busybox/libbb/procps.c
Eric Andersen 52499cb9ae Tito writes:
Hi,
I've spent the half night staring at the devilish  my_getpwuid and my_getgrgid functions
trying to find out a way to avoid actual and future potential buffer overflow problems
without breaking existing code.
Finally I've  found a not intrusive way to do this that surely doesn't break existing code
and fixes a couple of problems too.
The attached patch:
1) changes the behaviour of my_getpwuid and my_getgrgid to avoid potetntial buffer overflows
2) fixes all occurences of this function calls in tar.c , id.c , ls.c, whoami.c, logger.c, libbb.h.
3) The behaviour of tar, ls and  logger is unchanged.
4) The behavior of ps with somewhat longer usernames messing up output is fixed.
5) The only bigger change was the increasing of size of the buffers in id.c to avoid
     false negatives (unknown user: xxxxxx) with usernames longer than 8 chars.
     The value i used ( 32 chars ) was taken from the tar header ( see gname and uname).
     Maybe this buffers can be reduced a bit  ( to 16 or whatever ), this is up to you.
6) The increase of size of the binary is not so dramatic:
     size busybox
       text    data     bss     dec     hex filename
     239568    2300   36816  278684   4409c busybox
    size busybox_fixed
       text    data     bss     dec     hex filename
     239616    2300   36816  278732   440cc busybox
7) The behaviour of whoami changed:
    actually it  prints out an username cut down to the size of the buffer.
    This could be fixed by increasing the size of the buffer as in id.c or
    avoid the use of my_getpwuid and use getpwuid directly instead.
    Maybe this colud be also remain unchanged......

Please apply if you think it is ok to do so.
The diff applies on today's cvs tarball (2004-08-25).
Thanks in advance,
Ciao,
Tito
2004-08-26 22:18:59 +00:00

159 lines
3.3 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright 1998 by Albert Cahalan; all rights reserved.
* Copyright (C) 2002 by Vladimir Oleynik <dzo@simtreas.ru>
* GNU Library General Public License Version 2, or any later version
*
*/
#include <dirent.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <asm/page.h>
#include "libbb.h"
extern procps_status_t * procps_scan(int save_user_arg0
#ifdef CONFIG_SELINUX
, int use_selinux , security_id_t *sid
#endif
)
{
static DIR *dir;
struct dirent *entry;
static procps_status_t ret_status;
char *name;
int n;
char status[32];
char buf[1024];
FILE *fp;
procps_status_t curstatus;
int pid;
long tasknice;
struct stat sb;
if (!dir) {
dir = opendir("/proc");
if(!dir)
bb_error_msg_and_die("Can't open /proc");
}
for(;;) {
if((entry = readdir(dir)) == NULL) {
closedir(dir);
dir = 0;
return 0;
}
name = entry->d_name;
if (!(*name >= '0' && *name <= '9'))
continue;
memset(&curstatus, 0, sizeof(procps_status_t));
pid = atoi(name);
curstatus.pid = pid;
sprintf(status, "/proc/%d", pid);
if(stat(status, &sb))
continue;
my_getpwuid(curstatus.user, sb.st_uid, sizeof(curstatus.user));
sprintf(status, "/proc/%d/stat", pid);
if((fp = fopen(status, "r")) == NULL)
continue;
#ifdef CONFIG_SELINUX
if(use_selinux)
{
if(fstat_secure(fileno(fp), &sb, sid))
continue;
}
else
#endif
name = fgets(buf, sizeof(buf), fp);
fclose(fp);
if(name == NULL)
continue;
name = strrchr(buf, ')'); /* split into "PID (cmd" and "<rest>" */
if(name == 0 || name[1] != ' ')
continue;
*name = 0;
sscanf(buf, "%*s (%15c", curstatus.short_cmd);
n = sscanf(name+2,
"%c %d "
"%*s %*s %*s %*s " /* pgrp, session, tty, tpgid */
"%*s %*s %*s %*s %*s " /* flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
#ifdef FEATURE_CPU_USAGE_PERCENTAGE
"%lu %lu "
#else
"%*s %*s "
#endif
"%*s %*s %*s " /* cutime, cstime, priority */
"%ld "
"%*s %*s %*s " /* timeout, it_real_value, start_time */
"%*s " /* vsize */
"%ld",
curstatus.state, &curstatus.ppid,
#ifdef FEATURE_CPU_USAGE_PERCENTAGE
&curstatus.utime, &curstatus.stime,
#endif
&tasknice,
&curstatus.rss);
#ifdef FEATURE_CPU_USAGE_PERCENTAGE
if(n != 6)
#else
if(n != 4)
#endif
continue;
if (curstatus.rss == 0 && curstatus.state[0] != 'Z')
curstatus.state[1] = 'W';
else
curstatus.state[1] = ' ';
if (tasknice < 0)
curstatus.state[2] = '<';
else if (tasknice > 0)
curstatus.state[2] = 'N';
else
curstatus.state[2] = ' ';
#ifdef PAGE_SHIFT
curstatus.rss <<= (PAGE_SHIFT - 10); /* 2**10 = 1kb */
#else
curstatus.rss *= (getpagesize() >> 10); /* 2**10 = 1kb */
#endif
if(save_user_arg0) {
sprintf(status, "/proc/%d/cmdline", pid);
if((fp = fopen(status, "r")) == NULL)
continue;
if((n=fread(buf, 1, sizeof(buf)-1, fp)) > 0) {
if(buf[n-1]=='\n')
buf[--n] = 0;
name = buf;
while(n) {
if(((unsigned char)*name) < ' ')
*name = ' ';
name++;
n--;
}
*name = 0;
if(buf[0])
curstatus.cmd = strdup(buf);
/* if NULL it work true also */
}
fclose(fp);
}
return memcpy(&ret_status, &curstatus, sizeof(procps_status_t));
}
}
/* END CODE */
/*
Local Variables:
c-file-style: "linux"
c-basic-offset: 4
tab-width: 4
End:
*/