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/* ISC license. */
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <skalibs/types.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/sgetopt.h>
#include <skalibs/bytestr.h>
#include <skalibs/buffer.h>
#include <skalibs/stralloc.h>
#include <skalibs/strerr.h>
#include <skalibs/tai.h>
#include <skalibs/iopause.h>
#include <skalibs/selfpipe.h>
#include <skalibs/env.h>
#include <skalibs/exec.h>
#include <skalibs/djbunix.h>
#include <skalibs/unix-timed.h>
#include <skalibs/unixmessage.h>
#include "s6-sudo.h"
#define USAGE "s6-sudod [ -0 ] [ -1 ] [ -2 ] [ -d ] [ -t timeout ] args..."
#define dieusage() strerr_dieusage(100, USAGE)
#define dienomem() strerr_diefu1sys(111, "stralloc_catb")
static int handle_signals (pid_t pid, int *wstat)
{
int done = 0 ;
for (;;)
{
int sig = selfpipe_read() ;
switch (sig)
{
case -1 : strerr_diefu1sys(111, "read from selfpipe") ;
case 0 : return done ;
case SIGCHLD :
{
int w ;
pid_t r = wait_pid_nohang(pid, &w) ;
if ((r < 0) && (errno != ECHILD))
strerr_diefu1sys(111, "wait_pid_nohang") ;
else if (r > 0)
{
done = 1 ;
*wstat = w ;
}
break ;
}
default :
strerr_dief1sys(101, "internal inconsistency, please submit a bug-report") ;
}
}
}
int main (int argc, char const *const *argv, char const *const *envp)
{
iopause_fd x[2] = { { .events = IOPAUSE_READ }, { .fd = 0, .events = 0, .revents = 0 } } ;
unixmessage m ;
unsigned int nullfds = 0 ;
pid_t pid ;
int wstat ;
size_t envc = env_len(envp) ;
uint32_t cargc, cenvc, carglen, cenvlen ;
tain deadline = TAIN_INFINITE_RELATIVE ;
PROG = "s6-sudod" ;
{
subgetopt l = SUBGETOPT_ZERO ;
unsigned int t = 0 ;
for (;;)
{
int opt = subgetopt_r(argc, argv, "012dt:", &l) ;
if (opt < 0) break ;
switch (opt)
{
case '0' : nullfds |= 1 ; break ;
case '1' : nullfds |= 2 ; break ;
case '2' : nullfds |= 4 ; break ;
case 'd' : nullfds |= 15 ; break ;
case 't' : if (!uint0_scan(l.arg, &t)) dieusage() ; break ;
default : dieusage() ;
}
}
argc -= l.ind ; argv += l.ind ;
if (t) tain_from_millisecs(&deadline, t) ;
}
if ((ndelay_on(0) < 0) || (ndelay_on(1) < 0))
strerr_diefu1sys(111, "make socket non-blocking") ;
tain_now_set_stopwatch_g() ;
tain_add_g(&deadline, &deadline) ;
buffer_putnoflush(buffer_1small, S6_SUDO_BANNERB, S6_SUDO_BANNERB_LEN) ;
if (!buffer_timed_flush_g(buffer_1small, &deadline))
strerr_diefu1sys(111, "write banner to client") ;
if (unixmessage_timed_receive_g(unixmessage_receiver_0, &m, &deadline) <= 0)
strerr_diefu1sys(111, "read message from client") ;
if (m.nfds != 3)
strerr_dief1x(100, "client did not send 3 fds") ;
if (m.len < 16 + S6_SUDO_BANNERA_LEN)
strerr_dief1x(100, "wrong client message") ;
if (strncmp(m.s, S6_SUDO_BANNERA, S6_SUDO_BANNERA_LEN))
strerr_dief1x(100, "wrong client banner") ;
uint32_unpack_big(m.s + S6_SUDO_BANNERA_LEN, &cargc) ;
uint32_unpack_big(m.s + S6_SUDO_BANNERA_LEN + 4, &cenvc) ;
uint32_unpack_big(m.s + S6_SUDO_BANNERA_LEN + 8, &carglen) ;
uint32_unpack_big(m.s + S6_SUDO_BANNERA_LEN + 12, &cenvlen) ;
if (S6_SUDO_BANNERA_LEN + 16 + carglen + cenvlen != m.len)
strerr_dief1x(100, "wrong client argc/envlen") ;
if ((cargc > 131072) || (cenvc > 131072))
strerr_dief1x(100, "too many args/envvars from client") ;
if (nullfds & 1)
{
close(m.fds[0]) ;
m.fds[0] = open2("/dev/null", O_RDONLY) ;
if (m.fds[0] < 0) strerr_diefu2sys(111, "open /dev/null for ", "reading") ;
}
if (nullfds & 2)
{
close(m.fds[1]) ;
m.fds[1] = open2("/dev/null", O_WRONLY) ;
if (m.fds[1] < 0) strerr_diefu2sys(111, "open /dev/null for ", "writing") ;
}
if (nullfds & 4)
{
close(m.fds[2]) ;
m.fds[2] = 2 ;
}
{
char const *targv[argc + 1 + cargc] ;
char const *tenvp[envc + 1 + cenvc] ;
int p[2] ;
unsigned int i = 0 ;
for (; i < (unsigned int)argc ; i++) targv[i] = argv[i] ;
for (i = 0 ; i <= envc ; i++) tenvp[i] = envp[i] ;
if (!env_make(targv + argc, cargc, m.s + S6_SUDO_BANNERA_LEN + 16, carglen))
{
char c = errno ;
buffer_putnoflush(buffer_1small, &c, 1) ;
buffer_timed_flush_g(buffer_1small, &deadline) ;
errno = c ;
strerr_diefu1sys(111, "make child argv") ;
}
if (!env_make(tenvp + envc + 1, cenvc, m.s + S6_SUDO_BANNERA_LEN + 16 + carglen, cenvlen))
{
char c = errno ;
buffer_putnoflush(buffer_1small, &c, 1) ;
buffer_timed_flush_g(buffer_1small, &deadline) ;
errno = c ;
strerr_diefu1sys(111, "make child envp") ;
}
targv[argc + cargc] = 0 ;
for (i = 0 ; i < cenvc ; i++)
{
char const *var = tenvp[envc + 1 + i] ;
unsigned int j = 0 ;
size_t len = str_chr(var, '=') ;
if (!var[len])
{
char c = EINVAL ;
buffer_putnoflush(buffer_1small, &c, 1) ;
buffer_timed_flush_g(buffer_1small, &deadline) ;
strerr_dief1x(100, "bad environment from client") ;
}
for (; j < envc ; j++) if (!strncmp(var, tenvp[j], len+1)) break ;
if ((j < envc) && !tenvp[j][len+1]) tenvp[j] = var ;
}
x[0].fd = selfpipe_init() ;
if (x[0].fd < 0) strerr_diefu1sys(111, "selfpipe_init") ;
if (!selfpipe_trap(SIGCHLD)) strerr_diefu1sys(111, "trap SIGCHLD") ;
if (pipecoe(p) < 0) strerr_diefu1sys(111, "pipe") ;
pid = fork() ;
if (pid < 0) strerr_diefu1sys(111, "fork") ;
if (!pid)
{
char c ;
PROG = "s6-sudod (child)" ;
if ((fd_move(2, m.fds[2]) < 0)
|| (fd_move(1, m.fds[1]) < 0)
|| (fd_move(0, m.fds[0]) < 0))
{
char c = errno ;
fd_write(p[1], &c, 1) ;
strerr_diefu1sys(111, "move fds") ;
}
selfpipe_finish() ;
exec0_e(targv, tenvp) ;
c = errno ;
fd_write(p[1], &c, 1) ;
strerr_dieexec(c == ENOENT ? 127 : 126, targv[0]) ;
}
fd_close(p[1]) ;
{
char c ;
ssize_t r = fd_read(p[0], &c, 1) ;
if (r < 0) strerr_diefu1sys(111, "read from child") ;
if (r)
{
buffer_putnoflush(buffer_1small, &c, 1) ;
buffer_timed_flush_g(buffer_1small, &deadline) ;
return 111 ;
}
}
fd_close(p[0]) ;
}
fd_close(m.fds[0]) ;
fd_close(m.fds[1]) ;
if (!(nullfds & 4)) fd_close(m.fds[2]) ;
unixmessage_receiver_free(unixmessage_receiver_0) ;
buffer_putnoflush(buffer_1small, "", 1) ;
if (!buffer_timed_flush_g(buffer_1small, &deadline))
strerr_diefu1sys(111, "send confirmation to client") ;
for (;;)
{
if (iopause_g(x, 1 + !x[1].revents, 0) < 0) strerr_diefu1sys(111, "iopause") ;
if (x[0].revents && handle_signals(pid, &wstat)) break ;
if (x[1].revents && !(nullfds & 8))
{
kill(pid, SIGTERM) ;
kill(pid, SIGCONT) ;
return 1 ;
}
}
if (!x[1].revents)
{
char pack[UINT_PACK] ;
uint_pack_big(pack, (unsigned int)wstat) ;
buffer_putnoflush(buffer_1small, pack, UINT_PACK) ;
if (ndelay_off(1) < 0)
strerr_diefu1sys(111, "set stdout blocking") ;
if (!buffer_flush(buffer_1small))
strerr_diefu1sys(111, "write status to client") ;
}
return 0 ;
}
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