git: a8b8b7065c8e - stable/15 - libc/resolv: get rid of MD5

The branch stable/15 has been updated by fuz:

URL: https://cgit.FreeBSD.org/src/commit/?id=a8b8b7065c8ecb858bb1b9576663869d06bd37a4

commit a8b8b7065c8ecb858bb1b9576663869d06bd37a4
Author:     Robert Clausecker <fuz@FreeBSD.org>
AuthorDate: 2025-09-29 13:53:14 +0000
Commit:     Robert Clausecker <fuz@FreeBSD.org>
CommitDate: 2025-10-31 13:03:13 +0000

    libc/resolv: get rid of MD5
    
    MD5 is used by libc/resolv to generate a random sequence id from a
    current time stamp.  Replace this convoluted mechanism with a call
    to arc4random().  This permits us to entirely drop MD5 from libc,
    simplifying the MD5 rework proposed in D45670.
    
    Approved by:    markj
    Reviewed by:    kevans, markj
    See also:       D45670
    Event:          EuroBSDcon 2025
    Differential Revision:  https://reviews.freebsd.org/D52784
    
    (cherry picked from commit d518f64cef6db1d301377e78742b94ca96a881e3)
---
 include/resolv.h               |  4 +--
 lib/libc/Makefile              |  1 -
 lib/libc/include/port_before.h |  1 -
 lib/libc/md/Makefile.inc       |  3 ---
 lib/libc/resolv/Symbol.map     |  1 -
 lib/libc/resolv/res_init.c     | 61 +++++-------------------------------------
 6 files changed, 7 insertions(+), 64 deletions(-)

diff --git a/include/resolv.h b/include/resolv.h
index f32f52bab431..6ef79601b5f8 100644
--- a/include/resolv.h
+++ b/include/resolv.h
@@ -188,7 +188,7 @@ struct __res_state {
 			struct __res_state_ext *ext;	/*%< extension for IPv6 */
 		} _ext;
 	} _u;
-	u_char	*_rnd;			/*%< PRIVATE: random state */
+	u_char	*_rnd;			/*%< PRIVATE: random state (unused) */
 };
 
 typedef struct __res_state *res_state;
@@ -380,7 +380,6 @@ extern const struct res_sym __p_rcode_syms[];
 #define res_nisourserver	__res_nisourserver
 #define res_ownok		__res_ownok
 #define res_queriesmatch	__res_queriesmatch
-#define res_rndinit		__res_rndinit
 #define res_randomid		__res_randomid
 #define res_nrandomid		__res_nrandomid
 #define sym_ntop		__sym_ntop
@@ -445,7 +444,6 @@ int		dn_count_labels(const char *);
 int		dn_comp(const char *, u_char *, int, u_char **, u_char **);
 int		dn_expand(const u_char *, const u_char *, const u_char *,
 			  char *, int);
-void		res_rndinit(res_state);
 u_int		res_randomid(void);
 u_int		res_nrandomid(res_state);
 int		res_nameinquery(const char *, int, int, const u_char *,
diff --git a/lib/libc/Makefile b/lib/libc/Makefile
index d0c254e33396..8705568f6d34 100644
--- a/lib/libc/Makefile
+++ b/lib/libc/Makefile
@@ -109,7 +109,6 @@ NOASM=
 .include "${LIBC_SRCTOP}/inet/Makefile.inc"
 .include "${LIBC_SRCTOP}/isc/Makefile.inc"
 .include "${LIBC_SRCTOP}/locale/Makefile.inc"
-.include "${LIBC_SRCTOP}/md/Makefile.inc"
 .include "${LIBC_SRCTOP}/nameser/Makefile.inc"
 .include "${LIBC_SRCTOP}/net/Makefile.inc"
 .include "${LIBC_SRCTOP}/nls/Makefile.inc"
diff --git a/lib/libc/include/port_before.h b/lib/libc/include/port_before.h
index cfc43c53f157..aa2cd394104a 100644
--- a/lib/libc/include/port_before.h
+++ b/lib/libc/include/port_before.h
@@ -5,7 +5,6 @@
 #define _LIBC		1
 #define DO_PTHREADS	1
 #define USE_POLL	1
-#define HAVE_MD5	1
 
 #define ISC_SOCKLEN_T	socklen_t
 #define ISC_FORMAT_PRINTF(fmt, args) \
diff --git a/lib/libc/md/Makefile.inc b/lib/libc/md/Makefile.inc
deleted file mode 100644
index 82c5f0670485..000000000000
--- a/lib/libc/md/Makefile.inc
+++ /dev/null
@@ -1,3 +0,0 @@
-.PATH: ${SRCTOP}/sys/kern
-
-SRCS+=	md5c.c
diff --git a/lib/libc/resolv/Symbol.map b/lib/libc/resolv/Symbol.map
index 6b9c43298fb5..26daecbe2eff 100644
--- a/lib/libc/resolv/Symbol.map
+++ b/lib/libc/resolv/Symbol.map
@@ -103,6 +103,5 @@ FBSD_1.0 {
 };
 
 FBSD_1.4 {
-	__res_rndinit;
 	__res_nrandomid;
 };
diff --git a/lib/libc/resolv/res_init.c b/lib/libc/resolv/res_init.c
index 71ab2dcb7038..5a2fce013c8c 100644
--- a/lib/libc/resolv/res_init.c
+++ b/lib/libc/resolv/res_init.c
@@ -86,19 +86,6 @@
 #include <unistd.h>
 #include <netdb.h>
 
-#ifndef HAVE_MD5
-# include "../dst/md5.h"
-#else
-# ifdef SOLARIS2
-#  include <sys/md5.h>
-# elif _LIBC
-# include <md5.h>
-# endif
-#endif
-#ifndef _MD5_H_
-# define _MD5_H_ 1	/*%< make sure we do not include rsaref md5.h file */
-#endif
-
 #include "un-namespace.h"
 
 #include "port_after.h"
@@ -184,8 +171,6 @@ __res_vinit(res_state statp, int preinit) {
 		statp->options = RES_DEFAULT;
 	}
 
-	statp->_rnd = malloc(16);
-	res_rndinit(statp);
 	statp->id = res_nrandomid(statp);
 
 	memset(u, 0, sizeof(u));
@@ -733,48 +718,18 @@ net_mask(struct in_addr in)		/*!< XXX - should really use system's version of th
 }
 #endif
 
-static u_char srnd[16];
-
 void
-res_rndinit(res_state statp)
+freebsd15_res_rndinit(res_state statp)
 {
-	struct timeval now;
-	u_int32_t u32;
-	u_int16_t u16;
-	u_char *rnd = statp->_rnd == NULL ? srnd : statp->_rnd;
-
-	gettimeofday(&now, NULL);
-	u32 = now.tv_sec;
-	memcpy(rnd, &u32, 4);
-	u32 = now.tv_usec;
-	memcpy(rnd + 4, &u32, 4);
-	u32 += now.tv_sec;
-	memcpy(rnd + 8, &u32, 4);
-	u16 = getpid();
-	memcpy(rnd + 12, &u16, 2);
+	(void)statp;
 }
+__sym_compat(__res_rndinit, freebsd15_res_rndinit, FBSD_1.4);
 
 u_int
 res_nrandomid(res_state statp) {
-	struct timeval now;
-	u_int16_t u16;
-	MD5_CTX ctx;
-	u_char *rnd = statp->_rnd == NULL ? srnd : statp->_rnd;
-
-	gettimeofday(&now, NULL);
-	u16 = (u_int16_t) (now.tv_sec ^ now.tv_usec);
-	memcpy(rnd + 14, &u16, 2);
-#ifndef HAVE_MD5
-	MD5_Init(&ctx);
-	MD5_Update(&ctx, rnd, 16);
-	MD5_Final(rnd, &ctx);
-#else
-	MD5Init(&ctx);
-	MD5Update(&ctx, rnd, 16);
-	MD5Final(rnd, &ctx);
-#endif
-	memcpy(&u16, rnd + 14, 2);
-	return ((u_int) u16);
+	(void) statp;
+
+	return ((u_int)(arc4random() & 0xffff));
 }
 
 /*%
@@ -808,10 +763,6 @@ res_ndestroy(res_state statp) {
 		free(statp->_u._ext.ext);
 		statp->_u._ext.ext = NULL;
 	}
-	if (statp->_rnd != NULL) {
-		free(statp->_rnd);
-		statp->_rnd = NULL;
-	}
 	statp->options &= ~RES_INIT;
 }