPTO_AES_NIST_GMAC)
		return (true);
	if (alg >= CRYPTO_BLAKE2B && alg <= CRYPTO_BLAKE2S)
		return (true);
	if (alg >= CRYPTO_SHA2_224_HMAC && alg <= CRYPTO_POLY1305)
		return (true);
	if (alg == CRYPTO_AES_CCM_CBC_MAC)
		return (true);
	return (false);
}

static bool
alg_is_keyed_digest(int alg)
{

	if (alg >= CRYPTO_MD5_HMAC && alg <= CRYPTO_SHA1_KPDK)
		return (true);
	if (alg >= CRYPTO_SHA2_256_HMAC && alg <= CRYPTO_SHA2_512_HMAC)
		return (true);
	if (alg == CRYPTO_AES_NIST_GMAC)
		return (true);
	if (alg >= CRYPTO_BLAKE2B && alg <= CRYPTO_BLAKE2S)
		return (true);
	if (alg == CRYPTO_SHA2_224_HMAC)
		return (true);
	if (alg == CRYPTO_POLY1305)
		return (true);
	if (alg == CRYPTO_AES_CCM_CBC_MAC)
		return (true);
	return (false);
}

static bool
alg_is_aead(int alg)
{

	if (alg == CRYPTO_AES_NIST_GCM_16)
		return (true);
	if (alg == CRYPTO_AES_CCM_16)
		return (true);
	return (false);
}

static bool
alg_has_flag(int alg, int flag)
{

	if (alg < nitems(alg_flags))
		return ((alg_flags[alg] & flag) == flag);
	return (false);
}

int
main(void)
{
	int i;
	bool ok;

	for (i = 0; i <= CRYPTO_ALGORITHM_MAX; i++) {
		ok = true;
		if (alg_is_compression(i) !=
		    alg_has_flag(i, ALG_COMPRESSION)) {
			printf("%d: compression mismatch\n", i);
			ok = false;
		}
		if (alg_is_cipher(i) != alg_has_flag(i, ALG_CIPHER)) {
			printf("%d: cipher mismatch\n", i);
			ok = false;
		}
		if (alg_is_digest(i) != alg_has_flag(i, ALG_DIGEST)) {
			printf("%d: digest mismatch\n", i);
			ok = false;
		}
		if (alg_is_keyed_digest(i) !=
		    alg_has_flag(i, ALG_KEYED_DIGEST)) {
			printf("%d: keyed digest mismatch\n", i);
			ok = false;
		}
		if (alg_is_aead(i) != alg_has_flag(i, ALG_AEAD)) {
			printf("%d: aead mismatch\n", i);
			ok = false;
		}
		if (ok)
			printf("%d: all matched\n", i);
	}
}

[cem]

sys/opencrypto/crypto.c

98

Do these need to be flags? Is it possible for something to be a keyed digest and not a plain digest, in the sense we use for the latter?

If they don’t have to be flags, it is harder to specify an invalid combination.

711

I don’t know if this is mostly convention or true definition, but usually digest is used to refer to a hash function. The non-HMAC MAC algorithms (tags) are substantially different from hashes. I don’t know if it matters here; this is probably more about input parameters and output than anything else, and those are similar.

732

If this can’t be replaced by return (alg_flags... & flag) maybe the function should be named “flags” plural?

[jhb]

sys/opencrypto/crypto.c

98

I suppose they could be an enum instead and 'alg_is_digest' could check for both types. It is true that all "keyed" digests are always digests. I didn't want to use something else like "mac" since just being a digest that uses a key doesn't necessarily make an algorithm a mac.

711

Yes, it is mostly for the session modes (CSP_MODE_DIGEST). OTOH, it's debatable if we would really support GMAC and CBC_MAC as distinct algorithms. In theory IPsec supports a GMAC-only ESP mode, though I think we implement that as GCM with an empty payload perhaps? Actually, I probably need to go retest that as I might have broken it, and I probably should do it by using a GMAC-only mode.

[jhb]

• Switch to an enum.

[cem]

LGTM, thanks!

sys/opencrypto/crypto.c

95–99

Probably want to remove these names now.

[jhb]

• Compile fixes.