Root/fs/binfmt_aout.c

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/slab.h>
24#include <linux/binfmts.h>
25#include <linux/personality.h>
26#include <linux/init.h>
27
28#include <asm/system.h>
29#include <asm/uaccess.h>
30#include <asm/cacheflush.h>
31#include <asm/a.out-core.h>
32
33static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
34static int load_aout_library(struct file*);
35static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
36
37static struct linux_binfmt aout_format = {
38    .module = THIS_MODULE,
39    .load_binary = load_aout_binary,
40    .load_shlib = load_aout_library,
41    .core_dump = aout_core_dump,
42    .min_coredump = PAGE_SIZE
43};
44
45#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
46
47static int set_brk(unsigned long start, unsigned long end)
48{
49    start = PAGE_ALIGN(start);
50    end = PAGE_ALIGN(end);
51    if (end > start) {
52        unsigned long addr;
53        down_write(&current->mm->mmap_sem);
54        addr = do_brk(start, end - start);
55        up_write(&current->mm->mmap_sem);
56        if (BAD_ADDR(addr))
57            return addr;
58    }
59    return 0;
60}
61
62/*
63 * These are the only things you should do on a core-file: use only these
64 * macros to write out all the necessary info.
65 */
66
67static int dump_write(struct file *file, const void *addr, int nr)
68{
69    return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
70}
71
72#define DUMP_WRITE(addr, nr) \
73    if (!dump_write(file, (void *)(addr), (nr))) \
74        goto end_coredump;
75
76#define DUMP_SEEK(offset) \
77if (file->f_op->llseek) { \
78    if (file->f_op->llseek(file,(offset),0) != (offset)) \
79         goto end_coredump; \
80} else file->f_pos = (offset)
81
82/*
83 * Routine writes a core dump image in the current directory.
84 * Currently only a stub-function.
85 *
86 * Note that setuid/setgid files won't make a core-dump if the uid/gid
87 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
88 * field, which also makes sure the core-dumps won't be recursive if the
89 * dumping of the process results in another error..
90 */
91
92static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
93{
94    mm_segment_t fs;
95    int has_dumped = 0;
96    unsigned long dump_start, dump_size;
97    struct user dump;
98#ifdef __alpha__
99# define START_DATA(u) (u.start_data)
100#else
101# define START_DATA(u) ((u.u_tsize << PAGE_SHIFT) + u.start_code)
102#endif
103# define START_STACK(u) (u.start_stack)
104
105    fs = get_fs();
106    set_fs(KERNEL_DS);
107    has_dumped = 1;
108    current->flags |= PF_DUMPCORE;
109           strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
110    dump.u_ar0 = offsetof(struct user, regs);
111    dump.signal = signr;
112    aout_dump_thread(regs, &dump);
113
114/* If the size of the dump file exceeds the rlimit, then see what would happen
115   if we wrote the stack, but not the data area. */
116    if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > limit)
117        dump.u_dsize = 0;
118
119/* Make sure we have enough room to write the stack and data areas. */
120    if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
121        dump.u_ssize = 0;
122
123/* make sure we actually have a data and stack area to dump */
124    set_fs(USER_DS);
125    if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
126        dump.u_dsize = 0;
127    if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
128        dump.u_ssize = 0;
129
130    set_fs(KERNEL_DS);
131/* struct user */
132    DUMP_WRITE(&dump,sizeof(dump));
133/* Now dump all of the user data. Include malloced stuff as well */
134    DUMP_SEEK(PAGE_SIZE);
135/* now we start writing out the user space info */
136    set_fs(USER_DS);
137/* Dump the data area */
138    if (dump.u_dsize != 0) {
139        dump_start = START_DATA(dump);
140        dump_size = dump.u_dsize << PAGE_SHIFT;
141        DUMP_WRITE(dump_start,dump_size);
142    }
143/* Now prepare to dump the stack area */
144    if (dump.u_ssize != 0) {
145        dump_start = START_STACK(dump);
146        dump_size = dump.u_ssize << PAGE_SHIFT;
147        DUMP_WRITE(dump_start,dump_size);
148    }
149/* Finally dump the task struct. Not be used by gdb, but could be useful */
150    set_fs(KERNEL_DS);
151    DUMP_WRITE(current,sizeof(*current));
152end_coredump:
153    set_fs(fs);
154    return has_dumped;
155}
156
157/*
158 * create_aout_tables() parses the env- and arg-strings in new user
159 * memory and creates the pointer tables from them, and puts their
160 * addresses on the "stack", returning the new stack pointer value.
161 */
162static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
163{
164    char __user * __user *argv;
165    char __user * __user *envp;
166    unsigned long __user *sp;
167    int argc = bprm->argc;
168    int envc = bprm->envc;
169
170    sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
171#ifdef __alpha__
172/* whee.. test-programs are so much fun. */
173    put_user(0, --sp);
174    put_user(0, --sp);
175    if (bprm->loader) {
176        put_user(0, --sp);
177        put_user(1003, --sp);
178        put_user(bprm->loader, --sp);
179        put_user(1002, --sp);
180    }
181    put_user(bprm->exec, --sp);
182    put_user(1001, --sp);
183#endif
184    sp -= envc+1;
185    envp = (char __user * __user *) sp;
186    sp -= argc+1;
187    argv = (char __user * __user *) sp;
188#ifndef __alpha__
189    put_user((unsigned long) envp,--sp);
190    put_user((unsigned long) argv,--sp);
191#endif
192    put_user(argc,--sp);
193    current->mm->arg_start = (unsigned long) p;
194    while (argc-->0) {
195        char c;
196        put_user(p,argv++);
197        do {
198            get_user(c,p++);
199        } while (c);
200    }
201    put_user(NULL,argv);
202    current->mm->arg_end = current->mm->env_start = (unsigned long) p;
203    while (envc-->0) {
204        char c;
205        put_user(p,envp++);
206        do {
207            get_user(c,p++);
208        } while (c);
209    }
210    put_user(NULL,envp);
211    current->mm->env_end = (unsigned long) p;
212    return sp;
213}
214
215/*
216 * These are the functions used to load a.out style executables and shared
217 * libraries. There is no binary dependent code anywhere else.
218 */
219
220static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
221{
222    struct exec ex;
223    unsigned long error;
224    unsigned long fd_offset;
225    unsigned long rlim;
226    int retval;
227
228    ex = *((struct exec *) bprm->buf); /* exec-header */
229    if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
230         N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
231        N_TRSIZE(ex) || N_DRSIZE(ex) ||
232        i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
233        return -ENOEXEC;
234    }
235
236    /*
237     * Requires a mmap handler. This prevents people from using a.out
238     * as part of an exploit attack against /proc-related vulnerabilities.
239     */
240    if (!bprm->file->f_op || !bprm->file->f_op->mmap)
241        return -ENOEXEC;
242
243    fd_offset = N_TXTOFF(ex);
244
245    /* Check initial limits. This avoids letting people circumvent
246     * size limits imposed on them by creating programs with large
247     * arrays in the data or bss.
248     */
249    rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
250    if (rlim >= RLIM_INFINITY)
251        rlim = ~0;
252    if (ex.a_data + ex.a_bss > rlim)
253        return -ENOMEM;
254
255    /* Flush all traces of the currently running executable */
256    retval = flush_old_exec(bprm);
257    if (retval)
258        return retval;
259
260    /* OK, This is the point of no return */
261#ifdef __alpha__
262    SET_AOUT_PERSONALITY(bprm, ex);
263#else
264    set_personality(PER_LINUX);
265#endif
266
267    current->mm->end_code = ex.a_text +
268        (current->mm->start_code = N_TXTADDR(ex));
269    current->mm->end_data = ex.a_data +
270        (current->mm->start_data = N_DATADDR(ex));
271    current->mm->brk = ex.a_bss +
272        (current->mm->start_brk = N_BSSADDR(ex));
273    current->mm->free_area_cache = current->mm->mmap_base;
274    current->mm->cached_hole_size = 0;
275
276    install_exec_creds(bprm);
277     current->flags &= ~PF_FORKNOEXEC;
278
279    if (N_MAGIC(ex) == OMAGIC) {
280        unsigned long text_addr, map_size;
281        loff_t pos;
282
283        text_addr = N_TXTADDR(ex);
284
285#ifdef __alpha__
286        pos = fd_offset;
287        map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
288#else
289        pos = 32;
290        map_size = ex.a_text+ex.a_data;
291#endif
292        down_write(&current->mm->mmap_sem);
293        error = do_brk(text_addr & PAGE_MASK, map_size);
294        up_write(&current->mm->mmap_sem);
295        if (error != (text_addr & PAGE_MASK)) {
296            send_sig(SIGKILL, current, 0);
297            return error;
298        }
299
300        error = bprm->file->f_op->read(bprm->file,
301              (char __user *)text_addr,
302              ex.a_text+ex.a_data, &pos);
303        if ((signed long)error < 0) {
304            send_sig(SIGKILL, current, 0);
305            return error;
306        }
307             
308        flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
309    } else {
310        if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
311            (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
312        {
313            printk(KERN_NOTICE "executable not page aligned\n");
314        }
315
316        if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
317        {
318            printk(KERN_WARNING
319                   "fd_offset is not page aligned. Please convert program: %s\n",
320                   bprm->file->f_path.dentry->d_name.name);
321        }
322
323        if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
324            loff_t pos = fd_offset;
325            down_write(&current->mm->mmap_sem);
326            do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
327            up_write(&current->mm->mmap_sem);
328            bprm->file->f_op->read(bprm->file,
329                    (char __user *)N_TXTADDR(ex),
330                    ex.a_text+ex.a_data, &pos);
331            flush_icache_range((unsigned long) N_TXTADDR(ex),
332                       (unsigned long) N_TXTADDR(ex) +
333                       ex.a_text+ex.a_data);
334            goto beyond_if;
335        }
336
337        down_write(&current->mm->mmap_sem);
338        error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
339            PROT_READ | PROT_EXEC,
340            MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
341            fd_offset);
342        up_write(&current->mm->mmap_sem);
343
344        if (error != N_TXTADDR(ex)) {
345            send_sig(SIGKILL, current, 0);
346            return error;
347        }
348
349        down_write(&current->mm->mmap_sem);
350         error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
351                PROT_READ | PROT_WRITE | PROT_EXEC,
352                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
353                fd_offset + ex.a_text);
354        up_write(&current->mm->mmap_sem);
355        if (error != N_DATADDR(ex)) {
356            send_sig(SIGKILL, current, 0);
357            return error;
358        }
359    }
360beyond_if:
361    set_binfmt(&aout_format);
362
363    retval = set_brk(current->mm->start_brk, current->mm->brk);
364    if (retval < 0) {
365        send_sig(SIGKILL, current, 0);
366        return retval;
367    }
368
369    retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
370    if (retval < 0) {
371        /* Someone check-me: is this error path enough? */
372        send_sig(SIGKILL, current, 0);
373        return retval;
374    }
375
376    current->mm->start_stack =
377        (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
378#ifdef __alpha__
379    regs->gp = ex.a_gpvalue;
380#endif
381    start_thread(regs, ex.a_entry, current->mm->start_stack);
382    return 0;
383}
384
385static int load_aout_library(struct file *file)
386{
387    struct inode * inode;
388    unsigned long bss, start_addr, len;
389    unsigned long error;
390    int retval;
391    struct exec ex;
392
393    inode = file->f_path.dentry->d_inode;
394
395    retval = -ENOEXEC;
396    error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
397    if (error != sizeof(ex))
398        goto out;
399
400    /* We come in here for the regular a.out style of shared libraries */
401    if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
402        N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
403        i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
404        goto out;
405    }
406
407    /*
408     * Requires a mmap handler. This prevents people from using a.out
409     * as part of an exploit attack against /proc-related vulnerabilities.
410     */
411    if (!file->f_op || !file->f_op->mmap)
412        goto out;
413
414    if (N_FLAGS(ex))
415        goto out;
416
417    /* For QMAGIC, the starting address is 0x20 into the page. We mask
418       this off to get the starting address for the page */
419
420    start_addr = ex.a_entry & 0xfffff000;
421
422    if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
423        loff_t pos = N_TXTOFF(ex);
424
425        if (printk_ratelimit())
426        {
427            printk(KERN_WARNING
428                   "N_TXTOFF is not page aligned. Please convert library: %s\n",
429                   file->f_path.dentry->d_name.name);
430        }
431        down_write(&current->mm->mmap_sem);
432        do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
433        up_write(&current->mm->mmap_sem);
434        
435        file->f_op->read(file, (char __user *)start_addr,
436            ex.a_text + ex.a_data, &pos);
437        flush_icache_range((unsigned long) start_addr,
438                   (unsigned long) start_addr + ex.a_text + ex.a_data);
439
440        retval = 0;
441        goto out;
442    }
443    /* Now use mmap to map the library into memory. */
444    down_write(&current->mm->mmap_sem);
445    error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
446            PROT_READ | PROT_WRITE | PROT_EXEC,
447            MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
448            N_TXTOFF(ex));
449    up_write(&current->mm->mmap_sem);
450    retval = error;
451    if (error != start_addr)
452        goto out;
453
454    len = PAGE_ALIGN(ex.a_text + ex.a_data);
455    bss = ex.a_text + ex.a_data + ex.a_bss;
456    if (bss > len) {
457        down_write(&current->mm->mmap_sem);
458        error = do_brk(start_addr + len, bss - len);
459        up_write(&current->mm->mmap_sem);
460        retval = error;
461        if (error != start_addr + len)
462            goto out;
463    }
464    retval = 0;
465out:
466    return retval;
467}
468
469static int __init init_aout_binfmt(void)
470{
471    return register_binfmt(&aout_format);
472}
473
474static void __exit exit_aout_binfmt(void)
475{
476    unregister_binfmt(&aout_format);
477}
478
479core_initcall(init_aout_binfmt);
480module_exit(exit_aout_binfmt);
481MODULE_LICENSE("GPL");
482

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