arch/x86/ia32/ia32_aout.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  a.out loader for x86-64
   4  *
   5  *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
   6  *  Hacked together by Andi Kleen
   7  */
   8
   9 #include <linux/module.h>
  10
  11 #include <linux/time.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mm.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>
  19 #include <linux/fs.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>
  31
  32 #include <linux/uaccess.h>
  33 #include <asm/pgalloc.h>
  34 #include <asm/cacheflush.h>
  35 #include <asm/user32.h>
  36 #include <asm/ia32.h>
  37
  38 #undef WARN_OLD
  39
  40 static int load_aout_binary(struct linux_binprm *);
  41 static int load_aout_library(struct file *);
  42
  43 static struct linux_binfmt aout_format = {
  44         .module         = THIS_MODULE,
  45         .load_binary    = load_aout_binary,
  46         .load_shlib     = load_aout_library,
  47 };
  48
  49 static int set_brk(unsigned long start, unsigned long end)
  50 {
  51         start = PAGE_ALIGN(start);
  52         end = PAGE_ALIGN(end);
  53         if (end <= start)
  54                 return 0;
  55         return vm_brk(start, end - start);
  56 }
  57
  58
  59 /*
  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.
  63  */
  64 static u32 __user *create_aout_tables(char __user *p, struct linux_binprm *bprm)
  65 {
  66         u32 __user *argv, *envp, *sp;
  67         int argc = bprm->argc, envc = bprm->envc;
  68
  69         sp = (u32 __user *) ((-(unsigned long)sizeof(u32)) & (unsigned long) p);
  70         sp -= envc+1;
  71         envp = sp;
  72         sp -= argc+1;
  73         argv = sp;
  74         put_user((unsigned long) envp, --sp);
  75         put_user((unsigned long) argv, --sp);
  76         put_user(argc, --sp);
  77         current->mm->arg_start = (unsigned long) p;
  78         while (argc-- > 0) {
  79                 char c;
  80
  81                 put_user((u32)(unsigned long)p, argv++);
  82                 do {
  83                         get_user(c, p++);
  84                 } while (c);
  85         }
  86         put_user(0, argv);
  87         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
  88         while (envc-- > 0) {
  89                 char c;
  90
  91                 put_user((u32)(unsigned long)p, envp++);
  92                 do {
  93                         get_user(c, p++);
  94                 } while (c);
  95         }
  96         put_user(0, envp);
  97         current->mm->env_end = (unsigned long) p;
  98         return sp;
  99 }
 100
 101 /*
 102  * These are the functions used to load a.out style executables and shared
 103  * libraries.  There is no binary dependent code anywhere else.
 104  */
 105 static int load_aout_binary(struct linux_binprm *bprm)
 106 {
 107         unsigned long error, fd_offset, rlim;
 108         struct pt_regs *regs = current_pt_regs();
 109         struct exec ex;
 110         int retval;
 111
 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)) {
 118                 return -ENOEXEC;
 119         }
 120
 121         fd_offset = N_TXTOFF(ex);
 122
 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.
 126          */
 127         rlim = rlimit(RLIMIT_DATA);
 128         if (rlim >= RLIM_INFINITY)
 129                 rlim = ~0;
 130         if (ex.a_data + ex.a_bss > rlim)
 131                 return -ENOMEM;
 132
 133         /* Flush all traces of the currently running executable */
 134         retval = flush_old_exec(bprm);
 135         if (retval)
 136                 return retval;
 137
 138         /* OK, This is the point of no return */
 139         set_personality(PER_LINUX);
 140         set_personality_ia32(false);
 141
 142         setup_new_exec(bprm);
 143
 144         regs->cs = __USER32_CS;
 145         regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
 146                 regs->r13 = regs->r14 = regs->r15 = 0;
 147
 148         current->mm->end_code = ex.a_text +
 149                 (current->mm->start_code = N_TXTADDR(ex));
 150         current->mm->end_data = ex.a_data +
 151                 (current->mm->start_data = N_DATADDR(ex));
 152         current->mm->brk = ex.a_bss +
 153                 (current->mm->start_brk = N_BSSADDR(ex));
 154
 155         retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
 156         if (retval < 0)
 157                 return retval;
 158
 159         install_exec_creds(bprm);
 160
 161         if (N_MAGIC(ex) == OMAGIC) {
 162                 unsigned long text_addr, map_size;
 163
 164                 text_addr = N_TXTADDR(ex);
 165                 map_size = ex.a_text+ex.a_data;
 166
 167                 error = vm_brk(text_addr & PAGE_MASK, map_size);
 168
 169                 if (error)
 170                         return error;
 171
 172                 error = read_code(bprm->file, text_addr, 32,
 173                                   ex.a_text + ex.a_data);
 174                 if ((signed long)error < 0)
 175                         return error;
 176         } else {
 177 #ifdef WARN_OLD
 178                 static unsigned long error_time, error_time2;
 179                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
 180                     (N_MAGIC(ex) != NMAGIC) &&
 181                                 time_after(jiffies, error_time2 + 5*HZ)) {
 182                         printk(KERN_NOTICE "executable not page aligned\n");
 183                         error_time2 = jiffies;
 184                 }
 185
 186                 if ((fd_offset & ~PAGE_MASK) != 0 &&
 187                             time_after(jiffies, error_time + 5*HZ)) {
 188                         printk(KERN_WARNING
 189                                "fd_offset is not page aligned. Please convert "
 190                                "program: %pD\n",
 191                                bprm->file);
 192                         error_time = jiffies;
 193                 }
 194 #endif
 195
 196                 if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
 197                         error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
 198                         if (error)
 199                                 return error;
 200
 201                         read_code(bprm->file, N_TXTADDR(ex), fd_offset,
 202                                         ex.a_text+ex.a_data);
 203                         goto beyond_if;
 204                 }
 205
 206                 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
 207                                 PROT_READ | PROT_EXEC,
 208                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
 209                                 MAP_EXECUTABLE | MAP_32BIT,
 210                                 fd_offset);
 211
 212                 if (error != N_TXTADDR(ex))
 213                         return error;
 214
 215                 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
 216                                 PROT_READ | PROT_WRITE | PROT_EXEC,
 217                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
 218                                 MAP_EXECUTABLE | MAP_32BIT,
 219                                 fd_offset + ex.a_text);
 220                 if (error != N_DATADDR(ex))
 221                         return error;
 222         }
 223
 224 beyond_if:
 225         error = set_brk(current->mm->start_brk, current->mm->brk);
 226         if (error)
 227                 return error;
 228
 229         set_binfmt(&aout_format);
 230
 231         current->mm->start_stack =
 232                 (unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
 233         /* start thread */
 234         loadsegment(fs, 0);
 235         loadsegment(ds, __USER32_DS);
 236         loadsegment(es, __USER32_DS);
 237         load_gs_index(0);
 238         (regs)->ip = ex.a_entry;
 239         (regs)->sp = current->mm->start_stack;
 240         (regs)->flags = 0x200;
 241         (regs)->cs = __USER32_CS;
 242         (regs)->ss = __USER32_DS;
 243         regs->r8 = regs->r9 = regs->r10 = regs->r11 =
 244         regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
 245         set_fs(USER_DS);
 246         return 0;
 247 }
 248
 249 static int load_aout_library(struct file *file)
 250 {
 251         unsigned long bss, start_addr, len, error;
 252         int retval;
 253         struct exec ex;
 254         loff_t pos = 0;
 255
 256         retval = -ENOEXEC;
 257         error = kernel_read(file, &ex, sizeof(ex), &pos);
 258         if (error != sizeof(ex))
 259                 goto out;
 260
 261         /* We come in here for the regular a.out style of shared libraries */
 262         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
 263             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
 264             i_size_read(file_inode(file)) <
 265             ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
 266                 goto out;
 267         }
 268
 269         if (N_FLAGS(ex))
 270                 goto out;
 271
 272         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
 273            this off to get the starting address for the page */
 274
 275         start_addr =  ex.a_entry & 0xfffff000;
 276
 277         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
 278 #ifdef WARN_OLD
 279                 static unsigned long error_time;
 280                 if (time_after(jiffies, error_time + 5*HZ)) {
 281                         printk(KERN_WARNING
 282                                "N_TXTOFF is not page aligned. Please convert "
 283                                "library: %pD\n",
 284                                file);
 285                         error_time = jiffies;
 286                 }
 287 #endif
 288                 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
 289                 if (retval)
 290                         goto out;
 291
 292                 read_code(file, start_addr, N_TXTOFF(ex),
 293                           ex.a_text + ex.a_data);
 294                 retval = 0;
 295                 goto out;
 296         }
 297         /* Now use mmap to map the library into memory. */
 298         error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
 299                         PROT_READ | PROT_WRITE | PROT_EXEC,
 300                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_32BIT,
 301                         N_TXTOFF(ex));
 302         retval = error;
 303         if (error != start_addr)
 304                 goto out;
 305
 306         len = PAGE_ALIGN(ex.a_text + ex.a_data);
 307         bss = ex.a_text + ex.a_data + ex.a_bss;
 308         if (bss > len) {
 309                 retval = vm_brk(start_addr + len, bss - len);
 310                 if (retval)
 311                         goto out;
 312         }
 313         retval = 0;
 314 out:
 315         return retval;
 316 }
 317
 318 static int __init init_aout_binfmt(void)
 319 {
 320         register_binfmt(&aout_format);
 321         return 0;
 322 }
 323
 324 static void __exit exit_aout_binfmt(void)
 325 {
 326         unregister_binfmt(&aout_format);
 327 }
 328
 329 module_init(init_aout_binfmt);
 330 module_exit(exit_aout_binfmt);
 331 MODULE_LICENSE("GPL");