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/* This file handles the EXEC system call. It performs the work as follows:
* - see if the permissions allow the file to be executed
* - read the header and extract the sizes
* - fetch the initial args and environment from the user space
* - allocate the memory for the new process
* - copy the initial stack from PM to the process
* - read in the text and data segments and copy to the process
* - take care of setuid and setgid bits
* - fix up 'mproc' table
* - tell kernel about EXEC
* - save offset to initial argc (for procfs)
*
* The entry points into this file are:
* do_exec: perform the EXEC system call
* do_newexec: handle PM part of exec call after VFS
* do_execrestart: finish the special exec call for RS
* exec_restart: finish a regular exec call
*/
#include "pm.h"
#include <sys/stat.h>
#include <minix/callnr.h>
#include <minix/endpoint.h>
#include <minix/com.h>
#include <minix/vm.h>
#include <signal.h>
#include <libexec.h>
#include <sys/ptrace.h>
#include "mproc.h"
#define ESCRIPT (-2000) /* Returned by read_header for a #! script. */
#define PTRSIZE sizeof(char *) /* Size of pointers in argv[] and envp[]. */
/*===========================================================================*
* do_exec *
*===========================================================================*/
int
do_exec(void)
{
message m;
/* Forward call to VFS */
memset(&m, 0, sizeof(m));
m.m_type = VFS_PM_EXEC;
m.VFS_PM_ENDPT = mp->mp_endpoint;
m.VFS_PM_PATH = (void *)m_in.m_lc_pm_exec.name;
m.VFS_PM_PATH_LEN = m_in.m_lc_pm_exec.namelen;
m.VFS_PM_FRAME = (void *)m_in.m_lc_pm_exec.frame;
m.VFS_PM_FRAME_LEN = m_in.m_lc_pm_exec.framelen;
m.VFS_PM_PS_STR = m_in.m_lc_pm_exec.ps_str;
tell_vfs(mp, &m);
/* Do not reply */
return SUSPEND;
}
/*===========================================================================*
* do_newexec *
*===========================================================================*/
int do_newexec(void)
{
int proc_e, proc_n, allow_setuid;
vir_bytes ptr;
struct mproc *rmp;
struct exec_info args;
int r;
if (who_e != VFS_PROC_NR && who_e != RS_PROC_NR)
return EPERM;
proc_e= m_in.m_lexec_pm_exec_new.endpt;
if (pm_isokendpt(proc_e, &proc_n) != OK) {
panic("do_newexec: got bad endpoint: %d", proc_e);
}
rmp= &mproc[proc_n];
ptr= m_in.m_lexec_pm_exec_new.ptr;
r= sys_datacopy(who_e, ptr, SELF, (vir_bytes)&args, sizeof(args));
if (r != OK)
panic("do_newexec: sys_datacopy failed: %d", r);
allow_setuid = 0; /* Do not allow setuid execution */
rmp->mp_flags &= ~TAINTED; /* By default not tainted */
if (rmp->mp_tracer == NO_TRACER) {
/* Okay, setuid execution is allowed */
allow_setuid = 1;
}
if (allow_setuid && args.allow_setuid) {
rmp->mp_effuid = args.new_uid;
rmp->mp_effgid = args.new_gid;
}
/* Always update the saved user and group ID at this point. */
rmp->mp_svuid = rmp->mp_effuid;
rmp->mp_svgid = rmp->mp_effgid;
/* A process is considered 'tainted' when it's executing with
* setuid or setgid bit set, or when the real{u,g}id doesn't
* match the eff{u,g}id, respectively. */
if (allow_setuid && args.allow_setuid) {
/* Program has setuid and/or setgid bits set */
rmp->mp_flags |= TAINTED;
} else if (rmp->mp_effuid != rmp->mp_realuid ||
rmp->mp_effgid != rmp->mp_realgid) {
rmp->mp_flags |= TAINTED;
}
/* System will save command line for debugging, ps(1) output, etc. */
strncpy(rmp->mp_name, args.progname, PROC_NAME_LEN-1);
rmp->mp_name[PROC_NAME_LEN-1] = '\0';
/* Save offset to initial argc (for procfs) */
rmp->mp_frame_addr = (vir_bytes) args.stack_high - args.frame_len;
rmp->mp_frame_len = args.frame_len;
/* Kill process if something goes wrong after this point. */
rmp->mp_flags |= PARTIAL_EXEC;
mp->mp_reply.m_pm_lexec_exec_new.suid = (allow_setuid && args.allow_setuid);
return r;
}
/*===========================================================================*
* do_execrestart *
*===========================================================================*/
int do_execrestart(void)
{
int proc_e, proc_n, result;
struct mproc *rmp;
vir_bytes pc, ps_str;
if (who_e != RS_PROC_NR)
return EPERM;
proc_e = m_in.m_rs_pm_exec_restart.endpt;
if (pm_isokendpt(proc_e, &proc_n) != OK) {
panic("do_execrestart: got bad endpoint: %d", proc_e);
}
rmp = &mproc[proc_n];
result = m_in.m_rs_pm_exec_restart.result;
pc = m_in.m_rs_pm_exec_restart.pc;
ps_str = m_in.m_rs_pm_exec_restart.ps_str;
exec_restart(rmp, result, pc, rmp->mp_frame_addr, ps_str);
return OK;
}
/*===========================================================================*
* exec_restart *
*===========================================================================*/
void exec_restart(struct mproc *rmp, int result, vir_bytes pc, vir_bytes sp,
vir_bytes ps_str)
{
int r, sn;
if (result != OK)
{
if (rmp->mp_flags & PARTIAL_EXEC)
{
/* Use SIGKILL to signal that something went wrong */
sys_kill(rmp->mp_endpoint, SIGKILL);
return;
}
reply(rmp-mproc, result);
return;
}
rmp->mp_flags &= ~PARTIAL_EXEC;
/* Fix 'mproc' fields, tell kernel that exec is done, reset caught
* sigs.
*/
for (sn = 1; sn < _NSIG; sn++) {
if (sigismember(&rmp->mp_catch, sn)) {
sigdelset(&rmp->mp_catch, sn);
rmp->mp_sigact[sn].sa_handler = SIG_DFL;
sigemptyset(&rmp->mp_sigact[sn].sa_mask);
}
}
/* Cause a signal if this process is traced.
* Do this before making the process runnable again!
*/
if (rmp->mp_tracer != NO_TRACER && !(rmp->mp_trace_flags & TO_NOEXEC))
{
sn = (rmp->mp_trace_flags & TO_ALTEXEC) ? SIGSTOP : SIGTRAP;
check_sig(rmp->mp_pid, sn, FALSE /* ksig */);
}
/* Call kernel to exec with SP and PC set by VFS. */
r = sys_exec(rmp->mp_endpoint, sp, (vir_bytes)rmp->mp_name, pc, ps_str);
if (r != OK) panic("sys_exec failed: %d", r);
}
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