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Basically rewrite the dofork() routine, to add more error-checking and

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correct the error-checking that was there.  With the old code, an error
return from getpwuid(daemon_user) could turn the lpd process into a very
effective fork-bomb...

Reviewed by:	freebsd-audit freebsd-print (a little...)
MFC after:	6 days
This commit is contained in:
gad 2001-07-23 23:13:39 +00:00
parent fb0287a739
commit ae8a6131be
1 changed files with 55 additions and 14 deletions
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69
usr.sbin/lpr/lpd/printjob.c
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@ -77,8 +77,8 @@ static const char rcsid[] =
#include "pathnames.h"
#include "extern.h"
#define DORETURN 0 /* absorb fork error */
#define DOABORT 1 /* abort if dofork fails */
#define DORETURN 0 /* dofork should return "can't fork" error */
#define DOABORT 1 /* dofork should just die if fork() fails */
/*
* Error tokens
@ -106,6 +106,10 @@ static int prchild; /* id of pr process */
static char title[80]; /* ``pr'' title */
static char locale[80]; /* ``pr'' locale */
/* these two are set from pp->daemon_user, but only if they are needed */
static char *daemon_uname; /* set from pwd->pw_name */
static int daemon_defgid;
static char class[32]; /* classification field */
static char origin_host[MAXHOSTNAMELEN]; /* user's host machine */
/* indentation size in static characters */
@ -1401,11 +1405,24 @@ sendmail(struct printer *pp, char *user, int bombed)
static int
dofork(const struct printer *pp, int action)
{
register int i, forkpid;
int i, fail, forkpid;
struct passwd *pwd;
forkpid = -1;
if (daemon_uname == NULL) {
pwd = getpwuid(pp->daemon_user);
if (pwd == NULL) {
syslog(LOG_ERR, "%s: Can't lookup default daemon uid (%ld) in password file",
pp->printer, pp->daemon_user);
goto error_ret;
}
daemon_uname = strdup(pwd->pw_name);
daemon_defgid = pwd->pw_gid;
}
for (i = 0; i < 20; i++) {
if ((forkpid = fork()) < 0) {
forkpid = fork();
if (forkpid < 0) {
sleep((unsigned)(i*i));
continue;
}
@ -1413,25 +1430,49 @@ dofork(const struct printer *pp, int action)
* Child should run as daemon instead of root
*/
if (forkpid == 0) {
if ((pwd = getpwuid(pp->daemon_user)) == NULL) {
syslog(LOG_ERR, "Can't lookup default daemon uid (%ld) in password file",
pp->daemon_user);
errno = 0;
fail = initgroups(daemon_uname, daemon_defgid);
if (fail) {
syslog(LOG_ERR, "%s: initgroups(%s,%u): %m",
pp->printer, daemon_uname, daemon_defgid);
break;
}
fail = setgid(daemon_defgid);
if (fail) {
syslog(LOG_ERR, "%s: setgid(%u): %m",
pp->printer, daemon_defgid);
break;
}
fail = setuid(pp->daemon_user);
if (fail) {
syslog(LOG_ERR, "%s: setuid(%ld): %m",
pp->printer, pp->daemon_user);
break;
}
initgroups(pwd->pw_name, pwd->pw_gid);
setgid(pwd->pw_gid);
setuid(pp->daemon_user);
}
return(forkpid);
return forkpid;
}
syslog(LOG_ERR, "can't fork");
/*
* An error occurred. If the error is in the child process, then
* this routine MUST always exit(). DORETURN only effects how
* errors should be handled in the parent process.
*/
error_ret:
if (forkpid == 0) {
syslog(LOG_ERR, "%s: dofork(): aborting child process...",
pp->printer);
exit(1);
}
syslog(LOG_ERR, "%s: dofork(): failure in fork", pp->printer);
sleep(1); /* throttle errors, as a safety measure */
switch (action) {
case DORETURN:
return (-1);
return -1;
default:
syslog(LOG_ERR, "bad action (%d) to dofork", action);
/*FALL THRU*/
/* FALLTHROUGH */
case DOABORT:
exit(1);
}