/*
 *  linux/fs/exec.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * #!-checking implemented by tytso.
 */
/*
 * Demand-loading implemented 01.12.91 - no need to read anything but
 * the header into memory. The inode of the executable is put into
 * "current->executable", and page faults do the actual loading. Clean.
 *
 * Once more I can proudly say that linux stood up to being changed: it
 * was less than 2 hours work to get demand-loading completely implemented.
 *
 * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
 * current->executable is only used by the procfs.  This allows a dispatch
 * table to check for several different types  of binary formats.  We keep
 * trying until we recognize the file or we run out of supported binary
 * formats. 
 */

#include <linux/config.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/swap.h>
#define __NO_VERSION__
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/proc_fs.h>
#include <linux/ptrace.h>

#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/mmu_context.h>

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

int core_uses_pid;

static struct linux_binfmt *formats;
static rwlock_t binfmt_lock = RW_LOCK_UNLOCKED;

int register_binfmt(struct linux_binfmt * fmt)
{
        struct linux_binfmt ** tmp = &formats;

        if (!fmt)
                return -EINVAL;
        if (fmt->next)
                return -EBUSY;
        write_lock(&binfmt_lock);
        while (*tmp) {
                if (fmt == *tmp) {
                        write_unlock(&binfmt_lock);
                        return -EBUSY;
                }
                tmp = &(*tmp)->next;
        }
        fmt->next = formats;
        formats = fmt;
        write_unlock(&binfmt_lock);
        return 0;       
}

int unregister_binfmt(struct linux_binfmt * fmt)
{
        struct linux_binfmt ** tmp = &formats;

        write_lock(&binfmt_lock);
        while (*tmp) {
                if (fmt == *tmp) {
                        *tmp = fmt->next;
                        write_unlock(&binfmt_lock);
                        return 0;
                }
                tmp = &(*tmp)->next;
        }
        write_unlock(&binfmt_lock);
        return -EINVAL;
}

static inline void put_binfmt(struct linux_binfmt * fmt)
{
        if (fmt->module)
                __MOD_DEC_USE_COUNT(fmt->module);
}

/*
 * Note that a shared library must be both readable and executable due to
 * security reasons.
 *
 * Also note that we take the address to load from from the file itself.
 */
asmlinkage long sys_uselib(const char * library)
{
        struct file * file;
        struct nameidata nd;
        int error;

        error = user_path_walk(library, &nd);
        if (error)
                goto out;

        error = -EINVAL;
        if (!S_ISREG(nd.dentry->d_inode->i_mode))
                goto exit;

        error = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC);
        if (error)
                goto exit;

        file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
        error = PTR_ERR(file);
        if (IS_ERR(file))
                goto out;

        error = -ENOEXEC;
        if(file->f_op && file->f_op->read) {
                struct linux_binfmt * fmt;

                read_lock(&binfmt_lock);
                for (fmt = formats ; fmt ; fmt = fmt->next) {
                        if (!fmt->load_shlib)
                                continue;
                        if (!try_inc_mod_count(fmt->module))
                                continue;
                        read_unlock(&binfmt_lock);
                        error = fmt->load_shlib(file);
                        read_lock(&binfmt_lock);
                        put_binfmt(fmt);
                        if (error != -ENOEXEC)
                                break;
                }
                read_unlock(&binfmt_lock);
        }
        fput(file);
out:
        return error;
exit:
        path_release(&nd);
        goto out;
}

/*
 * count() counts the number of strings in array ARGV.
 */
static int count(char ** argv, int max)
{
        int i = 0;

        if (argv != NULL) {
                for (;;) {
                        char * p;

                        if (get_user(p, argv))
                                return -EFAULT;
                        if (!p)
                                break;
                        argv++;
                        if(++i > max)
                                return -E2BIG;
                }
        }
        return i;
}

/*
 * 'copy_strings()' copies argument/environment strings from user
 * memory to free pages in kernel mem. These are in a format ready
 * to be put directly into the top of new user memory.
 */
int copy_strings(int argc,char ** argv, struct linux_binprm *bprm) 
{
        struct page *kmapped_page = NULL;
        char *kaddr = NULL;
        int ret;

        while (argc-- > 0) {
                char *str;
                int len;
                unsigned long pos;

                if (get_user(str, argv+argc) ||
                                !(len = strnlen_user(str, bprm->p))) {
                        ret = -EFAULT;
                        goto out;
                }

                if (bprm->p < len)  {
                        ret = -E2BIG;
                        goto out;
                }

                bprm->p -= len;
                /* XXX: add architecture specific overflow check here. */ 
                pos = bprm->p;

                while (len > 0) {
                        int i, new, err;
                        int offset, bytes_to_copy;
                        struct page *page;

                        offset = pos % PAGE_SIZE;
                        i = pos/PAGE_SIZE;
                        page = bprm->page[i];
                        new = 0;
                        if (!page) {
                                page = alloc_page(GFP_HIGHUSER);
                                bprm->page[i] = page;
                                if (!page) {
                                        ret = -ENOMEM;
                                        goto out;
                                }
                                new = 1;
                        }

                        if (page != kmapped_page) {
                                if (kmapped_page)
                                        kunmap(kmapped_page);
                                kmapped_page = page;
                                kaddr = kmap(kmapped_page);
                        }
                        if (new && offset)
                                memset(kaddr, 0, offset);
                        bytes_to_copy = PAGE_SIZE - offset;
                        if (bytes_to_copy > len) {
                                bytes_to_copy = len;
                                if (new)
                                        memset(kaddr+offset+len, 0,
                                                PAGE_SIZE-offset-len);
                        }
                        err = copy_from_user(kaddr+offset, str, bytes_to_copy);
                        if (err) {
                                ret = -EFAULT;
                                goto out;
                        }

                        pos += bytes_to_copy;
                        str += bytes_to_copy;
                        len -= bytes_to_copy;
                }
        }
        ret = 0;
out:
        if (kmapped_page)
                kunmap(kmapped_page);
        return ret;
}

/*
 * Like copy_strings, but get argv and its values from kernel memory.
 */
int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
{
        int r;
        mm_segment_t oldfs = get_fs();
        set_fs(KERNEL_DS); 
        r = copy_strings(argc, argv, bprm);
        set_fs(oldfs);
        return r; 
}

/*
 * This routine is used to map in a page into an address space: needed by
 * execve() for the initial stack and environment pages.
 *
 * tsk->mmap_sem is held for writing.
 */
void put_dirty_page(struct task_struct * tsk, struct page *page, unsigned long address)
{
        pgd_t * pgd;
        pmd_t * pmd;
        pte_t * pte;

        if (page_count(page) != 1)
                printk(KERN_ERR "mem_map disagrees with %p at %08lx\n", page, address);
        pgd = pgd_offset(tsk->mm, address);

        spin_lock(&tsk->mm->page_table_lock);
        pmd = pmd_alloc(tsk->mm, pgd, address);
        if (!pmd)
                goto out;
        pte = pte_alloc_map(tsk->mm, pmd, address);
        if (!pte)
                goto out;
        if (!pte_none(*pte)) {
                pte_unmap(pte);
                goto out;
        }
        lru_cache_add(page);
        flush_dcache_page(page);
        flush_page_to_ram(page);
        set_pte(pte, pte_mkdirty(pte_mkwrite(mk_pte(page, PAGE_COPY))));
        page_add_rmap(page, pte);
        pte_unmap(pte);
        tsk->mm->rss++;
        spin_unlock(&tsk->mm->page_table_lock);

        /* no need for flush_tlb */
        return;
out:
        spin_unlock(&tsk->mm->page_table_lock);
        __free_page(page);
        force_sig(SIGKILL, tsk);
        return;
}

int setup_arg_pages(struct linux_binprm *bprm)
{
        unsigned long stack_base;
        struct vm_area_struct *mpnt;
        struct mm_struct *mm = current->mm;
        int i;

#ifdef ARCH_STACK_GROWSUP
        /* Move the argument and environment strings to the bottom of the
         * stack space.
         */
        int offset, j;
        char *to, *from;

        /* Start by shifting all the pages down */
        i = 0;
        for (j = 0; j < MAX_ARG_PAGES; j++) {
                struct page *page = bprm->page[j];
                if (!page)
                        continue;
                bprm->page[i++] = page;
        }

        /* Now move them within their pages */
        offset = bprm->p % PAGE_SIZE;
        to = kmap(bprm->page[0]);
        for (j = 1; j < i; j++) {
                memmove(to, to + offset, PAGE_SIZE - offset);
                from = kmap(bprm->page[j]);
                memcpy(to + PAGE_SIZE - offset, from, offset);
                kunmap(bprm[j - 1]);
                to = from;
        }
        memmove(to, to + offset, PAGE_SIZE - offset);
        kunmap(bprm[j - 1]);

        /* Adjust bprm->p to point to the end of the strings. */
        bprm->p = PAGE_SIZE * i - offset;
        stack_base = STACK_TOP - current->rlim[RLIMIT_STACK].rlim_max;
        mm->arg_start = stack_base;

        /* zero pages that were copied above */
        while (i < MAX_ARG_PAGES)
                bprm->page[i++] = NULL;
#else
        stack_base = STACK_TOP - MAX_ARG_PAGES * PAGE_SIZE;
        mm->arg_start = bprm->p + stack_base;
#endif

        bprm->p += stack_base;
        if (bprm->loader)
                bprm->loader += stack_base;
        bprm->exec += stack_base;

        mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
        if (!mpnt)
                return -ENOMEM;

        if (!vm_enough_memory((STACK_TOP - (PAGE_MASK & (unsigned long) bprm->p))>>PAGE_SHIFT)) {
                kmem_cache_free(vm_area_cachep, mpnt);
                return -ENOMEM;
        }

        down_write(&mm->mmap_sem);
        {
                mpnt->vm_mm = mm;
#ifdef ARCH_STACK_GROWSUP
                mpnt->vm_start = stack_base;
                mpnt->vm_end = PAGE_MASK &
                        (PAGE_SIZE - 1 + (unsigned long) bprm->p);
#else
                mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;
                mpnt->vm_end = STACK_TOP;
#endif
                mpnt->vm_page_prot = PAGE_COPY;
                mpnt->vm_flags = VM_STACK_FLAGS;
                mpnt->vm_ops = NULL;
                mpnt->vm_pgoff = 0;
                mpnt->vm_file = NULL;
                mpnt->vm_private_data = (void *) 0;
                insert_vm_struct(mm, mpnt);
                mm->total_vm = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
        } 

        for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
                struct page *page = bprm->page[i];
                if (page) {
                        bprm->page[i] = NULL;
                        put_dirty_page(current,page,stack_base);
                }
                stack_base += PAGE_SIZE;
        }
        up_write(&mm->mmap_sem);
        
        return 0;
}

struct file *open_exec(const char *name)
{
        struct nameidata nd;
        int err = path_lookup(name, LOOKUP_FOLLOW, &nd);
        struct file *file = ERR_PTR(err);

        if (!err) {
                struct inode *inode = nd.dentry->d_inode;
                file = ERR_PTR(-EACCES);
                if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
                    S_ISREG(inode->i_mode)) {
                        int err = permission(inode, MAY_EXEC);
                        if (!err && !(inode->i_mode & 0111))
                                err = -EACCES;
                        file = ERR_PTR(err);
                        if (!err) {
                                file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
                                if (!IS_ERR(file)) {
                                        err = deny_write_access(file);
                                        if (err) {
                                                fput(file);
                                                file = ERR_PTR(err);
                                        }
                                }
out:
                                return file;
                        }
                }
                path_release(&nd);
        }
        goto out;
}

int kernel_read(struct file *file, unsigned long offset,
        char * addr, unsigned long count)
{
        mm_segment_t old_fs;
        loff_t pos = offset;
        int result = -ENOSYS;

        if (!file->f_op->read)
                goto fail;
        old_fs = get_fs();
        set_fs(get_ds());
        result = file->f_op->read(file, addr, count, &pos);
        set_fs(old_fs);
fail:
        return result;
}

static int exec_mmap(struct mm_struct *mm)
{
        struct mm_struct * old_mm, *active_mm;

        /* Add it to the list of mm's */
        spin_lock(&mmlist_lock);
        list_add(&mm->mmlist, &init_mm.mmlist);
        mmlist_nr++;
        spin_unlock(&mmlist_lock);

        task_lock(current);
        old_mm = current->mm;
        active_mm = current->active_mm;
        current->mm = mm;
        current->active_mm = mm;
        activate_mm(active_mm, mm);
        task_unlock(current);
        mm_release();
        if (old_mm) {
                if (active_mm != old_mm) BUG();
                mmput(old_mm);
                return 0;
        }
        mmdrop(active_mm);
        return 0;
}

static struct dentry *clean_proc_dentry(struct task_struct *p)
{
        struct dentry *proc_dentry = p->proc_dentry;

        if (proc_dentry) {
                spin_lock(&dcache_lock);
                if (!list_empty(&proc_dentry->d_hash)) {
                        dget_locked(proc_dentry);
                        list_del_init(&proc_dentry->d_hash);
                } else
                        proc_dentry = NULL;
                spin_unlock(&dcache_lock);
        }
        return proc_dentry;
}

static inline void put_proc_dentry(struct dentry *dentry)
{
        if (dentry) {
                shrink_dcache_parent(dentry);
                dput(dentry);
        }
}

/*
 * This function makes sure the current process has its own signal table,
 * so that flush_signal_handlers can later reset the handlers without
 * disturbing other processes.  (Other processes might share the signal
 * table via the CLONE_SIGHAND option to clone().)
 */
static inline int de_thread(struct signal_struct *oldsig)
{
        struct signal_struct *newsig;
        int count;

        if (atomic_read(&current->sig->count) <= 1)
                return 0;

        newsig = kmem_cache_alloc(sigact_cachep, GFP_KERNEL);
        if (!newsig)
                return -ENOMEM;

        if (list_empty(&current->thread_group))
                goto out;
        /*
         * Kill all other threads in the thread group:
         */
        spin_lock_irq(&oldsig->siglock);
        if (oldsig->group_exit) {
                /*
                 * Another group action in progress, just
                 * return so that the signal is processed.
                 */
                spin_unlock_irq(&oldsig->siglock);
                kmem_cache_free(sigact_cachep, newsig);
                return -EAGAIN;
        }
        oldsig->group_exit = 1;
        __broadcast_thread_group(current, SIGKILL);

        /*
         * Account for the thread group leader hanging around:
         */
        count = 2;
        if (current->pid == current->tgid)
                count = 1;
        while (atomic_read(&oldsig->count) > count) {
                oldsig->group_exit_task = current;
                current->state = TASK_UNINTERRUPTIBLE;
                spin_unlock_irq(&oldsig->siglock);
                schedule();
                spin_lock_irq(&oldsig->siglock);
                if (oldsig->group_exit_task)
                        BUG();
        }
        spin_unlock_irq(&oldsig->siglock);

        /*
         * At this point all other threads have exited, all we have to
         * do is to wait for the thread group leader to become inactive,
         * and to assume its PID:
         */
        if (current->pid != current->tgid) {
                struct task_struct *leader = current->group_leader, *parent;
                struct dentry *proc_dentry1, *proc_dentry2;
                unsigned long state, ptrace;

                /*
                 * Wait for the thread group leader to be a zombie.
                 * It should already be zombie at this point, most
                 * of the time.
                 */
                while (leader->state != TASK_ZOMBIE)
                        yield();

                write_lock_irq(&tasklist_lock);
                proc_dentry1 = clean_proc_dentry(current);
                proc_dentry2 = clean_proc_dentry(leader);

                if (leader->tgid != current->tgid)
                        BUG();
                if (current->pid == current->tgid)
                        BUG();
                /*
                 * An exec() starts a new thread group with the
                 * TGID of the previous thread group. Rehash the
                 * two threads with a switched PID, and release
                 * the former thread group leader:
                 */
                ptrace = leader->ptrace;
                parent = leader->parent;

                ptrace_unlink(leader);
                ptrace_unlink(current);
                remove_parent(current);
                remove_parent(leader);
                /*
                 * Split up the last two remaining members of the
                 * thread group:
                 */
                list_del_init(&leader->thread_group);

                leader->pid = leader->tgid = current->pid;
                current->pid = current->tgid;
                current->parent = current->real_parent = leader->real_parent;
                leader->parent = leader->real_parent = child_reaper;
                current->exit_signal = SIGCHLD;

                add_parent(current, current->parent);
                add_parent(leader, leader->parent);
                if (ptrace) {
                        current->ptrace = ptrace;
                        __ptrace_link(current, parent);
                }
                
                list_add_tail(&current->tasks, &init_task.tasks);
                state = leader->state;
                write_unlock_irq(&tasklist_lock);

                if (state != TASK_ZOMBIE)
                        BUG();
                release_task(leader);

                put_proc_dentry(proc_dentry1);
                put_proc_dentry(proc_dentry2);
        }

out:
        spin_lock_init(&newsig->siglock);
        atomic_set(&newsig->count, 1);
        newsig->group_exit = 0;
        newsig->group_exit_code = 0;
        newsig->group_exit_task = NULL;
        memcpy(newsig->action, current->sig->action, sizeof(newsig->action));
        init_sigpending(&newsig->shared_pending);

        remove_thread_group(current, current->sig);
        spin_lock_irq(&current->sigmask_lock);
        current->sig = newsig;
        init_sigpending(&current->pending);
        recalc_sigpending();
        spin_unlock_irq(&current->sigmask_lock);

        if (atomic_dec_and_test(&oldsig->count))
                kmem_cache_free(sigact_cachep, oldsig);

        if (!list_empty(&current->thread_group))
                BUG();
        if (current->tgid != current->pid)
                BUG();
        return 0;
}
        
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */

static inline void flush_old_files(struct files_struct * files)
{
        long j = -1;

        write_lock(&files->file_lock);
        for (;;) {
                unsigned long set, i;

                j++;
                i = j * __NFDBITS;
                if (i >= files->max_fds || i >= files->max_fdset)
                        break;
                set = files->close_on_exec->fds_bits[j];
                if (!set)
                        continue;
                files->close_on_exec->fds_bits[j] = 0;
                write_unlock(&files->file_lock);
                for ( ; set ; i++,set >>= 1) {
                        if (set & 1) {
                                sys_close(i);
                        }
                }
                write_lock(&files->file_lock);

        }
        write_unlock(&files->file_lock);
}

int flush_old_exec(struct linux_binprm * bprm)
{
        char * name;
        int i, ch, retval;
        struct signal_struct * oldsig = current->sig;

        /* 
         * Release all of the old mmap stuff
         */
        retval = exec_mmap(bprm->mm);
        if (retval)
                goto mmap_failed;
        /*
         * Make sure we have a private signal table and that
         * we are unassociated from the previous thread group.
         */
        retval = de_thread(oldsig);
        if (retval)
                goto flush_failed;

        /* This is the point of no return */

        current->sas_ss_sp = current->sas_ss_size = 0;

        if (current->euid == current->uid && current->egid == current->gid)
                current->mm->dumpable = 1;
        name = bprm->filename;
        for (i=0; (ch = *(name++)) != '\0';) {
                if (ch == '/')
                        i = 0;
                else
                        if (i < 15)
                                current->comm[i++] = ch;
        }
        current->comm[i] = '\0';

        flush_thread();

        if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
            permission(bprm->file->f_dentry->d_inode,MAY_READ))
                current->mm->dumpable = 0;

        /* An exec changes our domain. We are no longer part of the thread
           group */
           
        current->self_exec_id++;
                        
        flush_signal_handlers(current);
        flush_old_files(current->files);

        return 0;

mmap_failed:
flush_failed:
        spin_lock_irq(&current->sigmask_lock);
        if (current->sig != oldsig) {
                kmem_cache_free(sigact_cachep, current->sig);
                current->sig = oldsig;
        }
        spin_unlock_irq(&current->sigmask_lock);
        return retval;
}

/*
 * We mustn't allow tracing of suid binaries, unless
 * the tracer has the capability to trace anything..
 */
static inline int must_not_trace_exec(struct task_struct * p)
{
        return (p->ptrace & PT_PTRACED) && !(p->ptrace & PT_PTRACE_CAP);
}

/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 */
int prepare_binprm(struct linux_binprm *bprm)
{
        int mode;
        struct inode * inode = bprm->file->f_dentry->d_inode;
        int retval;

        mode = inode->i_mode;
        /*
         * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
         * vfs_permission lets a non-executable through
         */
        if (!(mode & 0111))     /* with at least _one_ execute bit set */
                return -EACCES;
        if (bprm->file->f_op == NULL)
                return -EACCES;

        bprm->e_uid = current->euid;
        bprm->e_gid = current->egid;

        if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
                /* Set-uid? */
                if (mode & S_ISUID)
                        bprm->e_uid = inode->i_uid;

                /* Set-gid? */
                /*
                 * If setgid is set but no group execute bit then this
                 * is a candidate for mandatory locking, not a setgid
                 * executable.
                 */
                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
                        bprm->e_gid = inode->i_gid;
        }

        /* fill in binprm security blob */
        retval = security_ops->bprm_set_security(bprm);
        if (retval)
                return retval;

        memset(bprm->buf,0,BINPRM_BUF_SIZE);
        return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
}

/*
 * This function is used to produce the new IDs and capabilities
 * from the old ones and the file's capabilities.
 *
 * The formula used for evolving capabilities is:
 *
 *       pI' = pI
 * (***) pP' = (fP & X) | (fI & pI)
 *       pE' = pP' & fE          [NB. fE is 0 or ~0]
 *
 * I=Inheritable, P=Permitted, E=Effective // p=process, f=file
 * ' indicates post-exec(), and X is the global 'cap_bset'.
 *
 */

void compute_creds(struct linux_binprm *bprm) 
{
        int do_unlock = 0;

        if (bprm->e_uid != current->uid || bprm->e_gid != current->gid) {
                current->mm->dumpable = 0;
                
                lock_kernel();
                if (must_not_trace_exec(current)
                    || atomic_read(&current->fs->count) > 1
                    || atomic_read(&current->files->count) > 1
                    || atomic_read(&current->sig->count) > 1) {
                        if(!capable(CAP_SETUID)) {
                                bprm->e_uid = current->uid;
                                bprm->e_gid = current->gid;
                        }
                }
                do_unlock = 1;
        }

        current->suid = current->euid = current->fsuid = bprm->e_uid;
        current->sgid = current->egid = current->fsgid = bprm->e_gid;

        if(do_unlock)
                unlock_kernel();

        security_ops->bprm_compute_creds(bprm);
}

void remove_arg_zero(struct linux_binprm *bprm)
{
        if (bprm->argc) {
                unsigned long offset;
                char * kaddr;
                struct page *page;

                offset = bprm->p % PAGE_SIZE;
                goto inside;

                while (bprm->p++, *(kaddr+offset++)) {
                        if (offset != PAGE_SIZE)
                                continue;
                        offset = 0;
                        kunmap(page);
inside:
                        page = bprm->page[bprm->p/PAGE_SIZE];
                        kaddr = kmap(page);
                }
                kunmap(page);
                bprm->argc--;
        }
}

/*
 * cycle the list of binary formats handler, until one recognizes the image
 */
int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
{
        int try,retval=0;
        struct linux_binfmt *fmt;
#ifdef __alpha__
        /* handle /sbin/loader.. */
        {
            struct exec * eh = (struct exec *) bprm->buf;

            if (!bprm->loader && eh->fh.f_magic == 0x183 &&
                (eh->fh.f_flags & 0x3000) == 0x3000)
            {
                struct file * file;
                unsigned long loader;

                allow_write_access(bprm->file);
                fput(bprm->file);
                bprm->file = NULL;

                loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);

                file = open_exec("/sbin/loader");
                retval = PTR_ERR(file);
                if (IS_ERR(file))
                        return retval;

                /* Remember if the application is TASO.  */
                bprm->sh_bang = eh->ah.entry < 0x100000000;

                bprm->file = file;
                bprm->loader = loader;
                retval = prepare_binprm(bprm);
                if (retval<0)
                        return retval;
                /* should call search_binary_handler recursively here,
                   but it does not matter */
            }
        }
#endif
        retval = security_ops->bprm_check_security(bprm);
        if (retval) 
                return retval;

        /* kernel module loader fixup */
        /* so we don't try to load run modprobe in kernel space. */
        set_fs(USER_DS);
        for (try=0; try<2; try++) {
                read_lock(&binfmt_lock);
                for (fmt = formats ; fmt ; fmt = fmt->next) {
                        int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
                        if (!fn)
                                continue;
                        if (!try_inc_mod_count(fmt->module))
                                continue;
                        read_unlock(&binfmt_lock);
                        retval = fn(bprm, regs);
                        if (retval >= 0) {
                                put_binfmt(fmt);
                                allow_write_access(bprm->file);
                                if (bprm->file)
                                        fput(bprm->file);
                                bprm->file = NULL;
                                current->did_exec = 1;
                                return retval;
                        }
                        read_lock(&binfmt_lock);
                        put_binfmt(fmt);
                        if (retval != -ENOEXEC)
                                break;
                        if (!bprm->file) {
                                read_unlock(&binfmt_lock);
                                return retval;
                        }
                }
                read_unlock(&binfmt_lock);
                if (retval != -ENOEXEC) {
                        break;
#ifdef CONFIG_KMOD
                }else{
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
                        char modname[20];
                        if (printable(bprm->buf[0]) &&
                            printable(bprm->buf[1]) &&
                            printable(bprm->buf[2]) &&
                            printable(bprm->buf[3]))
                                break; /* -ENOEXEC */
                        sprintf(modname, "binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
                        request_module(modname);
#endif
                }
        }
        return retval;
}

/*
 * sys_execve() executes a new program.
 */
int do_execve(char * filename, char ** argv, char ** envp, struct pt_regs * regs)
{
        struct linux_binprm bprm;
        struct file *file;
        int retval;
        int i;

        file = open_exec(filename);

        retval = PTR_ERR(file);

        if (IS_ERR(file))
                return retval;

        bprm.p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
        memset(bprm.page, 0, MAX_ARG_PAGES*sizeof(bprm.page[0])); 

        bprm.file = file;
        bprm.filename = filename;
        bprm.sh_bang = 0;
        bprm.loader = 0;
        bprm.exec = 0;
        bprm.security = NULL;
        bprm.mm = mm_alloc();
        retval = -ENOMEM;
        if (!bprm.mm)
                goto out_file;

        retval = init_new_context(current, bprm.mm);
        if (retval < 0)
                goto out_mm;

        bprm.argc = count(argv, bprm.p / sizeof(void *));
        if ((retval = bprm.argc) < 0)
                goto out_mm;

        bprm.envc = count(envp, bprm.p / sizeof(void *));
        if ((retval = bprm.envc) < 0)
                goto out_mm;

        retval = security_ops->bprm_alloc_security(&bprm);
        if (retval) 
                goto out;

        retval = prepare_binprm(&bprm);
        if (retval < 0) 
                goto out; 

        retval = copy_strings_kernel(1, &bprm.filename, &bprm);
        if (retval < 0) 
                goto out; 

        bprm.exec = bprm.p;
        retval = copy_strings(bprm.envc, envp, &bprm);
        if (retval < 0) 
                goto out; 

        retval = copy_strings(bprm.argc, argv, &bprm);
        if (retval < 0) 
                goto out; 

        retval = search_binary_handler(&bprm,regs);
        if (retval >= 0) {
                /* execve success */
                security_ops->bprm_free_security(&bprm);
                return retval;
        }

out:
        /* Something went wrong, return the inode and free the argument pages*/
        for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
                struct page * page = bprm.page[i];
                if (page)
                        __free_page(page);
        }

        if (bprm.security)
                security_ops->bprm_free_security(&bprm);

out_mm:
        mmdrop(bprm.mm);

out_file:
        if (bprm.file) {
                allow_write_access(bprm.file);
                fput(bprm.file);
        }
        return retval;
}

void set_binfmt(struct linux_binfmt *new)
{
        struct linux_binfmt *old = current->binfmt;
        if (new && new->module)
                __MOD_INC_USE_COUNT(new->module);
        current->binfmt = new;
        if (old && old->module)
                __MOD_DEC_USE_COUNT(old->module);
}

int do_coredump(long signr, struct pt_regs * regs)
{
        struct linux_binfmt * binfmt;
        char corename[6+sizeof(current->comm)+10];
        struct file * file;
        struct inode * inode;
        int retval = 0;

        lock_kernel();
        binfmt = current->binfmt;
        if (!binfmt || !binfmt->core_dump)
                goto fail;
        if (!current->mm->dumpable)
                goto fail;
        current->mm->dumpable = 0;
        if (current->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
                goto fail;

        memcpy(corename,"core", 5); /* include trailing \0 */
        if (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)
                sprintf(&corename[4], ".%d", current->pid);
        file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW, 0600);
        if (IS_ERR(file))
                goto fail;
        inode = file->f_dentry->d_inode;
        if (inode->i_nlink > 1)
                goto close_fail;        /* multiple links - don't dump */
        if (d_unhashed(file->f_dentry))
                goto close_fail;

        if (!S_ISREG(inode->i_mode))
                goto close_fail;
        if (!file->f_op)
                goto close_fail;
        if (!file->f_op->write)
                goto close_fail;
        if (do_truncate(file->f_dentry, 0) != 0)
                goto close_fail;

        retval = binfmt->core_dump(signr, regs, file);

close_fail:
        filp_close(file, NULL);
fail:
        unlock_kernel();
        return retval;
}