minix/servers/pm/exec.c
David van Moolenbroek efd3487bc5 PM: send replies immediately
The original delayed reply functionality was there to support swapping
in processes as they are unblocked, but swap support is long gone.
These days, this code only incurs overhead and hides bugs.

Change-Id: I4aebcd80719daa1bec45ac91975ddc9a460d74d4
2014-03-01 09:05:00 +01:00

202 lines
5.7 KiB
C

/* 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 <string.h>
#include <libexec.h>
#include <sys/ptrace.h>
#include "mproc.h"
#include "param.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()
{
message m;
/* Forward call to VFS */
m.m_type = PM_EXEC;
m.PM_PROC = mp->mp_endpoint;
m.PM_PATH = m_in.exec_name;
m.PM_PATH_LEN = m_in.exec_len;
m.PM_FRAME = m_in.frame_ptr;
m.PM_FRAME_LEN = m_in.msg_frame_len;
m.PM_EXECFLAGS = m_in.PMEXEC_FLAGS;
m.PM_PS_STR = (vir_bytes)m_in.m1_p4; /* ps_strings pointer into the frame. */
tell_vfs(mp, &m);
/* Do not reply */
return SUSPEND;
}
/*===========================================================================*
* do_newexec *
*===========================================================================*/
int do_newexec(void)
{
int proc_e, proc_n, allow_setuid;
char *ptr;
struct mproc *rmp;
struct exec_info args;
int r, flags = 0;
if (who_e != VFS_PROC_NR && who_e != RS_PROC_NR)
return EPERM;
proc_e= m_in.EXC_NM_PROC;
if (pm_isokendpt(proc_e, &proc_n) != OK) {
panic("do_newexec: got bad endpoint: %d", proc_e);
}
rmp= &mproc[proc_n];
ptr= m_in.EXC_NM_PTR;
r= sys_datacopy(who_e, (vir_bytes)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;
}
/* 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.reply_res2= (vir_bytes) rmp->mp_frame_addr;
mp->mp_reply.reply_res3= flags;
if (allow_setuid && args.allow_setuid)
mp->mp_reply.reply_res3 |= EXC_NM_RF_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.EXC_RS_PROC;
if (pm_isokendpt(proc_e, &proc_n) != OK) {
panic("do_execrestart: got bad endpoint: %d", proc_e);
}
rmp = &mproc[proc_n];
result = m_in.EXC_RS_RESULT;
pc = (vir_bytes)m_in.EXC_RS_PC;
ps_str = (vir_bytes)m_in.EXC_RS_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, (char *) sp, rmp->mp_name, pc, ps_str);
if (r != OK) panic("sys_exec failed: %d", r);
}