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#include "config.h"
#define __USE_MISC
#define _SVID_SOURCE
#define _DEFAULT_SOURCE
# ifdef __linux__
# include <features.h>
# endif
# ifdef HAVE_ENVIRON
# define _GNU_SOURCE 1
# endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <limits.h>
#include <pwd.h>
#include <grp.h>
#include <inttypes.h>
#ifdef HAVE_ALLOCA_H
# include <alloca.h>
#endif
#include <signal.h>
#ifdef HAVE_PRCTL
# include <sys/prctl.h>
#elif defined(HAVE_PROCCTL)
# include <sys/procctl.h>
#endif
#define E_UTIL_SUID_ERR(args...) do { fprintf(stderr, "E_SUID_ERR: "); fprintf(stderr, ##args); } while (0)
static inline int
e_setuid_setup(uid_t *caller_uid, gid_t *caller_gid, char **caller_user, char **caller_group)
{
struct passwd *pwent;
struct group *grent;
static char buf[PATH_MAX];
*caller_uid = getuid();
*caller_gid = getgid();
pwent = getpwuid(*caller_uid);
if (!pwent)
{
E_UTIL_SUID_ERR("Unable to obtain passwd entry for calling user\n");
return 31;
}
if (!pwent->pw_name)
{
E_UTIL_SUID_ERR("Blank username for user\n");
return 32;
}
*caller_user = strdup(pwent->pw_name);
if (!(*caller_user))
{
E_UTIL_SUID_ERR("Unable to allocate memory for username\n");
return 33;
}
grent = getgrgid(*caller_gid);
if (!grent)
{
E_UTIL_SUID_ERR("Unable to obtain group entry for calling group\n");
return 34;
}
if (!grent->gr_name)
{
E_UTIL_SUID_ERR("Blank groupname for group\n");
return 35;
}
*caller_group = strdup(grent->gr_name);
if (!(*caller_group))
{
E_UTIL_SUID_ERR("Unable to allocate memory for groupname\n");
return 36;
}
if (setuid(0) != 0)
{
E_UTIL_SUID_ERR("Unable to assume root user privileges\n");
return 37;
}
if (setgid(0) != 0)
{
E_UTIL_SUID_ERR("Unable to assume root group privileges\n");
return 38;
}
pwent = getpwuid(getuid());
if (!pwent)
{
E_UTIL_SUID_ERR("Unable to obtain passwd entry\n");
return 39;
}
if (!pwent->pw_dir)
{
E_UTIL_SUID_ERR("No home dir for root\n");
return 40;
}
if (strlen(pwent->pw_dir) > (sizeof(buf) - 8))
{
E_UTIL_SUID_ERR("Root homedir too long\n");
return 41;
}
if (pwent->pw_dir[0] != '/')
{
E_UTIL_SUID_ERR("Root homedir %s is not a full path\n", pwent->pw_dir);
return 42;
}
if (!realpath(pwent->pw_dir, buf))
{
E_UTIL_SUID_ERR("Root homedir %s does not resolve\n", pwent->pw_dir);
return 43;
}
snprintf(buf, sizeof(buf), "HOME=%s", pwent->pw_dir);
if (putenv(buf) == -1)
{
E_UTIL_SUID_ERR("Unable to set $HOME environment\n");
return 44;
}
// change CWD to / to avoid path search dlopens finding libs in ./
if (chdir("/") != 0)
{
E_UTIL_SUID_ERR("Unable to change working dir to /\n");
return 45;
}
// die with parent - special as this is setuid
#ifdef HAVE_PRCTL
prctl(PR_SET_PDEATHSIG, SIGTERM);
#elif defined(HAVE_PROCCTL)
int sig = SIGTERM;
procctl(P_PID, 0, PROC_PDEATHSIG_CTL, &sig);
#endif
#ifdef HAVE_UNSETENV
# define NOENV(x) unsetenv(x)
// pass 1 - just nuke known dangerous env vars brutally if possible via
// unsetenv(). if you don't have unsetenv... there's pass 2 and 3
NOENV("IFS");
NOENV("CDPATH");
NOENV("LOCALDOMAIN");
NOENV("RES_OPTIONS");
NOENV("HOSTALIASES");
NOENV("NLSPATH");
NOENV("PATH_LOCALE");
NOENV("COLORTERM");
NOENV("LANG");
NOENV("LANGUAGE");
NOENV("LINGUAS");
NOENV("TERM");
NOENV("LD_PRELOAD");
NOENV("LD_LIBRARY_PATH");
NOENV("SHLIB_PATH");
NOENV("LIBPATH");
NOENV("AUTHSTATE");
NOENV("DYLD_*");
NOENV("KRB_CONF*");
NOENV("KRBCONFDIR");
NOENV("KRBTKFILE");
NOENV("KRB5_CONFIG*");
NOENV("KRB5_KTNAME");
NOENV("VAR_ACE");
NOENV("USR_ACE");
NOENV("DLC_ACE");
NOENV("TERMINFO");
NOENV("TERMINFO_DIRS");
NOENV("TERMPATH");
NOENV("TERMCAP");
NOENV("ENV");
NOENV("BASH_ENV");
NOENV("PS4");
NOENV("GLOBIGNORE");
NOENV("SHELLOPTS");
NOENV("JAVA_TOOL_OPTIONS");
NOENV("PERLIO_DEBUG");
NOENV("PERLLIB");
NOENV("PERL5LIB");
NOENV("PERL5OPT");
NOENV("PERL5DB");
NOENV("FPATH");
NOENV("NULLCMD");
NOENV("READNULLCMD");
NOENV("ZDOTDIR");
NOENV("TMPPREFIX");
NOENV("PYTHONPATH");
NOENV("PYTHONHOME");
NOENV("PYTHONINSPECT");
NOENV("RUBYLIB");
NOENV("RUBYOPT");
# ifdef HAVE_ENVIRON
if (environ)
{
int i, again;
// go over environment array again and again... safely
do
{
again = 0;
// walk through and find first entry that we don't like
for (i = 0; environ[i]; i++)
{
// if it begins with any of these, it's possibly nasty
if ((!strncmp(environ[i], "LD_", 3)) ||
(!strncmp(environ[i], "_RLD_", 5)) ||
(!strncmp(environ[i], "LC_", 3)) ||
(!strncmp(environ[i], "LDR_", 3)))
{
// unset it
char *tmp, *p;
tmp = strdup(environ[i]);
if (!tmp) abort();
p = strchr(tmp, '=');
if (!p) abort();
*p = 0;
NOENV(tmp);
free(tmp);
// and mark our do to try again from the start in case
// unsetenv changes environ ptr
again = 1;
break;
}
}
}
while (again);
}
# endif
#endif
// pass 2 - clear entire environment so it doesn't exist at all. if you
// can't do this... you're possibly in trouble... but the worst is still
// fixed in pass 3
#ifdef HAVE_CLEARENV
clearenv();
#else
# ifdef HAVE_ENVIRON
environ = NULL;
# endif
#endif
// pass 3 - set path and ifs to minimal defaults
putenv("PATH=/bin:/usr/bin:/sbin:/usr/sbin");
putenv("IFS= \t\n");
return 0;
}
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