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Re: [PATCH] Remove obsolete DNSSEC support [BZ #20591]


On 9.9.2016 13:43, Florian Weimer wrote:
> The removed function declaration have never been implemented in libresolv.
> 
> 2016-09-09  Florian Weimer  <fweimer@redhat.com>
> 
> 	[BZ #20591]
> 	Remove obsolete DNSSEC support.
> 	* resolv/arpa/nameser.h (ns_key_types, NS_KEY_*, NS_ALG_*)
> 	(NS_MD5_RSA_*, NS_DSA_*, NS_NXT_*, ns_sign, ns_sign2, ns_sign_tcp)
> 	(ns_sign_tcp2, ns_sign_tcp_init, ns_find_tsig, ns_verify)
> 	(ns_verify_tcp, ns_verify_tcp_init): Remove.
> 	(ns_cert_types): Add comment.
> 	* resolv/ns_print.c (ns_sprintrrf): Do not handle DNSSEC records
> 	separately.
> 	(KEY_RSA, KEY_HMAC_MD5, dst_s_id_calc, dst_s_get_int16)
> 	(dst_s_dns_key_id): Remove.
> 	* resolv/res_debug.c (__p_key_syms, __p_cert_syms): Remove unused
> 	variables.
> 
> diff --git a/NEWS b/NEWS
> index ba1ec71..5566125 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -40,6 +40,12 @@ Version 2.25
>    for the Linux quota interface which predates kernel version 2.4.22 has
>    been removed.
>  
> +* DNSSEC-related declarations and definitions have been removed from the
> +  <arpa/nameser.h> header file, and libresolv will no longer attempt to
> +  decode the data part of DNSSEC record types.  Previous versions of glibc
> +  only implemented minimal support for the previous version of DNSSEC, which
> +  is incompatible with the currently deployed version.
> +
>  Security related changes:
>  
>    On ARM EABI (32-bit), generating a backtrace for execution contexts which
> diff --git a/resolv/arpa/nameser.h b/resolv/arpa/nameser.h
> index 04f8844..cdbec23 100644
> --- a/resolv/arpa/nameser.h
> +++ b/resolv/arpa/nameser.h
> @@ -326,15 +326,7 @@ typedef enum __ns_class {
>  	ns_c_max = 65536
>  } ns_class;
>  
> -/* DNSSEC constants. */
> -
> -typedef enum __ns_key_types {
> -	ns_kt_rsa = 1,		/*%< key type RSA/MD5 */
> -	ns_kt_dh  = 2,		/*%< Diffie Hellman */
> -	ns_kt_dsa = 3,		/*%< Digital Signature Standard (MANDATORY) */
> -	ns_kt_private = 254	/*%< Private key type starts with OID */
> -} ns_key_types;
> -
> +/* Certificate type values in CERT resource records.  */
>  typedef enum __ns_cert_types {
>  	cert_t_pkix = 1,	/*%< PKIX (X.509v3) */
>  	cert_t_spki = 2,	/*%< SPKI */
> @@ -343,82 +335,6 @@ typedef enum __ns_cert_types {
>  	cert_t_oid  = 254	/*%< OID private type */
>  } ns_cert_types;
>  
> -/* Flags field of the KEY RR rdata. */
> -#define	NS_KEY_TYPEMASK		0xC000	/*%< Mask for "type" bits */
> -#define	NS_KEY_TYPE_AUTH_CONF	0x0000	/*%< Key usable for both */
> -#define	NS_KEY_TYPE_CONF_ONLY	0x8000	/*%< Key usable for confidentiality */
> -#define	NS_KEY_TYPE_AUTH_ONLY	0x4000	/*%< Key usable for authentication */
> -#define	NS_KEY_TYPE_NO_KEY	0xC000	/*%< No key usable for either; no key */
> -/* The type bits can also be interpreted independently, as single bits: */
> -#define	NS_KEY_NO_AUTH		0x8000	/*%< Key unusable for authentication */
> -#define	NS_KEY_NO_CONF		0x4000	/*%< Key unusable for confidentiality */
> -#define	NS_KEY_RESERVED2	0x2000	/* Security is *mandatory* if bit=0 */
> -#define	NS_KEY_EXTENDED_FLAGS	0x1000	/*%< reserved - must be zero */
> -#define	NS_KEY_RESERVED4	0x0800  /*%< reserved - must be zero */
> -#define	NS_KEY_RESERVED5	0x0400  /*%< reserved - must be zero */
> -#define	NS_KEY_NAME_TYPE	0x0300	/*%< these bits determine the type */
> -#define	NS_KEY_NAME_USER	0x0000	/*%< key is assoc. with user */
> -#define	NS_KEY_NAME_ENTITY	0x0200	/*%< key is assoc. with entity eg host */
> -#define	NS_KEY_NAME_ZONE	0x0100	/*%< key is zone key */
> -#define	NS_KEY_NAME_RESERVED	0x0300	/*%< reserved meaning */
> -#define	NS_KEY_RESERVED8	0x0080  /*%< reserved - must be zero */
> -#define	NS_KEY_RESERVED9	0x0040  /*%< reserved - must be zero */
> -#define	NS_KEY_RESERVED10	0x0020  /*%< reserved - must be zero */
> -#define	NS_KEY_RESERVED11	0x0010  /*%< reserved - must be zero */
> -#define	NS_KEY_SIGNATORYMASK	0x000F	/*%< key can sign RR's of same name */
> -#define	NS_KEY_RESERVED_BITMASK ( NS_KEY_RESERVED2 | \
> -				  NS_KEY_RESERVED4 | \
> -				  NS_KEY_RESERVED5 | \
> -				  NS_KEY_RESERVED8 | \
> -				  NS_KEY_RESERVED9 | \
> -				  NS_KEY_RESERVED10 | \
> -				  NS_KEY_RESERVED11 )
> -#define NS_KEY_RESERVED_BITMASK2 0xFFFF /*%< no bits defined here */
> -/* The Algorithm field of the KEY and SIG RR's is an integer, {1..254} */
> -#define	NS_ALG_MD5RSA		1	/*%< MD5 with RSA */
> -#define	NS_ALG_DH               2	/*%< Diffie Hellman KEY */
> -#define	NS_ALG_DSA              3	/*%< DSA KEY */
> -#define	NS_ALG_DSS              NS_ALG_DSA
> -#define	NS_ALG_EXPIRE_ONLY	253	/*%< No alg, no security */
> -#define	NS_ALG_PRIVATE_OID	254	/*%< Key begins with OID giving alg */
> -/* Protocol values  */
> -/* value 0 is reserved */
> -#define NS_KEY_PROT_TLS         1
> -#define NS_KEY_PROT_EMAIL       2
> -#define NS_KEY_PROT_DNSSEC      3
> -#define NS_KEY_PROT_IPSEC       4
> -#define NS_KEY_PROT_ANY		255
> -
> -/* Signatures */
> -#define	NS_MD5RSA_MIN_BITS	 512	/*%< Size of a mod or exp in bits */
> -#define	NS_MD5RSA_MAX_BITS	4096
> -	/* Total of binary mod and exp */
> -#define	NS_MD5RSA_MAX_BYTES	((NS_MD5RSA_MAX_BITS+7/8)*2+3)
> -	/* Max length of text sig block */
> -#define	NS_MD5RSA_MAX_BASE64	(((NS_MD5RSA_MAX_BYTES+2)/3)*4)
> -#define NS_MD5RSA_MIN_SIZE	((NS_MD5RSA_MIN_BITS+7)/8)
> -#define NS_MD5RSA_MAX_SIZE	((NS_MD5RSA_MAX_BITS+7)/8)
> -
> -#define NS_DSA_SIG_SIZE         41
> -#define NS_DSA_MIN_SIZE         213
> -#define NS_DSA_MAX_BYTES        405
> -
> -/* Offsets into SIG record rdata to find various values */
> -#define	NS_SIG_TYPE	0	/*%< Type flags */
> -#define	NS_SIG_ALG	2	/*%< Algorithm */
> -#define	NS_SIG_LABELS	3	/*%< How many labels in name */
> -#define	NS_SIG_OTTL	4	/*%< Original TTL */
> -#define	NS_SIG_EXPIR	8	/*%< Expiration time */
> -#define	NS_SIG_SIGNED	12	/*%< Signature time */
> -#define	NS_SIG_FOOT	16	/*%< Key footprint */
> -#define	NS_SIG_SIGNER	18	/*%< Domain name of who signed it */
> -/* How RR types are represented as bit-flags in NXT records */
> -#define	NS_NXT_BITS 8
> -#define	NS_NXT_BIT_SET(  n,p) (p[(n)/NS_NXT_BITS] |=  (0x80>>((n)%NS_NXT_BITS)))
> -#define	NS_NXT_BIT_CLEAR(n,p) (p[(n)/NS_NXT_BITS] &= ~(0x80>>((n)%NS_NXT_BITS)))
> -#define	NS_NXT_BIT_ISSET(n,p) (p[(n)/NS_NXT_BITS] &   (0x80>>((n)%NS_NXT_BITS)))
> -#define NS_NXT_MAX 127
> -
>  /*%
>   * EDNS0 extended flags and option codes, host order.
>   */
> @@ -498,25 +414,6 @@ int		ns_name_compress (const char *, u_char *, size_t,
>  int		ns_name_skip (const u_char **, const u_char *) __THROW;
>  void		ns_name_rollback (const u_char *, const u_char **,
>  				  const u_char **) __THROW;
> -int		ns_sign (u_char *, int *, int, int, void *,
> -			 const u_char *, int, u_char *, int *, time_t) __THROW;
> -int		ns_sign2 (u_char *, int *, int, int, void *,
> -			  const u_char *, int, u_char *, int *, time_t,
> -			  u_char **, u_char **) __THROW;
> -int		ns_sign_tcp (u_char *, int *, int, int,
> -			     ns_tcp_tsig_state *, int) __THROW;
> -int		ns_sign_tcp2 (u_char *, int *, int, int,
> -			      ns_tcp_tsig_state *, int,
> -			      u_char **, u_char **) __THROW;
> -int		ns_sign_tcp_init (void *, const u_char *, int,
> -				  ns_tcp_tsig_state *) __THROW;
> -u_char		*ns_find_tsig (u_char *, u_char *) __THROW;
> -int		ns_verify (u_char *, int *, void *, const u_char *, int,
> -			   u_char *, int *, time_t *, int) __THROW;
> -int		ns_verify_tcp (u_char *, int *, ns_tcp_tsig_state *, int)
> -     __THROW;
> -int		ns_verify_tcp_init (void *, const u_char *, int,
> -				    ns_tcp_tsig_state *) __THROW;
>  int		ns_samedomain (const char *, const char *) __THROW;
>  int		ns_subdomain (const char *, const char *) __THROW;
>  int		ns_makecanon (const char *, char *, size_t) __THROW;
> diff --git a/resolv/ns_print.c b/resolv/ns_print.c
> index 7a0e7d5..f55680c 100644
> --- a/resolv/ns_print.c
> +++ b/resolv/ns_print.c
> @@ -47,8 +47,6 @@ static int	addstr(const char *src, size_t len,
>  static int	addtab(size_t len, size_t target, int spaced,
>  		       char **buf, size_t *buflen);
>  
> -static u_int16_t dst_s_dns_key_id(const u_char *, const int);
> -
>  /* Macros. */
>  
>  #define	T(x) \
> @@ -436,124 +434,6 @@ ns_sprintrrf(const u_char *msg, size_t msglen,
>  		break;
>  	    }
>  
> -	case ns_t_key: {
> -		char base64_key[NS_MD5RSA_MAX_BASE64];
> -		u_int keyflags, protocol, algorithm, key_id;
> -		const char *leader;
> -		int n;
> -
> -		if (rdlen < 0U + NS_INT16SZ + NS_INT8SZ + NS_INT8SZ)
> -			goto formerr;
> -
> -		/* Key flags, Protocol, Algorithm. */
> -		key_id = dst_s_dns_key_id(rdata, edata-rdata);
> -		keyflags = ns_get16(rdata);  rdata += NS_INT16SZ;
> -		protocol = *rdata++;
> -		algorithm = *rdata++;
> -		len = SPRINTF((tmp, "0x%04x %u %u",
> -			       keyflags, protocol, algorithm));
> -		T(addstr(tmp, len, &buf, &buflen));
> -
> -		/* Public key data. */
> -		len = b64_ntop(rdata, edata - rdata,
> -			       base64_key, sizeof base64_key);
> -		if (len < 0)
> -			goto formerr;
> -		if (len > 15) {
> -			T(addstr(" (", 2, &buf, &buflen));
> -			leader = "\n\t\t";
> -			spaced = 0;
> -		} else
> -			leader = " ";
> -		for (n = 0; n < len; n += 48) {
> -			T(addstr(leader, strlen(leader), &buf, &buflen));
> -			T(addstr(base64_key + n, MIN(len - n, 48),
> -				 &buf, &buflen));
> -		}
> -		if (len > 15)
> -			T(addstr(" )", 2, &buf, &buflen));
> -		n = SPRINTF((tmp, " ; key_tag= %u", key_id));
> -		T(addstr(tmp, n, &buf, &buflen));
> -
> -		break;
> -	    }
> -
> -	case ns_t_sig: {
> -		char base64_key[NS_MD5RSA_MAX_BASE64];
> -		u_int type, algorithm, labels, footprint;
> -		const char *leader;
> -		u_long t;
> -		int n;
> -
> -		if (rdlen < 22U)
> -			goto formerr;
> -
> -		/* Type covered, Algorithm, Label count, Original TTL. */
> -	        type = ns_get16(rdata);  rdata += NS_INT16SZ;
> -		algorithm = *rdata++;
> -		labels = *rdata++;
> -		t = ns_get32(rdata);  rdata += NS_INT32SZ;
> -		len = SPRINTF((tmp, "%s %d %d %lu ",
> -			       p_type(type), algorithm, labels, t));
> -		T(addstr(tmp, len, &buf, &buflen));
> -		if (labels > (u_int)dn_count_labels(name))
> -			goto formerr;
> -
> -		/* Signature expiry. */
> -		t = ns_get32(rdata);  rdata += NS_INT32SZ;
> -		len = SPRINTF((tmp, "%s ", p_secstodate(t)));
> -		T(addstr(tmp, len, &buf, &buflen));
> -
> -		/* Time signed. */
> -		t = ns_get32(rdata);  rdata += NS_INT32SZ;
> -		len = SPRINTF((tmp, "%s ", p_secstodate(t)));
> -		T(addstr(tmp, len, &buf, &buflen));
> -
> -		/* Signature Footprint. */
> -		footprint = ns_get16(rdata);  rdata += NS_INT16SZ;
> -		len = SPRINTF((tmp, "%u ", footprint));
> -		T(addstr(tmp, len, &buf, &buflen));
> -
> -		/* Signer's name. */
> -		T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
> -
> -		/* Signature. */
> -		len = b64_ntop(rdata, edata - rdata,
> -			       base64_key, sizeof base64_key);
> -		if (len > 15) {
> -			T(addstr(" (", 2, &buf, &buflen));
> -			leader = "\n\t\t";
> -			spaced = 0;
> -		} else
> -			leader = " ";
> -		if (len < 0)
> -			goto formerr;
> -		for (n = 0; n < len; n += 48) {
> -			T(addstr(leader, strlen(leader), &buf, &buflen));
> -			T(addstr(base64_key + n, MIN(len - n, 48),
> -				 &buf, &buflen));
> -		}
> -		if (len > 15)
> -			T(addstr(" )", 2, &buf, &buflen));
> -		break;
> -	    }
> -
> -	case ns_t_nxt: {
> -		int n, c;
> -
> -		/* Next domain name. */
> -		T(addname(msg, msglen, &rdata, origin, &buf, &buflen));
> -
> -		/* Type bit map. */
> -		n = edata - rdata;
> -		for (c = 0; c < n*8; c++)
> -			if (NS_NXT_BIT_ISSET(c, rdata)) {
> -				len = SPRINTF((tmp, " %s", p_type(c)));
> -				T(addstr(tmp, len, &buf, &buflen));
> -			}
> -		break;
> -	    }
> -
>  	case ns_t_cert: {
>  		u_int c_type, key_tag, alg;
>  		int n;
> @@ -887,81 +767,3 @@ addtab(size_t len, size_t target, int spaced, char **buf, size_t *buflen) {
>  	}
>  	return (spaced);
>  }
> -
> -/* DST algorithm codes */
> -#define KEY_RSA			1
> -#define KEY_HMAC_MD5		157
> -
> -/*%
> - * calculates a checksum used in dst for an id.
> - * takes an array of bytes and a length.
> - * returns a 16  bit checksum.
> - */
> -static u_int16_t
> -dst_s_id_calc(const u_char *key, const int keysize)
> -{
> -	u_int32_t ac;
> -	const u_char *kp = key;
> -	int size = keysize;
> -
> -	if (!key || (keysize <= 0))
> -		return (0xffffU);
> -
> -	for (ac = 0; size > 1; size -= 2, kp += 2)
> -		ac += ((*kp) << 8) + *(kp + 1);
> -
> -	if (size > 0)
> -		ac += ((*kp) << 8);
> -	ac += (ac >> 16) & 0xffff;
> -
> -	return (ac & 0xffff);
> -}
> -
> -/*%
> - * dst_s_get_int16
> - *     This routine extracts a 16 bit integer from a two byte character
> - *     string.  The character string is assumed to be in network byte
> - *     order and may be unaligned.  The number returned is in host order.
> - * Parameter
> - *     buf     A two byte character string.
> - * Return
> - *     The converted integer value.
> - */
> -
> -static u_int16_t
> -dst_s_get_int16(const u_char *buf)
> -{
> -	u_int16_t a = 0;
> -	a = ((u_int16_t)(buf[0] << 8)) | ((u_int16_t)(buf[1]));
> -	return (a);
> -}
> -
> -/*%
> - * dst_s_dns_key_id() Function to calculate DNSSEC footprint from KEY record
> - *   rdata
> - * Input:
> - *	dns_key_rdata: the raw data in wire format
> - *      rdata_len: the size of the input data
> - * Output:
> - *      the key footprint/id calculated from the key data
> - */
> -static u_int16_t
> -dst_s_dns_key_id(const u_char *dns_key_rdata, const int rdata_len)
> -{
> -	if (!dns_key_rdata)
> -		return 0;
> -
> -	/* compute id */
> -	if (dns_key_rdata[3] == KEY_RSA)	/*%< Algorithm RSA */
> -		return dst_s_get_int16((const u_char *)
> -				       &dns_key_rdata[rdata_len - 3]);
> -	else if (dns_key_rdata[3] == KEY_HMAC_MD5)
> -		/* compatibility */
> -		return 0;
> -	else
> -		/* compute a checksum on the key part of the key rr */
> -		return dst_s_id_calc(dns_key_rdata, rdata_len);
> -}
> -
> -
> -/*! \file */
> diff --git a/resolv/res_debug.c b/resolv/res_debug.c
> index bd95590..9b33e19 100644
> --- a/resolv/res_debug.c
> +++ b/resolv/res_debug.c
> @@ -371,24 +371,6 @@ const struct res_sym __p_update_section_syms[] attribute_hidden = {
>  	{0,             (char *)0}
>  };
>  
> -const struct res_sym __p_key_syms[] attribute_hidden = {
> -	{NS_ALG_MD5RSA,		"RSA",		"RSA KEY with MD5 hash"},
> -	{NS_ALG_DH,		"DH",		"Diffie Hellman"},
> -	{NS_ALG_DSA,		"DSA",		"Digital Signature Algorithm"},
> -	{NS_ALG_EXPIRE_ONLY,	"EXPIREONLY",	"No algorithm"},
> -	{NS_ALG_PRIVATE_OID,	"PRIVATE",	"Algorithm obtained from OID"},
> -	{0,			NULL,		NULL}
> -};
> -
> -const struct res_sym __p_cert_syms[] attribute_hidden = {
> -	{cert_t_pkix,	"PKIX",		"PKIX (X.509v3) Certificate"},
> -	{cert_t_spki,	"SPKI",		"SPKI certificate"},
> -	{cert_t_pgp,	"PGP",		"PGP certificate"},
> -	{cert_t_url,	"URL",		"URL Private"},
> -	{cert_t_oid,	"OID",		"OID Private"},
> -	{0,		NULL,		NULL}
> -};
> -
>  /*
>   * Names of RR types and qtypes.  Types and qtypes are the same, except
>   * that T_ANY is a qtype but not a type.  (You can ask for records of type

It makes sense to me (but I did not thoroughly review the code).

-- 
Petr Spacek  @  Red Hat


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