1 // SPDX-License-Identifier: GPL-2.0-only
3 * a.out loader for x86-64
5 * Copyright (C) 1991, 1992, 1996 Linus Torvalds
6 * Hacked together by Andi Kleen
9 #include <linux/module.h>
11 #include <linux/time.h>
12 #include <linux/kernel.h>
14 #include <linux/mman.h>
15 #include <linux/a.out.h>
16 #include <linux/errno.h>
17 #include <linux/signal.h>
18 #include <linux/string.h>
20 #include <linux/file.h>
21 #include <linux/stat.h>
22 #include <linux/fcntl.h>
23 #include <linux/ptrace.h>
24 #include <linux/user.h>
25 #include <linux/binfmts.h>
26 #include <linux/personality.h>
27 #include <linux/init.h>
28 #include <linux/jiffies.h>
29 #include <linux/perf_event.h>
30 #include <linux/sched/task_stack.h>
32 #include <linux/uaccess.h>
33 #include <asm/cacheflush.h>
34 #include <asm/user32.h>
39 static int load_aout_binary(struct linux_binprm *);
40 static int load_aout_library(struct file *);
42 static struct linux_binfmt aout_format = {
43 .module = THIS_MODULE,
44 .load_binary = load_aout_binary,
45 .load_shlib = load_aout_library,
48 static int set_brk(unsigned long start, unsigned long end)
50 start = PAGE_ALIGN(start);
51 end = PAGE_ALIGN(end);
54 return vm_brk(start, end - start);
59 * create_aout_tables() parses the env- and arg-strings in new user
60 * memory and creates the pointer tables from them, and puts their
61 * addresses on the "stack", returning the new stack pointer value.
63 static u32 __user *create_aout_tables(char __user *p, struct linux_binprm *bprm)
65 u32 __user *argv, *envp, *sp;
66 int argc = bprm->argc, envc = bprm->envc;
68 sp = (u32 __user *) ((-(unsigned long)sizeof(u32)) & (unsigned long) p);
73 put_user((unsigned long) envp, --sp);
74 put_user((unsigned long) argv, --sp);
76 current->mm->arg_start = (unsigned long) p;
80 put_user((u32)(unsigned long)p, argv++);
86 current->mm->arg_end = current->mm->env_start = (unsigned long) p;
90 put_user((u32)(unsigned long)p, envp++);
96 current->mm->env_end = (unsigned long) p;
101 * These are the functions used to load a.out style executables and shared
102 * libraries. There is no binary dependent code anywhere else.
104 static int load_aout_binary(struct linux_binprm *bprm)
106 unsigned long error, fd_offset, rlim;
107 struct pt_regs *regs = current_pt_regs();
111 ex = *((struct exec *) bprm->buf); /* exec-header */
112 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
113 N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
114 N_TRSIZE(ex) || N_DRSIZE(ex) ||
115 i_size_read(file_inode(bprm->file)) <
116 ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
120 fd_offset = N_TXTOFF(ex);
122 /* Check initial limits. This avoids letting people circumvent
123 * size limits imposed on them by creating programs with large
124 * arrays in the data or bss.
126 rlim = rlimit(RLIMIT_DATA);
127 if (rlim >= RLIM_INFINITY)
129 if (ex.a_data + ex.a_bss > rlim)
132 /* Flush all traces of the currently running executable */
133 retval = begin_new_exec(bprm);
137 /* OK, This is the point of no return */
138 set_personality(PER_LINUX);
139 set_personality_ia32(false);
141 setup_new_exec(bprm);
143 regs->cs = __USER32_CS;
144 regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
145 regs->r13 = regs->r14 = regs->r15 = 0;
147 current->mm->end_code = ex.a_text +
148 (current->mm->start_code = N_TXTADDR(ex));
149 current->mm->end_data = ex.a_data +
150 (current->mm->start_data = N_DATADDR(ex));
151 current->mm->brk = ex.a_bss +
152 (current->mm->start_brk = N_BSSADDR(ex));
154 retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
158 if (N_MAGIC(ex) == OMAGIC) {
159 unsigned long text_addr, map_size;
161 text_addr = N_TXTADDR(ex);
162 map_size = ex.a_text+ex.a_data;
164 error = vm_brk(text_addr & PAGE_MASK, map_size);
169 error = read_code(bprm->file, text_addr, 32,
170 ex.a_text + ex.a_data);
171 if ((signed long)error < 0)
175 static unsigned long error_time, error_time2;
176 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
177 (N_MAGIC(ex) != NMAGIC) &&
178 time_after(jiffies, error_time2 + 5*HZ)) {
179 printk(KERN_NOTICE "executable not page aligned\n");
180 error_time2 = jiffies;
183 if ((fd_offset & ~PAGE_MASK) != 0 &&
184 time_after(jiffies, error_time + 5*HZ)) {
186 "fd_offset is not page aligned. Please convert "
189 error_time = jiffies;
193 if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
194 error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
198 read_code(bprm->file, N_TXTADDR(ex), fd_offset,
199 ex.a_text+ex.a_data);
203 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
204 PROT_READ | PROT_EXEC,
205 MAP_FIXED | MAP_PRIVATE | MAP_32BIT,
208 if (error != N_TXTADDR(ex))
211 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
212 PROT_READ | PROT_WRITE | PROT_EXEC,
213 MAP_FIXED | MAP_PRIVATE | MAP_32BIT,
214 fd_offset + ex.a_text);
215 if (error != N_DATADDR(ex))
220 error = set_brk(current->mm->start_brk, current->mm->brk);
224 set_binfmt(&aout_format);
226 current->mm->start_stack =
227 (unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
230 loadsegment(ds, __USER32_DS);
231 loadsegment(es, __USER32_DS);
233 (regs)->ip = ex.a_entry;
234 (regs)->sp = current->mm->start_stack;
235 (regs)->flags = 0x200;
236 (regs)->cs = __USER32_CS;
237 (regs)->ss = __USER32_DS;
238 regs->r8 = regs->r9 = regs->r10 = regs->r11 =
239 regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
243 static int load_aout_library(struct file *file)
245 unsigned long bss, start_addr, len, error;
251 error = kernel_read(file, &ex, sizeof(ex), &pos);
252 if (error != sizeof(ex))
255 /* We come in here for the regular a.out style of shared libraries */
256 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
257 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
258 i_size_read(file_inode(file)) <
259 ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
266 /* For QMAGIC, the starting address is 0x20 into the page. We mask
267 this off to get the starting address for the page */
269 start_addr = ex.a_entry & 0xfffff000;
271 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
273 static unsigned long error_time;
274 if (time_after(jiffies, error_time + 5*HZ)) {
276 "N_TXTOFF is not page aligned. Please convert "
279 error_time = jiffies;
282 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
286 read_code(file, start_addr, N_TXTOFF(ex),
287 ex.a_text + ex.a_data);
291 /* Now use mmap to map the library into memory. */
292 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
293 PROT_READ | PROT_WRITE | PROT_EXEC,
294 MAP_FIXED | MAP_PRIVATE | MAP_32BIT,
297 if (error != start_addr)
300 len = PAGE_ALIGN(ex.a_text + ex.a_data);
301 bss = ex.a_text + ex.a_data + ex.a_bss;
303 retval = vm_brk(start_addr + len, bss - len);
312 static int __init init_aout_binfmt(void)
314 register_binfmt(&aout_format);
318 static void __exit exit_aout_binfmt(void)
320 unregister_binfmt(&aout_format);
323 module_init(init_aout_binfmt);
324 module_exit(exit_aout_binfmt);
325 MODULE_LICENSE("GPL");