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NetBSD/sys/kern/exec_elf.c

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/* $NetBSD: exec_elf.c,v 1.6 1996/02/09 18:59:18 christos Exp $ */
/*
* Copyright (c) 1994 Christos Zoulas
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/exec.h>
#include <sys/exec_elf.h>
#include <sys/mman.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_map.h>
#include <machine/cpu.h>
#include <machine/reg.h>
#include <machine/exec.h>
#ifdef COMPAT_LINUX
#include <compat/linux/linux_exec.h>
#endif
#ifdef COMPAT_SVR4
#include <compat/svr4/svr4_exec.h>
#endif
int (*elf_probe_funcs[]) __P((struct proc *, struct exec_package *,
char *, u_long *)) = {
#ifdef COMPAT_SVR4
svr4_elf_probe,
#endif
#ifdef COMPAT_LINUX
linux_elf_probe
#endif
};
int elf_check_header __P((Elf32_Ehdr *, int));
int elf_load_file __P((struct proc *, char *, struct exec_vmcmd_set *,
u_long *, struct elf_args *, u_long *));
static int elf_read_from __P((struct proc *, struct vnode *, u_long,
caddr_t, int));
static void elf_load_psection __P((struct exec_vmcmd_set *,
struct vnode *, Elf32_Phdr *, u_long *, u_long *, int *));
#define ELF_ALIGN(a, b) ((a) & ~((b) - 1))
/*
* Copy arguments onto the stack in the normal way, but add some
* extra information in case of dynamic binding.
*/
void *
elf_copyargs(pack, arginfo, stack, argp)
struct exec_package *pack;
struct ps_strings *arginfo;
void *stack;
void *argp;
{
size_t len;
AuxInfo ai[ELF_AUX_ENTRIES], *a;
struct elf_args *ap;
stack = copyargs(pack, arginfo, stack, argp);
if (!stack)
return NULL;
/*
* Push extra arguments on the stack needed by dynamically
* linked binaries
*/
if ((ap = (struct elf_args *) pack->ep_emul_arg)) {
a = ai;
a->au_id = AUX_phdr;
a->au_v = ap->arg_phaddr;
a++;
a->au_id = AUX_phent;
a->au_v = ap->arg_phentsize;
a++;
a->au_id = AUX_phnum;
a->au_v = ap->arg_phnum;
a++;
a->au_id = AUX_pagesz;
a->au_v = NBPG;
a++;
a->au_id = AUX_base;
a->au_v = ap->arg_interp;
a++;
a->au_id = AUX_flags;
a->au_v = 0;
a++;
a->au_id = AUX_entry;
a->au_v = ap->arg_entry;
a++;
a->au_id = AUX_null;
a->au_v = 0;
a++;
free((char *) ap, M_TEMP);
len = ELF_AUX_ENTRIES * sizeof (AuxInfo);
if (copyout(ai, stack, len))
return NULL;
stack += len;
}
return stack;
}
/*
* elf_check_header():
*
* Check header for validity; return 0 of ok ENOEXEC if error
*
* XXX machine type needs to be moved to <machine/param.h> so
* just one comparison can be done. Unfortunately, there is both
* em_486 and em_386, so this would not work on the i386.
*/
int
elf_check_header(eh, type)
Elf32_Ehdr *eh;
int type;
{
if (bcmp(eh->e_ident, Elf32_e_ident, Elf32_e_siz) != 0)
return ENOEXEC;
switch (eh->e_machine) {
/* XXX */
#ifdef i386
case Elf32_em_386:
case Elf32_em_486:
#endif
#ifdef sparc
case Elf32_em_sparc:
#endif
break;
default:
return ENOEXEC;
}
if (eh->e_type != type)
return ENOEXEC;
return 0;
}
/*
* elf_load_psection():
*
* Load a psection at the appropriate address
*/
static void
elf_load_psection(vcset, vp, ph, addr, size, prot)
struct exec_vmcmd_set *vcset;
struct vnode *vp;
Elf32_Phdr *ph;
u_long *addr;
u_long *size;
int *prot;
{
u_long uaddr, msize, rm, rf;
long diff, offset;
/*
* If the user specified an address, then we load there.
*/
if (*addr != ELF32_NO_ADDR) {
if (ph->p_align > 1) {
*addr = ELF_ALIGN(*addr + ph->p_align, ph->p_align);
uaddr = ELF_ALIGN(ph->p_vaddr, ph->p_align);
} else
uaddr = ph->p_vaddr;
diff = ph->p_vaddr - uaddr;
} else {
*addr = uaddr = ph->p_vaddr;
if (ph->p_align > 1)
*addr = ELF_ALIGN(uaddr, ph->p_align);
diff = uaddr - *addr;
}
*prot |= (ph->p_flags & Elf32_pf_r) ? VM_PROT_READ : 0;
*prot |= (ph->p_flags & Elf32_pf_w) ? VM_PROT_WRITE : 0;
*prot |= (ph->p_flags & Elf32_pf_x) ? VM_PROT_EXECUTE : 0;
offset = ph->p_offset - diff;
*size = ph->p_filesz + diff;
msize = ph->p_memsz + diff;
NEW_VMCMD(vcset, vmcmd_map_readvn, *size, *addr, vp, offset, *prot);
/*
* Check if we need to extend the size of the segment
*/
rm = round_page(*addr + msize);
rf = round_page(*addr + *size);
if (rm != rf) {
NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP, 0, *prot);
*size = msize;
}
}
/*
* elf_read_from():
*
* Read from vnode into buffer at offset.
*/
static int
elf_read_from(p, vp, off, buf, size)
struct vnode *vp;
u_long off;
struct proc *p;
caddr_t buf;
int size;
{
int error;
int resid;
if ((error = vn_rdwr(UIO_READ, vp, buf, size,
off, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred,
&resid, p)) != 0)
return error;
/*
* See if we got all of it
*/
if (resid != 0)
return ENOEXEC;
return 0;
}
/*
* elf_load_file():
*
* Load a file (interpreter/library) pointed to by path
* [stolen from coff_load_shlib()]. Made slightly generic
* so it might be used externally.
*/
int
elf_load_file(p, path, vcset, entry, ap, last)
struct proc *p;
char *path;
struct exec_vmcmd_set *vcset;
u_long *entry;
struct elf_args *ap;
u_long *last;
{
int error, i;
struct nameidata nd;
Elf32_Ehdr eh;
Elf32_Phdr *ph = NULL;
u_long phsize;
char *bp = NULL;
u_long addr = *last;
bp = path;
/*
* 1. open file
* 2. read filehdr
* 3. map text, data, and bss out of it using VM_*
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, path, p);
if ((error = namei(&nd)) != 0) {
return error;
}
if ((error = elf_read_from(p, nd.ni_vp, 0, (caddr_t) &eh,
sizeof(eh))) != 0)
goto bad;
if ((error = elf_check_header(&eh, Elf32_et_dyn)) != 0)
goto bad;
phsize = eh.e_phnum * sizeof(Elf32_Phdr);
ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK);
if ((error = elf_read_from(p, nd.ni_vp, eh.e_phoff,
(caddr_t) ph, phsize)) != 0)
goto bad;
/*
* Load all the necessary sections
*/
for (i = 0; i < eh.e_phnum; i++) {
u_long size = 0;
int prot = 0;
switch (ph[i].p_type) {
case Elf32_pt_load:
elf_load_psection(vcset, nd.ni_vp, &ph[i], &addr,
&size, &prot);
/* If entry is within this section it must be text */
if (eh.e_entry >= ph[i].p_vaddr &&
eh.e_entry < (ph[i].p_vaddr + size)) {
*entry = addr + eh.e_entry;
ap->arg_interp = addr;
}
addr += size;
break;
case Elf32_pt_dynamic:
case Elf32_pt_phdr:
case Elf32_pt_note:
break;
default:
break;
}
}
bad:
if (ph != NULL)
free((char *) ph, M_TEMP);
*last = addr;
vrele(nd.ni_vp);
return error;
}
/*
* exec_elf_makecmds(): Prepare an Elf binary's exec package
*
* First, set of the various offsets/lengths in the exec package.
*
* Then, mark the text image busy (so it can be demand paged) or error
* out if this is not possible. Finally, set up vmcmds for the
* text, data, bss, and stack segments.
*
* XXX no demand paging (yet?)
*/
int
exec_elf_makecmds(p, epp)
struct proc *p;
struct exec_package *epp;
{
Elf32_Ehdr *eh = epp->ep_hdr;
Elf32_Phdr *ph, *pp;
Elf32_Addr phdr = 0;
int error, i, n, nload;
char interp[MAXPATHLEN];
u_long pos = 0, phsize;
if (epp->ep_hdrvalid < sizeof(Elf32_Ehdr))
return ENOEXEC;
if (elf_check_header(eh, Elf32_et_exec))
return ENOEXEC;
/*
* check if vnode is in open for writing, because we want to
* demand-page out of it. if it is, don't do it, for various
* reasons
*/
if (epp->ep_vp->v_writecount != 0) {
#ifdef DIAGNOSTIC
if (epp->ep_vp->v_flag & VTEXT)
panic("exec: a VTEXT vnode has writecount != 0\n");
#endif
return ETXTBSY;
}
/*
* Allocate space to hold all the program headers, and read them
* from the file
*/
phsize = eh->e_phnum * sizeof(Elf32_Phdr);
ph = (Elf32_Phdr *) malloc(phsize, M_TEMP, M_WAITOK);
if ((error = elf_read_from(p, epp->ep_vp, eh->e_phoff,
(caddr_t) ph, phsize)) != 0)
goto bad;
epp->ep_tsize = ELF32_NO_ADDR;
epp->ep_dsize = ELF32_NO_ADDR;
interp[0] = '\0';
for (i = 0; i < eh->e_phnum; i++) {
pp = &ph[i];
if (pp->p_type == Elf32_pt_interp) {
if (pp->p_filesz >= sizeof(interp))
goto bad;
if ((error = elf_read_from(p, epp->ep_vp, pp->p_offset,
(caddr_t) interp, pp->p_filesz)) != 0)
goto bad;
break;
}
}
/*
* On the same architecture, we may be emulating different systems.
* See which one will accept this executable. This currently only
* applies to Linux and SVR4 on the i386.
*
* Probe functions would normally see if the interpreter (if any)
* exists. Emulation packages may possibly replace the interpreter in
* interp[] with a changed path (/emul/xxx/<path>), and also
* set the ep_emul field in the exec package structure.
*/
if ((n = sizeof elf_probe_funcs / sizeof elf_probe_funcs[0])) {
error = ENOEXEC;
for (i = 0; i < n && error; i++)
error = elf_probe_funcs[i](p, epp, interp, &pos);
if (error)
goto bad;
}
/*
* Load all the necessary sections
*/
for (i = nload = 0; i < eh->e_phnum; i++) {
u_long addr = ELF32_NO_ADDR, size = 0;
int prot = 0;
pp = &ph[i];
switch (ph[i].p_type) {
case Elf32_pt_load:
/*
* XXX
* Can handle only 2 sections: text and data
*/
if (nload++ == 2)
goto bad;
elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
&ph[i], &addr, &size, &prot);
/*
* Decide whether it's text or data by looking
* at the entry point.
*/
if (eh->e_entry >= addr && eh->e_entry < (addr + size)){
epp->ep_taddr = addr;
epp->ep_tsize = size;
} else {
epp->ep_daddr = addr;
epp->ep_dsize = size;
}
break;
case Elf32_pt_shlib:
error = ENOEXEC;
goto bad;
case Elf32_pt_interp:
/* Already did this one */
case Elf32_pt_dynamic:
case Elf32_pt_note:
break;
case Elf32_pt_phdr:
/* Note address of program headers (in text segment) */
phdr = pp->p_vaddr;
break;
default:
/*
* Not fatal, we don't need to understand everything
* :-)
*/
break;
}
}
/*
* If no position to load the interpreter was set by a probe
* function, pick the same address that a non-fixed mmap(0, ..)
* would (i.e. something safely out of the way).
*/
if (pos == ELF32_NO_ADDR)
pos = round_page(epp->ep_daddr + MAXDSIZ);
/*
* Check if we found a dynamically linked binary and arrange to load
* it's interpreter
*/
if (interp[0]) {
struct elf_args *ap;
ap = (struct elf_args *) malloc(sizeof(struct elf_args),
M_TEMP, M_WAITOK);
if ((error = elf_load_file(p, interp, &epp->ep_vmcmds,
&epp->ep_entry, ap, &pos)) != 0) {
free((char *) ap, M_TEMP);
goto bad;
}
pos += phsize;
ap->arg_phaddr = phdr;
ap->arg_phentsize = eh->e_phentsize;
ap->arg_phnum = eh->e_phnum;
ap->arg_entry = eh->e_entry;
epp->ep_emul_arg = ap;
} else
epp->ep_entry = eh->e_entry;
free((char *) ph, M_TEMP);
epp->ep_vp->v_flag |= VTEXT;
return exec_aout_setup_stack(p, epp);
bad:
free((char *) ph, M_TEMP);
kill_vmcmds(&epp->ep_vmcmds);
return ENOEXEC;
}
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