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freebsd/sys/kern/imgact_elf.c
John Dyson 5856e12e69 Fully implement vfork. Vfork is now much much faster than even our 
fork. (On my machine, fork is about 240usecs, vfork is 78usecs.)

Implement rfork(!RFPROC !RFMEM), which allows a thread to divorce its memory
	from the other threads of a group.

Implement rfork(!RFPROC RFCFDG), which closes all file descriptors, eliminating
	possible existing shares with other threads/processes.

Implement rfork(!RFPROC RFFDG), which divorces the file descriptors for a
	thread from the rest of the group.

Fix the case where a thread does an exec.  It is almost nonsense for a thread
	to modify the other threads address space by an exec, so we
	now automatically divorce the address space before modifying it.
1997-04-13 01:48:35 +00:00

748 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 1.18 1997/04/01 10:41:48 bde 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 map_pages __P((struct vnode *vp, vm_offset_t offset, vm_offset_t *buf, vm_size_t size));
static void unmap_pages __P((vm_offset_t buf, vm_size_t size));
static int elf_check_permissions __P((struct proc *p, struct vnode *vp));
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));
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
map_pages(struct vnode *vp, vm_offset_t offset,
vm_offset_t *buf, vm_size_t size)
{
int error;
vm_offset_t kern_buf;
vm_size_t pageoff;
/*
* The request may not be aligned, and may even cross several
* page boundaries in the file...
*/
pageoff = (offset & PAGE_MASK);
offset -= pageoff; /* start of first aligned page to map */
size += pageoff;
size = round_page(size); /* size of aligned pages to map */
if (error = vm_mmap(kernel_map,
&kern_buf,
size,
VM_PROT_READ,
VM_PROT_READ,
0,
(caddr_t)vp,
offset))
return error;
*buf = kern_buf + pageoff;
return 0;
}
static void
unmap_pages(vm_offset_t buf, vm_size_t size)
{
vm_size_t pageoff;
pageoff = (buf & PAGE_MASK);
buf -= pageoff; /* start of first aligned page to map */
size += pageoff;
size = round_page(size);/* size of aligned pages to map */
vm_map_remove(kernel_map, buf, buf + size);
}
static int
elf_check_permissions(struct proc *p, struct vnode *vp)
{
struct vattr attr;
int error;
/*
* Check number of open-for-writes on the file and deny execution
* if there are any.
*/
if (vp->v_writecount) {
return (ETXTBSY);
}
/* Get file attributes */
error = VOP_GETATTR(vp, &attr, p->p_ucred, p);
if (error)
return (error);
/*
* 1) Check if file execution is disabled for the filesystem that this
* file resides on.
* 2) Insure that at least one execute bit is on - otherwise root
* will always succeed, and we don't want to happen unless the
* file really is executable.
* 3) Insure that the file is a regular file.
*/
if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
((attr.va_mode & 0111) == 0) ||
(attr.va_type != VREG)) {
return (EACCES);
}
/*
* Zero length files can't be exec'd
*/
if (attr.va_size == 0)
return (ENOEXEC);
/*
* Check for execute permission to file based on current credentials.
* Then call filesystem specific open routine (which does nothing
* in the general case).
*/
error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p);
if (error)
return (error);
error = VOP_OPEN(vp, FREAD, p->p_ucred, p);
if (error)
return (error);
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(kernel_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(kernel_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;
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;
NDINIT(&nd, LOOKUP, LOCKLEAF|FOLLOW, UIO_SYSSPACE, file, p);
if (error = namei(&nd))
goto fail;
if (nd.ni_vp == NULL) {
error = ENOEXEC;
goto fail;
}
/*
* Check permissions, modes, uid, etc on the file, and "open" it.
*/
error = elf_check_permissions(p, nd.ni_vp);
/*
* No longer need this, and it prevents demand paging.
*/
VOP_UNLOCK(nd.ni_vp, 0, p);
if (error)
goto fail;
/*
* Map in the header
*/
if (error = map_pages(nd.ni_vp, 0, (vm_offset_t *)&hdr, sizeof(hdr)))
goto fail;
/*
* Do we have a valid ELF 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;
if (error = map_pages(nd.ni_vp, hdr->e_phoff, (vm_offset_t *)&phdr,
header_size))
goto fail;
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 (phdr)
unmap_pages((vm_offset_t)phdr, header_size);
if (hdr)
unmap_pages((vm_offset_t)hdr, sizeof(hdr));
return error;
}
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, interp_len = 0;
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) {
/*
* Ouch ! we only get one page full of header...
* Try to map it in ourselves, and see how we go.
*/
if (error = map_pages(imgp->vp, hdr->e_phoff,
(vm_offset_t *)&mapped_phdr, header_size))
return (error);
/*
* Save manual mapping for cleanup
*/
phdr = mapped_phdr;
} 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) {
error = ENOEXEC;
goto fail;
}
interp_len = MAXPATHLEN;
if (error = map_pages(imgp->vp, phdr[i].p_offset,
(vm_offset_t *)&interp, interp_len))
goto fail;
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:
if (mapped_phdr)
unmap_pages((vm_offset_t)mapped_phdr, header_size);
if (interp)
unmap_pages((vm_offset_t)interp, interp_len);
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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