binfmt_flat: use proper user space accessors with relocs processing code

[mirror_ubuntu-artful-kernel.git] / fs / binfmt_flat.c

/****************************************************************************/
/*
 *  linux/fs/binfmt_flat.c
 *
 *      Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
 *      Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
 *      Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
 *      Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
 *  based heavily on:
 *
 *  linux/fs/binfmt_aout.c:
 *      Copyright (C) 1991, 1992, 1996  Linus Torvalds
 *  linux/fs/binfmt_flat.c for 2.0 kernel
 *          Copyright (C) 1998  Kenneth Albanowski <kjahds@kjahds.com>
 *      JAN/99 -- coded full program relocation (gerg@snapgear.com)
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/flat.h>
#include <linux/uaccess.h>

#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <asm/cacheflush.h>
#include <asm/page.h>

/****************************************************************************/

/*
 * User data (data section and bss) needs to be aligned.
 * We pick 0x20 here because it is the max value elf2flt has always
 * used in producing FLAT files, and because it seems to be large
 * enough to make all the gcc alignment related tests happy.
 */
#define FLAT_DATA_ALIGN (0x20)

/*
 * User data (stack) also needs to be aligned.
 * Here we can be a bit looser than the data sections since this
 * needs to only meet arch ABI requirements.
 */
#define FLAT_STACK_ALIGN        max_t(unsigned long, sizeof(void *), ARCH_SLAB_MINALIGN)

#define RELOC_FAILED 0xff00ff01         /* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff         /* Placeholder for unused library */

struct lib_info {
        struct {
                unsigned long start_code;               /* Start of text segment */
                unsigned long start_data;               /* Start of data segment */
                unsigned long start_brk;                /* End of data segment */
                unsigned long text_len;                 /* Length of text segment */
                unsigned long entry;                    /* Start address for this module */
                unsigned long build_date;               /* When this one was compiled */
                bool loaded;                            /* Has this library been loaded? */
        } lib_list[MAX_SHARED_LIBS];
};

#ifdef CONFIG_BINFMT_SHARED_FLAT
static int load_flat_shared_library(int id, struct lib_info *p);
#endif

static int load_flat_binary(struct linux_binprm *);
static int flat_core_dump(struct coredump_params *cprm);

static struct linux_binfmt flat_format = {
        .module         = THIS_MODULE,
        .load_binary    = load_flat_binary,
        .core_dump      = flat_core_dump,
        .min_coredump   = PAGE_SIZE
};

/****************************************************************************/
/*
 * Routine writes a core dump image in the current directory.
 * Currently only a stub-function.
 */

static int flat_core_dump(struct coredump_params *cprm)
{
        pr_warn("Process %s:%d received signr %d and should have core dumped\n",
                current->comm, current->pid, cprm->siginfo->si_signo);
        return 1;
}

/****************************************************************************/
/*
 * create_flat_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", recording the new stack pointer value.
 */

static int create_flat_tables(struct linux_binprm *bprm, unsigned long arg_start)
{
        char __user *p;
        unsigned long __user *sp;
        long i, len;

        p = (char __user *)arg_start;
        sp = (unsigned long __user *)current->mm->start_stack;

        sp -= bprm->envc + 1;
        sp -= bprm->argc + 1;
        sp -= flat_argvp_envp_on_stack() ? 2 : 0;
        sp -= 1;  /* &argc */

        current->mm->start_stack = (unsigned long)sp & -FLAT_STACK_ALIGN;
        sp = (unsigned long __user *)current->mm->start_stack;

        __put_user(bprm->argc, sp++);
        if (flat_argvp_envp_on_stack()) {
                unsigned long argv, envp;
                argv = (unsigned long)(sp + 2);
                envp = (unsigned long)(sp + 2 + bprm->argc + 1);
                __put_user(argv, sp++);
                __put_user(envp, sp++);
        }

        current->mm->arg_start = (unsigned long)p;
        for (i = bprm->argc; i > 0; i--) {
                __put_user((unsigned long)p, sp++);
                len = strnlen_user(p, MAX_ARG_STRLEN);
                if (!len || len > MAX_ARG_STRLEN)
                        return -EINVAL;
                p += len;
        }
        __put_user(0, sp++);
        current->mm->arg_end = (unsigned long)p;

        current->mm->env_start = (unsigned long) p;
        for (i = bprm->envc; i > 0; i--) {
                __put_user((unsigned long)p, sp++);
                len = strnlen_user(p, MAX_ARG_STRLEN);
                if (!len || len > MAX_ARG_STRLEN)
                        return -EINVAL;
                p += len;
        }
        __put_user(0, sp++);
        current->mm->env_end = (unsigned long)p;

        return 0;
}

/****************************************************************************/

#ifdef CONFIG_BINFMT_ZFLAT

#include <linux/zlib.h>

#define LBUFSIZE        4000

/* gzip flag byte */
#define ASCII_FLAG   0x01 /* bit 0 set: file probably ASCII text */
#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
#define COMMENT      0x10 /* bit 4 set: file comment present */
#define ENCRYPTED    0x20 /* bit 5 set: file is encrypted */
#define RESERVED     0xC0 /* bit 6,7:   reserved */

static int decompress_exec(
        struct linux_binprm *bprm,
        unsigned long offset,
        char *dst,
        long len,
        int fd)
{
        unsigned char *buf;
        z_stream strm;
        loff_t fpos;
        int ret, retval;

        pr_debug("decompress_exec(offset=%lx,buf=%p,len=%lx)\n", offset, dst, len);

        memset(&strm, 0, sizeof(strm));
        strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
        if (strm.workspace == NULL) {
                pr_debug("no memory for decompress workspace\n");
                return -ENOMEM;
        }
        buf = kmalloc(LBUFSIZE, GFP_KERNEL);
        if (buf == NULL) {
                pr_debug("no memory for read buffer\n");
                retval = -ENOMEM;
                goto out_free;
        }

        /* Read in first chunk of data and parse gzip header. */
        fpos = offset;
        ret = kernel_read(bprm->file, offset, buf, LBUFSIZE);

        strm.next_in = buf;
        strm.avail_in = ret;
        strm.total_in = 0;
        fpos += ret;

        retval = -ENOEXEC;

        /* Check minimum size -- gzip header */
        if (ret < 10) {
                pr_debug("file too small?\n");
                goto out_free_buf;
        }

        /* Check gzip magic number */
        if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
                pr_debug("unknown compression magic?\n");
                goto out_free_buf;
        }

        /* Check gzip method */
        if (buf[2] != 8) {
                pr_debug("unknown compression method?\n");
                goto out_free_buf;
        }
        /* Check gzip flags */
        if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
            (buf[3] & RESERVED)) {
                pr_debug("unknown flags?\n");
                goto out_free_buf;
        }

        ret = 10;
        if (buf[3] & EXTRA_FIELD) {
                ret += 2 + buf[10] + (buf[11] << 8);
                if (unlikely(ret >= LBUFSIZE)) {
                        pr_debug("buffer overflow (EXTRA)?\n");
                        goto out_free_buf;
                }
        }
        if (buf[3] & ORIG_NAME) {
                while (ret < LBUFSIZE && buf[ret++] != 0)
                        ;
                if (unlikely(ret == LBUFSIZE)) {
                        pr_debug("buffer overflow (ORIG_NAME)?\n");
                        goto out_free_buf;
                }
        }
        if (buf[3] & COMMENT) {
                while (ret < LBUFSIZE && buf[ret++] != 0)
                        ;
                if (unlikely(ret == LBUFSIZE)) {
                        pr_debug("buffer overflow (COMMENT)?\n");
                        goto out_free_buf;
                }
        }

        strm.next_in += ret;
        strm.avail_in -= ret;

        strm.next_out = dst;
        strm.avail_out = len;
        strm.total_out = 0;

        if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
                pr_debug("zlib init failed?\n");
                goto out_free_buf;
        }

        while ((ret = zlib_inflate(&strm, Z_NO_FLUSH)) == Z_OK) {
                ret = kernel_read(bprm->file, fpos, buf, LBUFSIZE);
                if (ret <= 0)
                        break;
                len -= ret;

                strm.next_in = buf;
                strm.avail_in = ret;
                strm.total_in = 0;
                fpos += ret;
        }

        if (ret < 0) {
                pr_debug("decompression failed (%d), %s\n",
                        ret, strm.msg);
                goto out_zlib;
        }

        retval = 0;
out_zlib:
        zlib_inflateEnd(&strm);
out_free_buf:
        kfree(buf);
out_free:
        kfree(strm.workspace);
        return retval;
}

#endif /* CONFIG_BINFMT_ZFLAT */

/****************************************************************************/

static unsigned long
calc_reloc(unsigned long r, struct lib_info *p, int curid, int internalp)
{
        unsigned long addr;
        int id;
        unsigned long start_brk;
        unsigned long start_data;
        unsigned long text_len;
        unsigned long start_code;

#ifdef CONFIG_BINFMT_SHARED_FLAT
        if (r == 0)
                id = curid;     /* Relocs of 0 are always self referring */
        else {
                id = (r >> 24) & 0xff;  /* Find ID for this reloc */
                r &= 0x00ffffff;        /* Trim ID off here */
        }
        if (id >= MAX_SHARED_LIBS) {
                pr_err("reference 0x%lx to shared library %d", r, id);
                goto failed;
        }
        if (curid != id) {
                if (internalp) {
                        pr_err("reloc address 0x%lx not in same module "
                               "(%d != %d)", r, curid, id);
                        goto failed;
                } else if (!p->lib_list[id].loaded &&
                           load_flat_shared_library(id, p) < 0) {
                        pr_err("failed to load library %d", id);
                        goto failed;
                }
                /* Check versioning information (i.e. time stamps) */
                if (p->lib_list[id].build_date && p->lib_list[curid].build_date &&
                                p->lib_list[curid].build_date < p->lib_list[id].build_date) {
                        pr_err("library %d is younger than %d", id, curid);
                        goto failed;
                }
        }
#else
        id = 0;
#endif

        start_brk = p->lib_list[id].start_brk;
        start_data = p->lib_list[id].start_data;
        start_code = p->lib_list[id].start_code;
        text_len = p->lib_list[id].text_len;

        if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
                pr_err("reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
                       r, start_brk-start_data+text_len, text_len);
                goto failed;
        }

        if (r < text_len)                       /* In text segment */
                addr = r + start_code;
        else                                    /* In data segment */
                addr = r - text_len + start_data;

        /* Range checked already above so doing the range tests is redundant...*/
        return addr;

failed:
        pr_cont(", killing %s!\n", current->comm);
        send_sig(SIGSEGV, current, 0);

        return RELOC_FAILED;
}

/****************************************************************************/

static void old_reloc(unsigned long rl)
{
        static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
        flat_v2_reloc_t r;
        unsigned long *ptr;

        r.value = rl;
#if defined(CONFIG_COLDFIRE)
        ptr = (unsigned long *) (current->mm->start_code + r.reloc.offset);
#else
        ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
#endif

        pr_debug("Relocation of variable at DATASEG+%x "
                 "(address %p, currently %lx) into segment %s\n",
                 r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);

        switch (r.reloc.type) {
        case OLD_FLAT_RELOC_TYPE_TEXT:
                *ptr += current->mm->start_code;
                break;
        case OLD_FLAT_RELOC_TYPE_DATA:
                *ptr += current->mm->start_data;
                break;
        case OLD_FLAT_RELOC_TYPE_BSS:
                *ptr += current->mm->end_data;
                break;
        default:
                pr_err("Unknown relocation type=%x\n", r.reloc.type);
                break;
        }

        pr_debug("Relocation became %lx\n", *ptr);
}

/****************************************************************************/

static int load_flat_file(struct linux_binprm *bprm,
                struct lib_info *libinfo, int id, unsigned long *extra_stack)
{
        struct flat_hdr *hdr;
        unsigned long textpos, datapos, realdatastart;
        unsigned long text_len, data_len, bss_len, stack_len, full_data, flags;
        unsigned long len, memp, memp_size, extra, rlim;
        unsigned long __user *reloc, *rp;
        struct inode *inode;
        int i, rev, relocs;
        loff_t fpos;
        unsigned long start_code, end_code;
        ssize_t result;
        int ret;

        hdr = ((struct flat_hdr *) bprm->buf);          /* exec-header */
        inode = file_inode(bprm->file);

        text_len  = ntohl(hdr->data_start);
        data_len  = ntohl(hdr->data_end) - ntohl(hdr->data_start);
        bss_len   = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
        stack_len = ntohl(hdr->stack_size);
        if (extra_stack) {
                stack_len += *extra_stack;
                *extra_stack = stack_len;
        }
        relocs    = ntohl(hdr->reloc_count);
        flags     = ntohl(hdr->flags);
        rev       = ntohl(hdr->rev);
        full_data = data_len + relocs * sizeof(unsigned long);

        if (strncmp(hdr->magic, "bFLT", 4)) {
                /*
                 * Previously, here was a printk to tell people
                 *   "BINFMT_FLAT: bad header magic".
                 * But for the kernel which also use ELF FD-PIC format, this
                 * error message is confusing.
                 * because a lot of people do not manage to produce good
                 */
                ret = -ENOEXEC;
                goto err;
        }

        if (flags & FLAT_FLAG_KTRACE)
                pr_info("Loading file: %s\n", bprm->filename);

        if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
                pr_err("bad flat file version 0x%x (supported 0x%lx and 0x%lx)\n",
                       rev, FLAT_VERSION, OLD_FLAT_VERSION);
                ret = -ENOEXEC;
                goto err;
        }

        /* Don't allow old format executables to use shared libraries */
        if (rev == OLD_FLAT_VERSION && id != 0) {
                pr_err("shared libraries are not available before rev 0x%lx\n",
                       FLAT_VERSION);
                ret = -ENOEXEC;
                goto err;
        }

        /*
         * Make sure the header params are sane.
         * 28 bits (256 MB) is way more than reasonable in this case.
         * If some top bits are set we have probable binary corruption.
        */
        if ((text_len | data_len | bss_len | stack_len | full_data) >> 28) {
                pr_err("bad header\n");
                ret = -ENOEXEC;
                goto err;
        }

        /*
         * fix up the flags for the older format,  there were all kinds
         * of endian hacks,  this only works for the simple cases
         */
        if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
                flags = FLAT_FLAG_RAM;

#ifndef CONFIG_BINFMT_ZFLAT
        if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
                pr_err("Support for ZFLAT executables is not enabled.\n");
                ret = -ENOEXEC;
                goto err;
        }
#endif

        /*
         * 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 (data_len + bss_len > rlim) {
                ret = -ENOMEM;
                goto err;
        }

        /* Flush all traces of the currently running executable */
        if (id == 0) {
                ret = flush_old_exec(bprm);
                if (ret)
                        goto err;

                /* OK, This is the point of no return */
                set_personality(PER_LINUX_32BIT);
                setup_new_exec(bprm);
        }

        /*
         * calculate the extra space we need to map in
         */
        extra = max_t(unsigned long, bss_len + stack_len,
                        relocs * sizeof(unsigned long));

        /*
         * there are a couple of cases here,  the separate code/data
         * case,  and then the fully copied to RAM case which lumps
         * it all together.
         */
        if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
                /*
                 * this should give us a ROM ptr,  but if it doesn't we don't
                 * really care
                 */
                pr_debug("ROM mapping of file (we hope)\n");

                textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
                                  MAP_PRIVATE|MAP_EXECUTABLE, 0);
                if (!textpos || IS_ERR_VALUE(textpos)) {
                        ret = textpos;
                        if (!textpos)
                                ret = -ENOMEM;
                        pr_err("Unable to mmap process text, errno %d\n", ret);
                        goto err;
                }

                len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
                len = PAGE_ALIGN(len);
                realdatastart = vm_mmap(NULL, 0, len,
                        PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);

                if (realdatastart == 0 || IS_ERR_VALUE(realdatastart)) {
                        ret = realdatastart;
                        if (!realdatastart)
                                ret = -ENOMEM;
                        pr_err("Unable to allocate RAM for process data, "
                               "errno %d\n", ret);
                        vm_munmap(textpos, text_len);
                        goto err;
                }
                datapos = ALIGN(realdatastart +
                                MAX_SHARED_LIBS * sizeof(unsigned long),
                                FLAT_DATA_ALIGN);

                pr_debug("Allocated data+bss+stack (%ld bytes): %lx\n",
                         data_len + bss_len + stack_len, datapos);

                fpos = ntohl(hdr->data_start);
#ifdef CONFIG_BINFMT_ZFLAT
                if (flags & FLAT_FLAG_GZDATA) {
                        result = decompress_exec(bprm, fpos, (char *)datapos,
                                                 full_data, 0);
                } else
#endif
                {
                        result = read_code(bprm->file, datapos, fpos,
                                        full_data);
                }
                if (IS_ERR_VALUE(result)) {
                        ret = result;
                        pr_err("Unable to read data+bss, errno %d\n", ret);
                        vm_munmap(textpos, text_len);
                        vm_munmap(realdatastart, len);
                        goto err;
                }

                reloc = (unsigned long __user *)
                        (datapos + (ntohl(hdr->reloc_start) - text_len));
                memp = realdatastart;
                memp_size = len;
        } else {

                len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
                len = PAGE_ALIGN(len);
                textpos = vm_mmap(NULL, 0, len,
                        PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);

                if (!textpos || IS_ERR_VALUE(textpos)) {
                        ret = textpos;
                        if (!textpos)
                                ret = -ENOMEM;
                        pr_err("Unable to allocate RAM for process text/data, "
                               "errno %d\n", ret);
                        goto err;
                }

                realdatastart = textpos + ntohl(hdr->data_start);
                datapos = ALIGN(realdatastart +
                                MAX_SHARED_LIBS * sizeof(unsigned long),
                                FLAT_DATA_ALIGN);

                reloc = (unsigned long __user *)
                        (datapos + (ntohl(hdr->reloc_start) - text_len));
                memp = textpos;
                memp_size = len;
#ifdef CONFIG_BINFMT_ZFLAT
                /*
                 * load it all in and treat it like a RAM load from now on
                 */
                if (flags & FLAT_FLAG_GZIP) {
                        result = decompress_exec(bprm, sizeof(struct flat_hdr),
                                         (((char *)textpos) + sizeof(struct flat_hdr)),
                                         (text_len + full_data
                                                  - sizeof(struct flat_hdr)),
                                         0);
                        memmove((void *) datapos, (void *) realdatastart,
                                        full_data);
                } else if (flags & FLAT_FLAG_GZDATA) {
                        result = read_code(bprm->file, textpos, 0, text_len);
                        if (!IS_ERR_VALUE(result))
                                result = decompress_exec(bprm, text_len, (char *) datapos,
                                                 full_data, 0);
                } else
#endif
                {
                        result = read_code(bprm->file, textpos, 0, text_len);
                        if (!IS_ERR_VALUE(result))
                                result = read_code(bprm->file, datapos,
                                                   ntohl(hdr->data_start),
                                                   full_data);
                }
                if (IS_ERR_VALUE(result)) {
                        ret = result;
                        pr_err("Unable to read code+data+bss, errno %d\n", ret);
                        vm_munmap(textpos, text_len + data_len + extra +
                                MAX_SHARED_LIBS * sizeof(unsigned long));
                        goto err;
                }
        }

        start_code = textpos + sizeof(struct flat_hdr);
        end_code = textpos + text_len;
        text_len -= sizeof(struct flat_hdr); /* the real code len */

        /* The main program needs a little extra setup in the task structure */
        if (id == 0) {
                current->mm->start_code = start_code;
                current->mm->end_code = end_code;
                current->mm->start_data = datapos;
                current->mm->end_data = datapos + data_len;
                /*
                 * set up the brk stuff, uses any slack left in data/bss/stack
                 * allocation.  We put the brk after the bss (between the bss
                 * and stack) like other platforms.
                 * Userspace code relies on the stack pointer starting out at
                 * an address right at the end of a page.
                 */
                current->mm->start_brk = datapos + data_len + bss_len;
                current->mm->brk = (current->mm->start_brk + 3) & ~3;
                current->mm->context.end_brk = memp + memp_size - stack_len;
        }

        if (flags & FLAT_FLAG_KTRACE) {
                pr_info("Mapping is %lx, Entry point is %x, data_start is %x\n",
                        textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
                pr_info("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
                        id ? "Lib" : "Load", bprm->filename,
                        start_code, end_code, datapos, datapos + data_len,
                        datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
        }

        /* Store the current module values into the global library structure */
        libinfo->lib_list[id].start_code = start_code;
        libinfo->lib_list[id].start_data = datapos;
        libinfo->lib_list[id].start_brk = datapos + data_len + bss_len;
        libinfo->lib_list[id].text_len = text_len;
        libinfo->lib_list[id].loaded = 1;
        libinfo->lib_list[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
        libinfo->lib_list[id].build_date = ntohl(hdr->build_date);

        /*
         * We just load the allocations into some temporary memory to
         * help simplify all this mumbo jumbo
         *
         * We've got two different sections of relocation entries.
         * The first is the GOT which resides at the beginning of the data segment
         * and is terminated with a -1.  This one can be relocated in place.
         * The second is the extra relocation entries tacked after the image's
         * data segment. These require a little more processing as the entry is
         * really an offset into the image which contains an offset into the
         * image.
         */
        if (flags & FLAT_FLAG_GOTPIC) {
                for (rp = (unsigned long __user *)datapos; ; rp++) {
                        unsigned long addr, rp_val;
                        if (get_user(rp_val, rp))
                                return -EFAULT;
                        if (rp_val == 0xffffffff)
                                break;
                        if (rp_val) {
                                addr = calc_reloc(rp_val, libinfo, id, 0);
                                if (addr == RELOC_FAILED) {
                                        ret = -ENOEXEC;
                                        goto err;
                                }
                                if (put_user(addr, rp))
                                        return -EFAULT;
                        }
                }
        }

        /*
         * Now run through the relocation entries.
         * We've got to be careful here as C++ produces relocatable zero
         * entries in the constructor and destructor tables which are then
         * tested for being not zero (which will always occur unless we're
         * based from address zero).  This causes an endless loop as __start
         * is at zero.  The solution used is to not relocate zero addresses.
         * This has the negative side effect of not allowing a global data
         * reference to be statically initialised to _stext (I've moved
         * __start to address 4 so that is okay).
         */
        if (rev > OLD_FLAT_VERSION) {
                unsigned long __maybe_unused persistent = 0;
                for (i = 0; i < relocs; i++) {
                        unsigned long addr, relval;

                        /*
                         * Get the address of the pointer to be
                         * relocated (of course, the address has to be
                         * relocated first).
                         */
                        if (get_user(relval, reloc + i))
                                return -EFAULT;
                        relval = ntohl(relval);
                        if (flat_set_persistent(relval, &persistent))
                                continue;
                        addr = flat_get_relocate_addr(relval);
                        rp = (unsigned long __user *)calc_reloc(addr, libinfo, id, 1);
                        if (rp == (unsigned long __user *)RELOC_FAILED) {
                                ret = -ENOEXEC;
                                goto err;
                        }

                        /* Get the pointer's value.  */
                        addr = flat_get_addr_from_rp(rp, relval, flags,
                                                        &persistent);
                        if (addr != 0) {
                                /*
                                 * Do the relocation.  PIC relocs in the data section are
                                 * already in target order
                                 */
                                if ((flags & FLAT_FLAG_GOTPIC) == 0)
                                        addr = ntohl(addr);
                                addr = calc_reloc(addr, libinfo, id, 0);
                                if (addr == RELOC_FAILED) {
                                        ret = -ENOEXEC;
                                        goto err;
                                }

                                /* Write back the relocated pointer.  */
                                flat_put_addr_at_rp(rp, addr, relval);
                        }
                }
        } else {
                for (i = 0; i < relocs; i++)
                        old_reloc(ntohl(reloc[i]));
        }

        flush_icache_range(start_code, end_code);

        /* zero the BSS,  BRK and stack areas */
        memset((void *)(datapos + data_len), 0, bss_len +
                        (memp + memp_size - stack_len -         /* end brk */
                        libinfo->lib_list[id].start_brk) +      /* start brk */
                        stack_len);

        return 0;
err:
        return ret;
}


/****************************************************************************/
#ifdef CONFIG_BINFMT_SHARED_FLAT

/*
 * Load a shared library into memory.  The library gets its own data
 * segment (including bss) but not argv/argc/environ.
 */

static int load_flat_shared_library(int id, struct lib_info *libs)
{
        struct linux_binprm bprm;
        int res;
        char buf[16];

        memset(&bprm, 0, sizeof(bprm));

        /* Create the file name */
        sprintf(buf, "/lib/lib%d.so", id);

        /* Open the file up */
        bprm.filename = buf;
        bprm.file = open_exec(bprm.filename);
        res = PTR_ERR(bprm.file);
        if (IS_ERR(bprm.file))
                return res;

        bprm.cred = prepare_exec_creds();
        res = -ENOMEM;
        if (!bprm.cred)
                goto out;

        /* We don't really care about recalculating credentials at this point
         * as we're past the point of no return and are dealing with shared
         * libraries.
         */
        bprm.cred_prepared = 1;

        res = prepare_binprm(&bprm);

        if (!res)
                res = load_flat_file(&bprm, libs, id, NULL);

        abort_creds(bprm.cred);

out:
        allow_write_access(bprm.file);
        fput(bprm.file);

        return res;
}

#endif /* CONFIG_BINFMT_SHARED_FLAT */
/****************************************************************************/

/*
 * These are the functions used to load flat style executables and shared
 * libraries.  There is no binary dependent code anywhere else.
 */

static int load_flat_binary(struct linux_binprm *bprm)
{
        struct lib_info libinfo;
        struct pt_regs *regs = current_pt_regs();
        unsigned long stack_len;
        unsigned long start_addr;
        int res;
        int i, j;

        memset(&libinfo, 0, sizeof(libinfo));

        /*
         * We have to add the size of our arguments to our stack size
         * otherwise it's too easy for users to create stack overflows
         * by passing in a huge argument list.  And yes,  we have to be
         * pedantic and include space for the argv/envp array as it may have
         * a lot of entries.
         */
        stack_len = PAGE_SIZE * MAX_ARG_PAGES - bprm->p;  /* the strings */
        stack_len += (bprm->argc + 1) * sizeof(char *);   /* the argv array */
        stack_len += (bprm->envc + 1) * sizeof(char *);   /* the envp array */
        stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);

        res = load_flat_file(bprm, &libinfo, 0, &stack_len);
        if (res < 0)
                return res;

        /* Update data segment pointers for all libraries */
        for (i = 0; i < MAX_SHARED_LIBS; i++)
                if (libinfo.lib_list[i].loaded)
                        for (j = 0; j < MAX_SHARED_LIBS; j++)
                                (-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
                                        (libinfo.lib_list[j].loaded) ?
                                                libinfo.lib_list[j].start_data : UNLOADED_LIB;

        install_exec_creds(bprm);

        set_binfmt(&flat_format);

        /* Stash our initial stack pointer into the mm structure */
        current->mm->start_stack =
                ((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
        pr_debug("sp=%lx\n", current->mm->start_stack);

        /* copy the arg pages onto the stack */
        res = transfer_args_to_stack(bprm, &current->mm->start_stack);
        if (!res)
                res = create_flat_tables(bprm, current->mm->start_stack);
        if (res)
                return res;

        /* Fake some return addresses to ensure the call chain will
         * initialise library in order for us.  We are required to call
         * lib 1 first, then 2, ... and finally the main program (id 0).
         */
        start_addr = libinfo.lib_list[0].entry;

#ifdef CONFIG_BINFMT_SHARED_FLAT
        for (i = MAX_SHARED_LIBS-1; i > 0; i--) {
                if (libinfo.lib_list[i].loaded) {
                        /* Push previos first to call address */
                        unsigned long __user *sp;
                        current->mm->start_stack -= sizeof(unsigned long);
                        sp = (unsigned long __user *)current->mm->start_stack;
                        __put_user(start_addr, sp);
                        start_addr = libinfo.lib_list[i].entry;
                }
        }
#endif

#ifdef FLAT_PLAT_INIT
        FLAT_PLAT_INIT(regs);
#endif

        pr_debug("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
                 regs, start_addr, current->mm->start_stack);
        start_thread(regs, start_addr, current->mm->start_stack);

        return 0;
}

/****************************************************************************/

static int __init init_flat_binfmt(void)
{
        register_binfmt(&flat_format);
        return 0;
}
core_initcall(init_flat_binfmt);

/****************************************************************************/