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freebsd/sys/kern/imgact_elf.c
Peter Wemm c8a7999933 Update the ELF image activator to use some of the exec resources rather 
than rolling it's own.  This means that it now uses the "safe"
exec_map_first_page() to get the ld.so headers rather than risking a panic
on a page fault failure (eg: NFS server goes down).
Since all the ELF tools go to a lot of trouble to make sure everything
lives in the first page for executables, this is a win.  I have not seen
any ELF executable on any system where all the headers didn't fit in the
first page with lots of room to spare.
I have been running variations of this code for some time on my pure ELF
systems.
1998-03-02 05:47:58 +00:00

646 lines
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/*-
* Copyright (c) 1995-1996 Søren Schmidt
* Copyright (c) 1996 Peter Wemm
* 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
* in this position and unchanged.
* 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 withough 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.
*
* $Id: imgact_elf.c,v 1.21 1998/02/09 06:09:21 eivind Exp $
*/
#include "opt_rlimit.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/exec.h>
#include <sys/mman.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/kernel.h>
#include <sys/sysent.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/syscall.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <sys/lock.h>
#include <vm/vm_map.h>
#include <vm/vm_prot.h>
#include <vm/vm_extern.h>
#include <machine/md_var.h>
#define MAX_PHDR 32 /* XXX enough ? */
static int elf_check_header __P((const Elf32_Ehdr *hdr, int type));
static int elf_load_section __P((struct vmspace *vmspace, struct vnode *vp, vm_offset_t offset, caddr_t vmaddr, size_t memsz, size_t filsz, vm_prot_t prot));
static int elf_load_file __P((struct proc *p, char *file, u_long *addr, u_long *entry));
static int elf_freebsd_fixup __P((int **stack_base, struct image_params *imgp));
static int exec_elf_imgact __P((struct image_params *imgp));
static int elf_trace = 0;
SYSCTL_INT(_debug, OID_AUTO, elf_trace, CTLFLAG_RW, &elf_trace, 0, "");
#define UPRINTF if (elf_trace) uprintf
static struct sysentvec elf_freebsd_sysvec = {
SYS_MAXSYSCALL,
sysent,
0,
0,
0,
0,
0,
elf_freebsd_fixup,
sendsig,
sigcode,
&szsigcode,
0,
"FreeBSD ELF"
};
static Elf32_Brandinfo freebsd_brand_info = {
"FreeBSD",
"",
"/usr/libexec/ld-elf.so.1",
&elf_freebsd_sysvec
};
static Elf32_Brandinfo *elf_brand_list[MAX_BRANDS] = {
&freebsd_brand_info,
NULL, NULL, NULL,
NULL, NULL, NULL, NULL
};
int
elf_insert_brand_entry(Elf32_Brandinfo *entry)
{
int i;
for (i=1; i<MAX_BRANDS; i++) {
if (elf_brand_list[i] == NULL) {
elf_brand_list[i] = entry;
break;
}
}
if (i == MAX_BRANDS)
return -1;
return 0;
}
int
elf_remove_brand_entry(Elf32_Brandinfo *entry)
{
int i;
for (i=1; i<MAX_BRANDS; i++) {
if (elf_brand_list[i] == entry) {
elf_brand_list[i] = NULL;
break;
}
}
if (i == MAX_BRANDS)
return -1;
return 0;
}
static int
elf_check_header(const Elf32_Ehdr *hdr, int type)
{
if (!(hdr->e_ident[EI_MAG0] == ELFMAG0 &&
hdr->e_ident[EI_MAG1] == ELFMAG1 &&
hdr->e_ident[EI_MAG2] == ELFMAG2 &&
hdr->e_ident[EI_MAG3] == ELFMAG3))
return ENOEXEC;
if (hdr->e_machine != EM_386 && hdr->e_machine != EM_486)
return ENOEXEC;
if (hdr->e_type != type)
return ENOEXEC;
return 0;
}
static int
elf_load_section(struct vmspace *vmspace, struct vnode *vp, vm_offset_t offset, caddr_t vmaddr, size_t memsz, size_t filsz, vm_prot_t prot)
{
size_t map_len;
vm_offset_t map_addr;
int error;
unsigned char *data_buf = 0;
size_t copy_len;
map_addr = trunc_page(vmaddr);
if (memsz > filsz)
map_len = trunc_page(offset+filsz) - trunc_page(offset);
else
map_len = round_page(offset+filsz) - trunc_page(offset);
if (error = vm_mmap (&vmspace->vm_map,
&map_addr,
map_len,
prot,
VM_PROT_ALL,
MAP_PRIVATE | MAP_FIXED,
(caddr_t)vp,
trunc_page(offset)))
return error;
if (memsz == filsz)
return 0;
/*
* We have to map the remaining bit of the file into the kernel's
* memory map, allocate some anonymous memory, and copy that last
* bit into it. The remaining space should be .bss...
*/
copy_len = (offset + filsz) - trunc_page(offset + filsz);
map_addr = trunc_page(vmaddr + filsz);
map_len = round_page(vmaddr + memsz) - map_addr;
if (map_len != 0) {
if (error = vm_map_find(&vmspace->vm_map, NULL, 0,
&map_addr, map_len, FALSE,
VM_PROT_ALL, VM_PROT_ALL,0))
return error;
}
if (error = vm_mmap(exec_map,
(vm_offset_t *)&data_buf,
PAGE_SIZE,
VM_PROT_READ,
VM_PROT_READ,
0,
(caddr_t)vp,
trunc_page(offset + filsz)))
return error;
error = copyout(data_buf, (caddr_t)map_addr, copy_len);
vm_map_remove(exec_map, (vm_offset_t)data_buf,
(vm_offset_t)data_buf + PAGE_SIZE);
/*
* set it to the specified protection
*/
vm_map_protect(&vmspace->vm_map, map_addr, map_addr + map_len, prot,
FALSE);
UPRINTF("bss size %d (%x)\n", map_len-copy_len, map_len-copy_len);
return error;
}
static int
elf_load_file(struct proc *p, char *file, u_long *addr, u_long *entry)
{
Elf32_Ehdr *hdr = NULL;
Elf32_Phdr *phdr = NULL;
struct nameidata nd;
struct vmspace *vmspace = p->p_vmspace;
struct vattr attr;
struct image_params image_params, *imgp;
vm_prot_t prot = 0;
unsigned long text_size = 0, data_size = 0;
unsigned long text_addr = 0, data_addr = 0;
int header_size = 0;
int error, i;
imgp = &image_params;
/*
* Initialize part of the common data
*/
imgp->proc = p;
imgp->uap = NULL;
imgp->attr = &attr;
imgp->firstpage = NULL;
imgp->image_header = (char *)kmem_alloc_wait(exec_map, PAGE_SIZE);
if (imgp->image_header == NULL) {
nd.ni_vp = NULL;
error = ENOMEM;
goto fail;
}
NDINIT(&nd, LOOKUP, LOCKLEAF|FOLLOW, UIO_SYSSPACE, file, p);
if (error = namei(&nd)) {
nd.ni_vp = NULL;
goto fail;
}
imgp->vp = nd.ni_vp;
/*
* Check permissions, modes, uid, etc on the file, and "open" it.
*/
error = exec_check_permissions(imgp);
if (error) {
VOP_UNLOCK(nd.ni_vp, 0, p);
goto fail;
}
error = exec_map_first_page(imgp);
VOP_UNLOCK(nd.ni_vp, 0, p);
if (error)
goto fail;
hdr = (Elf32_Ehdr *)imgp->image_header;
if (error = elf_check_header(hdr, ET_DYN))
goto fail;
/*
* ouch, need to bounds check in case user gives us a corrupted
* file with an insane header size
*/
if (hdr->e_phnum > MAX_PHDR) { /* XXX: ever more than this? */
error = ENOEXEC;
goto fail;
}
header_size = hdr->e_phentsize * hdr->e_phnum;
/* Only support headers that fit within first page for now */
if (header_size + hdr->e_phoff > PAGE_SIZE) {
error = ENOEXEC;
goto fail;
}
phdr = (Elf32_Phdr *)(imgp->image_header + hdr->e_phoff);
for (i = 0; i < hdr->e_phnum; i++) {
switch(phdr[i].p_type) {
case PT_NULL: /* NULL section */
UPRINTF ("ELF(file) PT_NULL section\n");
break;
case PT_LOAD: /* Loadable segment */
{
UPRINTF ("ELF(file) PT_LOAD section ");
if (phdr[i].p_flags & PF_X)
prot |= VM_PROT_EXECUTE;
if (phdr[i].p_flags & PF_W)
prot |= VM_PROT_WRITE;
if (phdr[i].p_flags & PF_R)
prot |= VM_PROT_READ;
if (error = elf_load_section(vmspace, nd.ni_vp,
phdr[i].p_offset,
(caddr_t)phdr[i].p_vaddr +
(*addr),
phdr[i].p_memsz,
phdr[i].p_filesz, prot))
goto fail;
/*
* Is this .text or .data ??
*
* We only handle one each of those yet XXX
*/
if (hdr->e_entry >= phdr[i].p_vaddr &&
hdr->e_entry <(phdr[i].p_vaddr+phdr[i].p_memsz)) {
text_addr = trunc_page(phdr[i].p_vaddr+(*addr));
text_size = round_page(phdr[i].p_memsz +
phdr[i].p_vaddr -
trunc_page(phdr[i].p_vaddr));
*entry=(unsigned long)hdr->e_entry+(*addr);
UPRINTF(".text <%08x,%08x> entry=%08x\n",
text_addr, text_size, *entry);
} else {
data_addr = trunc_page(phdr[i].p_vaddr+(*addr));
data_size = round_page(phdr[i].p_memsz +
phdr[i].p_vaddr -
trunc_page(phdr[i].p_vaddr));
UPRINTF(".data <%08x,%08x>\n",
data_addr, data_size);
}
}
break;
case PT_DYNAMIC:/* Dynamic link information */
UPRINTF ("ELF(file) PT_DYNAMIC section\n");
break;
case PT_INTERP: /* Path to interpreter */
UPRINTF ("ELF(file) PT_INTERP section\n");
break;
case PT_NOTE: /* Note section */
UPRINTF ("ELF(file) PT_NOTE section\n");
break;
case PT_SHLIB: /* Shared lib section */
UPRINTF ("ELF(file) PT_SHLIB section\n");
break;
case PT_PHDR: /* Program header table info */
UPRINTF ("ELF(file) PT_PHDR section\n");
break;
default:
UPRINTF ("ELF(file) %d section ??\n", phdr[i].p_type );
}
}
fail:
if (imgp->firstpage)
exec_unmap_first_page(imgp);
if (imgp->image_header)
kmem_free_wakeup(exec_map, (vm_offset_t)imgp->image_header,
PAGE_SIZE);
if (nd.ni_vp)
vrele(nd.ni_vp);
return error;
}
static int
exec_elf_imgact(struct image_params *imgp)
{
const Elf32_Ehdr *hdr = (const Elf32_Ehdr *) imgp->image_header;
const Elf32_Phdr *phdr, *mapped_phdr = NULL;
Elf32_Auxargs *elf_auxargs = NULL;
struct vmspace *vmspace;
vm_prot_t prot = 0;
u_long text_size = 0, data_size = 0;
u_long text_addr = 0, data_addr = 0;
u_long addr, entry = 0, proghdr = 0;
int error, i, header_size = 0;
const char *interp = NULL;
char *brand = NULL;
char path[MAXPATHLEN];
/*
* Do we have a valid ELF header ?
*/
if (elf_check_header(hdr, ET_EXEC))
return -1;
/*
* From here on down, we return an errno, not -1, as we've
* detected an ELF file.
*/
/*
* ouch, need to bounds check in case user gives us a corrupted
* file with an insane header size
*/
if (hdr->e_phnum > MAX_PHDR) { /* XXX: ever more than this? */
return ENOEXEC;
}
header_size = hdr->e_phentsize * hdr->e_phnum;
if ((hdr->e_phoff > PAGE_SIZE) ||
(hdr->e_phoff + header_size) > PAGE_SIZE) {
/* Only support headers in first page for now */
return ENOEXEC;
} else {
phdr = (const Elf32_Phdr*)
((const char *)imgp->image_header + hdr->e_phoff);
}
/*
* From this point on, we may have resources that need to be freed.
*/
if (error = exec_extract_strings(imgp))
goto fail;
exec_new_vmspace(imgp);
vmspace = imgp->proc->p_vmspace;
for (i = 0; i < hdr->e_phnum; i++) {
switch(phdr[i].p_type) {
case PT_NULL: /* NULL section */
UPRINTF ("ELF PT_NULL section\n");
break;
case PT_LOAD: /* Loadable segment */
{
UPRINTF ("ELF PT_LOAD section ");
if (phdr[i].p_flags & PF_X)
prot |= VM_PROT_EXECUTE;
if (phdr[i].p_flags & PF_W)
prot |= VM_PROT_WRITE;
if (phdr[i].p_flags & PF_R)
prot |= VM_PROT_READ;
if (error = elf_load_section(vmspace, imgp->vp,
phdr[i].p_offset,
(caddr_t)phdr[i].p_vaddr,
phdr[i].p_memsz,
phdr[i].p_filesz, prot))
goto fail;
/*
* Is this .text or .data ??
*
* We only handle one each of those yet XXX
*/
if (hdr->e_entry >= phdr[i].p_vaddr &&
hdr->e_entry <(phdr[i].p_vaddr+phdr[i].p_memsz)) {
text_addr = trunc_page(phdr[i].p_vaddr);
text_size = round_page(phdr[i].p_memsz +
phdr[i].p_vaddr -
text_addr);
entry = (u_long)hdr->e_entry;
UPRINTF(".text <%08x,%08x> entry=%08x\n",
text_addr, text_size, entry);
} else {
data_addr = trunc_page(phdr[i].p_vaddr);
data_size = round_page(phdr[i].p_memsz +
phdr[i].p_vaddr -
data_addr);
UPRINTF(".data <%08x,%08x>\n",
data_addr, data_size);
}
}
break;
case PT_DYNAMIC:/* Dynamic link information */
UPRINTF ("ELF PT_DYNAMIC section ??\n");
break;
case PT_INTERP: /* Path to interpreter */
UPRINTF ("ELF PT_INTERP section ");
if (phdr[i].p_filesz > MAXPATHLEN ||
phdr[i].p_offset + phdr[i].p_filesz > PAGE_SIZE) {
error = ENOEXEC;
goto fail;
}
interp = imgp->image_header + phdr[i].p_offset;
UPRINTF("<%s>\n", interp);
break;
case PT_NOTE: /* Note section */
UPRINTF ("ELF PT_NOTE section\n");
break;
case PT_SHLIB: /* Shared lib section */
UPRINTF ("ELF PT_SHLIB section\n");
break;
case PT_PHDR: /* Program header table info */
UPRINTF ("ELF PT_PHDR section <%x>\n", phdr[i].p_vaddr);
proghdr = phdr[i].p_vaddr;
break;
default:
UPRINTF ("ELF %d section ??\n", phdr[i].p_type);
}
}
vmspace->vm_tsize = text_size >> PAGE_SHIFT;
vmspace->vm_taddr = (caddr_t)text_addr;
vmspace->vm_dsize = data_size >> PAGE_SHIFT;
vmspace->vm_daddr = (caddr_t)data_addr;
addr = 2*MAXDSIZ; /* May depend on OS type XXX */
imgp->entry_addr = entry;
/*
* So which kind (brand) of ELF binary do we have at hand
* FreeBSD, Linux, SVR4 or something else ??
* If its has a interpreter section try that first
*/
if (interp) {
for (i=0; i<MAX_BRANDS; i++) {
if (elf_brand_list[i] != NULL) {
if (!strcmp(interp, elf_brand_list[i]->interp_path)) {
imgp->proc->p_sysent =
elf_brand_list[i]->sysvec;
strcpy(path, elf_brand_list[i]->emul_path);
strcat(path, elf_brand_list[i]->interp_path);
UPRINTF("interpreter=<%s> %s\n",
elf_brand_list[i]->interp_path,
elf_brand_list[i]->emul_path);
break;
}
}
}
}
/*
* If there is no interpreter, or recognition of it
* failed, se if the binary is branded.
*/
if (!interp || i == MAX_BRANDS) {
brand = (char *)&(hdr->e_ident[EI_BRAND]);
for (i=0; i<MAX_BRANDS; i++) {
if (elf_brand_list[i] != NULL) {
if (!strcmp(brand, elf_brand_list[i]->brand)) {
imgp->proc->p_sysent = elf_brand_list[i]->sysvec;
if (interp) {
strcpy(path, elf_brand_list[i]->emul_path);
strcat(path, elf_brand_list[i]->interp_path);
UPRINTF("interpreter=<%s> %s\n",
elf_brand_list[i]->interp_path,
elf_brand_list[i]->emul_path);
}
break;
}
}
}
}
if (i == MAX_BRANDS) {
uprintf("ELF binary type not known\n");
error = ENOEXEC;
goto fail;
}
if (interp) {
if (error = elf_load_file(imgp->proc,
path,
&addr, /* XXX */
&imgp->entry_addr)) {
uprintf("ELF interpreter %s not found\n", path);
goto fail;
}
}
UPRINTF("Executing %s binary\n", elf_brand_list[i]->brand);
/*
* Construct auxargs table (used by the fixup routine)
*/
elf_auxargs = malloc(sizeof(Elf32_Auxargs), M_TEMP, M_WAITOK);
elf_auxargs->execfd = -1;
elf_auxargs->phdr = proghdr;
elf_auxargs->phent = hdr->e_phentsize;
elf_auxargs->phnum = hdr->e_phnum;
elf_auxargs->pagesz = PAGE_SIZE;
elf_auxargs->base = addr;
elf_auxargs->flags = 0;
elf_auxargs->entry = entry;
elf_auxargs->trace = elf_trace;
imgp->auxargs = elf_auxargs;
imgp->interpreted = 0;
/* don't allow modifying the file while we run it */
imgp->vp->v_flag |= VTEXT;
fail:
return error;
}
static int
elf_freebsd_fixup(int **stack_base, struct image_params *imgp)
{
Elf32_Auxargs *args = (Elf32_Auxargs *)imgp->auxargs;
int *pos;
pos = *stack_base + (imgp->argc + imgp->envc + 2);
if (args->trace) {
AUXARGS_ENTRY(pos, AT_DEBUG, 1);
}
if (args->execfd != -1) {
AUXARGS_ENTRY(pos, AT_EXECFD, args->execfd);
}
AUXARGS_ENTRY(pos, AT_PHDR, args->phdr);
AUXARGS_ENTRY(pos, AT_PHENT, args->phent);
AUXARGS_ENTRY(pos, AT_PHNUM, args->phnum);
AUXARGS_ENTRY(pos, AT_PAGESZ, args->pagesz);
AUXARGS_ENTRY(pos, AT_FLAGS, args->flags);
AUXARGS_ENTRY(pos, AT_ENTRY, args->entry);
AUXARGS_ENTRY(pos, AT_BASE, args->base);
AUXARGS_ENTRY(pos, AT_NULL, 0);
free(imgp->auxargs, M_TEMP);
imgp->auxargs = NULL;
(*stack_base)--;
**stack_base = (int)imgp->argc;
return 0;
}
/*
* Tell kern_execve.c about it, with a little help from the linker.
* Since `const' objects end up in the text segment, TEXT_SET is the
* correct directive to use.
*/
static const struct execsw elf_execsw = {exec_elf_imgact, "ELF"};
TEXT_SET(execsw_set, elf_execsw);
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