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linux/fs/binfmt_flat.c
David Howells a6f76f23d2 CRED: Make execve() take advantage of copy-on-write credentials 
Make execve() take advantage of copy-on-write credentials, allowing it to set
up the credentials in advance, and then commit the whole lot after the point
of no return.

This patch and the preceding patches have been tested with the LTP SELinux
testsuite.

This patch makes several logical sets of alteration:

 (1) execve().

     The credential bits from struct linux_binprm are, for the most part,
     replaced with a single credentials pointer (bprm->cred).  This means that
     all the creds can be calculated in advance and then applied at the point
     of no return with no possibility of failure.

     I would like to replace bprm->cap_effective with:

	cap_isclear(bprm->cap_effective)

     but this seems impossible due to special behaviour for processes of pid 1
     (they always retain their parent's capability masks where normally they'd
     be changed - see cap_bprm_set_creds()).

     The following sequence of events now happens:

     (a) At the start of do_execve, the current task's cred_exec_mutex is
     	 locked to prevent PTRACE_ATTACH from obsoleting the calculation of
     	 creds that we make.

     (a) prepare_exec_creds() is then called to make a copy of the current
     	 task's credentials and prepare it.  This copy is then assigned to
     	 bprm->cred.

  	 This renders security_bprm_alloc() and security_bprm_free()
     	 unnecessary, and so they've been removed.

     (b) The determination of unsafe execution is now performed immediately
     	 after (a) rather than later on in the code.  The result is stored in
     	 bprm->unsafe for future reference.

     (c) prepare_binprm() is called, possibly multiple times.

     	 (i) This applies the result of set[ug]id binaries to the new creds
     	     attached to bprm->cred.  Personality bit clearance is recorded,
     	     but now deferred on the basis that the exec procedure may yet
     	     fail.

         (ii) This then calls the new security_bprm_set_creds().  This should
	     calculate the new LSM and capability credentials into *bprm->cred.

	     This folds together security_bprm_set() and parts of
	     security_bprm_apply_creds() (these two have been removed).
	     Anything that might fail must be done at this point.

         (iii) bprm->cred_prepared is set to 1.

	     bprm->cred_prepared is 0 on the first pass of the security
	     calculations, and 1 on all subsequent passes.  This allows SELinux
	     in (ii) to base its calculations only on the initial script and
	     not on the interpreter.

     (d) flush_old_exec() is called to commit the task to execution.  This
     	 performs the following steps with regard to credentials:

	 (i) Clear pdeath_signal and set dumpable on certain circumstances that
	     may not be covered by commit_creds().

         (ii) Clear any bits in current->personality that were deferred from
             (c.i).

     (e) install_exec_creds() [compute_creds() as was] is called to install the
     	 new credentials.  This performs the following steps with regard to
     	 credentials:

         (i) Calls security_bprm_committing_creds() to apply any security
             requirements, such as flushing unauthorised files in SELinux, that
             must be done before the credentials are changed.

	     This is made up of bits of security_bprm_apply_creds() and
	     security_bprm_post_apply_creds(), both of which have been removed.
	     This function is not allowed to fail; anything that might fail
	     must have been done in (c.ii).

         (ii) Calls commit_creds() to apply the new credentials in a single
             assignment (more or less).  Possibly pdeath_signal and dumpable
             should be part of struct creds.

	 (iii) Unlocks the task's cred_replace_mutex, thus allowing
	     PTRACE_ATTACH to take place.

         (iv) Clears The bprm->cred pointer as the credentials it was holding
             are now immutable.

         (v) Calls security_bprm_committed_creds() to apply any security
             alterations that must be done after the creds have been changed.
             SELinux uses this to flush signals and signal handlers.

     (f) If an error occurs before (d.i), bprm_free() will call abort_creds()
     	 to destroy the proposed new credentials and will then unlock
     	 cred_replace_mutex.  No changes to the credentials will have been
     	 made.

 (2) LSM interface.

     A number of functions have been changed, added or removed:

     (*) security_bprm_alloc(), ->bprm_alloc_security()
     (*) security_bprm_free(), ->bprm_free_security()

     	 Removed in favour of preparing new credentials and modifying those.

     (*) security_bprm_apply_creds(), ->bprm_apply_creds()
     (*) security_bprm_post_apply_creds(), ->bprm_post_apply_creds()

     	 Removed; split between security_bprm_set_creds(),
     	 security_bprm_committing_creds() and security_bprm_committed_creds().

     (*) security_bprm_set(), ->bprm_set_security()

     	 Removed; folded into security_bprm_set_creds().

     (*) security_bprm_set_creds(), ->bprm_set_creds()

     	 New.  The new credentials in bprm->creds should be checked and set up
     	 as appropriate.  bprm->cred_prepared is 0 on the first call, 1 on the
     	 second and subsequent calls.

     (*) security_bprm_committing_creds(), ->bprm_committing_creds()
     (*) security_bprm_committed_creds(), ->bprm_committed_creds()

     	 New.  Apply the security effects of the new credentials.  This
     	 includes closing unauthorised files in SELinux.  This function may not
     	 fail.  When the former is called, the creds haven't yet been applied
     	 to the process; when the latter is called, they have.

 	 The former may access bprm->cred, the latter may not.

 (3) SELinux.

     SELinux has a number of changes, in addition to those to support the LSM
     interface changes mentioned above:

     (a) The bprm_security_struct struct has been removed in favour of using
     	 the credentials-under-construction approach.

     (c) flush_unauthorized_files() now takes a cred pointer and passes it on
     	 to inode_has_perm(), file_has_perm() and dentry_open().

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:24 +11:00

940 lines
27 KiB
C
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/****************************************************************************/
/*
* linux/fs/binfmt_flat.c
*
* Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
* Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
* Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
* Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
* based heavily on:
*
* linux/fs/binfmt_aout.c:
* Copyright (C) 1991, 1992, 1996 Linus Torvalds
* linux/fs/binfmt_flat.c for 2.0 kernel
* Copyright (C) 1998 Kenneth Albanowski <kjahds@kjahds.com>
* JAN/99 -- coded full program relocation (gerg@snapgear.com)
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/flat.h>
#include <linux/syscalls.h>
#include <asm/byteorder.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unaligned.h>
#include <asm/cacheflush.h>
/****************************************************************************/
#if 0
#define DEBUG 1
#endif
#ifdef DEBUG
#define DBG_FLT(a...) printk(a)
#else
#define DBG_FLT(a...)
#endif
#define RELOC_FAILED 0xff00ff01 /* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff /* Placeholder for unused library */
struct lib_info {
struct {
unsigned long start_code; /* Start of text segment */
unsigned long start_data; /* Start of data segment */
unsigned long start_brk; /* End of data segment */
unsigned long text_len; /* Length of text segment */
unsigned long entry; /* Start address for this module */
unsigned long build_date; /* When this one was compiled */
short loaded; /* Has this library been loaded? */
} lib_list[MAX_SHARED_LIBS];
};
#ifdef CONFIG_BINFMT_SHARED_FLAT
static int load_flat_shared_library(int id, struct lib_info *p);
#endif
static int load_flat_binary(struct linux_binprm *, struct pt_regs * regs);
static int flat_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
static struct linux_binfmt flat_format = {
.module = THIS_MODULE,
.load_binary = load_flat_binary,
.core_dump = flat_core_dump,
.min_coredump = PAGE_SIZE
};
/****************************************************************************/
/*
* Routine writes a core dump image in the current directory.
* Currently only a stub-function.
*/
static int flat_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
{
printk("Process %s:%d received signr %d and should have core dumped\n",
current->comm, current->pid, (int) signr);
return(1);
}
/****************************************************************************/
/*
* create_flat_tables() parses the env- and arg-strings in new user
* memory and creates the pointer tables from them, and puts their
* addresses on the "stack", returning the new stack pointer value.
*/
static unsigned long create_flat_tables(
unsigned long pp,
struct linux_binprm * bprm)
{
unsigned long *argv,*envp;
unsigned long * sp;
char * p = (char*)pp;
int argc = bprm->argc;
int envc = bprm->envc;
char uninitialized_var(dummy);
sp = (unsigned long *) ((-(unsigned long)sizeof(char *))&(unsigned long) p);
sp -= envc+1;
envp = sp;
sp -= argc+1;
argv = sp;
flat_stack_align(sp);
if (flat_argvp_envp_on_stack()) {
--sp; put_user((unsigned long) envp, sp);
--sp; put_user((unsigned long) argv, sp);
}
put_user(argc,--sp);
current->mm->arg_start = (unsigned long) p;
while (argc-->0) {
put_user((unsigned long) p, argv++);
do {
get_user(dummy, p); p++;
} while (dummy);
}
put_user((unsigned long) NULL, argv);
current->mm->arg_end = current->mm->env_start = (unsigned long) p;
while (envc-->0) {
put_user((unsigned long)p, envp); envp++;
do {
get_user(dummy, p); p++;
} while (dummy);
}
put_user((unsigned long) NULL, envp);
current->mm->env_end = (unsigned long) p;
return (unsigned long)sp;
}
/****************************************************************************/
#ifdef CONFIG_BINFMT_ZFLAT
#include <linux/zlib.h>
#define LBUFSIZE 4000
/* gzip flag byte */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */
#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
#define ORIG_NAME 0x08 /* bit 3 set: original file name present */
#define COMMENT 0x10 /* bit 4 set: file comment present */
#define ENCRYPTED 0x20 /* bit 5 set: file is encrypted */
#define RESERVED 0xC0 /* bit 6,7: reserved */
static int decompress_exec(
struct linux_binprm *bprm,
unsigned long offset,
char *dst,
long len,
int fd)
{
unsigned char *buf;
z_stream strm;
loff_t fpos;
int ret, retval;
DBG_FLT("decompress_exec(offset=%x,buf=%x,len=%x)\n",(int)offset, (int)dst, (int)len);
memset(&strm, 0, sizeof(strm));
strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
if (strm.workspace == NULL) {
DBG_FLT("binfmt_flat: no memory for decompress workspace\n");
return -ENOMEM;
}
buf = kmalloc(LBUFSIZE, GFP_KERNEL);
if (buf == NULL) {
DBG_FLT("binfmt_flat: no memory for read buffer\n");
retval = -ENOMEM;
goto out_free;
}
/* Read in first chunk of data and parse gzip header. */
fpos = offset;
ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);
strm.next_in = buf;
strm.avail_in = ret;
strm.total_in = 0;
retval = -ENOEXEC;
/* Check minimum size -- gzip header */
if (ret < 10) {
DBG_FLT("binfmt_flat: file too small?\n");
goto out_free_buf;
}
/* Check gzip magic number */
if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
DBG_FLT("binfmt_flat: unknown compression magic?\n");
goto out_free_buf;
}
/* Check gzip method */
if (buf[2] != 8) {
DBG_FLT("binfmt_flat: unknown compression method?\n");
goto out_free_buf;
}
/* Check gzip flags */
if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
(buf[3] & RESERVED)) {
DBG_FLT("binfmt_flat: unknown flags?\n");
goto out_free_buf;
}
ret = 10;
if (buf[3] & EXTRA_FIELD) {
ret += 2 + buf[10] + (buf[11] << 8);
if (unlikely(LBUFSIZE <= ret)) {
DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
goto out_free_buf;
}
}
if (buf[3] & ORIG_NAME) {
while (ret < LBUFSIZE && buf[ret++] != 0)
;
if (unlikely(LBUFSIZE == ret)) {
DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
goto out_free_buf;
}
}
if (buf[3] & COMMENT) {
while (ret < LBUFSIZE && buf[ret++] != 0)
;
if (unlikely(LBUFSIZE == ret)) {
DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
goto out_free_buf;
}
}
strm.next_in += ret;
strm.avail_in -= ret;
strm.next_out = dst;
strm.avail_out = len;
strm.total_out = 0;
if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
DBG_FLT("binfmt_flat: zlib init failed?\n");
goto out_free_buf;
}
while ((ret = zlib_inflate(&strm, Z_NO_FLUSH)) == Z_OK) {
ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);
if (ret <= 0)
break;
if (ret >= (unsigned long) -4096)
break;
len -= ret;
strm.next_in = buf;
strm.avail_in = ret;
strm.total_in = 0;
}
if (ret < 0) {
DBG_FLT("binfmt_flat: decompression failed (%d), %s\n",
ret, strm.msg);
goto out_zlib;
}
retval = 0;
out_zlib:
zlib_inflateEnd(&strm);
out_free_buf:
kfree(buf);
out_free:
kfree(strm.workspace);
return retval;
}
#endif /* CONFIG_BINFMT_ZFLAT */
/****************************************************************************/
static unsigned long
calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
{
unsigned long addr;
int id;
unsigned long start_brk;
unsigned long start_data;
unsigned long text_len;
unsigned long start_code;
#ifdef CONFIG_BINFMT_SHARED_FLAT
if (r == 0)
id = curid; /* Relocs of 0 are always self referring */
else {
id = (r >> 24) & 0xff; /* Find ID for this reloc */
r &= 0x00ffffff; /* Trim ID off here */
}
if (id >= MAX_SHARED_LIBS) {
printk("BINFMT_FLAT: reference 0x%x to shared library %d",
(unsigned) r, id);
goto failed;
}
if (curid != id) {
if (internalp) {
printk("BINFMT_FLAT: reloc address 0x%x not in same module "
"(%d != %d)", (unsigned) r, curid, id);
goto failed;
} else if ( ! p->lib_list[id].loaded &&
load_flat_shared_library(id, p) > (unsigned long) -4096) {
printk("BINFMT_FLAT: failed to load library %d", id);
goto failed;
}
/* Check versioning information (i.e. time stamps) */
if (p->lib_list[id].build_date && p->lib_list[curid].build_date &&
p->lib_list[curid].build_date < p->lib_list[id].build_date) {
printk("BINFMT_FLAT: library %d is younger than %d", id, curid);
goto failed;
}
}
#else
id = 0;
#endif
start_brk = p->lib_list[id].start_brk;
start_data = p->lib_list[id].start_data;
start_code = p->lib_list[id].start_code;
text_len = p->lib_list[id].text_len;
if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
printk("BINFMT_FLAT: reloc outside program 0x%x (0 - 0x%x/0x%x)",
(int) r,(int)(start_brk-start_code),(int)text_len);
goto failed;
}
if (r < text_len) /* In text segment */
addr = r + start_code;
else /* In data segment */
addr = r - text_len + start_data;
/* Range checked already above so doing the range tests is redundant...*/
return(addr);
failed:
printk(", killing %s!\n", current->comm);
send_sig(SIGSEGV, current, 0);
return RELOC_FAILED;
}
/****************************************************************************/
void old_reloc(unsigned long rl)
{
#ifdef DEBUG
char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
#endif
flat_v2_reloc_t r;
unsigned long *ptr;
r.value = rl;
#if defined(CONFIG_COLDFIRE)
ptr = (unsigned long *) (current->mm->start_code + r.reloc.offset);
#else
ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
#endif
#ifdef DEBUG
printk("Relocation of variable at DATASEG+%x "
"(address %p, currently %x) into segment %s\n",
r.reloc.offset, ptr, (int)*ptr, segment[r.reloc.type]);
#endif
switch (r.reloc.type) {
case OLD_FLAT_RELOC_TYPE_TEXT:
*ptr += current->mm->start_code;
break;
case OLD_FLAT_RELOC_TYPE_DATA:
*ptr += current->mm->start_data;
break;
case OLD_FLAT_RELOC_TYPE_BSS:
*ptr += current->mm->end_data;
break;
default:
printk("BINFMT_FLAT: Unknown relocation type=%x\n", r.reloc.type);
break;
}
#ifdef DEBUG
printk("Relocation became %x\n", (int)*ptr);
#endif
}
/****************************************************************************/
static int load_flat_file(struct linux_binprm * bprm,
struct lib_info *libinfo, int id, unsigned long *extra_stack)
{
struct flat_hdr * hdr;
unsigned long textpos = 0, datapos = 0, result;
unsigned long realdatastart = 0;
unsigned long text_len, data_len, bss_len, stack_len, flags;
unsigned long len, reallen, memp = 0;
unsigned long extra, rlim;
unsigned long *reloc = 0, *rp;
struct inode *inode;
int i, rev, relocs = 0;
loff_t fpos;
unsigned long start_code, end_code;
int ret;
hdr = ((struct flat_hdr *) bprm->buf); /* exec-header */
inode = bprm->file->f_path.dentry->d_inode;
text_len = ntohl(hdr->data_start);
data_len = ntohl(hdr->data_end) - ntohl(hdr->data_start);
bss_len = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
stack_len = ntohl(hdr->stack_size);
if (extra_stack) {
stack_len += *extra_stack;
*extra_stack = stack_len;
}
relocs = ntohl(hdr->reloc_count);
flags = ntohl(hdr->flags);
rev = ntohl(hdr->rev);
if (strncmp(hdr->magic, "bFLT", 4)) {
/*
* Previously, here was a printk to tell people
* "BINFMT_FLAT: bad header magic".
* But for the kernel which also use ELF FD-PIC format, this
* error message is confusing.
* because a lot of people do not manage to produce good
*/
ret = -ENOEXEC;
goto err;
}
if (flags & FLAT_FLAG_KTRACE)
printk("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
printk("BINFMT_FLAT: bad flat file version 0x%x (supported "
"0x%lx and 0x%lx)\n",
rev, FLAT_VERSION, OLD_FLAT_VERSION);
ret = -ENOEXEC;
goto err;
}
/* Don't allow old format executables to use shared libraries */
if (rev == OLD_FLAT_VERSION && id != 0) {
printk("BINFMT_FLAT: shared libraries are not available before rev 0x%x\n",
(int) FLAT_VERSION);
ret = -ENOEXEC;
goto err;
}
/*
* fix up the flags for the older format, there were all kinds
* of endian hacks, this only works for the simple cases
*/
if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
flags = FLAT_FLAG_RAM;
#ifndef CONFIG_BINFMT_ZFLAT
if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
printk("Support for ZFLAT executables is not enabled.\n");
ret = -ENOEXEC;
goto err;
}
#endif
/*
* Check initial limits. This avoids letting people circumvent
* size limits imposed on them by creating programs with large
* arrays in the data or bss.
*/
rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
if (rlim >= RLIM_INFINITY)
rlim = ~0;
if (data_len + bss_len > rlim) {
ret = -ENOMEM;
goto err;
}
/* Flush all traces of the currently running executable */
if (id == 0) {
result = flush_old_exec(bprm);
if (result) {
ret = result;
goto err;
}
/* OK, This is the point of no return */
set_personality(PER_LINUX_32BIT);
}
/*
* calculate the extra space we need to map in
*/
extra = max_t(unsigned long, bss_len + stack_len,
relocs * sizeof(unsigned long));
/*
* there are a couple of cases here, the separate code/data
* case, and then the fully copied to RAM case which lumps
* it all together.
*/
if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
/*
* this should give us a ROM ptr, but if it doesn't we don't
* really care
*/
DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
down_write(&current->mm->mmap_sem);
textpos = do_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_EXECUTABLE, 0);
up_write(&current->mm->mmap_sem);
if (!textpos || textpos >= (unsigned long) -4096) {
if (!textpos)
textpos = (unsigned long) -ENOMEM;
printk("Unable to mmap process text, errno %d\n", (int)-textpos);
ret = textpos;
goto err;
}
len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
down_write(&current->mm->mmap_sem);
realdatastart = do_mmap(0, 0, len,
PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
/* Remap to use all availabe slack region space */
if (realdatastart && (realdatastart < (unsigned long)-4096)) {
reallen = kobjsize((void *)realdatastart);
if (reallen > len) {
realdatastart = do_mremap(realdatastart, len,
reallen, MREMAP_FIXED, realdatastart);
}
}
up_write(&current->mm->mmap_sem);
if (realdatastart == 0 || realdatastart >= (unsigned long)-4096) {
if (!realdatastart)
realdatastart = (unsigned long) -ENOMEM;
printk("Unable to allocate RAM for process data, errno %d\n",
(int)-realdatastart);
do_munmap(current->mm, textpos, text_len);
ret = realdatastart;
goto err;
}
datapos = realdatastart + MAX_SHARED_LIBS * sizeof(unsigned long);
DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
(int)(data_len + bss_len + stack_len), (int)datapos);
fpos = ntohl(hdr->data_start);
#ifdef CONFIG_BINFMT_ZFLAT
if (flags & FLAT_FLAG_GZDATA) {
result = decompress_exec(bprm, fpos, (char *) datapos,
data_len + (relocs * sizeof(unsigned long)), 0);
} else
#endif
{
result = bprm->file->f_op->read(bprm->file, (char *) datapos,
data_len + (relocs * sizeof(unsigned long)), &fpos);
}
if (result >= (unsigned long)-4096) {
printk("Unable to read data+bss, errno %d\n", (int)-result);
do_munmap(current->mm, textpos, text_len);
do_munmap(current->mm, realdatastart, data_len + extra);
ret = result;
goto err;
}
reloc = (unsigned long *) (datapos+(ntohl(hdr->reloc_start)-text_len));
memp = realdatastart;
} else {
len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
down_write(&current->mm->mmap_sem);
textpos = do_mmap(0, 0, len,
PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
/* Remap to use all availabe slack region space */
if (textpos && (textpos < (unsigned long) -4096)) {
reallen = kobjsize((void *)textpos);
if (reallen > len) {
textpos = do_mremap(textpos, len, reallen,
MREMAP_FIXED, textpos);
}
}
up_write(&current->mm->mmap_sem);
if (!textpos || textpos >= (unsigned long) -4096) {
if (!textpos)
textpos = (unsigned long) -ENOMEM;
printk("Unable to allocate RAM for process text/data, errno %d\n",
(int)-textpos);
ret = textpos;
goto err;
}
realdatastart = textpos + ntohl(hdr->data_start);
datapos = realdatastart + MAX_SHARED_LIBS * sizeof(unsigned long);
reloc = (unsigned long *) (textpos + ntohl(hdr->reloc_start) +
MAX_SHARED_LIBS * sizeof(unsigned long));
memp = textpos;
#ifdef CONFIG_BINFMT_ZFLAT
/*
* load it all in and treat it like a RAM load from now on
*/
if (flags & FLAT_FLAG_GZIP) {
result = decompress_exec(bprm, sizeof (struct flat_hdr),
(((char *) textpos) + sizeof (struct flat_hdr)),
(text_len + data_len + (relocs * sizeof(unsigned long))
- sizeof (struct flat_hdr)),
0);
memmove((void *) datapos, (void *) realdatastart,
data_len + (relocs * sizeof(unsigned long)));
} else if (flags & FLAT_FLAG_GZDATA) {
fpos = 0;
result = bprm->file->f_op->read(bprm->file,
(char *) textpos, text_len, &fpos);
if (result < (unsigned long) -4096)
result = decompress_exec(bprm, text_len, (char *) datapos,
data_len + (relocs * sizeof(unsigned long)), 0);
}
else
#endif
{
fpos = 0;
result = bprm->file->f_op->read(bprm->file,
(char *) textpos, text_len, &fpos);
if (result < (unsigned long) -4096) {
fpos = ntohl(hdr->data_start);
result = bprm->file->f_op->read(bprm->file, (char *) datapos,
data_len + (relocs * sizeof(unsigned long)), &fpos);
}
}
if (result >= (unsigned long)-4096) {
printk("Unable to read code+data+bss, errno %d\n",(int)-result);
do_munmap(current->mm, textpos, text_len + data_len + extra +
MAX_SHARED_LIBS * sizeof(unsigned long));
ret = result;
goto err;
}
}
if (flags & FLAT_FLAG_KTRACE)
printk("Mapping is %x, Entry point is %x, data_start is %x\n",
(int)textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
/* The main program needs a little extra setup in the task structure */
start_code = textpos + sizeof (struct flat_hdr);
end_code = textpos + text_len;
if (id == 0) {
current->mm->start_code = start_code;
current->mm->end_code = end_code;
current->mm->start_data = datapos;
current->mm->end_data = datapos + data_len;
/*
* set up the brk stuff, uses any slack left in data/bss/stack
* allocation. We put the brk after the bss (between the bss
* and stack) like other platforms.
*/
current->mm->start_brk = datapos + data_len + bss_len;
current->mm->brk = (current->mm->start_brk + 3) & ~3;
current->mm->context.end_brk = memp + kobjsize((void *) memp) - stack_len;
}
if (flags & FLAT_FLAG_KTRACE)
printk("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
id ? "Lib" : "Load", bprm->filename,
(int) start_code, (int) end_code,
(int) datapos,
(int) (datapos + data_len),
(int) (datapos + data_len),
(int) (((datapos + data_len + bss_len) + 3) & ~3));
text_len -= sizeof(struct flat_hdr); /* the real code len */
/* Store the current module values into the global library structure */
libinfo->lib_list[id].start_code = start_code;
libinfo->lib_list[id].start_data = datapos;
libinfo->lib_list[id].start_brk = datapos + data_len + bss_len;
libinfo->lib_list[id].text_len = text_len;
libinfo->lib_list[id].loaded = 1;
libinfo->lib_list[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
libinfo->lib_list[id].build_date = ntohl(hdr->build_date);
/*
* We just load the allocations into some temporary memory to
* help simplify all this mumbo jumbo
*
* We've got two different sections of relocation entries.
* The first is the GOT which resides at the begining of the data segment
* and is terminated with a -1. This one can be relocated in place.
* The second is the extra relocation entries tacked after the image's
* data segment. These require a little more processing as the entry is
* really an offset into the image which contains an offset into the
* image.
*/
if (flags & FLAT_FLAG_GOTPIC) {
for (rp = (unsigned long *)datapos; *rp != 0xffffffff; rp++) {
unsigned long addr;
if (*rp) {
addr = calc_reloc(*rp, libinfo, id, 0);
if (addr == RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
}
*rp = addr;
}
}
}
/*
* Now run through the relocation entries.
* We've got to be careful here as C++ produces relocatable zero
* entries in the constructor and destructor tables which are then
* tested for being not zero (which will always occur unless we're
* based from address zero). This causes an endless loop as __start
* is at zero. The solution used is to not relocate zero addresses.
* This has the negative side effect of not allowing a global data
* reference to be statically initialised to _stext (I've moved
* __start to address 4 so that is okay).
*/
if (rev > OLD_FLAT_VERSION) {
unsigned long persistent = 0;
for (i=0; i < relocs; i++) {
unsigned long addr, relval;
/* Get the address of the pointer to be
relocated (of course, the address has to be
relocated first). */
relval = ntohl(reloc[i]);
if (flat_set_persistent (relval, &persistent))
continue;
addr = flat_get_relocate_addr(relval);
rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
if (rp == (unsigned long *)RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
}
/* Get the pointer's value. */
addr = flat_get_addr_from_rp(rp, relval, flags,
&persistent);
if (addr != 0) {
/*
* Do the relocation. PIC relocs in the data section are
* already in target order
*/
if ((flags & FLAT_FLAG_GOTPIC) == 0)
addr = ntohl(addr);
addr = calc_reloc(addr, libinfo, id, 0);
if (addr == RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
}
/* Write back the relocated pointer. */
flat_put_addr_at_rp(rp, addr, relval);
}
}
} else {
for (i=0; i < relocs; i++)
old_reloc(ntohl(reloc[i]));
}
flush_icache_range(start_code, end_code);
/* zero the BSS, BRK and stack areas */
memset((void*)(datapos + data_len), 0, bss_len +
(memp + kobjsize((void *) memp) - stack_len - /* end brk */
libinfo->lib_list[id].start_brk) + /* start brk */
stack_len);
return 0;
err:
return ret;
}
/****************************************************************************/
#ifdef CONFIG_BINFMT_SHARED_FLAT
/*
* Load a shared library into memory. The library gets its own data
* segment (including bss) but not argv/argc/environ.
*/
static int load_flat_shared_library(int id, struct lib_info *libs)
{
struct linux_binprm bprm;
int res;
char buf[16];
/* Create the file name */
sprintf(buf, "/lib/lib%d.so", id);
/* Open the file up */
bprm.filename = buf;
bprm.file = open_exec(bprm.filename);
res = PTR_ERR(bprm.file);
if (IS_ERR(bprm.file))
return res;
res = prepare_binprm(&bprm);
if (res <= (unsigned long)-4096)
res = load_flat_file(&bprm, libs, id, NULL);
if (bprm.file) {
allow_write_access(bprm.file);
fput(bprm.file);
bprm.file = NULL;
}
return(res);
}
#endif /* CONFIG_BINFMT_SHARED_FLAT */
/****************************************************************************/
/*
* These are the functions used to load flat style executables and shared
* libraries. There is no binary dependent code anywhere else.
*/
static int load_flat_binary(struct linux_binprm * bprm, struct pt_regs * regs)
{
struct lib_info libinfo;
unsigned long p = bprm->p;
unsigned long stack_len;
unsigned long start_addr;
unsigned long *sp;
int res;
int i, j;
memset(&libinfo, 0, sizeof(libinfo));
/*
* We have to add the size of our arguments to our stack size
* otherwise it's too easy for users to create stack overflows
* by passing in a huge argument list. And yes, we have to be
* pedantic and include space for the argv/envp array as it may have
* a lot of entries.
*/
#define TOP_OF_ARGS (PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *))
stack_len = TOP_OF_ARGS - bprm->p; /* the strings */
stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
res = load_flat_file(bprm, &libinfo, 0, &stack_len);
if (res > (unsigned long)-4096)
return res;
/* Update data segment pointers for all libraries */
for (i=0; i<MAX_SHARED_LIBS; i++)
if (libinfo.lib_list[i].loaded)
for (j=0; j<MAX_SHARED_LIBS; j++)
(-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
(libinfo.lib_list[j].loaded)?
libinfo.lib_list[j].start_data:UNLOADED_LIB;
install_exec_creds(bprm);
current->flags &= ~PF_FORKNOEXEC;
set_binfmt(&flat_format);
p = ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
DBG_FLT("p=%x\n", (int)p);
/* copy the arg pages onto the stack, this could be more efficient :-) */
for (i = TOP_OF_ARGS - 1; i >= bprm->p; i--)
* (char *) --p =
((char *) page_address(bprm->page[i/PAGE_SIZE]))[i % PAGE_SIZE];
sp = (unsigned long *) create_flat_tables(p, bprm);
/* Fake some return addresses to ensure the call chain will
* initialise library in order for us. We are required to call
* lib 1 first, then 2, ... and finally the main program (id 0).
*/
start_addr = libinfo.lib_list[0].entry;
#ifdef CONFIG_BINFMT_SHARED_FLAT
for (i = MAX_SHARED_LIBS-1; i>0; i--) {
if (libinfo.lib_list[i].loaded) {
/* Push previos first to call address */
--sp; put_user(start_addr, sp);
start_addr = libinfo.lib_list[i].entry;
}
}
#endif
/* Stash our initial stack pointer into the mm structure */
current->mm->start_stack = (unsigned long )sp;
#ifdef FLAT_PLAT_INIT
FLAT_PLAT_INIT(regs);
#endif
DBG_FLT("start_thread(regs=0x%x, entry=0x%x, start_stack=0x%x)\n",
(int)regs, (int)start_addr, (int)current->mm->start_stack);
start_thread(regs, start_addr, current->mm->start_stack);
return 0;
}
/****************************************************************************/
static int __init init_flat_binfmt(void)
{
return register_binfmt(&flat_format);
}
/****************************************************************************/
core_initcall(init_flat_binfmt);
/****************************************************************************/
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