binfmt_aout.c

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    1 /*
    2  *  linux/fs/binfmt_aout.c
    3  *
    4  *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
    5  */
    6 
    7 #include <linux/module.h>
    8 
    9 #include <linux/time.h>
   10 #include <linux/kernel.h>
   11 #include <linux/mm.h>
   12 #include <linux/mman.h>
   13 #include <linux/a.out.h>
   14 #include <linux/errno.h>
   15 #include <linux/signal.h>
   16 #include <linux/string.h>
   17 #include <linux/fs.h>
   18 #include <linux/file.h>
   19 #include <linux/stat.h>
   20 #include <linux/fcntl.h>
   21 #include <linux/ptrace.h>
   22 #include <linux/user.h>
   23 #include <linux/binfmts.h>
   24 #include <linux/personality.h>
   25 #include <linux/init.h>
   26 #include <linux/coredump.h>
   27 #include <linux/slab.h>
   28 
   29 #include <asm/uaccess.h>
   30 #include <asm/cacheflush.h>
   31 #include <asm/a.out-core.h>
   32 
   33 static int load_aout_binary(struct linux_binprm *);
   34 static int load_aout_library(struct file*);
   35 
   36 #ifdef CONFIG_COREDUMP
   37 /*
   38  * Routine writes a core dump image in the current directory.
   39  * Currently only a stub-function.
   40  *
   41  * Note that setuid/setgid files won't make a core-dump if the uid/gid
   42  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
   43  * field, which also makes sure the core-dumps won't be recursive if the
   44  * dumping of the process results in another error..
   45  */
   46 static int aout_core_dump(struct coredump_params *cprm)
   47 {
   48         struct file *file = cprm->file;
   49         mm_segment_t fs;
   50         int has_dumped = 0;
   51         void __user *dump_start;
   52         int dump_size;
   53         struct user dump;
   54 #ifdef __alpha__
   55 #       define START_DATA(u)    ((void __user *)u.start_data)
   56 #else
   57 #       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
   58                                  u.start_code))
   59 #endif
   60 #       define START_STACK(u)   ((void __user *)u.start_stack)
   61 
   62         fs = get_fs();
   63         set_fs(KERNEL_DS);
   64         has_dumped = 1;
   65         current->flags |= PF_DUMPCORE;
   66         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
   67         dump.u_ar0 = offsetof(struct user, regs);
   68         dump.signal = cprm->siginfo->si_signo;
   69         aout_dump_thread(cprm->regs, &dump);
   70 
   71 /* If the size of the dump file exceeds the rlimit, then see what would happen
   72    if we wrote the stack, but not the data area.  */
   73         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
   74                 dump.u_dsize = 0;
   75 
   76 /* Make sure we have enough room to write the stack and data areas. */
   77         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
   78                 dump.u_ssize = 0;
   79 
   80 /* make sure we actually have a data and stack area to dump */
   81         set_fs(USER_DS);
   82         if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
   83                 dump.u_dsize = 0;
   84         if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
   85                 dump.u_ssize = 0;
   86 
   87         set_fs(KERNEL_DS);
   88 /* struct user */
   89         if (!dump_write(file, &dump, sizeof(dump)))
   90                 goto end_coredump;
   91 /* Now dump all of the user data.  Include malloced stuff as well */
   92         if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
   93                 goto end_coredump;
   94 /* now we start writing out the user space info */
   95         set_fs(USER_DS);
   96 /* Dump the data area */
   97         if (dump.u_dsize != 0) {
   98                 dump_start = START_DATA(dump);
   99                 dump_size = dump.u_dsize << PAGE_SHIFT;
  100                 if (!dump_write(file, dump_start, dump_size))
  101                         goto end_coredump;
  102         }
  103 /* Now prepare to dump the stack area */
  104         if (dump.u_ssize != 0) {
  105                 dump_start = START_STACK(dump);
  106                 dump_size = dump.u_ssize << PAGE_SHIFT;
  107                 if (!dump_write(file, dump_start, dump_size))
  108                         goto end_coredump;
  109         }
  110 end_coredump:
  111         set_fs(fs);
  112         return has_dumped;
  113 }
  114 #else
  115 #define aout_core_dump NULL
  116 #endif
  117 
  118 static struct linux_binfmt aout_format = {
  119         .module         = THIS_MODULE,
  120         .load_binary    = load_aout_binary,
  121         .load_shlib     = load_aout_library,
  122         .core_dump      = aout_core_dump,
  123         .min_coredump   = PAGE_SIZE
  124 };
  125 
  126 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
  127 
  128 static int set_brk(unsigned long start, unsigned long end)
  129 {
  130         start = PAGE_ALIGN(start);
  131         end = PAGE_ALIGN(end);
  132         if (end > start) {
  133                 unsigned long addr;
  134                 addr = vm_brk(start, end - start);
  135                 if (BAD_ADDR(addr))
  136                         return addr;
  137         }
  138         return 0;
  139 }
  140 
  141 /*
  142  * create_aout_tables() parses the env- and arg-strings in new user
  143  * memory and creates the pointer tables from them, and puts their
  144  * addresses on the "stack", returning the new stack pointer value.
  145  */
  146 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
  147 {
  148         char __user * __user *argv;
  149         char __user * __user *envp;
  150         unsigned long __user *sp;
  151         int argc = bprm->argc;
  152         int envc = bprm->envc;
  153 
  154         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
  155 #ifdef __alpha__
  156 /* whee.. test-programs are so much fun. */
  157         put_user(0, --sp);
  158         put_user(0, --sp);
  159         if (bprm->loader) {
  160                 put_user(0, --sp);
  161                 put_user(1003, --sp);
  162                 put_user(bprm->loader, --sp);
  163                 put_user(1002, --sp);
  164         }
  165         put_user(bprm->exec, --sp);
  166         put_user(1001, --sp);
  167 #endif
  168         sp -= envc+1;
  169         envp = (char __user * __user *) sp;
  170         sp -= argc+1;
  171         argv = (char __user * __user *) sp;
  172 #ifndef __alpha__
  173         put_user((unsigned long) envp,--sp);
  174         put_user((unsigned long) argv,--sp);
  175 #endif
  176         put_user(argc,--sp);
  177         current->mm->arg_start = (unsigned long) p;
  178         while (argc-->0) {
  179                 char c;
  180                 put_user(p,argv++);
  181                 do {
  182                         get_user(c,p++);
  183                 } while (c);
  184         }
  185         put_user(NULL,argv);
  186         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
  187         while (envc-->0) {
  188                 char c;
  189                 put_user(p,envp++);
  190                 do {
  191                         get_user(c,p++);
  192                 } while (c);
  193         }
  194         put_user(NULL,envp);
  195         current->mm->env_end = (unsigned long) p;
  196         return sp;
  197 }
  198 
  199 /*
  200  * These are the functions used to load a.out style executables and shared
  201  * libraries.  There is no binary dependent code anywhere else.
  202  */
  203 
  204 static int load_aout_binary(struct linux_binprm * bprm)
  205 {
  206         struct pt_regs *regs = current_pt_regs();
  207         struct exec ex;
  208         unsigned long error;
  209         unsigned long fd_offset;
  210         unsigned long rlim;
  211         int retval;
  212 
  213         ex = *((struct exec *) bprm->buf);              /* exec-header */
  214         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
  215              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
  216             N_TRSIZE(ex) || N_DRSIZE(ex) ||
  217             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
  218                 return -ENOEXEC;
  219         }
  220 
  221         /*
  222          * Requires a mmap handler. This prevents people from using a.out
  223          * as part of an exploit attack against /proc-related vulnerabilities.
  224          */
  225         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
  226                 return -ENOEXEC;
  227 
  228         fd_offset = N_TXTOFF(ex);
  229 
  230         /* Check initial limits. This avoids letting people circumvent
  231          * size limits imposed on them by creating programs with large
  232          * arrays in the data or bss.
  233          */
  234         rlim = rlimit(RLIMIT_DATA);
  235         if (rlim >= RLIM_INFINITY)
  236                 rlim = ~0;
  237         if (ex.a_data + ex.a_bss > rlim)
  238                 return -ENOMEM;
  239 
  240         /* Flush all traces of the currently running executable */
  241         retval = flush_old_exec(bprm);
  242         if (retval)
  243                 return retval;
  244 
  245         /* OK, This is the point of no return */
  246 #ifdef __alpha__
  247         SET_AOUT_PERSONALITY(bprm, ex);
  248 #else
  249         set_personality(PER_LINUX);
  250 #endif
  251         setup_new_exec(bprm);
  252 
  253         current->mm->end_code = ex.a_text +
  254                 (current->mm->start_code = N_TXTADDR(ex));
  255         current->mm->end_data = ex.a_data +
  256                 (current->mm->start_data = N_DATADDR(ex));
  257         current->mm->brk = ex.a_bss +
  258                 (current->mm->start_brk = N_BSSADDR(ex));
  259         current->mm->free_area_cache = current->mm->mmap_base;
  260         current->mm->cached_hole_size = 0;
  261 
  262         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
  263         if (retval < 0) {
  264                 /* Someone check-me: is this error path enough? */
  265                 send_sig(SIGKILL, current, 0);
  266                 return retval;
  267         }
  268 
  269         install_exec_creds(bprm);
  270 
  271         if (N_MAGIC(ex) == OMAGIC) {
  272                 unsigned long text_addr, map_size;
  273                 loff_t pos;
  274 
  275                 text_addr = N_TXTADDR(ex);
  276 
  277 #ifdef __alpha__
  278                 pos = fd_offset;
  279                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
  280 #else
  281                 pos = 32;
  282                 map_size = ex.a_text+ex.a_data;
  283 #endif
  284                 error = vm_brk(text_addr & PAGE_MASK, map_size);
  285                 if (error != (text_addr & PAGE_MASK)) {
  286                         send_sig(SIGKILL, current, 0);
  287                         return error;
  288                 }
  289 
  290                 error = bprm->file->f_op->read(bprm->file,
  291                           (char __user *)text_addr,
  292                           ex.a_text+ex.a_data, &pos);
  293                 if ((signed long)error < 0) {
  294                         send_sig(SIGKILL, current, 0);
  295                         return error;
  296                 }
  297                          
  298                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
  299         } else {
  300                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
  301                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
  302                 {
  303                         printk(KERN_NOTICE "executable not page aligned\n");
  304                 }
  305 
  306                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
  307                 {
  308                         printk(KERN_WARNING 
  309                                "fd_offset is not page aligned. Please convert program: %s\n",
  310                                bprm->file->f_path.dentry->d_name.name);
  311                 }
  312 
  313                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
  314                         loff_t pos = fd_offset;
  315                         vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
  316                         bprm->file->f_op->read(bprm->file,
  317                                         (char __user *)N_TXTADDR(ex),
  318                                         ex.a_text+ex.a_data, &pos);
  319                         flush_icache_range((unsigned long) N_TXTADDR(ex),
  320                                            (unsigned long) N_TXTADDR(ex) +
  321                                            ex.a_text+ex.a_data);
  322                         goto beyond_if;
  323                 }
  324 
  325                 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
  326                         PROT_READ | PROT_EXEC,
  327                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
  328                         fd_offset);
  329 
  330                 if (error != N_TXTADDR(ex)) {
  331                         send_sig(SIGKILL, current, 0);
  332                         return error;
  333                 }
  334 
  335                 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
  336                                 PROT_READ | PROT_WRITE | PROT_EXEC,
  337                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
  338                                 fd_offset + ex.a_text);
  339                 if (error != N_DATADDR(ex)) {
  340                         send_sig(SIGKILL, current, 0);
  341                         return error;
  342                 }
  343         }
  344 beyond_if:
  345         set_binfmt(&aout_format);
  346 
  347         retval = set_brk(current->mm->start_brk, current->mm->brk);
  348         if (retval < 0) {
  349                 send_sig(SIGKILL, current, 0);
  350                 return retval;
  351         }
  352 
  353         current->mm->start_stack =
  354                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
  355 #ifdef __alpha__
  356         regs->gp = ex.a_gpvalue;
  357 #endif
  358         start_thread(regs, ex.a_entry, current->mm->start_stack);
  359         return 0;
  360 }
  361 
  362 static int load_aout_library(struct file *file)
  363 {
  364         struct inode * inode;
  365         unsigned long bss, start_addr, len;
  366         unsigned long error;
  367         int retval;
  368         struct exec ex;
  369 
  370         inode = file->f_path.dentry->d_inode;
  371 
  372         retval = -ENOEXEC;
  373         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
  374         if (error != sizeof(ex))
  375                 goto out;
  376 
  377         /* We come in here for the regular a.out style of shared libraries */
  378         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
  379             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
  380             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
  381                 goto out;
  382         }
  383 
  384         /*
  385          * Requires a mmap handler. This prevents people from using a.out
  386          * as part of an exploit attack against /proc-related vulnerabilities.
  387          */
  388         if (!file->f_op || !file->f_op->mmap)
  389                 goto out;
  390 
  391         if (N_FLAGS(ex))
  392                 goto out;
  393 
  394         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
  395            this off to get the starting address for the page */
  396 
  397         start_addr =  ex.a_entry & 0xfffff000;
  398 
  399         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
  400                 loff_t pos = N_TXTOFF(ex);
  401 
  402                 if (printk_ratelimit())
  403                 {
  404                         printk(KERN_WARNING 
  405                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
  406                                file->f_path.dentry->d_name.name);
  407                 }
  408                 vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
  409                 
  410                 file->f_op->read(file, (char __user *)start_addr,
  411                         ex.a_text + ex.a_data, &pos);
  412                 flush_icache_range((unsigned long) start_addr,
  413                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
  414 
  415                 retval = 0;
  416                 goto out;
  417         }
  418         /* Now use mmap to map the library into memory. */
  419         error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
  420                         PROT_READ | PROT_WRITE | PROT_EXEC,
  421                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
  422                         N_TXTOFF(ex));
  423         retval = error;
  424         if (error != start_addr)
  425                 goto out;
  426 
  427         len = PAGE_ALIGN(ex.a_text + ex.a_data);
  428         bss = ex.a_text + ex.a_data + ex.a_bss;
  429         if (bss > len) {
  430                 error = vm_brk(start_addr + len, bss - len);
  431                 retval = error;
  432                 if (error != start_addr + len)
  433                         goto out;
  434         }
  435         retval = 0;
  436 out:
  437         return retval;
  438 }
  439 
  440 static int __init init_aout_binfmt(void)
  441 {
  442         register_binfmt(&aout_format);
  443         return 0;
  444 }
  445 
  446 static void __exit exit_aout_binfmt(void)
  447 {
  448         unregister_binfmt(&aout_format);
  449 }
  450 
  451 core_initcall(init_aout_binfmt);
  452 module_exit(exit_aout_binfmt);
  453 MODULE_LICENSE("GPL");
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FreeBSD/Linux Kernel Cross Reference sys/fs/binfmt_aout.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/binfmt_aout.c
