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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 | ||
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 | */ | |
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 | ||
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 | ||
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 | ||
331 | static int __init init_aout_binfmt(void) | |
332 | { | |
333 | register_binfmt(&aout_format); | |
334 | return 0; | |
335 | } | |
336 | ||
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"); |