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Fork before performing tcpwrappers check.

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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.
This commit is contained in:
hpa 2001-07-20 06:59:54 +00:00
parent e4650ab86f
commit 81822ea738
10 changed files with 862 additions and 711 deletions
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16
README
View file

@ -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.

1
config.h.in
View file

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

2
configure.in
View file

@ -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")

5
tftp/tftpsubs.h
View file

@ -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

2
tftpd/Makefile
View file

@ -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 $@

71
tftpd/misc.c Normal file
View file

@ -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;
}

14
tftpd/remap.c
View file

@ -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;

7
tftpd/remap.h
View file

@ -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 */

99
tftpd/tftpd.c
View file

@ -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;
alarm(0);
/* Close file descriptors we don't need */
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);

54
tftpd/tftpd.h Normal file
View file

@ -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