ssl_ciph.c

一个用于点对点传输加密的工具包源码

/* ssl/ssl_ciph.c */
/* Copyright (C) 1995-1998 Eric Young ([e-mail])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([e-mail]).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson ([e-mail]).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young ([e-mail])"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson ([e-mail])"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <openssl/objects.h>
#include <openssl/comp.h>
#include "ssl_locl.h"

#define SSL_ENC_DES_IDX		0
#define SSL_ENC_3DES_IDX	1
#define SSL_ENC_RC4_IDX		2
#define SSL_ENC_RC2_IDX		3
#define SSL_ENC_IDEA_IDX	4
#define SSL_ENC_eFZA_IDX	5
#define SSL_ENC_NULL_IDX	6
#define SSL_ENC_NUM_IDX		7

static const EVP_CIPHER *ssl_cipher_methods[SSL_ENC_NUM_IDX]={
	NULL,NULL,NULL,NULL,NULL,NULL,
	};

static STACK_OF(SSL_COMP) *ssl_comp_methods=NULL;

#define SSL_MD_MD5_IDX	0
#define SSL_MD_SHA1_IDX	1
#define SSL_MD_NUM_IDX	2
static const EVP_MD *ssl_digest_methods[SSL_MD_NUM_IDX]={
	NULL,NULL,
	};

#define CIPHER_ADD	1
#define CIPHER_KILL	2
#define CIPHER_DEL	3
#define CIPHER_ORD	4
#define CIPHER_SPECIAL	5

typedef struct cipher_order_st
	{
	SSL_CIPHER *cipher;
	int active;
	int dead;
	struct cipher_order_st *next,*prev;
	} CIPHER_ORDER;

static const SSL_CIPHER cipher_aliases[]={
	/* Don't include eNULL unless specifically enabled */
	{0,SSL_TXT_ALL, 0,SSL_ALL & ~SSL_eNULL, SSL_ALL ,0,0,0,SSL_ALL,SSL_ALL}, /* must be first */
	{0,SSL_TXT_kRSA,0,SSL_kRSA,  0,0,0,0,SSL_MKEY_MASK,0},
	{0,SSL_TXT_kDHr,0,SSL_kDHr,  0,0,0,0,SSL_MKEY_MASK,0},
	{0,SSL_TXT_kDHd,0,SSL_kDHd,  0,0,0,0,SSL_MKEY_MASK,0},
	{0,SSL_TXT_kEDH,0,SSL_kEDH,  0,0,0,0,SSL_MKEY_MASK,0},
	{0,SSL_TXT_kFZA,0,SSL_kFZA,  0,0,0,0,SSL_MKEY_MASK,0},
	{0,SSL_TXT_DH,	0,SSL_DH,    0,0,0,0,SSL_MKEY_MASK,0},
	{0,SSL_TXT_EDH,	0,SSL_EDH,   0,0,0,0,SSL_MKEY_MASK|SSL_AUTH_MASK,0},

	{0,SSL_TXT_aRSA,0,SSL_aRSA,  0,0,0,0,SSL_AUTH_MASK,0},
	{0,SSL_TXT_aDSS,0,SSL_aDSS,  0,0,0,0,SSL_AUTH_MASK,0},
	{0,SSL_TXT_aFZA,0,SSL_aFZA,  0,0,0,0,SSL_AUTH_MASK,0},
	{0,SSL_TXT_aNULL,0,SSL_aNULL,0,0,0,0,SSL_AUTH_MASK,0},
	{0,SSL_TXT_aDH, 0,SSL_aDH,   0,0,0,0,SSL_AUTH_MASK,0},
	{0,SSL_TXT_DSS,	0,SSL_DSS,   0,0,0,0,SSL_AUTH_MASK,0},

	{0,SSL_TXT_DES,	0,SSL_DES,   0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_3DES,0,SSL_3DES,  0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_RC4,	0,SSL_RC4,   0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_RC2,	0,SSL_RC2,   0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_IDEA,0,SSL_IDEA,  0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_eNULL,0,SSL_eNULL,0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_eFZA,0,SSL_eFZA,  0,0,0,0,SSL_ENC_MASK,0},

	{0,SSL_TXT_MD5,	0,SSL_MD5,   0,0,0,0,SSL_MAC_MASK,0},
	{0,SSL_TXT_SHA1,0,SSL_SHA1,  0,0,0,0,SSL_MAC_MASK,0},
	{0,SSL_TXT_SHA,	0,SSL_SHA,   0,0,0,0,SSL_MAC_MASK,0},

	{0,SSL_TXT_NULL,0,SSL_NULL,  0,0,0,0,SSL_ENC_MASK,0},
	{0,SSL_TXT_RSA,	0,SSL_RSA,   0,0,0,0,SSL_AUTH_MASK|SSL_MKEY_MASK,0},
	{0,SSL_TXT_ADH,	0,SSL_ADH,   0,0,0,0,SSL_AUTH_MASK|SSL_MKEY_MASK,0},
	{0,SSL_TXT_FZA,	0,SSL_FZA,   0,0,0,0,SSL_AUTH_MASK|SSL_MKEY_MASK|SSL_ENC_MASK,0},

	{0,SSL_TXT_SSLV2, 0,SSL_SSLV2, 0,0,0,0,SSL_SSL_MASK,0},
	{0,SSL_TXT_SSLV3, 0,SSL_SSLV3, 0,0,0,0,SSL_SSL_MASK,0},
	{0,SSL_TXT_TLSV1, 0,SSL_TLSV1, 0,0,0,0,SSL_SSL_MASK,0},

	{0,SSL_TXT_EXP   ,0, 0,SSL_EXPORT, 0,0,0,0,SSL_EXP_MASK},
	{0,SSL_TXT_EXPORT,0, 0,SSL_EXPORT, 0,0,0,0,SSL_EXP_MASK},
	{0,SSL_TXT_EXP40, 0, 0, SSL_EXP40, 0,0,0,0,SSL_STRONG_MASK},
	{0,SSL_TXT_EXP56, 0, 0, SSL_EXP56, 0,0,0,0,SSL_STRONG_MASK},
	{0,SSL_TXT_LOW,   0, 0,   SSL_LOW, 0,0,0,0,SSL_STRONG_MASK},
	{0,SSL_TXT_MEDIUM,0, 0,SSL_MEDIUM, 0,0,0,0,SSL_STRONG_MASK},
	{0,SSL_TXT_HIGH,  0, 0,  SSL_HIGH, 0,0,0,0,SSL_STRONG_MASK},
	};

static int init_ciphers=1;

static void load_ciphers(void)
	{
	init_ciphers=0;
	ssl_cipher_methods[SSL_ENC_DES_IDX]= 
		EVP_get_cipherbyname(SN_des_cbc);
	ssl_cipher_methods[SSL_ENC_3DES_IDX]=
		EVP_get_cipherbyname(SN_des_ede3_cbc);
	ssl_cipher_methods[SSL_ENC_RC4_IDX]=
		EVP_get_cipherbyname(SN_rc4);
	ssl_cipher_methods[SSL_ENC_RC2_IDX]= 
		EVP_get_cipherbyname(SN_rc2_cbc);
	ssl_cipher_methods[SSL_ENC_IDEA_IDX]= 
		EVP_get_cipherbyname(SN_idea_cbc);

	ssl_digest_methods[SSL_MD_MD5_IDX]=
		EVP_get_digestbyname(SN_md5);
	ssl_digest_methods[SSL_MD_SHA1_IDX]=
		EVP_get_digestbyname(SN_sha1);
	}

int ssl_cipher_get_evp(SSL_SESSION *s, const EVP_CIPHER **enc,
	     const EVP_MD **md, SSL_COMP **comp)
	{
	int i;
	SSL_CIPHER *c;

	c=s->cipher;
	if (c == NULL) return(0);
	if (comp != NULL)
		{
		SSL_COMP ctmp;

		if (s->compress_meth == 0)
			*comp=NULL;
		else if (ssl_comp_methods == NULL)
			{
			/* bad */
			*comp=NULL;
			}
		else
			{

			ctmp.id=s->compress_meth;
			i=sk_SSL_COMP_find(ssl_comp_methods,&ctmp);
			if (i >= 0)
				*comp=sk_SSL_COMP_value(ssl_comp_methods,i);
			else
				*comp=NULL;
			}
		}

	if ((enc == NULL) || (md == NULL)) return(0);

	switch (c->algorithms & SSL_ENC_MASK)
		{
	case SSL_DES:
		i=SSL_ENC_DES_IDX;
		break;
	case SSL_3DES:
		i=SSL_ENC_3DES_IDX;
		break;
	case SSL_RC4:
		i=SSL_ENC_RC4_IDX;
		break;
	case SSL_RC2:
		i=SSL_ENC_RC2_IDX;
		break;
	case SSL_IDEA:
		i=SSL_ENC_IDEA_IDX;
		break;
	case SSL_eNULL:
		i=SSL_ENC_NULL_IDX;
		break;
	default:
		i= -1;
		break;
		}

	if ((i < 0) || (i > SSL_ENC_NUM_IDX))
		*enc=NULL;
	else
		{
		if (i == SSL_ENC_NULL_IDX)
			*enc=EVP_enc_null();
		else
			*enc=ssl_cipher_methods[i];
		}

	switch (c->algorithms & SSL_MAC_MASK)
		{
	case SSL_MD5:
		i=SSL_MD_MD5_IDX;
		break;
	case SSL_SHA1:
		i=SSL_MD_SHA1_IDX;
		break;
	default:
		i= -1;
		break;
		}
	if ((i < 0) || (i > SSL_MD_NUM_IDX))
		*md=NULL;
	else
		*md=ssl_digest_methods[i];

	if ((*enc != NULL) && (*md != NULL))
		return(1);
	else
		return(0);
	}

#define ITEM_SEP(a) \
	(((a) == ':') || ((a) == ' ') || ((a) == ';') || ((a) == ','))

static void ll_append_tail(CIPHER_ORDER **head, CIPHER_ORDER *curr,
	     CIPHER_ORDER **tail)
	{
	if (curr == *tail) return;
	if (curr == *head)
		*head=curr->next;
	if (curr->prev != NULL)
		curr->prev->next=curr->next;
	if (curr->next != NULL) /* should always be true */
		curr->next->prev=curr->prev;
	(*tail)->next=curr;
	curr->prev= *tail;
	curr->next=NULL;
	*tail=curr;
	}

static unsigned long ssl_cipher_get_disabled(void)
	{
	unsigned long mask;

	mask = SSL_kFZA;
#ifdef NO_RSA
	mask |= SSL_aRSA|SSL_kRSA;
#endif
#ifdef NO_DSA
	mask |= SSL_aDSS;
#endif
#ifdef NO_DH
	mask |= SSL_kDHr|SSL_kDHd|SSL_kEDH|SSL_aDH;
#endif

#ifdef SSL_FORBID_ENULL
	mask |= SSL_eNULL;
#endif

	mask |= (ssl_cipher_methods[SSL_ENC_DES_IDX ] == NULL) ? SSL_DES :0;
	mask |= (ssl_cipher_methods[SSL_ENC_3DES_IDX] == NULL) ? SSL_3DES:0;
	mask |= (ssl_cipher_methods[SSL_ENC_RC4_IDX ] == NULL) ? SSL_RC4 :0;
	mask |= (ssl_cipher_methods[SSL_ENC_RC2_IDX ] == NULL) ? SSL_RC2 :0;
	mask |= (ssl_cipher_methods[SSL_ENC_IDEA_IDX] == NULL) ? SSL_IDEA:0;
	mask |= (ssl_cipher_methods[SSL_ENC_eFZA_IDX] == NULL) ? SSL_eFZA:0;

	mask |= (ssl_digest_methods[SSL_MD_MD5_IDX ] == NULL) ? SSL_MD5 :0;
	mask |= (ssl_digest_methods[SSL_MD_SHA1_IDX] == NULL) ? SSL_SHA1:0;

	return(mask);
	}

static void ssl_cipher_collect_ciphers(const SSL_METHOD *ssl_method,
		int num_of_ciphers, unsigned long mask, CIPHER_ORDER *list,
		CIPHER_ORDER **head_p, CIPHER_ORDER **tail_p)
	{
	int i, list_num;
	SSL_CIPHER *c;

	/*
	 * We have num_of_ciphers descriptions compiled in, depending on the
	 * method selected (SSLv2 and/or SSLv3, TLSv1 etc).
	 * These will later be sorted in a linked list with at most num
	 * entries.
	 */

	/* Get the initial list of ciphers */
	list_num = 0;	/* actual count of ciphers */
	for (i = 0; i < num_of_ciphers; i++)
		{
		c = ssl_method->get_cipher(i);
		/* drop those that use any of that is not available */
		if ((c != NULL) && c->valid && !(c->algorithms & mask))
			{
			list[list_num].cipher = c;
			list[list_num].next = NULL;
			list[list_num].prev = NULL;
			list[list_num].active = 0;
			list_num++;
			/*
			if (!sk_push(ca_list,(char *)c)) goto err;
			*/
			}
		}

	/*
	 * Prepare linked list from list entries
	 */	
	for (i = 1; i < list_num - 1; i++)
		{
		list[i].prev = &(list[i-1]);
		list[i].next = &(list[i+1]);
		}
	if (list_num > 0)
		{
		(*head_p) = &(list[0]);
		(*head_p)->prev = NULL;
		(*head_p)->next = &(list[1]);
		(*tail_p) = &(list[list_num - 1]);
		(*tail_p)->prev = &(list[list_num - 2]);
		(*tail_p)->next = NULL;
		}
	}

static void ssl_cipher_collect_aliases(SSL_CIPHER **ca_list,
			int num_of_group_aliases, unsigned long mask,
			CIPHER_ORDER *head)
	{
	CIPHER_ORDER *ciph_curr;
	SSL_CIPHER **ca_curr;
	int i;

	/*
	 * First, add the real ciphers as already collected
	 */
	ciph_curr = head;
	ca_curr = ca_list;
	while (ciph_curr != NULL)
		{
		*ca_curr = ciph_curr->cipher;
		ca_curr++;
		ciph_curr = ciph_curr->next;
		}

	/*
	 * Now we add the available ones from the cipher_aliases[] table.
	 * They represent either an algorithm, that must be fully
	 * supported (not match any bit in mask) or represent a cipher
	 * strength value (will be added in any case because algorithms=0).
	 */
	for (i = 0; i < num_of_group_aliases; i++)
		{
		if ((i == 0) ||		/* always fetch "ALL" */
		    !(cipher_aliases[i].algorithms & mask))
			{
			*ca_curr = (SSL_CIPHER *)(cipher_aliases + i);
			ca_curr++;
			}
		}

	*ca_curr = NULL;	/* end of list */
	}

static void ssl_cipher_apply_rule(unsigned long algorithms, unsigned long mask,
		unsigned long algo_strength, unsigned long mask_strength,
		int rule, int strength_bits, CIPHER_ORDER *list,
		CIPHER_ORDER **head_p, CIPHER_ORDER **tail_p)
	{
	CIPHER_ORDER *head, *tail, *curr, *curr2, *tail2;
	SSL_CIPHER *cp;
	unsigned long ma, ma_s;

#ifdef CIPHER_DEBUG
	printf("Applying rule %d with %08lx %08lx %08lx %08lx (%d)\n",
		rule, algorithms, mask, algo_strength, mask_strength,
		strength_bits);
#endif

	curr = head = *head_p;
	curr2 = head;
	tail2 = tail = *tail_p;
	for (;;)
		{
		if ((curr == NULL) || (curr == tail2)) break;
		curr = curr2;
		curr2 = curr->next;

		cp = curr->cipher;

		/*
		 * Selection criteria is either the number of strength_bits
		 * or the algorithm used.
		 */
		if (strength_bits == -1)
			{
			ma = mask & cp->algorithms;
			ma_s = mask_strength & cp->algo_strength;

#ifdef CIPHER_DEBUG
			printf("\nName: %s:\nAlgo = %08lx Algo_strength = %08lx\nMask = %08lx Mask_strength %08lx\n", cp->name, cp->algorithms, cp->algo_strength, mask, mask_strength);
			printf("ma = %08lx ma_s %08lx, ma&algo=%08lx, ma_s&algos=%08lx\n", ma, ma_s, ma&algorithms, ma_s&algo_strength);
#endif
			/*
			 * Select: if none of the mask bit was met from the
			 * cipher or not all of the bits were met, the
			 * selection does not apply.
			 */
			if (((ma == 0) && (ma_s == 0)) ||
			    ((ma & algorithms) != ma) ||
			    ((ma_s & algo_strength) != ma_s))
				continue; /* does not apply */
			}
		else if (strength_bits != cp->strength_bits)
			continue;	/* does not apply */

#ifdef CIPHER_DEBUG
		printf("Action = %d\n", rule);
#endif

		/* add the cipher if it has not been added yet. */
		if (rule == CIPHER_ADD)
			{
			if (!curr->active)
				{
				ll_append_tail(&head, curr, &tail);
				curr->active = 1;
				}
			}
		/* Move the added cipher to this location */
		else if (rule == CIPHER_ORD)
			{
			if (curr->active)
				{
				ll_append_tail(&head, curr, &tail);
				}
			}
		else if	(rule == CIPHER_DEL)
			curr->active = 0;
		else if (rule == CIPHER_KILL)
			{
			if (head == curr)
				head = curr->next;
			else
				curr->prev->next = curr->next;
			if (tail == curr)
				tail = curr->prev;
			curr->active = 0;
			if (curr->next != NULL)
				curr->next->prev = curr->prev;
			if (curr->prev != NULL)
				curr->prev->next = curr->next;
			curr->next = NULL;
			curr->prev = NULL;
			}
		}

	*head_p = head;
	*tail_p = tail;
	}

static int ssl_cipher_strength_sort(CIPHER_ORDER *list, CIPHER_ORDER **head_p,
				     CIPHER_ORDER **tail_p)
	{
	int max_strength_bits, i, *number_uses;
	CIPHER_ORDER *curr;

	/*
	 * This routine sorts the ciphers with descending strength. The sorting
	 * must keep the pre-sorted sequence, so we apply the normal sorting
	 * routine as '+' movement to the end of the list.
	 */
	max_strength_bits = 0;
	curr = *head_p;
	while (curr != NULL)
		{
		if (curr->active &&
		    (curr->cipher->strength_bits > max_strength_bits))
		    max_strength_bits = curr->cipher->strength_bits;
		curr = curr->next;
		}

	number_uses = OPENSSL_malloc((max_strength_bits + 1) * sizeof(int));
	if (!number_uses)
	{
		SSLerr(SSL_F_SSL_CIPHER_STRENGTH_SORT,ERR_R_MALLOC_FAILURE);
		return(0);
	}
	memset(number_uses, 0, (max_strength_bits + 1) * sizeof(int));

	/*
	 * Now find the strength_bits values actually used
	 */
	curr = *head_p;
	while (curr != NULL)
		{
		if (curr->active)
			number_uses[curr->cipher->strength_bits]++;