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/* ISC license. */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <skalibs/posixishard.h>
#include <skalibs/posixplz.h>
#include <skalibs/types.h>
#include <skalibs/env.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/buffer.h>
#include <skalibs/strerr2.h>
#include <skalibs/tai.h>
#include <skalibs/djbunix.h>
#include <skalibs/unix-timed.h>
#include <utmps/utmpx.h>
#include "utmps-internal.h"
static int fd = -1 ;
static void get0 (char *s, size_t n)
{
tain deadline ;
tain_ulong(&deadline, 30) ;
tain_add_g(&deadline, &deadline) ;
if (buffer_timed_get_g(buffer_0small, s, n, &deadline) < n)
strerr_diefu1sys(111, "read from stdin") ;
}
static void flush1 (void)
{
tain deadline ;
tain_ulong(&deadline, 30) ;
tain_add_g(&deadline, &deadline) ;
if (!buffer_timed_flush_g(buffer_1small, &deadline))
strerr_diefu1sys(111, "write to stdout") ;
}
static void answer (int e)
{
unsigned char c = e ;
buffer_putnoflush(buffer_1small, (char *)&c, 1) ;
flush1() ;
}
static void maybe_open (void)
{
if (fd < 0)
{
mode_t m = umask(0) ;
fd = open("utmp", O_RDWR | O_CREAT, 0644) ;
umask(m) ;
if (fd < 0)
{
answer(errno) ;
strerr_diefu1sys(111, "open utmp file") ;
}
}
}
static int read_utmp_entry_unlocked (char *s)
{
ssize_t r = read(fd, s, sizeof(struct utmpx)) ;
if (r < 0) goto err ;
if (!r) return 0 ;
if (r == sizeof(struct utmpx)) return 1 ;
errno = EPIPE ;
err:
unlink_void("utmp") ;
answer(errno) ;
strerr_diefu1sys(111, "read utmp file") ;
}
static void lockit (int w)
{
if (fd_lock(fd, w, 0) < 1)
{
unlink_void("utmp") ;
answer(errno) ;
strerr_diefu1sys(111, "read utmp file") ;
}
}
static inline void unlockit (void)
{
fd_unlock(fd) ;
}
static int idmatch (unsigned short type, char const *id, struct utmpx const *b)
{
if (type == BOOT_TIME || type == OLD_TIME || type == NEW_TIME)
{
if (type == (unsigned short)b->ut_type) return 1 ;
}
else if (type == INIT_PROCESS || type == LOGIN_PROCESS || type == USER_PROCESS || type == DEAD_PROCESS)
{
if ((b->ut_type == INIT_PROCESS || b->ut_type == LOGIN_PROCESS || b->ut_type == USER_PROCESS || b->ut_type == DEAD_PROCESS)
&& !strncmp(id, b->ut_id, UTMPS_UT_IDSIZE)) return 1 ;
}
return 0 ;
}
static inline int onestepback (void)
{
return lseek(fd, -(off_t)sizeof(struct utmpx), SEEK_CUR) >= 0 ;
}
static void do_getent (void)
{
struct utmpx b ;
char buf[1 + sizeof(struct utmpx)] = "" ;
maybe_open() ;
lockit(0) ;
if (!read_utmp_entry_unlocked(buf+1))
{
unlockit() ;
answer(ESRCH) ;
return ;
}
unlockit() ;
utmps_utmpx_unpack(buf+1, &b) ;
utmps_utmpx_pack(buf+1, &b) ;
buffer_putnoflush(buffer_1small, buf, 1 + sizeof(struct utmpx)) ;
flush1() ;
}
static void do_getid (void)
{
unsigned short type ;
char rbuf[USHORT_PACK + UTMPS_UT_IDSIZE] ;
char sbuf[1 + sizeof(struct utmpx)] = "" ;
get0(rbuf, USHORT_PACK + UTMPS_UT_IDSIZE) ;
ushort_unpack_big(rbuf, &type) ;
maybe_open() ;
lockit(0) ;
for (;;)
{
struct utmpx b ;
if (!read_utmp_entry_unlocked(sbuf+1))
{
unlockit() ;
answer(ESRCH) ;
return ;
}
utmps_utmpx_unpack(sbuf+1, &b) ;
if (idmatch(type, rbuf + USHORT_PACK, &b)) break ;
}
unlockit() ;
buffer_putnoflush(buffer_1small, sbuf, 1 + sizeof(struct utmpx)) ;
flush1() ;
}
static void do_getline (void)
{
char rbuf[UTMPS_UT_LINESIZE] ;
char sbuf[1 + sizeof(struct utmpx)] = "" ;
get0(rbuf, UTMPS_UT_LINESIZE) ;
maybe_open() ;
lockit(0) ;
for (;;)
{
struct utmpx b ;
if (!read_utmp_entry_unlocked(sbuf+1))
{
unlockit() ;
answer(ESRCH) ;
return ;
}
utmps_utmpx_unpack(sbuf+1, &b) ;
if ((b.ut_type == LOGIN_PROCESS || b.ut_type == USER_PROCESS)
&& !strncmp(rbuf, b.ut_line, UTMPS_UT_LINESIZE)) break ;
}
unlockit() ;
buffer_putnoflush(buffer_1small, sbuf, 1 + sizeof(struct utmpx)) ;
flush1() ;
}
static void do_putline (uid_t uid, gid_t gid)
{
struct utmpx u ;
char buf[sizeof(struct utmpx)] ;
get0(buf, sizeof(struct utmpx)) ;
if (uid && gid != getegid())
{
answer(EPERM) ;
return ;
}
utmps_utmpx_unpack(buf, &u) ;
maybe_open() ;
lockit(1) ;
onestepback() ; /* compatibility with glibc implementation */
for (;;)
{
struct utmpx b ;
char tmp[sizeof(struct utmpx)] ;
if (!read_utmp_entry_unlocked(tmp)) break ;
utmps_utmpx_unpack(tmp, &b) ;
if (idmatch(u.ut_type, u.ut_id, &b) && !strncmp(u.ut_line, b.ut_line, UTMPS_UT_LINESIZE))
{
if (!onestepback())
{
unlockit() ;
answer(errno) ;
return ;
}
break ;
}
}
utmps_utmpx_pack(buf, &u) ;
if (allwrite(fd, buf, sizeof(struct utmpx)) < sizeof(struct utmpx))
{
unlockit() ;
answer(errno) ;
strerr_diefu1sys(111, "write to utmp") ;
}
fsync(fd) ;
unlockit() ;
answer(0) ;
}
static void do_rewind (void)
{
maybe_open() ;
if (lseek(fd, 0, SEEK_SET) < 0) { answer(errno) ; return ; }
answer(0) ;
}
int main (void)
{
uid_t uid ;
gid_t gid ;
char const *x ;
PROG = "utmps-utmpd" ;
x = ucspi_get("REMOTEEUID") ;
if (!x) strerr_diefu1x(100, "get $IPCREMOTEEUID from environment") ;
if (!uid0_scan(x, &uid)) strerr_dieinvalid(100, "IPCREMOTEEUID") ;
x = ucspi_get("REMOTEEGID") ;
if (!x) strerr_diefu1x(100, "get $IPCREMOTEEGID from environment") ;
if (!gid0_scan(x, &gid)) strerr_dieinvalid(100, "IPCREMOTEEGID") ;
if (ndelay_on(0) < 0) strerr_diefu1sys(111, "set stdin non-blocking") ;
tain_now_set_stopwatch_g() ;
for (;;)
{
tain deadline ;
char c ;
tain_add_g(&deadline, &tain_infinite_relative) ;
if (!buffer_timed_get_g(buffer_0small, &c, 1, &deadline)) break ;
switch (c)
{
case 'e' : do_getent() ; break ;
case 'i' : do_getid() ; break ;
case 'l' : do_getline() ; break ;
case 'E' : do_putline(uid, gid) ; break ;
case 'r' : do_rewind() ; break ;
default :
errno = EPROTO ;
strerr_diefu1sys(1, "interpret stdin") ;
}
}
return 0 ;
}
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