1/*
2 *  linux/fs/binfmt_aout.c
3 *
4 *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
5 */
6
7#include <linux/module.h>
8
9#include <linux/time.h>
10#include <linux/kernel.h>
11#include <linux/mm.h>
12#include <linux/mman.h>
13#include <linux/a.out.h>
14#include <linux/errno.h>
15#include <linux/signal.h>
16#include <linux/string.h>
17#include <linux/fs.h>
18#include <linux/file.h>
19#include <linux/stat.h>
20#include <linux/fcntl.h>
21#include <linux/ptrace.h>
22#include <linux/user.h>
23#include <linux/binfmts.h>
24#include <linux/personality.h>
25#include <linux/init.h>
26#include <linux/coredump.h>
27#include <linux/slab.h>
28
29#include <asm/uaccess.h>
30#include <asm/cacheflush.h>
31#include <asm/a.out-core.h>
32
33static int load_aout_binary(struct linux_binprm *);
34static int load_aout_library(struct file*);
35
36#ifdef CONFIG_COREDUMP
37/*
38 * Routine writes a core dump image in the current directory.
39 * Currently only a stub-function.
40 *
41 * Note that setuid/setgid files won't make a core-dump if the uid/gid
42 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
43 * field, which also makes sure the core-dumps won't be recursive if the
44 * dumping of the process results in another error..
45 */
46static int aout_core_dump(struct coredump_params *cprm)
47{
48	mm_segment_t fs;
49	int has_dumped = 0;
50	void __user *dump_start;
51	int dump_size;
52	struct user dump;
53#ifdef __alpha__
54#       define START_DATA(u)	((void __user *)u.start_data)
55#else
56#	define START_DATA(u)	((void __user *)((u.u_tsize << PAGE_SHIFT) + \
57				 u.start_code))
58#endif
59#       define START_STACK(u)   ((void __user *)u.start_stack)
60
61	fs = get_fs();
62	set_fs(KERNEL_DS);
63	has_dumped = 1;
64       	strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
65	dump.u_ar0 = offsetof(struct user, regs);
66	dump.signal = cprm->siginfo->si_signo;
67	aout_dump_thread(cprm->regs, &dump);
68
69/* If the size of the dump file exceeds the rlimit, then see what would happen
70   if we wrote the stack, but not the data area.  */
71	if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
72		dump.u_dsize = 0;
73
74/* Make sure we have enough room to write the stack and data areas. */
75	if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
76		dump.u_ssize = 0;
77
78/* make sure we actually have a data and stack area to dump */
79	set_fs(USER_DS);
80	if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
81		dump.u_dsize = 0;
82	if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
83		dump.u_ssize = 0;
84
85	set_fs(KERNEL_DS);
86/* struct user */
87	if (!dump_emit(cprm, &dump, sizeof(dump)))
88		goto end_coredump;
89/* Now dump all of the user data.  Include malloced stuff as well */
90	if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump)))
91		goto end_coredump;
92/* now we start writing out the user space info */
93	set_fs(USER_DS);
94/* Dump the data area */
95	if (dump.u_dsize != 0) {
96		dump_start = START_DATA(dump);
97		dump_size = dump.u_dsize << PAGE_SHIFT;
98		if (!dump_emit(cprm, dump_start, dump_size))
99			goto end_coredump;
100	}
101/* Now prepare to dump the stack area */
102	if (dump.u_ssize != 0) {
103		dump_start = START_STACK(dump);
104		dump_size = dump.u_ssize << PAGE_SHIFT;
105		if (!dump_emit(cprm, dump_start, dump_size))
106			goto end_coredump;
107	}
108end_coredump:
109	set_fs(fs);
110	return has_dumped;
111}
112#else
113#define aout_core_dump NULL
114#endif
115
116static struct linux_binfmt aout_format = {
117	.module		= THIS_MODULE,
118	.load_binary	= load_aout_binary,
119	.load_shlib	= load_aout_library,
120	.core_dump	= aout_core_dump,
121	.min_coredump	= PAGE_SIZE
122};
123
124#define BAD_ADDR(x)	((unsigned long)(x) >= TASK_SIZE)
125
126static int set_brk(unsigned long start, unsigned long end)
127{
128	start = PAGE_ALIGN(start);
129	end = PAGE_ALIGN(end);
130	if (end > start) {
131		unsigned long addr;
132		addr = vm_brk(start, end - start);
133		if (BAD_ADDR(addr))
134			return addr;
135	}
136	return 0;
137}
138
139/*
140 * create_aout_tables() parses the env- and arg-strings in new user
141 * memory and creates the pointer tables from them, and puts their
142 * addresses on the "stack", returning the new stack pointer value.
143 */
144static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
145{
146	char __user * __user *argv;
147	char __user * __user *envp;
148	unsigned long __user *sp;
149	int argc = bprm->argc;
150	int envc = bprm->envc;
151
152	sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
153#ifdef __alpha__
154/* whee.. test-programs are so much fun. */
155	put_user(0, --sp);
156	put_user(0, --sp);
157	if (bprm->loader) {
158		put_user(0, --sp);
159		put_user(1003, --sp);
160		put_user(bprm->loader, --sp);
161		put_user(1002, --sp);
162	}
163	put_user(bprm->exec, --sp);
164	put_user(1001, --sp);
165#endif
166	sp -= envc+1;
167	envp = (char __user * __user *) sp;
168	sp -= argc+1;
169	argv = (char __user * __user *) sp;
170#ifndef __alpha__
171	put_user((unsigned long) envp,--sp);
172	put_user((unsigned long) argv,--sp);
173#endif
174	put_user(argc,--sp);
175	current->mm->arg_start = (unsigned long) p;
176	while (argc-->0) {
177		char c;
178		put_user(p,argv++);
179		do {
180			get_user(c,p++);
181		} while (c);
182	}
183	put_user(NULL,argv);
184	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
185	while (envc-->0) {
186		char c;
187		put_user(p,envp++);
188		do {
189			get_user(c,p++);
190		} while (c);
191	}
192	put_user(NULL,envp);
193	current->mm->env_end = (unsigned long) p;
194	return sp;
195}
196
197/*
198 * These are the functions used to load a.out style executables and shared
199 * libraries.  There is no binary dependent code anywhere else.
200 */
201
202static int load_aout_binary(struct linux_binprm * bprm)
203{
204	struct pt_regs *regs = current_pt_regs();
205	struct exec ex;
206	unsigned long error;
207	unsigned long fd_offset;
208	unsigned long rlim;
209	int retval;
210
211	ex = *((struct exec *) bprm->buf);		/* exec-header */
212	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
213	     N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
214	    N_TRSIZE(ex) || N_DRSIZE(ex) ||
215	    i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
216		return -ENOEXEC;
217	}
218
219	/*
220	 * Requires a mmap handler. This prevents people from using a.out
221	 * as part of an exploit attack against /proc-related vulnerabilities.
222	 */
223	if (!bprm->file->f_op->mmap)
224		return -ENOEXEC;
225
226	fd_offset = N_TXTOFF(ex);
227
228	/* Check initial limits. This avoids letting people circumvent
229	 * size limits imposed on them by creating programs with large
230	 * arrays in the data or bss.
231	 */
232	rlim = rlimit(RLIMIT_DATA);
233	if (rlim >= RLIM_INFINITY)
234		rlim = ~0;
235	if (ex.a_data + ex.a_bss > rlim)
236		return -ENOMEM;
237
238	/* Flush all traces of the currently running executable */
239	retval = flush_old_exec(bprm);
240	if (retval)
241		return retval;
242
243	/* OK, This is the point of no return */
244#ifdef __alpha__
245	SET_AOUT_PERSONALITY(bprm, ex);
246#else
247	set_personality(PER_LINUX);
248#endif
249	setup_new_exec(bprm);
250
251	current->mm->end_code = ex.a_text +
252		(current->mm->start_code = N_TXTADDR(ex));
253	current->mm->end_data = ex.a_data +
254		(current->mm->start_data = N_DATADDR(ex));
255	current->mm->brk = ex.a_bss +
256		(current->mm->start_brk = N_BSSADDR(ex));
257
258	retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
259	if (retval < 0)
260		return retval;
261
262	install_exec_creds(bprm);
263
264	if (N_MAGIC(ex) == OMAGIC) {
265		unsigned long text_addr, map_size;
266		loff_t pos;
267
268		text_addr = N_TXTADDR(ex);
269
270#ifdef __alpha__
271		pos = fd_offset;
272		map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
273#else
274		pos = 32;
275		map_size = ex.a_text+ex.a_data;
276#endif
277		error = vm_brk(text_addr & PAGE_MASK, map_size);
278		if (error != (text_addr & PAGE_MASK))
279			return error;
280
281		error = read_code(bprm->file, text_addr, pos,
282				  ex.a_text+ex.a_data);
283		if ((signed long)error < 0)
284			return error;
285	} else {
286		if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
287		    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
288		{
289			printk(KERN_NOTICE "executable not page aligned\n");
290		}
291
292		if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
293		{
294			printk(KERN_WARNING
295			       "fd_offset is not page aligned. Please convert program: %pD\n",
296			       bprm->file);
297		}
298
299		if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
300			vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
301			read_code(bprm->file, N_TXTADDR(ex), fd_offset,
302				  ex.a_text + ex.a_data);
303			goto beyond_if;
304		}
305
306		error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
307			PROT_READ | PROT_EXEC,
308			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
309			fd_offset);
310
311		if (error != N_TXTADDR(ex))
312			return error;
313
314		error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
315				PROT_READ | PROT_WRITE | PROT_EXEC,
316				MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
317				fd_offset + ex.a_text);
318		if (error != N_DATADDR(ex))
319			return error;
320	}
321beyond_if:
322	set_binfmt(&aout_format);
323
324	retval = set_brk(current->mm->start_brk, current->mm->brk);
325	if (retval < 0)
326		return retval;
327
328	current->mm->start_stack =
329		(unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
330#ifdef __alpha__
331	regs->gp = ex.a_gpvalue;
332#endif
333	start_thread(regs, ex.a_entry, current->mm->start_stack);
334	return 0;
335}
336
337static int load_aout_library(struct file *file)
338{
339	struct inode * inode;
340	unsigned long bss, start_addr, len;
341	unsigned long error;
342	int retval;
343	struct exec ex;
344
345	inode = file_inode(file);
346
347	retval = -ENOEXEC;
348	error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
349	if (error != sizeof(ex))
350		goto out;
351
352	/* We come in here for the regular a.out style of shared libraries */
353	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
354	    N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
355	    i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
356		goto out;
357	}
358
359	/*
360	 * Requires a mmap handler. This prevents people from using a.out
361	 * as part of an exploit attack against /proc-related vulnerabilities.
362	 */
363	if (!file->f_op->mmap)
364		goto out;
365
366	if (N_FLAGS(ex))
367		goto out;
368
369	/* For  QMAGIC, the starting address is 0x20 into the page.  We mask
370	   this off to get the starting address for the page */
371
372	start_addr =  ex.a_entry & 0xfffff000;
373
374	if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
375		if (printk_ratelimit())
376		{
377			printk(KERN_WARNING
378			       "N_TXTOFF is not page aligned. Please convert library: %pD\n",
379			       file);
380		}
381		vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
382
383		read_code(file, start_addr, N_TXTOFF(ex),
384			  ex.a_text + ex.a_data);
385		retval = 0;
386		goto out;
387	}
388	/* Now use mmap to map the library into memory. */
389	error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
390			PROT_READ | PROT_WRITE | PROT_EXEC,
391			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
392			N_TXTOFF(ex));
393	retval = error;
394	if (error != start_addr)
395		goto out;
396
397	len = PAGE_ALIGN(ex.a_text + ex.a_data);
398	bss = ex.a_text + ex.a_data + ex.a_bss;
399	if (bss > len) {
400		error = vm_brk(start_addr + len, bss - len);
401		retval = error;
402		if (error != start_addr + len)
403			goto out;
404	}
405	retval = 0;
406out:
407	return retval;
408}
409
410static int __init init_aout_binfmt(void)
411{
412	register_binfmt(&aout_format);
413	return 0;
414}
415
416static void __exit exit_aout_binfmt(void)
417{
418	unregister_binfmt(&aout_format);
419}
420
421core_initcall(init_aout_binfmt);
422module_exit(exit_aout_binfmt);
423MODULE_LICENSE("GPL");
424