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 = begin_new_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; 176 177 178 if (N_MAGIC(ex) == OMAGIC) { 179 unsigned long text_addr, map_size; 180 loff_t pos; 181 182 text_addr = N_TXTADDR(ex); 183 184 #ifdef __alpha__ 185 pos = fd_offset; 186 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1; 187 #else 188 pos = 32; 189 map_size = ex.a_text+ex.a_data; 190 #endif 191 error = vm_brk(text_addr & PAGE_MASK, map_size); 192 if (error) 193 return error; 194 195 error = read_code(bprm->file, text_addr, pos, 196 ex.a_text+ex.a_data); 197 if ((signed long)error < 0) 198 return error; 199 } else { 200 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) && 201 (N_MAGIC(ex) != NMAGIC) && printk_ratelimit()) 202 { 203 printk(KERN_NOTICE "executable not page aligned\n"); 204 } 205 206 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit()) 207 { 208 printk(KERN_WARNING 209 "fd_offset is not page aligned. Please convert program: %pD\n", 210 bprm->file); 211 } 212 213 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) { 214 error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data); 215 if (error) 216 return error; 217 218 read_code(bprm->file, N_TXTADDR(ex), fd_offset, 219 ex.a_text + ex.a_data); 220 goto beyond_if; 221 } 222 223 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text, 224 PROT_READ | PROT_EXEC, 225 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE, 226 fd_offset); 227 228 if (error != N_TXTADDR(ex)) 229 return error; 230 231 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data, 232 PROT_READ | PROT_WRITE | PROT_EXEC, 233 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE, 234 fd_offset + ex.a_text); 235 if (error != N_DATADDR(ex)) 236 return error; 237 } 238 beyond_if: 239 set_binfmt(&aout_format); 240 241 retval = set_brk(current->mm->start_brk, current->mm->brk); 242 if (retval < 0) 243 return retval; 244 245 current->mm->start_stack = 246 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm); 247 #ifdef __alpha__ 248 regs->gp = ex.a_gpvalue; 249 #endif 250 finalize_exec(bprm); 251 start_thread(regs, ex.a_entry, current->mm->start_stack); 252 return 0; 253 } 254 load_aout_library(struct file * file)255 static int load_aout_library(struct file *file) 256 { 257 struct inode * inode; 258 unsigned long bss, start_addr, len; 259 unsigned long error; 260 int retval; 261 struct exec ex; 262 loff_t pos = 0; 263 264 inode = file_inode(file); 265 266 retval = -ENOEXEC; 267 error = kernel_read(file, &ex, sizeof(ex), &pos); 268 if (error != sizeof(ex)) 269 goto out; 270 271 /* We come in here for the regular a.out style of shared libraries */ 272 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) || 273 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) || 274 i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) { 275 goto out; 276 } 277 278 /* 279 * Requires a mmap handler. This prevents people from using a.out 280 * as part of an exploit attack against /proc-related vulnerabilities. 281 */ 282 if (!file->f_op->mmap) 283 goto out; 284 285 if (N_FLAGS(ex)) 286 goto out; 287 288 /* For QMAGIC, the starting address is 0x20 into the page. We mask 289 this off to get the starting address for the page */ 290 291 start_addr = ex.a_entry & 0xfffff000; 292 293 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) { 294 if (printk_ratelimit()) 295 { 296 printk(KERN_WARNING 297 "N_TXTOFF is not page aligned. Please convert library: %pD\n", 298 file); 299 } 300 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss); 301 if (retval) 302 goto out; 303 304 read_code(file, start_addr, N_TXTOFF(ex), 305 ex.a_text + ex.a_data); 306 retval = 0; 307 goto out; 308 } 309 /* Now use mmap to map the library into memory. */ 310 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data, 311 PROT_READ | PROT_WRITE | PROT_EXEC, 312 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE, 313 N_TXTOFF(ex)); 314 retval = error; 315 if (error != start_addr) 316 goto out; 317 318 len = PAGE_ALIGN(ex.a_text + ex.a_data); 319 bss = ex.a_text + ex.a_data + ex.a_bss; 320 if (bss > len) { 321 retval = vm_brk(start_addr + len, bss - len); 322 if (retval) 323 goto out; 324 } 325 retval = 0; 326 out: 327 return retval; 328 } 329 init_aout_binfmt(void)330 static int __init init_aout_binfmt(void) 331 { 332 register_binfmt(&aout_format); 333 return 0; 334 } 335 exit_aout_binfmt(void)336 static void __exit exit_aout_binfmt(void) 337 { 338 unregister_binfmt(&aout_format); 339 } 340 341 core_initcall(init_aout_binfmt); 342 module_exit(exit_aout_binfmt); 343 MODULE_LICENSE("GPL"); 344