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09c434b8 1// SPDX-License-Identifier: GPL-2.0-only
1da177e4
LT
2/*
3 * linux/fs/binfmt_aout.c
4 *
5 * Copyright (C) 1991, 1992, 1996 Linus Torvalds
6 */
7
8#include <linux/module.h>
9
10#include <linux/time.h>
11#include <linux/kernel.h>
12#include <linux/mm.h>
13#include <linux/mman.h>
14#include <linux/a.out.h>
15#include <linux/errno.h>
16#include <linux/signal.h>
17#include <linux/string.h>
18#include <linux/fs.h>
19#include <linux/file.h>
20#include <linux/stat.h>
21#include <linux/fcntl.h>
22#include <linux/ptrace.h>
23#include <linux/user.h>
1da177e4
LT
24#include <linux/binfmts.h>
25#include <linux/personality.h>
26#include <linux/init.h>
088e7af7 27#include <linux/coredump.h>
5a0e3ad6 28#include <linux/slab.h>
68db0cf1 29#include <linux/sched/task_stack.h>
1da177e4 30
7c0f6ba6 31#include <linux/uaccess.h>
1da177e4
LT
32#include <asm/cacheflush.h>
33
71613c3b 34static int load_aout_binary(struct linux_binprm *);
1da177e4 35static int load_aout_library(struct file*);
1da177e4 36
046d662f
AK
37static struct linux_binfmt aout_format = {
38 .module = THIS_MODULE,
39 .load_binary = load_aout_binary,
40 .load_shlib = load_aout_library,
046d662f
AK
41};
42
43#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
44
45static int set_brk(unsigned long start, unsigned long end)
46{
47 start = PAGE_ALIGN(start);
48 end = PAGE_ALIGN(end);
5d22fc25
LT
49 if (end > start)
50 return vm_brk(start, end - start);
046d662f
AK
51 return 0;
52}
1da177e4
LT
53
54/*
55 * create_aout_tables() parses the env- and arg-strings in new user
56 * memory and creates the pointer tables from them, and puts their
57 * addresses on the "stack", returning the new stack pointer value.
58 */
59static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
60{
61 char __user * __user *argv;
62 char __user * __user *envp;
63 unsigned long __user *sp;
64 int argc = bprm->argc;
65 int envc = bprm->envc;
66
67 sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
1da177e4
LT
68#ifdef __alpha__
69/* whee.. test-programs are so much fun. */
70 put_user(0, --sp);
71 put_user(0, --sp);
72 if (bprm->loader) {
73 put_user(0, --sp);
17580d7f 74 put_user(1003, --sp);
1da177e4 75 put_user(bprm->loader, --sp);
17580d7f 76 put_user(1002, --sp);
1da177e4
LT
77 }
78 put_user(bprm->exec, --sp);
17580d7f 79 put_user(1001, --sp);
1da177e4
LT
80#endif
81 sp -= envc+1;
82 envp = (char __user * __user *) sp;
83 sp -= argc+1;
84 argv = (char __user * __user *) sp;
17580d7f 85#ifndef __alpha__
1da177e4
LT
86 put_user((unsigned long) envp,--sp);
87 put_user((unsigned long) argv,--sp);
88#endif
89 put_user(argc,--sp);
90 current->mm->arg_start = (unsigned long) p;
91 while (argc-->0) {
92 char c;
93 put_user(p,argv++);
94 do {
95 get_user(c,p++);
96 } while (c);
97 }
98 put_user(NULL,argv);
99 current->mm->arg_end = current->mm->env_start = (unsigned long) p;
100 while (envc-->0) {
101 char c;
102 put_user(p,envp++);
103 do {
104 get_user(c,p++);
105 } while (c);
106 }
107 put_user(NULL,envp);
108 current->mm->env_end = (unsigned long) p;
109 return sp;
110}
111
112/*
113 * These are the functions used to load a.out style executables and shared
114 * libraries. There is no binary dependent code anywhere else.
115 */
116
71613c3b 117static int load_aout_binary(struct linux_binprm * bprm)
1da177e4 118{
71613c3b 119 struct pt_regs *regs = current_pt_regs();
1da177e4
LT
120 struct exec ex;
121 unsigned long error;
122 unsigned long fd_offset;
123 unsigned long rlim;
124 int retval;
125
126 ex = *((struct exec *) bprm->buf); /* exec-header */
127 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
128 N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
129 N_TRSIZE(ex) || N_DRSIZE(ex) ||
496ad9aa 130 i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
1da177e4
LT
131 return -ENOEXEC;
132 }
133
8454aeef
ET
134 /*
135 * Requires a mmap handler. This prevents people from using a.out
136 * as part of an exploit attack against /proc-related vulnerabilities.
137 */
72c2d531 138 if (!bprm->file->f_op->mmap)
8454aeef
ET
139 return -ENOEXEC;
140
1da177e4
LT
141 fd_offset = N_TXTOFF(ex);
142
143 /* Check initial limits. This avoids letting people circumvent
144 * size limits imposed on them by creating programs with large
145 * arrays in the data or bss.
146 */
d554ed89 147 rlim = rlimit(RLIMIT_DATA);
1da177e4
LT
148 if (rlim >= RLIM_INFINITY)
149 rlim = ~0;
150 if (ex.a_data + ex.a_bss > rlim)
151 return -ENOMEM;
152
153 /* Flush all traces of the currently running executable */
2388777a 154 retval = begin_new_exec(bprm);
1da177e4
LT
155 if (retval)
156 return retval;
157
158 /* OK, This is the point of no return */
17580d7f 159#ifdef __alpha__
1da177e4 160 SET_AOUT_PERSONALITY(bprm, ex);
1da177e4
LT
161#else
162 set_personality(PER_LINUX);
163#endif
221af7f8 164 setup_new_exec(bprm);
1da177e4
LT
165
166 current->mm->end_code = ex.a_text +
167 (current->mm->start_code = N_TXTADDR(ex));
168 current->mm->end_data = ex.a_data +
169 (current->mm->start_data = N_DATADDR(ex));
170 current->mm->brk = ex.a_bss +
171 (current->mm->start_brk = N_BSSADDR(ex));
1da177e4 172
6414fa6a 173 retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
19d860a1 174 if (retval < 0)
6414fa6a 175 return retval;
6414fa6a 176
1da177e4
LT
177
178 if (N_MAGIC(ex) == OMAGIC) {
179 unsigned long text_addr, map_size;
180 loff_t pos;
181
182 text_addr = N_TXTADDR(ex);
183
fe30af97 184#ifdef __alpha__
1da177e4
LT
185 pos = fd_offset;
186 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
187#else
188 pos = 32;
189 map_size = ex.a_text+ex.a_data;
190#endif
e4eb1ff6 191 error = vm_brk(text_addr & PAGE_MASK, map_size);
5d22fc25 192 if (error)
1da177e4 193 return error;
1da177e4 194
3dc20cb2
AV
195 error = read_code(bprm->file, text_addr, pos,
196 ex.a_text+ex.a_data);
19d860a1 197 if ((signed long)error < 0)
1da177e4 198 return error;
1da177e4 199 } else {
1da177e4 200 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
2e50b6cc 201 (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
1da177e4
LT
202 {
203 printk(KERN_NOTICE "executable not page aligned\n");
1da177e4
LT
204 }
205
2e50b6cc 206 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
1da177e4
LT
207 {
208 printk(KERN_WARNING
a455589f
AV
209 "fd_offset is not page aligned. Please convert program: %pD\n",
210 bprm->file);
1da177e4
LT
211 }
212
213 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
864778b1 214 error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
5d22fc25 215 if (error)
864778b1
MH
216 return error;
217
3dc20cb2
AV
218 read_code(bprm->file, N_TXTADDR(ex), fd_offset,
219 ex.a_text + ex.a_data);
1da177e4
LT
220 goto beyond_if;
221 }
222
6be5ceb0 223 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
1da177e4
LT
224 PROT_READ | PROT_EXEC,
225 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
226 fd_offset);
1da177e4 227
19d860a1 228 if (error != N_TXTADDR(ex))
1da177e4 229 return error;
1da177e4 230
6be5ceb0 231 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
1da177e4
LT
232 PROT_READ | PROT_WRITE | PROT_EXEC,
233 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
234 fd_offset + ex.a_text);
19d860a1 235 if (error != N_DATADDR(ex))
1da177e4 236 return error;
1da177e4
LT
237 }
238beyond_if:
239 set_binfmt(&aout_format);
240
241 retval = set_brk(current->mm->start_brk, current->mm->brk);
19d860a1 242 if (retval < 0)
1da177e4 243 return retval;
1da177e4 244
1da177e4
LT
245 current->mm->start_stack =
246 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
247#ifdef __alpha__
248 regs->gp = ex.a_gpvalue;
249#endif
b8383831 250 finalize_exec(bprm);
1da177e4 251 start_thread(regs, ex.a_entry, current->mm->start_stack);
1da177e4
LT
252 return 0;
253}
254
255static int load_aout_library(struct file *file)
256{
257 struct inode * inode;
258 unsigned long bss, start_addr, len;
259 unsigned long error;
260 int retval;
261 struct exec ex;
bdd1d2d3 262 loff_t pos = 0;
1da177e4 263
496ad9aa 264 inode = file_inode(file);
1da177e4
LT
265
266 retval = -ENOEXEC;
bdd1d2d3 267 error = kernel_read(file, &ex, sizeof(ex), &pos);
1da177e4
LT
268 if (error != sizeof(ex))
269 goto out;
270
271 /* We come in here for the regular a.out style of shared libraries */
272 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
273 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
274 i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
275 goto out;
276 }
277
8454aeef
ET
278 /*
279 * Requires a mmap handler. This prevents people from using a.out
280 * as part of an exploit attack against /proc-related vulnerabilities.
281 */
72c2d531 282 if (!file->f_op->mmap)
8454aeef
ET
283 goto out;
284
1da177e4
LT
285 if (N_FLAGS(ex))
286 goto out;
287
288 /* For QMAGIC, the starting address is 0x20 into the page. We mask
289 this off to get the starting address for the page */
290
291 start_addr = ex.a_entry & 0xfffff000;
292
293 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
2e50b6cc 294 if (printk_ratelimit())
1da177e4
LT
295 {
296 printk(KERN_WARNING
a455589f
AV
297 "N_TXTOFF is not page aligned. Please convert library: %pD\n",
298 file);
1da177e4 299 }
864778b1 300 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
5d22fc25 301 if (retval)
864778b1
MH
302 goto out;
303
3dc20cb2
AV
304 read_code(file, start_addr, N_TXTOFF(ex),
305 ex.a_text + ex.a_data);
1da177e4
LT
306 retval = 0;
307 goto out;
308 }
309 /* Now use mmap to map the library into memory. */
6be5ceb0 310 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
1da177e4
LT
311 PROT_READ | PROT_WRITE | PROT_EXEC,
312 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
313 N_TXTOFF(ex));
1da177e4
LT
314 retval = error;
315 if (error != start_addr)
316 goto out;
317
318 len = PAGE_ALIGN(ex.a_text + ex.a_data);
319 bss = ex.a_text + ex.a_data + ex.a_bss;
320 if (bss > len) {
5d22fc25
LT
321 retval = vm_brk(start_addr + len, bss - len);
322 if (retval)
1da177e4
LT
323 goto out;
324 }
325 retval = 0;
326out:
327 return retval;
328}
329
330static int __init init_aout_binfmt(void)
331{
8fc3dc5a
AV
332 register_binfmt(&aout_format);
333 return 0;
1da177e4
LT
334}
335
336static void __exit exit_aout_binfmt(void)
337{
338 unregister_binfmt(&aout_format);
339}
340
341core_initcall(init_aout_binfmt);
342module_exit(exit_aout_binfmt);
343MODULE_LICENSE("GPL");