minix/servers/pm/exec.c

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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 ps)
*
* The entry points into this file are:
* do_exec: perform the EXEC system call
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* exec_newmem: allocate new memory map for a process that tries to exec
* do_execrestart: finish the special exec call for RS
* exec_restart: finish a regular exec call
* find_share: find a process whose text segment can be shared
*/
#include "pm.h"
#include <sys/stat.h>
#include <minix/callnr.h>
endpoint-aware conversion of servers. 'who', indicating caller number in pm and fs and some other servers, has been removed in favour of 'who_e' (endpoint) and 'who_p' (proc nr.). In both PM and FS, isokendpt() convert endpoints to process slot numbers, returning OK if it was a valid and consistent endpoint number. okendpt() does the same but panic()s if it doesn't succeed. (In PM, this is pm_isok..) pm and fs keep their own records of process endpoints in their proc tables, which are needed to make kernel calls about those processes. message field names have changed. fs drivers are endpoints. fs now doesn't try to get out of driver deadlock, as the protocol isn't supposed to let that happen any more. (A warning is printed if ELOCKED is detected though.) fproc[].fp_task (indicating which driver the process is suspended on) became an int. PM and FS now get endpoint numbers of initial boot processes from the kernel. These happen to be the same as the old proc numbers, to let user processes reach them with the old numbers, but FS and PM don't know that. All new processes after INIT, even after the generation number wraps around, get endpoint numbers with generation 1 and higher, so the first instances of the boot processes are the only processes ever to have endpoint numbers in the old proc number range. More return code checks of sys_* functions have been added. IS has become endpoint-aware. Ditched the 'text' and 'data' fields in the kernel dump (which show locations, not sizes, so aren't terribly useful) in favour of the endpoint number. Proc number is still visible. Some other dumps (e.g. dmap, rs) show endpoint numbers now too which got the formatting changed. PM reading segments using rw_seg() has changed - it uses other fields in the message now instead of encoding the segment and process number and fd in the fd field. For that it uses _read_pm() and _write_pm() which to _taskcall()s directly in pm/misc.c. PM now sys_exit()s itself on panic(), instead of sys_abort(). RS also talks in endpoints instead of process numbers.
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#include <minix/endpoint.h>
#include <minix/com.h>
#include <minix/vm.h>
#include <a.out.h>
#include <signal.h>
#include <string.h>
#include "mproc.h"
#include "param.h"
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#define ESCRIPT (-2000) /* Returned by read_header for a #! script. */
#define PTRSIZE sizeof(char *) /* Size of pointers in argv[] and envp[]. */
/*===========================================================================*
* do_exec *
*===========================================================================*/
PUBLIC int do_exec()
{
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int r;
/* Save parameters */
mp->mp_exec_path= m_in.exec_name;
mp->mp_exec_path_len= m_in.exec_len;
mp->mp_exec_frame= m_in.stack_ptr;
mp->mp_exec_frame_len= m_in.stack_bytes;
/* Forward call to FS */
if (mp->mp_fs_call != PM_IDLE)
{
panic(__FILE__, "do_exec: not idle", mp->mp_fs_call);
}
mp->mp_fs_call= PM_EXEC;
r= notify(FS_PROC_NR);
if (r != OK)
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panic(__FILE__, "do_exec: unable to notify FS", r);
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/* Do not reply */
return SUSPEND;
}
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/*===========================================================================*
* exec_newmem *
*===========================================================================*/
PUBLIC int exec_newmem()
{
int proc_e, proc_n, allow_setuid;
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char *ptr;
struct mproc *rmp;
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struct exec_newmem args;
int r, flags;
char *stack_top;
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if (who_e != FS_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(__FILE__, "exec_newmem: got bad endpoint",
proc_e);
}
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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(__FILE__, "exec_newmem: sys_datacopy failed", r);
if((r=vm_exec_newmem(proc_e, &args, sizeof(args), &stack_top, &flags)) == OK) {
allow_setuid= 0; /* Do not allow setuid execution */
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if ((rmp->mp_flags & TRACED) == 0) {
/* Okay, setuid execution is allowed */
allow_setuid= 1;
rmp->mp_effuid = args.new_uid;
rmp->mp_effgid = args.new_gid;
}
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/* 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';
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/* Save offset to initial argc (for ps) */
rmp->mp_procargs = (vir_bytes) stack_top - args.args_bytes;
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/* Kill process if something goes wrong after this point. */
rmp->mp_flags |= PARTIAL_EXEC;
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mp->mp_reply.reply_res2= (vir_bytes) stack_top;
mp->mp_reply.reply_res3= flags;
if (allow_setuid)
mp->mp_reply.reply_res3 |= EXC_NM_RF_ALLOW_SETUID;
}
return r;
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}
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/*===========================================================================*
* do_execrestart *
*===========================================================================*/
PUBLIC int do_execrestart()
{
int proc_e, proc_n, result;
struct mproc *rmp;
if (who_e != RS_PROC_NR)
return EPERM;
proc_e= m_in.EXC_RS_PROC;
if (pm_isokendpt(proc_e, &proc_n) != OK)
{
panic(__FILE__, "do_execrestart: got bad endpoint",
proc_e);
}
rmp= &mproc[proc_n];
result= m_in.EXC_RS_RESULT;
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exec_restart(rmp, result);
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return OK;
}
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/*===========================================================================*
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* exec_restart *
*===========================================================================*/
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PUBLIC void exec_restart(rmp, result)
struct mproc *rmp;
int result;
{
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int r, sn;
vir_bytes pc;
char *new_sp;
if (result != OK)
{
if (rmp->mp_flags & PARTIAL_EXEC)
{
printf("partial exec; killing process\n");
/* Use SIGILL signal that something went wrong */
rmp->mp_sigstatus = SIGILL;
exit_proc(rmp, 0, FALSE /*dump_core*/);
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return;
}
setreply(rmp-mproc, result);
return;
}
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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);
}
}
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new_sp= (char *)rmp->mp_procargs;
pc= 0; /* for now */
r= sys_exec(rmp->mp_endpoint, new_sp, rmp->mp_name, pc);
if (r != OK) panic(__FILE__, "sys_exec failed", r);
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/* Cause a signal if this process is traced. */
if (rmp->mp_flags & TRACED) check_sig(rmp->mp_pid, SIGTRAP);
}