ia32_aout.c

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/*
 *  a.out loader for x86-64
 *
 *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
 *  Hacked together by Andi Kleen
 */

#include <linux/module.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/jiffies.h>

#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
#include <asm/user32.h>
#include <asm/ia32.h>

#undef WARN_OLD
#undef CORE_DUMP /* definitely broken */

static int load_aout_binary(struct linux_binprm *, struct pt_regs *regs);
static int load_aout_library(struct file *);

#ifdef CORE_DUMP
static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file,
              unsigned long limit);

/*
 * fill in the user structure for a core dump..
 */
static void dump_thread32(struct pt_regs *regs, struct user32 *dump)
{
    u32 fs, gs;

/* changed the size calculations - should hopefully work better. lbt */
    dump->magic = CMAGIC;
    dump->start_code = 0;
    dump->start_stack = regs->sp & ~(PAGE_SIZE - 1);
    dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
    dump->u_dsize = ((unsigned long)
             (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
    dump->u_dsize -= dump->u_tsize;
    dump->u_ssize = 0;
    dump->u_debugreg[0] = current->thread.debugreg0;
    dump->u_debugreg[1] = current->thread.debugreg1;
    dump->u_debugreg[2] = current->thread.debugreg2;
    dump->u_debugreg[3] = current->thread.debugreg3;
    dump->u_debugreg[4] = 0;
    dump->u_debugreg[5] = 0;
    dump->u_debugreg[6] = current->thread.debugreg6;
    dump->u_debugreg[7] = current->thread.debugreg7;

    if (dump->start_stack < 0xc0000000) {
        unsigned long tmp;

        tmp = (unsigned long) (0xc0000000 - dump->start_stack);
        dump->u_ssize = tmp >> PAGE_SHIFT;
    }

    dump->regs.bx = regs->bx;
    dump->regs.cx = regs->cx;
    dump->regs.dx = regs->dx;
    dump->regs.si = regs->si;
    dump->regs.di = regs->di;
    dump->regs.bp = regs->bp;
    dump->regs.ax = regs->ax;
    dump->regs.ds = current->thread.ds;
    dump->regs.es = current->thread.es;
    savesegment(fs, fs);
    dump->regs.fs = fs;
    savesegment(gs, gs);
    dump->regs.gs = gs;
    dump->regs.orig_ax = regs->orig_ax;
    dump->regs.ip = regs->ip;
    dump->regs.cs = regs->cs;
    dump->regs.flags = regs->flags;
    dump->regs.sp = regs->sp;
    dump->regs.ss = regs->ss;

#if 1 /* FIXME */
    dump->u_fpvalid = 0;
#else
    dump->u_fpvalid = dump_fpu(regs, &dump->i387);
#endif
}

#endif

static struct linux_binfmt aout_format = {
    .module     = THIS_MODULE,
    .load_binary    = load_aout_binary,
    .load_shlib = load_aout_library,
#ifdef CORE_DUMP
    .core_dump  = aout_core_dump,
#endif
    .min_coredump   = PAGE_SIZE
};

static void set_brk(unsigned long start, unsigned long end)
{
    start = PAGE_ALIGN(start);
    end = PAGE_ALIGN(end);
    if (end <= start)
        return;
    vm_brk(start, end - start);
}

#ifdef CORE_DUMP
/*
 * These are the only things you should do on a core-file: use only these
 * macros to write out all the necessary info.
 */

#include <linux/coredump.h>

#define DUMP_WRITE(addr, nr)                 \
    if (!dump_write(file, (void *)(addr), (nr))) \
        goto end_coredump;

#define DUMP_SEEK(offset)       \
    if (!dump_seek(file, offset))   \
        goto end_coredump;

#define START_DATA()    (u.u_tsize << PAGE_SHIFT)
#define START_STACK(u)  (u.start_stack)

/*
 * Routine writes a core dump image in the current directory.
 * Currently only a stub-function.
 *
 * Note that setuid/setgid files won't make a core-dump if the uid/gid
 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
 * field, which also makes sure the core-dumps won't be recursive if the
 * dumping of the process results in another error..
 */

static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file,
              unsigned long limit)
{
    mm_segment_t fs;
    int has_dumped = 0;
    unsigned long dump_start, dump_size;
    struct user32 dump;

    fs = get_fs();
    set_fs(KERNEL_DS);
    has_dumped = 1;
    current->flags |= PF_DUMPCORE;
    strncpy(dump.u_comm, current->comm, sizeof(current->comm));
    dump.u_ar0 = offsetof(struct user32, regs);
    dump.signal = signr;
    dump_thread32(regs, &dump);

    /*
     * If the size of the dump file exceeds the rlimit, then see
     * what would happen if we wrote the stack, but not the data
     * area.
     */
    if ((dump.u_dsize + dump.u_ssize + 1) * PAGE_SIZE > limit)
        dump.u_dsize = 0;

    /* Make sure we have enough room to write the stack and data areas. */
    if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
        dump.u_ssize = 0;

    /* make sure we actually have a data and stack area to dump */
    set_fs(USER_DS);
    if (!access_ok(VERIFY_READ, (void *) (unsigned long)START_DATA(dump),
               dump.u_dsize << PAGE_SHIFT))
        dump.u_dsize = 0;
    if (!access_ok(VERIFY_READ, (void *) (unsigned long)START_STACK(dump),
               dump.u_ssize << PAGE_SHIFT))
        dump.u_ssize = 0;

    set_fs(KERNEL_DS);
    /* struct user */
    DUMP_WRITE(&dump, sizeof(dump));
    /* Now dump all of the user data.  Include malloced stuff as well */
    DUMP_SEEK(PAGE_SIZE);
    /* now we start writing out the user space info */
    set_fs(USER_DS);
    /* Dump the data area */
    if (dump.u_dsize != 0) {
        dump_start = START_DATA(dump);
        dump_size = dump.u_dsize << PAGE_SHIFT;
        DUMP_WRITE(dump_start, dump_size);
    }
    /* Now prepare to dump the stack area */
    if (dump.u_ssize != 0) {
        dump_start = START_STACK(dump);
        dump_size = dump.u_ssize << PAGE_SHIFT;
        DUMP_WRITE(dump_start, dump_size);
    }
end_coredump:
    set_fs(fs);
    return has_dumped;
}
#endif

/*
 * create_aout_tables() parses the env- and arg-strings in new user
 * memory and creates the pointer tables from them, and puts their
 * addresses on the "stack", returning the new stack pointer value.
 */
static u32 __user *create_aout_tables(char __user *p, struct linux_binprm *bprm)
{
    u32 __user *argv, *envp, *sp;
    int argc = bprm->argc, envc = bprm->envc;

    sp = (u32 __user *) ((-(unsigned long)sizeof(u32)) & (unsigned long) p);
    sp -= envc+1;
    envp = sp;
    sp -= argc+1;
    argv = sp;
    put_user((unsigned long) envp, --sp);
    put_user((unsigned long) argv, --sp);
    put_user(argc, --sp);
    current->mm->arg_start = (unsigned long) p;
    while (argc-- > 0) {
        char c;

        put_user((u32)(unsigned long)p, argv++);
        do {
            get_user(c, p++);
        } while (c);
    }
    put_user(0, argv);
    current->mm->arg_end = current->mm->env_start = (unsigned long) p;
    while (envc-- > 0) {
        char c;

        put_user((u32)(unsigned long)p, envp++);
        do {
            get_user(c, p++);
        } while (c);
    }
    put_user(0, envp);
    current->mm->env_end = (unsigned long) p;
    return sp;
}

/*
 * These are the functions used to load a.out style executables and shared
 * libraries.  There is no binary dependent code anywhere else.
 */
static int load_aout_binary(struct linux_binprm *bprm, struct pt_regs *regs)
{
    unsigned long error, fd_offset, rlim;
    struct exec ex;
    int retval;

    ex = *((struct exec *) bprm->buf);      /* exec-header */
    if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
         N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
        N_TRSIZE(ex) || N_DRSIZE(ex) ||
        i_size_read(bprm->file->f_path.dentry->d_inode) <
        ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
        return -ENOEXEC;
    }

    fd_offset = N_TXTOFF(ex);

    /* Check initial limits. This avoids letting people circumvent
     * size limits imposed on them by creating programs with large
     * arrays in the data or bss.
     */
    rlim = rlimit(RLIMIT_DATA);
    if (rlim >= RLIM_INFINITY)
        rlim = ~0;
    if (ex.a_data + ex.a_bss > rlim)
        return -ENOMEM;

    /* Flush all traces of the currently running executable */
    retval = flush_old_exec(bprm);
    if (retval)
        return retval;

    /* OK, This is the point of no return */
    set_personality(PER_LINUX);
    set_personality_ia32(false);

    setup_new_exec(bprm);

    regs->cs = __USER32_CS;
    regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
        regs->r13 = regs->r14 = regs->r15 = 0;

    current->mm->end_code = ex.a_text +
        (current->mm->start_code = N_TXTADDR(ex));
    current->mm->end_data = ex.a_data +
        (current->mm->start_data = N_DATADDR(ex));
    current->mm->brk = ex.a_bss +
        (current->mm->start_brk = N_BSSADDR(ex));
    current->mm->free_area_cache = TASK_UNMAPPED_BASE;
    current->mm->cached_hole_size = 0;

    retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
    if (retval < 0) {
        /* Someone check-me: is this error path enough? */
        send_sig(SIGKILL, current, 0);
        return retval;
    }

    install_exec_creds(bprm);

    if (N_MAGIC(ex) == OMAGIC) {
        unsigned long text_addr, map_size;
        loff_t pos;

        text_addr = N_TXTADDR(ex);

        pos = 32;
        map_size = ex.a_text+ex.a_data;

        error = vm_brk(text_addr & PAGE_MASK, map_size);

        if (error != (text_addr & PAGE_MASK)) {
            send_sig(SIGKILL, current, 0);
            return error;
        }

        error = bprm->file->f_op->read(bprm->file,
             (char __user *)text_addr,
              ex.a_text+ex.a_data, &pos);
        if ((signed long)error < 0) {
            send_sig(SIGKILL, current, 0);
            return error;
        }

        flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
    } else {
#ifdef WARN_OLD
        static unsigned long error_time, error_time2;
        if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
            (N_MAGIC(ex) != NMAGIC) &&
                time_after(jiffies, error_time2 + 5*HZ)) {
            printk(KERN_NOTICE "executable not page aligned\n");
            error_time2 = jiffies;
        }

        if ((fd_offset & ~PAGE_MASK) != 0 &&
                time_after(jiffies, error_time + 5*HZ)) {
            printk(KERN_WARNING
                   "fd_offset is not page aligned. Please convert "
                   "program: %s\n",
                   bprm->file->f_path.dentry->d_name.name);
            error_time = jiffies;
        }
#endif

        if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
            loff_t pos = fd_offset;

            vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
            bprm->file->f_op->read(bprm->file,
                    (char __user *)N_TXTADDR(ex),
                    ex.a_text+ex.a_data, &pos);
            flush_icache_range((unsigned long) N_TXTADDR(ex),
                       (unsigned long) N_TXTADDR(ex) +
                       ex.a_text+ex.a_data);
            goto beyond_if;
        }

        error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
                PROT_READ | PROT_EXEC,
                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
                MAP_EXECUTABLE | MAP_32BIT,
                fd_offset);

        if (error != N_TXTADDR(ex)) {
            send_sig(SIGKILL, current, 0);
            return error;
        }

        error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
                PROT_READ | PROT_WRITE | PROT_EXEC,
                MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
                MAP_EXECUTABLE | MAP_32BIT,
                fd_offset + ex.a_text);
        if (error != N_DATADDR(ex)) {
            send_sig(SIGKILL, current, 0);
            return error;
        }
    }
beyond_if:
    set_binfmt(&aout_format);

    set_brk(current->mm->start_brk, current->mm->brk);

    current->mm->start_stack =
        (unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
    /* start thread */
    loadsegment(fs, 0);
    loadsegment(ds, __USER32_DS);
    loadsegment(es, __USER32_DS);
    load_gs_index(0);
    (regs)->ip = ex.a_entry;
    (regs)->sp = current->mm->start_stack;
    (regs)->flags = 0x200;
    (regs)->cs = __USER32_CS;
    (regs)->ss = __USER32_DS;
    regs->r8 = regs->r9 = regs->r10 = regs->r11 =
    regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
    set_fs(USER_DS);
    return 0;
}

static int load_aout_library(struct file *file)
{
    struct inode *inode;
    unsigned long bss, start_addr, len, error;
    int retval;
    struct exec ex;

    inode = file->f_path.dentry->d_inode;

    retval = -ENOEXEC;
    error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
    if (error != sizeof(ex))
        goto out;

    /* We come in here for the regular a.out style of shared libraries */
    if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
        N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
        i_size_read(inode) <
        ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
        goto out;
    }

    if (N_FLAGS(ex))
        goto out;

    /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
       this off to get the starting address for the page */

    start_addr =  ex.a_entry & 0xfffff000;

    if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
        loff_t pos = N_TXTOFF(ex);

#ifdef WARN_OLD
        static unsigned long error_time;
        if (time_after(jiffies, error_time + 5*HZ)) {
            printk(KERN_WARNING
                   "N_TXTOFF is not page aligned. Please convert "
                   "library: %s\n",
                   file->f_path.dentry->d_name.name);
            error_time = jiffies;
        }
#endif
        vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);

        file->f_op->read(file, (char __user *)start_addr,
            ex.a_text + ex.a_data, &pos);
        flush_icache_range((unsigned long) start_addr,
                   (unsigned long) start_addr + ex.a_text +
                   ex.a_data);

        retval = 0;
        goto out;
    }
    /* Now use mmap to map the library into memory. */
    error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
            PROT_READ | PROT_WRITE | PROT_EXEC,
            MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_32BIT,
            N_TXTOFF(ex));
    retval = error;
    if (error != start_addr)
        goto out;

    len = PAGE_ALIGN(ex.a_text + ex.a_data);
    bss = ex.a_text + ex.a_data + ex.a_bss;
    if (bss > len) {
        error = vm_brk(start_addr + len, bss - len);
        retval = error;
        if (error != start_addr + len)
            goto out;
    }
    retval = 0;
out:
    return retval;
}

static int __init init_aout_binfmt(void)
{
    register_binfmt(&aout_format);
    return 0;
}

static void __exit exit_aout_binfmt(void)
{
    unregister_binfmt(&aout_format);
}

module_init(init_aout_binfmt);
module_exit(exit_aout_binfmt);
MODULE_LICENSE("GPL");