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NetBSD/sys/kern/exec_elf.c

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/* $NetBSD: exec_elf.c,v 1.69.2.2 2015/03/29 09:07:55 martin Exp $ */
/*-
* Copyright (c) 1994, 2000, 2005 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Christos Zoulas.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
/*
* Copyright (c) 1996 Christopher G. Demetriou
* 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/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.69.2.2 2015/03/29 09:07:55 martin Exp $");
#ifdef _KERNEL_OPT
#include "opt_pax.h"
#endif /* _KERNEL_OPT */
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/kmem.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/exec.h>
#include <sys/exec_elf.h>
#include <sys/syscall.h>
#include <sys/signalvar.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/kauth.h>
#include <sys/bitops.h>
#include <sys/cprng.h>
#include <sys/cpu.h>
#include <machine/reg.h>
#include <compat/common/compat_util.h>
#include <sys/pax.h>
#include <uvm/uvm_param.h>
extern struct emul emul_netbsd;
#define elf_check_header ELFNAME(check_header)
#define elf_copyargs ELFNAME(copyargs)
#define elf_load_interp ELFNAME(load_interp)
#define elf_load_psection ELFNAME(load_psection)
#define exec_elf_makecmds ELFNAME2(exec,makecmds)
#define netbsd_elf_signature ELFNAME2(netbsd,signature)
#define netbsd_elf_probe ELFNAME2(netbsd,probe)
#define coredump ELFNAMEEND(coredump)
#define elf_free_emul_arg ELFNAME(free_emul_arg)
static int
elf_load_interp(struct lwp *, struct exec_package *, char *,
struct exec_vmcmd_set *, u_long *, Elf_Addr *);
static void
elf_load_psection(struct exec_vmcmd_set *, struct vnode *, const Elf_Phdr *,
Elf_Addr *, u_long *, int);
int netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *);
int netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *,
vaddr_t *);
static void elf_free_emul_arg(void *);
/* round up and down to page boundaries. */
#define ELF_ROUND(a, b) (((a) + (b) - 1) & ~((b) - 1))
#define ELF_TRUNC(a, b) ((a) & ~((b) - 1))
static void
elf_placedynexec(struct lwp *l, struct exec_package *epp, Elf_Ehdr *eh,
Elf_Phdr *ph)
{
Elf_Addr align, offset;
int i;
for (align = i = 0; i < eh->e_phnum; i++)
if (ph[i].p_type == PT_LOAD && ph[i].p_align > align)
align = ph[i].p_align;
#ifdef PAX_ASLR
if (pax_aslr_active(l)) {
size_t pax_align, l2, delta;
uint32_t r;
pax_align = align;
r = cprng_fast32();
if (pax_align == 0)
pax_align = PGSHIFT;
l2 = ilog2(pax_align);
delta = PAX_ASLR_DELTA(r, l2, PAX_ASLR_DELTA_EXEC_LEN);
offset = ELF_TRUNC(delta, pax_align) + PAGE_SIZE;
#ifdef PAX_ASLR_DEBUG
uprintf("r=0x%x l2=0x%zx PGSHIFT=0x%x Delta=0x%zx\n", r, l2,
PGSHIFT, delta);
uprintf("pax offset=0x%llx entry=0x%llx\n",
(unsigned long long)offset,
(unsigned long long)eh->e_entry);
#endif /* PAX_ASLR_DEBUG */
} else
#endif /* PAX_ASLR */
offset = MAX(align, PAGE_SIZE);
offset += epp->ep_vm_minaddr;
for (i = 0; i < eh->e_phnum; i++)
ph[i].p_vaddr += offset;
epp->ep_entryoffset = offset;
eh->e_entry += offset;
}
/*
* Copy arguments onto the stack in the normal way, but add some
* extra information in case of dynamic binding.
*/
int
elf_copyargs(struct lwp *l, struct exec_package *pack,
struct ps_strings *arginfo, char **stackp, void *argp)
{
size_t len, vlen;
AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname;
struct elf_args *ap;
int error;
if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0)
return error;
a = ai;
execname = NULL;
memset(ai, 0, sizeof(ai));
/*
* Push extra arguments on the stack needed by dynamically
* linked binaries
*/
if ((ap = (struct elf_args *)pack->ep_emul_arg)) {
struct vattr *vap = pack->ep_vap;
a->a_type = AT_PHDR;
a->a_v = ap->arg_phaddr;
a++;
a->a_type = AT_PHENT;
a->a_v = ap->arg_phentsize;
a++;
a->a_type = AT_PHNUM;
a->a_v = ap->arg_phnum;
a++;
a->a_type = AT_PAGESZ;
a->a_v = PAGE_SIZE;
a++;
a->a_type = AT_BASE;
a->a_v = ap->arg_interp;
a++;
a->a_type = AT_FLAGS;
a->a_v = 0;
a++;
a->a_type = AT_ENTRY;
a->a_v = ap->arg_entry;
a++;
a->a_type = AT_EUID;
if (vap->va_mode & S_ISUID)
a->a_v = vap->va_uid;
else
a->a_v = kauth_cred_geteuid(l->l_cred);
a++;
a->a_type = AT_RUID;
a->a_v = kauth_cred_getuid(l->l_cred);
a++;
a->a_type = AT_EGID;
if (vap->va_mode & S_ISGID)
a->a_v = vap->va_gid;
else
a->a_v = kauth_cred_getegid(l->l_cred);
a++;
a->a_type = AT_RGID;
a->a_v = kauth_cred_getgid(l->l_cred);
a++;
a->a_type = AT_STACKBASE;
a->a_v = l->l_proc->p_stackbase;
a++;
if (pack->ep_path) {
execname = a;
a->a_type = AT_SUN_EXECNAME;
a++;
}
exec_free_emul_arg(pack);
}
a->a_type = AT_NULL;
a->a_v = 0;
a++;
vlen = (a - ai) * sizeof(ai[0]);
KASSERT(vlen <= sizeof(ai));
if (execname) {
char *path = pack->ep_path;
execname->a_v = (uintptr_t)(*stackp + vlen);
len = strlen(path) + 1;
if ((error = copyout(path, (*stackp + vlen), len)) != 0)
return error;
len = ALIGN(len);
} else
len = 0;
if ((error = copyout(ai, *stackp, vlen)) != 0)
return error;
*stackp += vlen + len;
return 0;
}
/*
* elf_check_header():
*
* Check header for validity; return 0 if ok, ENOEXEC if error
*/
int
elf_check_header(Elf_Ehdr *eh)
{
if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 ||
eh->e_ident[EI_CLASS] != ELFCLASS)
return ENOEXEC;
switch (eh->e_machine) {
ELFDEFNNAME(MACHDEP_ID_CASES)
default:
return ENOEXEC;
}
if (ELF_EHDR_FLAGS_OK(eh) == 0)
return ENOEXEC;
if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM)
return ENOEXEC;
return 0;
}
/*
* elf_load_psection():
*
* Load a psection at the appropriate address
*/
static void
elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp,
const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int flags)
{
u_long msize, psize, rm, rf;
long diff, offset;
int vmprot = 0;
/*
* If the user specified an address, then we load there.
*/
if (*addr == ELFDEFNNAME(NO_ADDR))
*addr = ph->p_vaddr;
if (ph->p_align > 1) {
/*
* Make sure we are virtually aligned as we are supposed to be.
*/
diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align);
KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align));
/*
* But make sure to not map any pages before the start of the
* psection by limiting the difference to within a page.
*/
diff &= PAGE_MASK;
} else
diff = 0;
vmprot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0;
vmprot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0;
vmprot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0;
/*
* Adjust everything so it all starts on a page boundary.
*/
*addr -= diff;
offset = ph->p_offset - diff;
*size = ph->p_filesz + diff;
msize = ph->p_memsz + diff;
if (ph->p_align >= PAGE_SIZE) {
if ((ph->p_flags & PF_W) != 0) {
/*
* Because the pagedvn pager can't handle zero fill
* of the last data page if it's not page aligned we
* map the last page readvn.
*/
psize = trunc_page(*size);
} else {
psize = round_page(*size);
}
} else {
psize = *size;
}
if (psize > 0) {
NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ?
vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp,
offset, vmprot, flags);
flags &= VMCMD_RELATIVE;
}
if (psize < *size) {
NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize,
*addr + psize, vp, offset + psize, vmprot, flags);
}
/*
* Check if we need to extend the size of the segment (does
* bss extend page the next page boundary)?
*/
rm = round_page(*addr + msize);
rf = round_page(*addr + *size);
if (rm != rf) {
NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP,
0, vmprot, flags & VMCMD_RELATIVE);
*size = msize;
}
}
/*
* elf_load_interp():
*
* Load an interpreter pointed to by path.
*/
static int
elf_load_interp(struct lwp *l, struct exec_package *epp, char *path,
struct exec_vmcmd_set *vcset, u_long *entryoff, Elf_Addr *last)
{
int error, i;
struct vnode *vp;
struct vattr attr;
Elf_Ehdr eh;
Elf_Phdr *ph = NULL;
const Elf_Phdr *base_ph;
const Elf_Phdr *last_ph;
u_long phsize;
Elf_Addr addr = *last;
struct proc *p;
bool use_topdown;
p = l->l_proc;
KASSERT(p->p_vmspace);
if (__predict_true(p->p_vmspace != proc0.p_vmspace)) {
use_topdown = p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN;
} else {
#ifdef __USE_TOPDOWN_VM
use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM;
#else
use_topdown = false;
#endif
}
/*
* 1. open file
* 2. read filehdr
* 3. map text, data, and bss out of it using VM_*
*/
vp = epp->ep_interp;
if (vp == NULL) {
error = emul_find_interp(l, epp, path);
if (error != 0)
return error;
vp = epp->ep_interp;
}
/* We'll tidy this ourselves - otherwise we have locking issues */
epp->ep_interp = NULL;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
/*
* Similarly, if it's not marked as executable, or it's not a regular
* file, we don't allow it to be used.
*/
if (vp->v_type != VREG) {
error = EACCES;
goto badunlock;
}
if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0)
goto badunlock;
/* get attributes */
if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0)
goto badunlock;
/*
* Check mount point. Though we're not trying to exec this binary,
* we will be executing code from it, so if the mount point
* disallows execution or set-id-ness, we punt or kill the set-id.
*/
if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
error = EACCES;
goto badunlock;
}
if (vp->v_mount->mnt_flag & MNT_NOSUID)
epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);
#ifdef notyet /* XXX cgd 960926 */
XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?)
XXXps: this problem will make it impossible to use an interpreter
from a file system which actually does something in VOP_OPEN
#endif
error = vn_marktext(vp);
if (error)
goto badunlock;
VOP_UNLOCK(vp);
if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0)
goto bad;
if ((error = elf_check_header(&eh)) != 0)
goto bad;
if (eh.e_type != ET_DYN || eh.e_phnum == 0) {
error = ENOEXEC;
goto bad;
}
phsize = eh.e_phnum * sizeof(Elf_Phdr);
ph = kmem_alloc(phsize, KM_SLEEP);
if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0)
goto bad;
#ifdef ELF_INTERP_NON_RELOCATABLE
/*
* Evil hack: Only MIPS should be non-relocatable, and the
* psections should have a high address (typically 0x5ffe0000).
* If it's now relocatable, it should be linked at 0 and the
* psections should have zeros in the upper part of the address.
* Otherwise, force the load at the linked address.
*/
if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0)
*last = ELFDEFNNAME(NO_ADDR);
#endif
/*
* 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 (*last == ELFDEFNNAME(NO_ADDR)) {
u_long limit = 0;
/*
* Find the start and ending addresses of the psections to
* be loaded. This will give us the size.
*/
for (i = 0, base_ph = NULL; i < eh.e_phnum; i++) {
if (ph[i].p_type == PT_LOAD) {
u_long psize = ph[i].p_vaddr + ph[i].p_memsz;
if (base_ph == NULL)
base_ph = &ph[i];
if (psize > limit)
limit = psize;
}
}
if (base_ph == NULL) {
error = ENOEXEC;
goto bad;
}
/*
* Now compute the size and load address.
*/
addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p,
epp->ep_daddr,
round_page(limit) - trunc_page(base_ph->p_vaddr));
} else
addr = *last; /* may be ELF_LINK_ADDR */
/*
* Load all the necessary sections
*/
for (i = 0, base_ph = NULL, last_ph = NULL; i < eh.e_phnum; i++) {
switch (ph[i].p_type) {
case PT_LOAD: {
u_long size;
int flags;
if (base_ph == NULL) {
/*
* First encountered psection is always the
* base psection. Make sure it's aligned
* properly (align down for topdown and align
* upwards for not topdown).
*/
base_ph = &ph[i];
flags = VMCMD_BASE;
if (addr == ELF_LINK_ADDR)
addr = ph[i].p_vaddr;
if (use_topdown)
addr = ELF_TRUNC(addr, ph[i].p_align);
else
addr = ELF_ROUND(addr, ph[i].p_align);
} else {
u_long limit = round_page(last_ph->p_vaddr
+ last_ph->p_memsz);
u_long base = trunc_page(ph[i].p_vaddr);
/*
* If there is a gap in between the psections,
* map it as inaccessible so nothing else
* mmap'ed will be placed there.
*/
if (limit != base) {
NEW_VMCMD2(vcset, vmcmd_map_zero,
base - limit,
limit - base_ph->p_vaddr, NULLVP,
0, VM_PROT_NONE, VMCMD_RELATIVE);
}
addr = ph[i].p_vaddr - base_ph->p_vaddr;
flags = VMCMD_RELATIVE;
}
last_ph = &ph[i];
elf_load_psection(vcset, vp, &ph[i], &addr,
&size, flags);
/*
* If entry is within this psection then this
* must contain the .text section. *entryoff is
* relative to the base psection.
*/
if (eh.e_entry >= ph[i].p_vaddr &&
eh.e_entry < (ph[i].p_vaddr + size)) {
*entryoff = eh.e_entry - base_ph->p_vaddr;
}
addr += size;
break;
}
default:
break;
}
}
kmem_free(ph, phsize);
/*
* This value is ignored if TOPDOWN.
*/
*last = addr;
vrele(vp);
return 0;
badunlock:
VOP_UNLOCK(vp);
bad:
if (ph != NULL)
kmem_free(ph, phsize);
#ifdef notyet /* XXX cgd 960926 */
(maybe) VOP_CLOSE it
#endif
vrele(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.
*/
int
exec_elf_makecmds(struct lwp *l, struct exec_package *epp)
{
Elf_Ehdr *eh = epp->ep_hdr;
Elf_Phdr *ph, *pp;
Elf_Addr phdr = 0, computed_phdr = 0, pos = 0, end_text = 0;
int error, i;
char *interp = NULL;
u_long phsize;
struct elf_args *ap;
bool is_dyn = false;
if (epp->ep_hdrvalid < sizeof(Elf_Ehdr))
return ENOEXEC;
if ((error = elf_check_header(eh)) != 0)
return error;
if (eh->e_type == ET_DYN)
/*
* XXX allow for executing shared objects. It seems silly
* but other ELF-based systems allow it as well.
*/
is_dyn = true;
else if (eh->e_type != ET_EXEC)
return ENOEXEC;
if (eh->e_phnum == 0)
return ENOEXEC;
error = vn_marktext(epp->ep_vp);
if (error)
return error;
/*
* Allocate space to hold all the program headers, and read them
* from the file
*/
phsize = eh->e_phnum * sizeof(Elf_Phdr);
ph = kmem_alloc(phsize, KM_SLEEP);
if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) !=
0)
goto bad;
epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR);
epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR);
for (i = 0; i < eh->e_phnum; i++) {
pp = &ph[i];
if (pp->p_type == PT_INTERP) {
if (pp->p_filesz < 2 || pp->p_filesz > MAXPATHLEN) {
error = ENOEXEC;
goto bad;
}
interp = PNBUF_GET();
if ((error = exec_read_from(l, epp->ep_vp,
pp->p_offset, interp, pp->p_filesz)) != 0)
goto bad;
/* Ensure interp is NUL-terminated and of the expected length */
if (strnlen(interp, pp->p_filesz) != pp->p_filesz - 1) {
error = ENOEXEC;
goto bad;
}
break;
}
}
/*
* On the same architecture, we may be emulating different systems.
* See which one will accept this executable.
*
* 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>).
*/
pos = ELFDEFNNAME(NO_ADDR);
if (epp->ep_esch->u.elf_probe_func) {
vaddr_t startp = (vaddr_t)pos;
error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp,
&startp);
if (error)
goto bad;
pos = (Elf_Addr)startp;
}
#if defined(PAX_MPROTECT) || defined(PAX_SEGVGUARD) || defined(PAX_ASLR)
l->l_proc->p_pax = epp->ep_pax_flags;
#endif /* PAX_MPROTECT || PAX_SEGVGUARD || PAX_ASLR */
if (is_dyn)
elf_placedynexec(l, epp, eh, ph);
/*
* Load all the necessary sections
*/
for (i = 0; i < eh->e_phnum; i++) {
Elf_Addr addr = ELFDEFNNAME(NO_ADDR);
u_long size = 0;
switch (ph[i].p_type) {
case PT_LOAD:
elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
&ph[i], &addr, &size, VMCMD_FIXED);
/*
* Consider this as text segment, if it is executable.
* If there is more than one text segment, pick the
* largest.
*/
if (ph[i].p_flags & PF_X) {
if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) ||
size > epp->ep_tsize) {
epp->ep_taddr = addr;
epp->ep_tsize = size;
}
end_text = addr + size;
} else {
epp->ep_daddr = addr;
epp->ep_dsize = size;
}
if (ph[i].p_offset == 0) {
computed_phdr = ph[i].p_vaddr + eh->e_phoff;
}
break;
case PT_SHLIB:
/* SCO has these sections. */
case PT_INTERP:
/* Already did this one. */
case PT_DYNAMIC:
case PT_NOTE:
break;
case PT_PHDR:
/* Note address of program headers (in text segment) */
phdr = ph[i].p_vaddr;
break;
default:
/*
* Not fatal; we don't need to understand everything.
*/
break;
}
}
if (epp->ep_vmcmds.evs_used == 0) {
/* No VMCMD; there was no PT_LOAD section, or those
* sections were empty */
error = ENOEXEC;
goto bad;
}
if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
epp->ep_daddr = round_page(end_text);
epp->ep_dsize = 0;
}
/*
* Check if we found a dynamically linked binary and arrange to load
* its interpreter
*/
if (interp) {
u_int nused = epp->ep_vmcmds.evs_used;
u_long interp_offset = 0;
if ((error = elf_load_interp(l, epp, interp,
&epp->ep_vmcmds, &interp_offset, &pos)) != 0) {
goto bad;
}
if (epp->ep_vmcmds.evs_used == nused) {
/* elf_load_interp() has not set up any new VMCMD */
error = ENOEXEC;
goto bad;
}
ap = kmem_alloc(sizeof(*ap), KM_SLEEP);
ap->arg_interp = epp->ep_vmcmds.evs_cmds[nused].ev_addr;
epp->ep_entryoffset = interp_offset;
epp->ep_entry = ap->arg_interp + interp_offset;
PNBUF_PUT(interp);
} else {
epp->ep_entry = eh->e_entry;
if (epp->ep_flags & EXEC_FORCEAUX) {
ap = kmem_alloc(sizeof(*ap), KM_SLEEP);
ap->arg_interp = (vaddr_t)NULL;
} else
ap = NULL;
}
if (ap) {
ap->arg_phaddr = phdr ? phdr : computed_phdr;
ap->arg_phentsize = eh->e_phentsize;
ap->arg_phnum = eh->e_phnum;
ap->arg_entry = eh->e_entry;
epp->ep_emul_arg = ap;
epp->ep_emul_arg_free = elf_free_emul_arg;
}
#ifdef ELF_MAP_PAGE_ZERO
/* Dell SVR4 maps page zero, yeuch! */
NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0,
epp->ep_vp, 0, VM_PROT_READ);
#endif
kmem_free(ph, phsize);
return (*epp->ep_esch->es_setup_stack)(l, epp);
bad:
if (interp)
PNBUF_PUT(interp);
exec_free_emul_arg(epp);
kmem_free(ph, phsize);
kill_vmcmds(&epp->ep_vmcmds);
return error;
}
int
netbsd_elf_signature(struct lwp *l, struct exec_package *epp,
Elf_Ehdr *eh)
{
size_t i;
Elf_Shdr *sh;
Elf_Nhdr *np;
size_t shsize, nsize;
int error;
int isnetbsd = 0;
char *ndata, *ndesc;
#ifdef DIAGNOSTIC
const char *badnote;
#define BADNOTE(n) badnote = (n)
#else
#define BADNOTE(n)
#endif
epp->ep_pax_flags = 0;
if (eh->e_shnum > ELF_MAXSHNUM || eh->e_shnum == 0)
return ENOEXEC;
shsize = eh->e_shnum * sizeof(Elf_Shdr);
sh = kmem_alloc(shsize, KM_SLEEP);
error = exec_read_from(l, epp->ep_vp, eh->e_shoff, sh, shsize);
if (error)
goto out;
np = kmem_alloc(ELF_MAXNOTESIZE, KM_SLEEP);
for (i = 0; i < eh->e_shnum; i++) {
Elf_Shdr *shp = &sh[i];
if (shp->sh_type != SHT_NOTE ||
shp->sh_size > ELF_MAXNOTESIZE ||
shp->sh_size < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ)
continue;
error = exec_read_from(l, epp->ep_vp, shp->sh_offset, np,
shp->sh_size);
if (error)
continue;
/* Point to the note, skip the header */
ndata = (char *)(np + 1);
/*
* Padding is present if necessary to ensure 4-byte alignment.
* The actual section size is therefore:
* header size + 4-byte aligned name + 4-byte aligned desc
* Ensure this size is consistent with what is indicated
* in sh_size. The first check avoids integer overflows.
*
* Binaries from before NetBSD 1.6 have two notes in the same
* note section. The second note was never used, so as long as
* the section is at least as big as it should be, it's ok.
* These binaries also have a second note section with a note of
* type ELF_NOTE_TYPE_NETBSD_TAG, which can be ignored as well.
*/
if (np->n_namesz > shp->sh_size || np->n_descsz > shp->sh_size) {
BADNOTE("note size limit");
goto bad;
}
nsize = sizeof(*np) + roundup(np->n_namesz, 4) +
roundup(np->n_descsz, 4);
if (nsize > shp->sh_size) {
BADNOTE("note size");
goto bad;
}
ndesc = ndata + roundup(np->n_namesz, 4);
switch (np->n_type) {
case ELF_NOTE_TYPE_NETBSD_TAG:
/* It is us */
if (np->n_namesz == ELF_NOTE_NETBSD_NAMESZ &&
np->n_descsz == ELF_NOTE_NETBSD_DESCSZ &&
memcmp(ndata, ELF_NOTE_NETBSD_NAME,
ELF_NOTE_NETBSD_NAMESZ) == 0) {
memcpy(&epp->ep_osversion, ndesc,
ELF_NOTE_NETBSD_DESCSZ);
isnetbsd = 1;
break;
}
/*
* Ignore SuSE tags; SuSE's n_type is the same as NetBSD's
* one.
*/
if (np->n_namesz == ELF_NOTE_SUSE_NAMESZ &&
memcmp(ndata, ELF_NOTE_SUSE_NAME,
ELF_NOTE_SUSE_NAMESZ) == 0)
break;
BADNOTE("NetBSD tag");
goto bad;
case ELF_NOTE_TYPE_PAX_TAG:
if (np->n_namesz == ELF_NOTE_PAX_NAMESZ &&
np->n_descsz == ELF_NOTE_PAX_DESCSZ &&
memcmp(ndata, ELF_NOTE_PAX_NAME,
ELF_NOTE_PAX_NAMESZ) == 0) {
memcpy(&epp->ep_pax_flags, ndesc,
sizeof(epp->ep_pax_flags));
break;
}
BADNOTE("PaX tag");
goto bad;
case ELF_NOTE_TYPE_MARCH_TAG:
/* Copy the machine arch into the package. */
if (np->n_namesz == ELF_NOTE_MARCH_NAMESZ
&& memcmp(ndata, ELF_NOTE_MARCH_NAME,
ELF_NOTE_MARCH_NAMESZ) == 0) {
/* Do not truncate the buffer */
if (np->n_descsz > sizeof(epp->ep_machine_arch)) {
BADNOTE("description size limit");
goto bad;
}
/*
* Ensure ndesc is NUL-terminated and of the
* expected length.
*/
if (strnlen(ndesc, np->n_descsz) + 1 !=
np->n_descsz) {
BADNOTE("description size");
goto bad;
}
strlcpy(epp->ep_machine_arch, ndesc,
sizeof(epp->ep_machine_arch));
break;
}
BADNOTE("march tag");
goto bad;
case ELF_NOTE_TYPE_MCMODEL_TAG:
/* arch specific check for code model */
#ifdef ELF_MD_MCMODEL_CHECK
if (np->n_namesz == ELF_NOTE_MCMODEL_NAMESZ
&& memcmp(ndata, ELF_NOTE_MCMODEL_NAME,
ELF_NOTE_MCMODEL_NAMESZ) == 0) {
ELF_MD_MCMODEL_CHECK(epp, ndesc, np->n_descsz);
break;
}
BADNOTE("mcmodel tag");
goto bad;
#endif
break;
case ELF_NOTE_TYPE_SUSE_VERSION_TAG:
break;
default:
BADNOTE("unknown tag");
bad:
#ifdef DIAGNOSTIC
/* Ignore GNU tags */
if (np->n_namesz == ELF_NOTE_GNU_NAMESZ &&
memcmp(ndata, ELF_NOTE_GNU_NAME,
ELF_NOTE_GNU_NAMESZ) == 0)
break;
int ns = MIN(np->n_namesz, shp->sh_size - sizeof(*np));
printf("%s: Unknown elf note type %d (%s): "
"[namesz=%d, descsz=%d name=%-*.*s]\n",
epp->ep_kname, np->n_type, badnote, np->n_namesz,
np->n_descsz, ns, ns, ndata);
#endif
break;
}
}
kmem_free(np, ELF_MAXNOTESIZE);
error = isnetbsd ? 0 : ENOEXEC;
out:
kmem_free(sh, shsize);
return error;
}
int
netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp,
vaddr_t *pos)
{
int error;
if ((error = netbsd_elf_signature(l, epp, eh)) != 0)
return error;
#ifdef ELF_MD_PROBE_FUNC
if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0)
return error;
#elif defined(ELF_INTERP_NON_RELOCATABLE)
*pos = ELF_LINK_ADDR;
#endif
epp->ep_flags |= EXEC_FORCEAUX;
return 0;
}
void
elf_free_emul_arg(void *arg)
{
struct elf_args *ap = arg;
KASSERT(ap != NULL);
kmem_free(ap, sizeof(*ap));
}
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