1 // SPDX-License-Identifier: GPL-2.0-only
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>
24 #include <linux/binfmts.h>
25 #include <linux/personality.h>
26 #include <linux/init.h>
27 #include <linux/coredump.h>
28 #include <linux/slab.h>
29 #include <linux/sched/task_stack.h>
30
31 #include <linux/uaccess.h>
32 #include <asm/cacheflush.h>
33
34 static int load_aout_binary(struct linux_binprm *);
35 static int load_aout_library(struct file*);
36
37 static struct linux_binfmt aout_format = {
38 .module = THIS_MODULE,
39 .load_binary = load_aout_binary,
40 .load_shlib = load_aout_library,
41 };
42
43 #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
44
set_brk(unsigned long start,unsigned long end)45 static int set_brk(unsigned long start, unsigned long end)
46 {
47 start = PAGE_ALIGN(start);
48 end = PAGE_ALIGN(end);
49 if (end > start)
50 return vm_brk(start, end - start);
51 return 0;
52 }
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 */
create_aout_tables(char __user * p,struct linux_binprm * bprm)59 static 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);
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);
74 put_user(1003, --sp);
75 put_user(bprm->loader, --sp);
76 put_user(1002, --sp);
77 }
78 put_user(bprm->exec, --sp);
79 put_user(1001, --sp);
80 #endif
81 sp -= envc+1;
82 envp = (char __user * __user *) sp;
83 sp -= argc+1;
84 argv = (char __user * __user *) sp;
85 #ifndef __alpha__
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
load_aout_binary(struct linux_binprm * bprm)117 static int load_aout_binary(struct linux_binprm * bprm)
118 {
119 struct pt_regs *regs = current_pt_regs();
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) ||
130 i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
131 return -ENOEXEC;
132 }
133
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 */
138 if (!bprm->file->f_op->mmap)
139 return -ENOEXEC;
140
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 */
147 rlim = rlimit(RLIMIT_DATA);
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 */
154 retval = flush_old_exec(bprm);
155 if (retval)
156 return retval;
157
158 /* OK, This is the point of no return */
159 #ifdef __alpha__
160 SET_AOUT_PERSONALITY(bprm, ex);
161 #else
162 set_personality(PER_LINUX);
163 #endif
164 setup_new_exec(bprm);
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));
172
173 retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
174 if (retval < 0)
175 return retval;
176
177 install_exec_creds(bprm);
178
179 if (N_MAGIC(ex) == OMAGIC) {
180 unsigned long text_addr, map_size;
181 loff_t pos;
182
183 text_addr = N_TXTADDR(ex);
184
185 #ifdef __alpha__
186 pos = fd_offset;
187 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
188 #else
189 pos = 32;
190 map_size = ex.a_text+ex.a_data;
191 #endif
192 error = vm_brk(text_addr & PAGE_MASK, map_size);
193 if (error)
194 return error;
195
196 error = read_code(bprm->file, text_addr, pos,
197 ex.a_text+ex.a_data);
198 if ((signed long)error < 0)
199 return error;
200 } else {
201 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
202 (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
203 {
204 printk(KERN_NOTICE "executable not page aligned\n");
205 }
206
207 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
208 {
209 printk(KERN_WARNING
210 "fd_offset is not page aligned. Please convert program: %pD\n",
211 bprm->file);
212 }
213
214 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
215 error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
216 if (error)
217 return error;
218
219 read_code(bprm->file, N_TXTADDR(ex), fd_offset,
220 ex.a_text + ex.a_data);
221 goto beyond_if;
222 }
223
224 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
225 PROT_READ | PROT_EXEC,
226 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
227 fd_offset);
228
229 if (error != N_TXTADDR(ex))
230 return error;
231
232 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
233 PROT_READ | PROT_WRITE | PROT_EXEC,
234 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
235 fd_offset + ex.a_text);
236 if (error != N_DATADDR(ex))
237 return error;
238 }
239 beyond_if:
240 set_binfmt(&aout_format);
241
242 retval = set_brk(current->mm->start_brk, current->mm->brk);
243 if (retval < 0)
244 return retval;
245
246 current->mm->start_stack =
247 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
248 #ifdef __alpha__
249 regs->gp = ex.a_gpvalue;
250 #endif
251 finalize_exec(bprm);
252 start_thread(regs, ex.a_entry, current->mm->start_stack);
253 return 0;
254 }
255
load_aout_library(struct file * file)256 static int load_aout_library(struct file *file)
257 {
258 struct inode * inode;
259 unsigned long bss, start_addr, len;
260 unsigned long error;
261 int retval;
262 struct exec ex;
263 loff_t pos = 0;
264
265 inode = file_inode(file);
266
267 retval = -ENOEXEC;
268 error = kernel_read(file, &ex, sizeof(ex), &pos);
269 if (error != sizeof(ex))
270 goto out;
271
272 /* We come in here for the regular a.out style of shared libraries */
273 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
274 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
275 i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
276 goto out;
277 }
278
279 /*
280 * Requires a mmap handler. This prevents people from using a.out
281 * as part of an exploit attack against /proc-related vulnerabilities.
282 */
283 if (!file->f_op->mmap)
284 goto out;
285
286 if (N_FLAGS(ex))
287 goto out;
288
289 /* For QMAGIC, the starting address is 0x20 into the page. We mask
290 this off to get the starting address for the page */
291
292 start_addr = ex.a_entry & 0xfffff000;
293
294 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
295 if (printk_ratelimit())
296 {
297 printk(KERN_WARNING
298 "N_TXTOFF is not page aligned. Please convert library: %pD\n",
299 file);
300 }
301 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
302 if (retval)
303 goto out;
304
305 read_code(file, start_addr, N_TXTOFF(ex),
306 ex.a_text + ex.a_data);
307 retval = 0;
308 goto out;
309 }
310 /* Now use mmap to map the library into memory. */
311 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
312 PROT_READ | PROT_WRITE | PROT_EXEC,
313 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
314 N_TXTOFF(ex));
315 retval = error;
316 if (error != start_addr)
317 goto out;
318
319 len = PAGE_ALIGN(ex.a_text + ex.a_data);
320 bss = ex.a_text + ex.a_data + ex.a_bss;
321 if (bss > len) {
322 retval = vm_brk(start_addr + len, bss - len);
323 if (retval)
324 goto out;
325 }
326 retval = 0;
327 out:
328 return retval;
329 }
330
init_aout_binfmt(void)331 static int __init init_aout_binfmt(void)
332 {
333 register_binfmt(&aout_format);
334 return 0;
335 }
336
exit_aout_binfmt(void)337 static void __exit exit_aout_binfmt(void)
338 {
339 unregister_binfmt(&aout_format);
340 }
341
342 core_initcall(init_aout_binfmt);
343 module_exit(exit_aout_binfmt);
344 MODULE_LICENSE("GPL");
345
