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/pgalloc.h>
34 #include <asm/cacheflush.h>
35 #include <asm/user32.h>
40 static int load_aout_binary(struct linux_binprm *);
41 static int load_aout_library(struct file *);
43 static struct linux_binfmt aout_format = {
44 .module = THIS_MODULE,
45 .load_binary = load_aout_binary,
46 .load_shlib = load_aout_library,
49 static int set_brk(unsigned long start, unsigned long end)
51 start = PAGE_ALIGN(start);
52 end = PAGE_ALIGN(end);
55 return vm_brk(start, end - start);
60 * create_aout_tables() parses the env- and arg-strings in new user
61 * memory and creates the pointer tables from them, and puts their
62 * addresses on the "stack", returning the new stack pointer value.
64 static u32 __user *create_aout_tables(char __user *p, struct linux_binprm *bprm)
66 u32 __user *argv, *envp, *sp;
67 int argc = bprm->argc, envc = bprm->envc;
69 sp = (u32 __user *) ((-(unsigned long)sizeof(u32)) & (unsigned long) p);
74 put_user((unsigned long) envp, --sp);
75 put_user((unsigned long) argv, --sp);
77 current->mm->arg_start = (unsigned long) p;
81 put_user((u32)(unsigned long)p, argv++);
87 current->mm->arg_end = current->mm->env_start = (unsigned long) p;
91 put_user((u32)(unsigned long)p, envp++);
97 current->mm->env_end = (unsigned long) p;
102 * These are the functions used to load a.out style executables and shared
103 * libraries. There is no binary dependent code anywhere else.
105 static int load_aout_binary(struct linux_binprm *bprm)
107 unsigned long error, fd_offset, rlim;
108 struct pt_regs *regs = current_pt_regs();
112 ex = *((struct exec *) bprm->buf); /* exec-header */
113 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
114 N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
115 N_TRSIZE(ex) || N_DRSIZE(ex) ||
116 i_size_read(file_inode(bprm->file)) <
117 ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
121 fd_offset = N_TXTOFF(ex);
123 /* Check initial limits. This avoids letting people circumvent
124 * size limits imposed on them by creating programs with large
125 * arrays in the data or bss.
127 rlim = rlimit(RLIMIT_DATA);
128 if (rlim >= RLIM_INFINITY)
130 if (ex.a_data + ex.a_bss > rlim)
133 /* Flush all traces of the currently running executable */
134 retval = flush_old_exec(bprm);
138 /* OK, This is the point of no return */
139 set_personality(PER_LINUX);
140 set_personality_ia32(false);
142 setup_new_exec(bprm);
143 install_exec_creds(bprm);
145 regs->cs = __USER32_CS;
146 regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
147 regs->r13 = regs->r14 = regs->r15 = 0;
149 current->mm->end_code = ex.a_text +
150 (current->mm->start_code = N_TXTADDR(ex));
151 current->mm->end_data = ex.a_data +
152 (current->mm->start_data = N_DATADDR(ex));
153 current->mm->brk = ex.a_bss +
154 (current->mm->start_brk = N_BSSADDR(ex));
156 retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
160 if (N_MAGIC(ex) == OMAGIC) {
161 unsigned long text_addr, map_size;
163 text_addr = N_TXTADDR(ex);
164 map_size = ex.a_text+ex.a_data;
166 error = vm_brk(text_addr & PAGE_MASK, map_size);
171 error = read_code(bprm->file, text_addr, 32,
172 ex.a_text + ex.a_data);
173 if ((signed long)error < 0)
177 static unsigned long error_time, error_time2;
178 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
179 (N_MAGIC(ex) != NMAGIC) &&
180 time_after(jiffies, error_time2 + 5*HZ)) {
181 printk(KERN_NOTICE "executable not page aligned\n");
182 error_time2 = jiffies;
185 if ((fd_offset & ~PAGE_MASK) != 0 &&
186 time_after(jiffies, error_time + 5*HZ)) {
188 "fd_offset is not page aligned. Please convert "
191 error_time = jiffies;
195 if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
196 error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
200 read_code(bprm->file, N_TXTADDR(ex), fd_offset,
201 ex.a_text+ex.a_data);
205 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
206 PROT_READ | PROT_EXEC,
207 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
208 MAP_EXECUTABLE | MAP_32BIT,
211 if (error != N_TXTADDR(ex))
214 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
215 PROT_READ | PROT_WRITE | PROT_EXEC,
216 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
217 MAP_EXECUTABLE | MAP_32BIT,
218 fd_offset + ex.a_text);
219 if (error != N_DATADDR(ex))
224 error = set_brk(current->mm->start_brk, current->mm->brk);
228 set_binfmt(&aout_format);
230 current->mm->start_stack =
231 (unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
234 loadsegment(ds, __USER32_DS);
235 loadsegment(es, __USER32_DS);
237 (regs)->ip = ex.a_entry;
238 (regs)->sp = current->mm->start_stack;
239 (regs)->flags = 0x200;
240 (regs)->cs = __USER32_CS;
241 (regs)->ss = __USER32_DS;
242 regs->r8 = regs->r9 = regs->r10 = regs->r11 =
243 regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
248 static int load_aout_library(struct file *file)
250 unsigned long bss, start_addr, len, error;
256 error = kernel_read(file, &ex, sizeof(ex), &pos);
257 if (error != sizeof(ex))
260 /* We come in here for the regular a.out style of shared libraries */
261 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
262 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
263 i_size_read(file_inode(file)) <
264 ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
271 /* For QMAGIC, the starting address is 0x20 into the page. We mask
272 this off to get the starting address for the page */
274 start_addr = ex.a_entry & 0xfffff000;
276 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
278 static unsigned long error_time;
279 if (time_after(jiffies, error_time + 5*HZ)) {
281 "N_TXTOFF is not page aligned. Please convert "
284 error_time = jiffies;
287 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
291 read_code(file, start_addr, N_TXTOFF(ex),
292 ex.a_text + ex.a_data);
296 /* Now use mmap to map the library into memory. */
297 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
298 PROT_READ | PROT_WRITE | PROT_EXEC,
299 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_32BIT,
302 if (error != start_addr)
305 len = PAGE_ALIGN(ex.a_text + ex.a_data);
306 bss = ex.a_text + ex.a_data + ex.a_bss;
308 retval = vm_brk(start_addr + len, bss - len);
317 static int __init init_aout_binfmt(void)
319 register_binfmt(&aout_format);
323 static void __exit exit_aout_binfmt(void)
325 unregister_binfmt(&aout_format);
328 module_init(init_aout_binfmt);
329 module_exit(exit_aout_binfmt);
330 MODULE_LICENSE("GPL");