/*===========================================================================*
* insert_arg *
*===========================================================================*/
static int insert_arg(
char stack[ARG_MAX], /* pointer to stack image within PM */
vir_bytes *stk_bytes, /* size of initial stack */
char *arg, /* argument to prepend/replace as new argv[0] */
int replace
)
{
/* Patch the stack so that arg will become argv[0]. Be careful, the stack may
* be filled with garbage, although it normally looks like this:
* nargs argv[0] ... argv[nargs-1] NULL envp[0] ... NULL
* followed by the strings "pointed" to by the argv[i] and the envp[i]. The
* pointers are really offsets from the start of stack.
* Return true iff the operation succeeded.
*/
int offset, a0, a1, old_bytes = *stk_bytes;
/* Prepending arg adds at least one string and a zero byte. */
offset = strlen(arg) + 1;
a0 = (int) ((char **) stack)[1]; /* argv[0] */
if (a0 < 4 * PTRSIZE || a0 >= old_bytes) return(FALSE);
a1 = a0; /* a1 will point to the strings to be moved */
if (replace) {
/* Move a1 to the end of argv[0][] (argv[1] if nargs > 1). */
do {
if (a1 == old_bytes) return(FALSE);
--offset;
} while (stack[a1++] != 0);
} else {
offset += PTRSIZE; /* new argv[0] needs new pointer in argv[] */
a0 += PTRSIZE; /* location of new argv[0][]. */
}
/* stack will grow by offset bytes (or shrink by -offset bytes) */
if ((*stk_bytes += offset) > ARG_MAX) return(FALSE);
/* Reposition the strings by offset bytes */
memmove(stack + a1 + offset, stack + a1, old_bytes - a1);
strcpy(stack + a0, arg); /* Put arg in the new space. */
if (!replace) {
/* Make space for a new argv[0]. */
memmove(stack + 2 * PTRSIZE, stack + 1 * PTRSIZE, a0 - 2 * PTRSIZE);
((char **) stack)[0]++; /* nargs++; */
}
/* Now patch up argv[] and envp[] by offset. */
patch_ptr(stack, (vir_bytes) offset);
((char **) stack)[1] = (char *) a0; /* set argv[0] correctly */
return(TRUE);
}
static int do_exec(int proc_e, char *exec, size_t exec_len, char *progname,
char *frame, int frame_len)
{
int r;
vir_bytes vsp;
struct exec_info execi;
int i;
execi.proc_e = proc_e;
execi.image = exec;
execi.image_len = exec_len;
strncpy(execi.progname, progname, PROC_NAME_LEN-1);
execi.progname[PROC_NAME_LEN-1] = '\0';
execi.frame_len = frame_len;
for(i = 0; exec_loaders[i].load_object != NULL; i++) {
r = (*exec_loaders[i].load_object)(&execi);
/* Loaded successfully, so no need to try other loaders */
if (r == OK) break;
}
/* No exec loader could load the object */
if (r != OK) {
printf("RS: do_exec: loading error %d\n", r);
return r;
}
/* Patch up stack and copy it from RS to new core image. */
vsp = execi.stack_top;
vsp -= frame_len;
patch_ptr(frame, vsp);
r = sys_datacopy(SELF, (vir_bytes) frame,
proc_e, (vir_bytes) vsp, (phys_bytes)frame_len);
if (r != OK) {
printf("RS: stack_top is 0x%lx; tried to copy to 0x%lx in %d\n",
execi.stack_top, vsp, proc_e);
printf("do_exec: copying out new stack failed: %d\n", r);
exec_restart(proc_e, r, execi.pc);
return r;
}
return exec_restart(proc_e, OK, execi.pc);
}
/*===========================================================================*
* pm_exec *
*===========================================================================*/
PUBLIC int pm_exec(int proc_e, char *path, vir_bytes path_len, char *frame,
vir_bytes frame_len, vir_bytes *pc)
{
/* Perform the execve(name, argv, envp) call. The user library builds a
* complete stack image, including pointers, args, environ, etc. The stack
* is copied to a buffer inside VFS, and then to the new core image.
*/
int r, r1, round, proc_s;
vir_bytes vsp;
struct fproc *rfp;
struct vnode *vp;
char *cp;
static char mbuf[ARG_MAX]; /* buffer for stack and zeroes */
struct exec_info execi;
int i;
okendpt(proc_e, &proc_s);
rfp = fp = &fproc[proc_s];
who_e = proc_e;
who_p = proc_s;
super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE); /* su? */
/* Get the exec file name. */
if ((r = fetch_name(path, path_len, 0)) != OK) return(r);
/* Fetch the stack from the user before destroying the old core image. */
if (frame_len > ARG_MAX) {
printf("VFS: pm_exec: stack too big\n");
return(ENOMEM); /* stack too big */
}
r = sys_datacopy(proc_e, (vir_bytes) frame, SELF, (vir_bytes) mbuf,
(phys_bytes) frame_len);
if (r != OK) { /* can't fetch stack (e.g. bad virtual addr) */
printf("pm_exec: sys_datacopy failed\n");
return(r);
}
/* The default is to keep the original user and group IDs */
execi.new_uid = rfp->fp_effuid;
execi.new_gid = rfp->fp_effgid;
for (round= 0; round < 2; round++) {
/* round = 0 (first attempt), or 1 (interpreted script) */
/* Save the name of the program */
(cp= strrchr(user_fullpath, '/')) ? cp++ : (cp= user_fullpath);
strncpy(execi.progname, cp, PROC_NAME_LEN-1);
execi.progname[PROC_NAME_LEN-1] = '\0';
execi.setugid = 0;
/* Open executable */
if ((vp = eat_path(PATH_NOFLAGS, fp)) == NULL) return(err_code);
execi.vp = vp;
if ((vp->v_mode & I_TYPE) != I_REGULAR)
r = ENOEXEC;
else if ((r1 = forbidden(vp, X_BIT)) != OK)
r = r1;
else
r = req_stat(vp->v_fs_e, vp->v_inode_nr, VFS_PROC_NR,
(char *) &(execi.sb), 0, 0);
if (r != OK) {
put_vnode(vp);
return(r);
}
if (round == 0) {
/* Deal with setuid/setgid executables */
if (vp->v_mode & I_SET_UID_BIT) {
execi.new_uid = vp->v_uid;
execi.setugid = 1;
}
if (vp->v_mode & I_SET_GID_BIT) {
execi.new_gid = vp->v_gid;
execi.setugid = 1;
}
}
r = map_header(&execi.hdr, execi.vp);
if (r != OK) {
put_vnode(vp);
return(r);
}
if (!is_script(execi.hdr, execi.vp->v_size) || round != 0)
break;
/* Get fresh copy of the file name. */
if ((r = fetch_name(path, path_len, 0)) != OK)
printf("VFS pm_exec: 2nd fetch_name failed\n");
else if ((r = patch_stack(vp, mbuf, &frame_len)) != OK)
printf("VFS pm_exec: patch_stack failed\n");
put_vnode(vp);
if (r != OK) return(r);
}
execi.proc_e = proc_e;
execi.frame_len = frame_len;
for(i = 0; exec_loaders[i].load_object != NULL; i++) {
r = (*exec_loaders[i].load_object)(&execi);
/* Loaded successfully, so no need to try other loaders */
if (r == OK) break;
}
put_vnode(vp);
/* No exec loader could load the object */
if (r != OK) {
return(ENOEXEC);
}
/* Save off PC */
*pc = execi.pc;
/* Patch up stack and copy it from VFS to new core image. */
vsp = execi.stack_top;
vsp -= frame_len;
patch_ptr(mbuf, vsp);
if ((r = sys_datacopy(SELF, (vir_bytes) mbuf, proc_e, (vir_bytes) vsp,
(phys_bytes)frame_len)) != OK) {
printf("VFS: datacopy failed (%d) trying to copy to %lu\n", r, vsp);
return(r);
}
if (r != OK) return(r);
clo_exec(rfp);
if (execi.setugid) {
/* If after loading the image we're still allowed to run with
* setuid or setgid, change the credentials now */
rfp->fp_effuid = execi.new_uid;
rfp->fp_effgid = execi.new_gid;
}
/* This child has now exec()ced. */
rfp->fp_execced = 1;
return(OK);
}
