linux/fs/binfmt_aout.c
Linus Torvalds 96d4f267e4 Remove 'type' argument from access_ok() function
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-03 18:57:57 -08:00

427 lines
11 KiB
C

/*
* linux/fs/binfmt_aout.c
*
* Copyright (C) 1991, 1992, 1996 Linus Torvalds
*/
#include <linux/module.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/a.out.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/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/coredump.h>
#include <linux/slab.h>
#include <linux/sched/task_stack.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/a.out-core.h>
static int load_aout_binary(struct linux_binprm *);
static int load_aout_library(struct file*);
#ifdef CONFIG_COREDUMP
/*
* Routine writes a core dump image in the current directory.
* Currently only a stub-function.
*
* Note that setuid/setgid files won't make a core-dump if the uid/gid
* changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
* field, which also makes sure the core-dumps won't be recursive if the
* dumping of the process results in another error..
*/
static int aout_core_dump(struct coredump_params *cprm)
{
mm_segment_t fs;
int has_dumped = 0;
void __user *dump_start;
int dump_size;
struct user dump;
#ifdef __alpha__
# define START_DATA(u) ((void __user *)u.start_data)
#else
# define START_DATA(u) ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
u.start_code))
#endif
# define START_STACK(u) ((void __user *)u.start_stack)
fs = get_fs();
set_fs(KERNEL_DS);
has_dumped = 1;
strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
dump.u_ar0 = offsetof(struct user, regs);
dump.signal = cprm->siginfo->si_signo;
aout_dump_thread(cprm->regs, &dump);
/* If the size of the dump file exceeds the rlimit, then see what would happen
if we wrote the stack, but not the data area. */
if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
dump.u_dsize = 0;
/* Make sure we have enough room to write the stack and data areas. */
if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
dump.u_ssize = 0;
/* make sure we actually have a data and stack area to dump */
set_fs(USER_DS);
if (!access_ok(START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
dump.u_dsize = 0;
if (!access_ok(START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
dump.u_ssize = 0;
set_fs(KERNEL_DS);
/* struct user */
if (!dump_emit(cprm, &dump, sizeof(dump)))
goto end_coredump;
/* Now dump all of the user data. Include malloced stuff as well */
if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump)))
goto end_coredump;
/* now we start writing out the user space info */
set_fs(USER_DS);
/* Dump the data area */
if (dump.u_dsize != 0) {
dump_start = START_DATA(dump);
dump_size = dump.u_dsize << PAGE_SHIFT;
if (!dump_emit(cprm, dump_start, dump_size))
goto end_coredump;
}
/* Now prepare to dump the stack area */
if (dump.u_ssize != 0) {
dump_start = START_STACK(dump);
dump_size = dump.u_ssize << PAGE_SHIFT;
if (!dump_emit(cprm, dump_start, dump_size))
goto end_coredump;
}
end_coredump:
set_fs(fs);
return has_dumped;
}
#else
#define aout_core_dump NULL
#endif
static struct linux_binfmt aout_format = {
.module = THIS_MODULE,
.load_binary = load_aout_binary,
.load_shlib = load_aout_library,
.core_dump = aout_core_dump,
.min_coredump = PAGE_SIZE
};
#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
static int set_brk(unsigned long start, unsigned long end)
{
start = PAGE_ALIGN(start);
end = PAGE_ALIGN(end);
if (end > start)
return vm_brk(start, end - start);
return 0;
}
/*
* create_aout_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 __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
{
char __user * __user *argv;
char __user * __user *envp;
unsigned long __user *sp;
int argc = bprm->argc;
int envc = bprm->envc;
sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
#ifdef __alpha__
/* whee.. test-programs are so much fun. */
put_user(0, --sp);
put_user(0, --sp);
if (bprm->loader) {
put_user(0, --sp);
put_user(1003, --sp);
put_user(bprm->loader, --sp);
put_user(1002, --sp);
}
put_user(bprm->exec, --sp);
put_user(1001, --sp);
#endif
sp -= envc+1;
envp = (char __user * __user *) sp;
sp -= argc+1;
argv = (char __user * __user *) sp;
#ifndef __alpha__
put_user((unsigned long) envp,--sp);
put_user((unsigned long) argv,--sp);
#endif
put_user(argc,--sp);
current->mm->arg_start = (unsigned long) p;
while (argc-->0) {
char c;
put_user(p,argv++);
do {
get_user(c,p++);
} while (c);
}
put_user(NULL,argv);
current->mm->arg_end = current->mm->env_start = (unsigned long) p;
while (envc-->0) {
char c;
put_user(p,envp++);
do {
get_user(c,p++);
} while (c);
}
put_user(NULL,envp);
current->mm->env_end = (unsigned long) p;
return sp;
}
/*
* These are the functions used to load a.out style executables and shared
* libraries. There is no binary dependent code anywhere else.
*/
static int load_aout_binary(struct linux_binprm * bprm)
{
struct pt_regs *regs = current_pt_regs();
struct exec ex;
unsigned long error;
unsigned long fd_offset;
unsigned long rlim;
int retval;
ex = *((struct exec *) bprm->buf); /* exec-header */
if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
N_TRSIZE(ex) || N_DRSIZE(ex) ||
i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
return -ENOEXEC;
}
/*
* Requires a mmap handler. This prevents people from using a.out
* as part of an exploit attack against /proc-related vulnerabilities.
*/
if (!bprm->file->f_op->mmap)
return -ENOEXEC;
fd_offset = N_TXTOFF(ex);
/* 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 = rlimit(RLIMIT_DATA);
if (rlim >= RLIM_INFINITY)
rlim = ~0;
if (ex.a_data + ex.a_bss > rlim)
return -ENOMEM;
/* Flush all traces of the currently running executable */
retval = flush_old_exec(bprm);
if (retval)
return retval;
/* OK, This is the point of no return */
#ifdef __alpha__
SET_AOUT_PERSONALITY(bprm, ex);
#else
set_personality(PER_LINUX);
#endif
setup_new_exec(bprm);
current->mm->end_code = ex.a_text +
(current->mm->start_code = N_TXTADDR(ex));
current->mm->end_data = ex.a_data +
(current->mm->start_data = N_DATADDR(ex));
current->mm->brk = ex.a_bss +
(current->mm->start_brk = N_BSSADDR(ex));
retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
if (retval < 0)
return retval;
install_exec_creds(bprm);
if (N_MAGIC(ex) == OMAGIC) {
unsigned long text_addr, map_size;
loff_t pos;
text_addr = N_TXTADDR(ex);
#ifdef __alpha__
pos = fd_offset;
map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
#else
pos = 32;
map_size = ex.a_text+ex.a_data;
#endif
error = vm_brk(text_addr & PAGE_MASK, map_size);
if (error)
return error;
error = read_code(bprm->file, text_addr, pos,
ex.a_text+ex.a_data);
if ((signed long)error < 0)
return error;
} else {
if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
(N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
{
printk(KERN_NOTICE "executable not page aligned\n");
}
if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
{
printk(KERN_WARNING
"fd_offset is not page aligned. Please convert program: %pD\n",
bprm->file);
}
if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
if (error)
return error;
read_code(bprm->file, N_TXTADDR(ex), fd_offset,
ex.a_text + ex.a_data);
goto beyond_if;
}
error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
PROT_READ | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
fd_offset);
if (error != N_TXTADDR(ex))
return error;
error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
fd_offset + ex.a_text);
if (error != N_DATADDR(ex))
return error;
}
beyond_if:
set_binfmt(&aout_format);
retval = set_brk(current->mm->start_brk, current->mm->brk);
if (retval < 0)
return retval;
current->mm->start_stack =
(unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
#ifdef __alpha__
regs->gp = ex.a_gpvalue;
#endif
finalize_exec(bprm);
start_thread(regs, ex.a_entry, current->mm->start_stack);
return 0;
}
static int load_aout_library(struct file *file)
{
struct inode * inode;
unsigned long bss, start_addr, len;
unsigned long error;
int retval;
struct exec ex;
loff_t pos = 0;
inode = file_inode(file);
retval = -ENOEXEC;
error = kernel_read(file, &ex, sizeof(ex), &pos);
if (error != sizeof(ex))
goto out;
/* We come in here for the regular a.out style of shared libraries */
if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
goto out;
}
/*
* Requires a mmap handler. This prevents people from using a.out
* as part of an exploit attack against /proc-related vulnerabilities.
*/
if (!file->f_op->mmap)
goto out;
if (N_FLAGS(ex))
goto out;
/* For QMAGIC, the starting address is 0x20 into the page. We mask
this off to get the starting address for the page */
start_addr = ex.a_entry & 0xfffff000;
if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
if (printk_ratelimit())
{
printk(KERN_WARNING
"N_TXTOFF is not page aligned. Please convert library: %pD\n",
file);
}
retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
if (retval)
goto out;
read_code(file, start_addr, N_TXTOFF(ex),
ex.a_text + ex.a_data);
retval = 0;
goto out;
}
/* Now use mmap to map the library into memory. */
error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
N_TXTOFF(ex));
retval = error;
if (error != start_addr)
goto out;
len = PAGE_ALIGN(ex.a_text + ex.a_data);
bss = ex.a_text + ex.a_data + ex.a_bss;
if (bss > len) {
retval = vm_brk(start_addr + len, bss - len);
if (retval)
goto out;
}
retval = 0;
out:
return retval;
}
static int __init init_aout_binfmt(void)
{
register_binfmt(&aout_format);
return 0;
}
static void __exit exit_aout_binfmt(void)
{
unregister_binfmt(&aout_format);
}
core_initcall(init_aout_binfmt);
module_exit(exit_aout_binfmt);
MODULE_LICENSE("GPL");