minix/servers/rs/exec.c

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#include "inc.h"
#include <a.out.h>
#define BLOCK_SIZE 1024
static int do_exec(int proc_e, char *exec, size_t exec_len, char *progname,
char *frame, int frame_len);
FORWARD _PROTOTYPE( int read_header, (char *exec, size_t exec_len, int *sep_id,
vir_bytes *text_bytes, vir_bytes *data_bytes,
vir_bytes *bss_bytes, phys_bytes *tot_bytes, vir_bytes *pc,
int *hdrlenp) );
FORWARD _PROTOTYPE( int exec_newmem, (int proc_e, vir_bytes text_bytes,
vir_bytes data_bytes, vir_bytes bss_bytes, vir_bytes tot_bytes,
vir_bytes frame_len, int sep_id,
Dev_t st_dev, ino_t st_ino, time_t st_ctime, char *progname,
int new_uid, int new_gid,
vir_bytes *stack_topp, int *load_textp, int *allow_setuidp) );
FORWARD _PROTOTYPE( int exec_restart, (int proc_e, int result) );
FORWARD _PROTOTYPE( void patch_ptr, (char stack[ARG_MAX],
vir_bytes base) );
FORWARD _PROTOTYPE( int read_seg, (char *exec, size_t exec_len, off_t off,
int proc_e, int seg, phys_bytes seg_bytes) );
int dev_execve(int proc_e, char *exec, size_t exec_len, char **argv,
char **Xenvp)
{
char * const *ap;
char * const *ep;
char *frame;
char **vp;
char *sp, *progname;
size_t argc;
size_t frame_size;
size_t string_off;
size_t n;
int ov;
message m;
int r;
/* Assumptions: size_t and char *, it's all the same thing. */
/* Create a stack image that only needs to be patched up slightly
* by the kernel to be used for the process to be executed.
*/
ov= 0; /* No overflow yet. */
frame_size= 0; /* Size of the new initial stack. */
string_off= 0; /* Offset to start of the strings. */
argc= 0; /* Argument count. */
for (ap= argv; *ap != NULL; ap++) {
n = sizeof(*ap) + strlen(*ap) + 1;
frame_size+= n;
if (frame_size < n) ov= 1;
string_off+= sizeof(*ap);
argc++;
}
#if 0
printf("here: %s, %d\n", __FILE__, __LINE__);
for (ep= envp; *ep != NULL; ep++) {
n = sizeof(*ep) + strlen(*ep) + 1;
frame_size+= n;
if (frame_size < n) ov= 1;
string_off+= sizeof(*ap);
}
#endif
/* Add an argument count and two terminating nulls. */
frame_size+= sizeof(argc) + sizeof(*ap) + sizeof(*ep);
string_off+= sizeof(argc) + sizeof(*ap) + sizeof(*ep);
/* Align. */
frame_size= (frame_size + sizeof(char *) - 1) & ~(sizeof(char *) - 1);
/* The party is off if there is an overflow. */
if (ov || frame_size < 3 * sizeof(char *)) {
errno= E2BIG;
return -1;
}
/* Allocate space for the stack frame. */
if ((frame = (char *) sbrk(frame_size)) == (char *) -1) {
errno = E2BIG;
return -1;
}
/* Set arg count, init pointers to vector and string tables. */
* (size_t *) frame = argc;
vp = (char **) (frame + sizeof(argc));
sp = frame + string_off;
/* Load the argument vector and strings. */
for (ap= argv; *ap != NULL; ap++) {
*vp++= (char *) (sp - frame);
n= strlen(*ap) + 1;
memcpy(sp, *ap, n);
sp+= n;
}
*vp++= NULL;
#if 0
/* Load the environment vector and strings. */
for (ep= envp; *ep != NULL; ep++) {
*vp++= (char *) (sp - frame);
n= strlen(*ep) + 1;
memcpy(sp, *ep, n);
sp+= n;
}
#endif
*vp++= NULL;
/* Padding. */
while (sp < frame + frame_size) *sp++= 0;
(progname=strrchr(argv[0], '/')) ? progname++ : (progname=argv[0]);
r = do_exec(proc_e, exec, exec_len, progname, frame, frame_size);
/* Return the memory used for the frame and exit. */
(void) sbrk(-frame_size);
return r;
}
static int do_exec(int proc_e, char *exec, size_t exec_len, char *progname,
char *frame, int frame_len)
{
int r;
int hdrlen, sep_id, load_text, allow_setuid;
int need_restart, error;
vir_bytes stack_top, vsp;
vir_bytes text_bytes, data_bytes, bss_bytes, pc;
phys_bytes tot_bytes;
off_t off;
uid_t new_uid;
gid_t new_gid;
need_restart= 0;
error= 0;
/* Read the file header and extract the segment sizes. */
r = read_header(exec, exec_len, &sep_id,
&text_bytes, &data_bytes, &bss_bytes,
&tot_bytes, &pc, &hdrlen);
if (r != OK)
{
printf("do_exec: read_header failed\n");
goto fail;
}
need_restart= 1;
new_uid= getuid();
new_gid= getgid();
/* XXX what should we use to identify the executable? */
r= exec_newmem(proc_e, text_bytes, data_bytes, bss_bytes, tot_bytes,
frame_len, sep_id, 0 /*dev*/, proc_e /*inum*/, 0 /*ctime*/,
progname, new_uid, new_gid, &stack_top, &load_text,
&allow_setuid);
if (r != OK)
{
printf("do_exec: exec_newmap failed: %d\n", r);
error= r;
goto fail;
}
/* Patch up stack and copy it from RS to new core image. */
vsp = 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",
stack_top, vsp);
printf("do_exec: copying out new stack failed: %d\n", r);
error= r;
goto fail;
}
off = hdrlen;
/* Read in text and data segments. */
if (load_text) {
r= read_seg(exec, exec_len, off, proc_e, T, text_bytes);
if (r != OK)
{
printf("do_exec: read_seg failed: %d\n", r);
error= r;
goto fail;
}
}
else
printf("do_exec: not loading text segment\n");
off += text_bytes;
r= read_seg(exec, exec_len, off, proc_e, D, data_bytes);
if (r != OK)
{
printf("do_exec: read_seg failed: %d\n", r);
error= r;
goto fail;
}
return exec_restart(proc_e, OK);
fail:
printf("do_exec(fail): error = %d\n", error);
if (need_restart)
exec_restart(proc_e, error);
return error;
}
/*===========================================================================*
* exec_newmem *
*===========================================================================*/
PRIVATE int exec_newmem(proc_e, text_bytes, data_bytes, bss_bytes, tot_bytes,
frame_len, sep_id, st_dev, st_ino, st_ctime, progname,
new_uid, new_gid, stack_topp, load_textp, allow_setuidp)
int proc_e;
vir_bytes text_bytes;
vir_bytes data_bytes;
vir_bytes bss_bytes;
vir_bytes tot_bytes;
vir_bytes frame_len;
int sep_id;
dev_t st_dev;
ino_t st_ino;
time_t st_ctime;
int new_uid;
int new_gid;
char *progname;
vir_bytes *stack_topp;
int *load_textp;
int *allow_setuidp;
{
int r;
struct exec_newmem e;
message m;
e.text_bytes= text_bytes;
e.data_bytes= data_bytes;
e.bss_bytes= bss_bytes;
e.tot_bytes= tot_bytes;
e.args_bytes= frame_len;
e.sep_id= sep_id;
e.st_dev= st_dev;
e.st_ino= st_ino;
e.st_ctime= st_ctime;
e.new_uid= new_uid;
e.new_gid= new_gid;
strncpy(e.progname, progname, sizeof(e.progname)-1);
e.progname[sizeof(e.progname)-1]= '\0';
m.m_type= EXEC_NEWMEM;
m.EXC_NM_PROC= proc_e;
m.EXC_NM_PTR= (char *)&e;
r= sendrec(PM_PROC_NR, &m);
if (r != OK)
return r;
#if 0
printf("exec_newmem: r = %d, m_type = %d\n", r, m.m_type);
#endif
*stack_topp= m.m1_i1;
*load_textp= !!(m.m1_i2 & EXC_NM_RF_LOAD_TEXT);
*allow_setuidp= !!(m.m1_i2 & EXC_NM_RF_ALLOW_SETUID);
#if 0
printf("RS: exec_newmem: stack_top = 0x%x\n", *stack_topp);
printf("RS: exec_newmem: load_text = %d\n", *load_textp);
#endif
return m.m_type;
}
/*===========================================================================*
* exec_restart *
*===========================================================================*/
PRIVATE int exec_restart(proc_e, result)
int proc_e;
int result;
{
int r;
message m;
m.m_type= EXEC_RESTART;
m.EXC_RS_PROC= proc_e;
m.EXC_RS_RESULT= result;
r= sendrec(PM_PROC_NR, &m);
if (r != OK)
return r;
return m.m_type;
}
/*===========================================================================*
* read_header *
*===========================================================================*/
PRIVATE int read_header(exec, exec_len, sep_id, text_bytes, data_bytes,
bss_bytes, tot_bytes, pc, hdrlenp)
char *exec; /* executable image */
size_t exec_len; /* size of the image */
int *sep_id; /* true iff sep I&D */
vir_bytes *text_bytes; /* place to return text size */
vir_bytes *data_bytes; /* place to return initialized data size */
vir_bytes *bss_bytes; /* place to return bss size */
phys_bytes *tot_bytes; /* place to return total size */
vir_bytes *pc; /* program entry point (initial PC) */
int *hdrlenp;
{
/* Read the header and extract the text, data, bss and total sizes from it. */
off_t pos;
block_t b;
struct exec hdr; /* a.out header is read in here */
/* Read the header and check the magic number. The standard MINIX header
* is defined in <a.out.h>. It consists of 8 chars followed by 6 longs.
* Then come 4 more longs that are not used here.
* Byte 0: magic number 0x01
* Byte 1: magic number 0x03
* Byte 2: normal = 0x10 (not checked, 0 is OK), separate I/D = 0x20
* Byte 3: CPU type, Intel 16 bit = 0x04, Intel 32 bit = 0x10,
* Motorola = 0x0B, Sun SPARC = 0x17
* Byte 4: Header length = 0x20
* Bytes 5-7 are not used.
*
* Now come the 6 longs
* Bytes 8-11: size of text segments in bytes
* Bytes 12-15: size of initialized data segment in bytes
* Bytes 16-19: size of bss in bytes
* Bytes 20-23: program entry point
* Bytes 24-27: total memory allocated to program (text, data + stack)
* Bytes 28-31: size of symbol table in bytes
* The longs are represented in a machine dependent order,
* little-endian on the 8088, big-endian on the 68000.
* The header is followed directly by the text and data segments, and the
* symbol table (if any). The sizes are given in the header. Only the
* text and data segments are copied into memory by exec. The header is
* used here only. The symbol table is for the benefit of a debugger and
* is ignored here.
*/
int r;
pos= 0; /* Read from the start of the file */
if (exec_len < sizeof(hdr)) return(ENOEXEC);
memcpy(&hdr, exec, sizeof(hdr));
/* Check magic number, cpu type, and flags. */
if (BADMAG(hdr)) return(ENOEXEC);
#if (CHIP == INTEL && _WORD_SIZE == 2)
if (hdr.a_cpu != A_I8086) return(ENOEXEC);
#endif
#if (CHIP == INTEL && _WORD_SIZE == 4)
if (hdr.a_cpu != A_I80386) return(ENOEXEC);
#endif
if ((hdr.a_flags & ~(A_NSYM | A_EXEC | A_SEP)) != 0) return(ENOEXEC);
*sep_id = !!(hdr.a_flags & A_SEP); /* separate I & D or not */
/* Get text and data sizes. */
*text_bytes = (vir_bytes) hdr.a_text; /* text size in bytes */
*data_bytes = (vir_bytes) hdr.a_data; /* data size in bytes */
*bss_bytes = (vir_bytes) hdr.a_bss; /* bss size in bytes */
*tot_bytes = hdr.a_total; /* total bytes to allocate for prog */
if (*tot_bytes == 0) return(ENOEXEC);
if (!*sep_id) {
/* If I & D space is not separated, it is all considered data. Text=0*/
*data_bytes += *text_bytes;
*text_bytes = 0;
}
*pc = hdr.a_entry; /* initial address to start execution */
*hdrlenp = hdr.a_hdrlen & BYTE; /* header length */
return(OK);
}
/*===========================================================================*
* patch_ptr *
*===========================================================================*/
PRIVATE void patch_ptr(stack, base)
char stack[ARG_MAX]; /* pointer to stack image within PM */
vir_bytes base; /* virtual address of stack base inside user */
{
/* When doing an exec(name, argv, envp) call, the user builds up a stack
* image with arg and env pointers relative to the start of the stack. Now
* these pointers must be relocated, since the stack is not positioned at
* address 0 in the user's address space.
*/
char **ap, flag;
vir_bytes v;
flag = 0; /* counts number of 0-pointers seen */
ap = (char **) stack; /* points initially to 'nargs' */
ap++; /* now points to argv[0] */
while (flag < 2) {
if (ap >= (char **) &stack[ARG_MAX]) return; /* too bad */
if (*ap != NULL) {
v = (vir_bytes) *ap; /* v is relative pointer */
v += base; /* relocate it */
*ap = (char *) v; /* put it back */
} else {
flag++;
}
ap++;
}
}
/*===========================================================================*
* read_seg *
*===========================================================================*/
PRIVATE int read_seg(exec, exec_len, off, proc_e, seg, seg_bytes)
char *exec; /* executable image */
size_t exec_len; /* size of the image */
off_t off; /* offset in file */
int proc_e; /* process number (endpoint) */
int seg; /* T, D, or S */
phys_bytes seg_bytes; /* how much is to be transferred? */
{
/*
* The byte count on read is usually smaller than the segment count, because
* a segment is padded out to a click multiple, and the data segment is only
* partially initialized.
*/
int r;
off_t n, o, b_off, seg_off;
if (off+seg_bytes > exec_len) return ENOEXEC;
r= sys_vircopy(SELF, D, (vir_bytes)exec+off, proc_e, seg, 0, seg_bytes);
return r;
}