Fork before performing tcpwrappers check.

Don't rely on nonstandard bsd_signal() function, instead
 require that the platform has sigaction().  This is 2001,
 after all.  This may resolve some potential portability
 problems.

Log a message if memory allocation fails, instead of dying silently.

Clean up the main dispatch loop.

Use <sysexits.h> for exit codes, if it exists.

Reformat tftpd.c to match the other files.

README

@@ -4,6 +4,22 @@ This is tftp-hpa-0.18; this version was put out by H. Peter Anvin
 ===> IMPORTANT: SEE THE FILE "README.security" FOR IMPORTANT SECURITY
 ===> CHANGES IN THIS VERSION!!!!!!!!!
 
+Changes in 0.19:
+	Fork before performing tcpwrappers check.
+
+	Don't rely on nonstandard bsd_signal() function, instead
+	require that the platform has sigaction().  This is 2001,
+	after all.  This may resolve some potential portability
+	problems.
+
+	Log a message if memory allocation fails, instead of dying
+	silently.
+
+	Clean up the main dispatch loop.
+
+	Use <sysexits.h> for exit codes, if it exists.
+
+
 Changes in 0.18:
 	Support (almost) arbitrary filename remappings via regular
 	expression-based rulesets.

config.h.in

@@ -22,4 +22,5 @@
 #undef HAVE_STRUCT_IN_PKTINFO
 #undef HAVE_SETREUID
 #undef HAVE_SETREGID
+#undef HAVE_SYSEXITS_H
 #undef WITH_REGEX

configure.in

@@ -49,6 +49,8 @@ PA_ADD_CFLAGS(-pipe)
 
 PA_SIGSETJMP([AC_DEFINE(HAVE_SIGSETJMP)])
 
+AC_CHECK_HEADERS(sysexits.h)
+
 LIBXTRA=false
 
 AC_SEARCH_LIBS(xmalloc, iberty, , LIBXTRA=true LIBOBJS="$LIBOBJS xmalloc.o")

tftp/tftpsubs.h

@@ -42,6 +42,9 @@
  * Prototypes for read-ahead/write-behind subroutines for tftp user and
  * server.
  */
+#ifndef TFTPSUBS_H
+#define TFTPSUBS_H
+
 #include <stdlib.h>
 
 struct tftphdr *r_init(void);
@@ -62,3 +65,5 @@ extern int segsize;
  */
 extern void *xmalloc(size_t);
 extern char *xstrdup(const char *);
+
+#endif

tftpd/Makefile

@@ -3,7 +3,7 @@ all: tftpd
 -include ../MCONFIG
 -include ../MRULES
 
-OBJS = tftpd.o tftpsubs.o recvfrom.o $(TFTPDOBJS)
+OBJS = tftpd.o tftpsubs.o recvfrom.o misc.o $(TFTPDOBJS)
 
 tftpd: $(OBJS)
 	$(CC) $(LDFLAGS) $^ $(LIBS) -o $@

tftpd/misc.c

@@ -0,0 +1,71 @@
+/* $Id$ */
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2001 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software available under the same license
+ *   as the "OpenBSD" operating system, distributed at
+ *   http://www.openbsd.org/.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * misc.c
+ *
+ * Minor help routines.
+ */
+
+#include <syslog.h>
+#include <signal.h>
+#include <string.h>
+#include "tftpd.h"
+
+/*
+ * Set the signal handler and flags.  Basically a user-friendly
+ * wrapper around sigaction().
+ */
+void set_signal(int signum, void (*handler)(int), int flags)
+{
+  struct sigaction sa;
+
+  memset(&sa, 0, sizeof sa);
+  sa.sa_handler = handler;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = flags;
+  
+  if ( sigaction(signum, &sa, NULL) ) {
+    syslog(LOG_ERR, "sigaction: %m");
+    exit(EX_OSERR);
+  }
+}
+
+/*
+ * malloc() that syslogs an error message and bails if it fails.
+ */
+void *tfmalloc(size_t size)
+{
+  void *p = malloc(size);
+
+  if ( !p ) {
+    syslog(LOG_ERR, "malloc: %m");
+    exit(EX_OSERR);
+  }
+
+  return p;
+}
+
+/*
+ * strdup() that does the equivalent
+ */
+char *tfstrdup(const char *str)
+{
+  char *p = strdup(str);
+
+  if ( !p ) {
+    syslog(LOG_ERR, "strdup: %m");
+    exit(EX_OSERR);
+  }
+
+  return p;
+}
+  

tftpd/remap.c

@@ -22,7 +22,7 @@
 #include <syslog.h>
 #include <regex.h>
 
-#include "tftpsubs.h"
+#include "tftpd.h"
 #include "remap.h"
 
 #define DEADMAN_MAX_STEPS	1024    /* Timeout after this many steps */
@@ -197,7 +197,7 @@ static int parseline(char *line, struct rule *r, int lineno)
 
   /* Read the rewrite pattern, if any */
   if ( readescstring(buffer, &line) ) {
-    r->pattern = xstrdup(buffer);
+    r->pattern = tfstrdup(buffer);
   } else {
     r->pattern = "";
   }
@@ -212,7 +212,7 @@ struct rule *parserulefile(FILE *f)
   char line[LINE_MAX];
   struct rule *first_rule = NULL;
   struct rule **last_rule = &first_rule;
-  struct rule *this_rule  = xmalloc(sizeof(struct rule));
+  struct rule *this_rule  = tfmalloc(sizeof(struct rule));
   int rv;
   int lineno = 0;
   int err = 0;
@@ -224,7 +224,7 @@ struct rule *parserulefile(FILE *f)
     if ( rv > 0 ) {
       *last_rule = this_rule;
       last_rule = &this_rule->next;
-      this_rule = xmalloc(sizeof(struct rule));
+      this_rule = tfmalloc(sizeof(struct rule));
     }
   }
 
@@ -232,7 +232,7 @@ struct rule *parserulefile(FILE *f)
 
   if ( err ) {
     /* Bail on error, we have already logged an error message */
-    exit(1);
+    exit(EX_CONFIG);
   }
 
   return first_rule;
@@ -241,7 +241,7 @@ struct rule *parserulefile(FILE *f)
 /* Execute a rule set on a string; returns a malloc'd new string. */
 char *rewrite_string(const char *input, const struct rule *rules, int is_put)
 {
-  char *current = xstrdup(input);
+  char *current = tfstrdup(input);
   char *newstr;
   const struct rule *ruleptr = rules;
   regmatch_t pmatch[10];
@@ -272,7 +272,7 @@ char *rewrite_string(const char *input, const struct rule *rules, int is_put)
 	
 	if ( ruleptr->rule_flags & RULE_REWRITE ) {
 	  len = genmatchstring(NULL, ruleptr->pattern, current, pmatch);
-	  newstr = xmalloc(len+1);
+	  newstr = tfmalloc(len+1);
 	  genmatchstring(newstr, ruleptr->pattern, current, pmatch);
 	  free(current);
 	  current = newstr;

tftpd/remap.h

@@ -15,6 +15,9 @@
  * Prototypes for regular-expression based filename remapping.
  */
 
+#ifndef TFTPD_REMAP_H
+#define TFTPD_REMAP_H
+
 #include <stdlib.h>
 #include <stdio.h>
 #include "../config.h"
@@ -30,4 +33,6 @@ struct rule *parserulefile(FILE *);
 /* Execute a rule set on a string; returns a malloc'd new string. */
 char *rewrite_string(const char *, const struct rule *, int);
 
-#endif
+#endif /* WITH_REGEX */
+#endif /* TFTPD_REMAP_H */
+

tftpd/tftpd.c

@@ -74,7 +74,7 @@ static const char *rcsid = "tftp-hpa $Id$";
 #include <unistd.h>
 #include <limits.h>
 
-#include "../config.h"
+#include "tftpd.h"
 #include "tftpsubs.h"
 #include "recvfrom.h"
 #include "remap.h"
@@ -88,14 +88,6 @@ int allow_severity	= -1;	/* Don't log at all */
 struct request_info wrap_request;
 #endif
 
-void bsd_signal(int, void (*)(int));
-
-#ifndef HAVE_SIGSETJMP
-#define sigsetjmp(x,y)  setjmp(x)
-#define siglongjmp(x,y) longjmp(x,y)
-#define sigjmp_buf jmp_buf
-#endif
-
 #define	TIMEOUT 5		/* Default timeout (seconds) */
 #define TRIES   4		/* Number of attempts to send each packet */
 #define TIMEOUT_LIMIT (TRIES*(TRIES+1)/2)
@@ -167,7 +159,7 @@ usage(void)
 {
   syslog(LOG_ERR, "Usage: %s [-vc][-m mappings][-u user][-t timeout][-r option...] [-s] [directory ...]",
 	 __progname);
-	exit(1);
+  exit(EX_USAGE);
 }
 
 int
@@ -213,7 +205,7 @@ main(int argc, char **argv)
       }
       if ( !opt->o_opt ) {
 	syslog(LOG_ERR, "Unknown option: %s", optarg);
-			exit(1);
+	exit(EX_USAGE);
       }
       break;
 #ifdef WITH_REGEX
@@ -222,12 +214,12 @@ main(int argc, char **argv)
 	FILE *f;
 	if ( rewrite_rules ) {
 	  syslog(LOG_ERR, "Multiple -m options");
-		      exit(1);
+	  exit(EX_USAGE);
 	}
 	f = fopen(optarg, "rt");
 	if ( !f ) {
 	  syslog(LOG_ERR, "Cannot open map file: %s: %m", optarg);
-		      exit(1);
+	  exit(EX_NOINPUT);
 	}
 	rewrite_rules = parserulefile(f);
 	fclose(f);
@@ -249,7 +241,7 @@ main(int argc, char **argv)
       dirs = calloc(ndirs+2, sizeof(char *));
     if (dirs == NULL) {
       syslog(LOG_ERR, "malloc: %m");
-			exit(1);
+      exit(EX_OSERR);
     }			
     dirs[n++] = argv[optind];
     dirs[n] = NULL;
@@ -259,38 +251,38 @@ main(int argc, char **argv)
   if (secure) {
     if (ndirs == 0) {
       syslog(LOG_ERR, "no -s directory");
-			exit(1);
+      exit(EX_USAGE);
     }
     if (ndirs > 1) {
       syslog(LOG_ERR, "too many -s directories");
-			exit(1);
+      exit(EX_USAGE);
     }
     if (chdir(dirs[0])) {
       syslog(LOG_ERR, "%s: %m", dirs[0]);
-			exit(1);
+      exit(EX_NOINPUT);
     }
   }
   
   pw = getpwnam(user);
   if (!pw) {
     syslog(LOG_ERR, "no user %s: %m", user);
-		exit(1);
+    exit(EX_NOUSER);
   }
   
   if (ioctl(fd, FIONBIO, &on) < 0) {
     syslog(LOG_ERR, "ioctl(FIONBIO): %m");
-		exit(1);
+    exit(EX_OSERR);
   }
   
   /* This means we don't want to wait() for children */
-	bsd_signal(SIGCHLD, SIG_IGN);
+  set_signal(SIGCHLD, SIG_IGN, SA_NOCLDSTOP);
   
   /* Take SIGHUP and use it to set a variable.  This
      is polled synchronously to make sure we don't
      lose packets as a result. */
-	bsd_signal(SIGHUP, handle_sighup);
+  set_signal(SIGHUP, handle_sighup, 0);
   
-	do {
+  while ( 1 ) {
     fd_set readset;
     struct timeval tv_timeout;
     int rv;
@@ -316,9 +308,23 @@ main(int argc, char **argv)
     
     if (n < 0) {
       syslog(LOG_ERR, "recvfrom: %m");
-	    exit(1);
+      exit(EX_IOERR);
     }
     
+    /*
+     * Now that we have read the request packet from the UDP
+     * socket, we fork and go back to listening to the socket.
+     */
+    pid = fork();
+    if (pid < 0) {
+      syslog(LOG_ERR, "fork: %m");
+      exit(EX_OSERR);	/* Return to inetd, just in case */
+    } else if ( pid == 0 )
+      break;			/* Child exit, parent loop */
+  }
+  
+  /* Child process: handle the actual request here */
+  
 #ifdef HAVE_TCPWRAPPERS
   /* Verify if this was a legal request for us.  This has to be
      done before the chroot, while /etc is still accessible. */
@@ -333,31 +339,18 @@ main(int argc, char **argv)
     if ( deny_severity != -1 )
       syslog(deny_severity, "connection refused from %s",
 	     inet_ntoa(from.sin_addr));
-	    exit(1);		/* Access denied */
+    exit(EX_NOPERM);	/* Access denied */
   } else if ( allow_severity != -1 ) {
     syslog(allow_severity, "connect from %s",
 	   inet_ntoa(from.sin_addr));
   }
 #endif
   
-	/*
-	 * Now that we have read the request packet from the UDP
-	 * socket, we fork and go back to listening to the socket.
-	 */
-	  pid = fork();
-	  if (pid < 0) {
-	    syslog(LOG_ERR, "fork: %m");
-	    exit(1);		/* Return to inetd, just in case */
-	  }
-	} while ( pid > 0 );	/* Parent process continues... */
-
-	/* Child process: handle the actual request here */
-
   /* Chroot and drop privileges */
   
   if (secure && chroot(".")) {
     syslog(LOG_ERR, "chroot: %m");
-		exit(1);
+    exit(EX_OSERR);
   }
   
 #ifdef HAVE_SETREGID
@@ -376,31 +369,35 @@ main(int argc, char **argv)
   
   if ( setrv ) {
     syslog(LOG_ERR, "cannot drop privileges: %m");
-	  exit(1);
+    exit(EX_OSERR);
   }
   
-	/* Close file descriptors we don't need */
+  /* Ignore SIGHUP */
+  set_signal(SIGHUP, SIG_IGN, 0);
   
-	from.sin_family = AF_INET;
+  /* Close file descriptors we don't need */
-	alarm(0);
   close(fd);
   close(1);
   
+  /* Other basic setup */
+  from.sin_family = AF_INET;
+  alarm(0);
+  
   /* Process the request... */
   
   peer = socket(AF_INET, SOCK_DGRAM, 0);
   if (peer < 0) {
     syslog(LOG_ERR, "socket: %m");
-		exit(1);
+    exit(EX_IOERR);
   }
   myaddr.sin_port = htons(0); /* We want a new local port */
   if (bind(peer, (struct sockaddr *)&myaddr, sizeof (myaddr)) < 0) {
     syslog(LOG_ERR, "bind: %m");
-		exit(1);
+    exit(EX_IOERR);
   }
   if (connect(peer, (struct sockaddr *)&from, sizeof(from)) < 0) {
     syslog(LOG_ERR, "connect: %m");
-		exit(1);
+    exit(EX_IOERR);
   }
   tp = (struct tftphdr *)buf;
   tp->th_opcode = ntohs(tp->th_opcode);
@@ -515,7 +512,7 @@ tftp(struct tftphdr *tp, int size)
     else
       (*pf->f_send)(pf, NULL, 0);
   }
-	exit(1);
+  exit(EX_SOFTWARE);		/* We should never get here */
 }
 
 static int blksize_set;
@@ -789,7 +786,7 @@ oack:
       goto abort;
     }
     for ( ; ; ) {
-	          bsd_signal(SIGALRM, timer);
+      set_signal(SIGALRM, timer, SA_RESTART);
       alarm(rexmtval);
       n = recv(peer, ackbuf, sizeof(ackbuf), 0);
       alarm(0);
@@ -834,7 +831,7 @@ send_data:
     }
     read_ahead(file, pf->f_convert);
     for ( ; ; ) {
-		        bsd_signal(SIGALRM, timer);
+      set_signal(SIGALRM, timer, SA_RESTART);
       alarm(rexmtval);	/* read the ack */
       n = recv(peer, ackbuf, sizeof (ackbuf), 0);
       alarm(0);
@@ -899,7 +896,7 @@ recvfile(struct formats *pf, struct tftphdr *oap, int oacklen)
     }
     block++;
     (void) sigsetjmp(timeoutbuf,1);
-		bsd_signal(SIGALRM, timer);
+    set_signal(SIGALRM, timer, SA_RESTART);
   send_ack:
     if (send(peer, ackbuf, acksize, 0) != acksize) {
       syslog(LOG_ERR, "tftpd: write(ack): %m");
@@ -907,7 +904,7 @@ send_ack:
     }
     write_behind(file, pf->f_convert);
     for ( ; ; ) {
-		        bsd_signal(SIGALRM, timer);
+      set_signal(SIGALRM, timer, SA_RESTART);
       alarm(rexmtval);
       n = recv(peer, dp, PKTSIZE, 0);
       alarm(0);
@@ -944,7 +941,7 @@ send_ack:
   ap->th_block = htons((u_short)(block));
   (void) send(peer, ackbuf, 4, 0);
   
-	bsd_signal(SIGALRM, justquit);      /* just quit on timeout */
+  set_signal(SIGALRM, justquit, SA_RESETHAND); /* just quit on timeout */
   alarm(rexmtval);
   n = recv(peer, buf, sizeof (buf), 0); /* normally times out and quits */
   alarm(0);

tftpd/tftpd.h

@@ -0,0 +1,54 @@
+/* $Id$ */
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2001 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software available under the same license
+ *   as the "OpenBSD" operating system, distributed at
+ *   http://www.openbsd.org/.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * tftpd.h
+ *
+ * Prototypes for various functions that are part of the tftpd server.
+ */
+
+#ifndef TFTPD_TFTPD_H
+#define TFTPD_TFTPD_H
+
+#include <stdlib.h>
+#include <stdio.h>
+#include "../config.h"
+#ifdef HAVE_SYSEXITS_H
+#include <sysexits.h>
+#else
+#define EX_USAGE        64      /* command line usage error */
+#define EX_DATAERR      65      /* data format error */
+#define EX_NOINPUT      66      /* cannot open input */
+#define EX_NOUSER       67      /* addressee unknown */
+#define EX_NOHOST       68      /* host name unknown */
+#define EX_UNAVAILABLE  69      /* service unavailable */
+#define EX_SOFTWARE     70      /* internal software error */
+#define EX_OSERR        71      /* system error (e.g., can't fork) */
+#define EX_OSFILE       72      /* critical OS file missing */
+#define EX_CANTCREAT    73      /* can't create (user) output file */
+#define EX_IOERR        74      /* input/output error */
+#define EX_TEMPFAIL     75      /* temp failure; user is invited to retry */
+#define EX_PROTOCOL     76      /* remote error in protocol */
+#define EX_NOPERM       77      /* permission denied */
+#define EX_CONFIG       78      /* configuration error */
+#endif
+
+#ifndef HAVE_SIGSETJMP
+#define sigsetjmp(x,y)  setjmp(x)
+#define siglongjmp(x,y) longjmp(x,y)
+#define sigjmp_buf jmp_buf
+#endif
+
+void set_signal(int, void (*)(int), int);
+void *tfmalloc(size_t);
+char *tfstrdup(const char *);
+
+#endif