/*
 *  linux/fs/binfmt_aout.c
 *
 *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
 */

#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/coredump.h>
#include <linux/slab.h>
#include <linux/sched/task_stack.h>

#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/a.out-core.h>

static int load_aout_binary(struct linux_binprm *);
static int load_aout_library(struct file*);

#ifdef CONFIG_COREDUMP
/*
 * 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(struct coredump_params *cprm)
{
        mm_segment_t fs;
        int has_dumped = 0;
        void __user *dump_start;
        int dump_size;
        struct user dump;
#ifdef __alpha__
#       define START_DATA(u)    ((void __user *)u.start_data)
#else
#       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
                                 u.start_code))
#endif
#       define START_STACK(u)   ((void __user *)u.start_stack)

        fs = get_fs();
        set_fs(KERNEL_DS);
        has_dumped = 1;
        strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
        dump.u_ar0 = offsetof(struct user, regs);
        dump.signal = cprm->siginfo->si_signo;
        aout_dump_thread(cprm->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 > cprm->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 > cprm->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, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
                dump.u_dsize = 0;
        if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
                dump.u_ssize = 0;

        set_fs(KERNEL_DS);
/* struct user */
        if (!dump_emit(cprm, &dump, sizeof(dump)))
                goto end_coredump;
/* Now dump all of the user data.  Include malloced stuff as well */
        if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump)))
                goto end_coredump;
/* 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;
                if (!dump_emit(cprm, dump_start, dump_size))
                        goto end_coredump;
        }
/* Now prepare to dump the stack area */
        if (dump.u_ssize != 0) {
                dump_start = START_STACK(dump);
                dump_size = dump.u_ssize << PAGE_SHIFT;
                if (!dump_emit(cprm, dump_start, dump_size))
                        goto end_coredump;
        }
end_coredump:
        set_fs(fs);
        return has_dumped;
}
#else
#define aout_core_dump NULL
#endif

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

#define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)

static int 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);
        return 0;
}

/*
 * 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 unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
{
        char __user * __user *argv;
        char __user * __user *envp;
        unsigned long __user *sp;
        int argc = bprm->argc;
        int envc = bprm->envc;

        sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
#ifdef __alpha__
/* whee.. test-programs are so much fun. */
        put_user(0, --sp);
        put_user(0, --sp);
        if (bprm->loader) {
                put_user(0, --sp);
                put_user(1003, --sp);
                put_user(bprm->loader, --sp);
                put_user(1002, --sp);
        }
        put_user(bprm->exec, --sp);
        put_user(1001, --sp);
#endif
        sp -= envc+1;
        envp = (char __user * __user *) sp;
        sp -= argc+1;
        argv = (char __user * __user *) sp;
#ifndef __alpha__
        put_user((unsigned long) envp,--sp);
        put_user((unsigned long) argv,--sp);
#endif
        put_user(argc,--sp);
        current->mm->arg_start = (unsigned long) p;
        while (argc-->0) {
                char c;
                put_user(p,argv++);
                do {
                        get_user(c,p++);
                } while (c);
        }
        put_user(NULL,argv);
        current->mm->arg_end = current->mm->env_start = (unsigned long) p;
        while (envc-->0) {
                char c;
                put_user(p,envp++);
                do {
                        get_user(c,p++);
                } while (c);
        }
        put_user(NULL,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 = current_pt_regs();
        struct exec ex;
        unsigned long error;
        unsigned long fd_offset;
        unsigned long rlim;
        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(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
                return -ENOEXEC;
        }

        /*
         * Requires a mmap handler. This prevents people from using a.out
         * as part of an exploit attack against /proc-related vulnerabilities.
         */
        if (!bprm->file->f_op->mmap)
                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 */
#ifdef __alpha__
        SET_AOUT_PERSONALITY(bprm, ex);
#else
        set_personality(PER_LINUX);
#endif
        setup_new_exec(bprm);

        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));

        retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
        if (retval < 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);

#ifdef __alpha__
                pos = fd_offset;
                map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
#else
                pos = 32;
                map_size = ex.a_text+ex.a_data;
#endif
                error = vm_brk(text_addr & PAGE_MASK, map_size);
                if (error)
                        return error;

                error = read_code(bprm->file, text_addr, pos,
                                  ex.a_text+ex.a_data);
                if ((signed long)error < 0)
                        return error;
        } else {
                if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
                    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
                {
                        printk(KERN_NOTICE "executable not page aligned\n");
                }

                if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
                {
                        printk(KERN_WARNING 
                               "fd_offset is not page aligned. Please convert program: %pD\n",
                               bprm->file);
                }

                if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
                        error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
                        if (error)
                                return error;

                        read_code(bprm->file, N_TXTADDR(ex), fd_offset,
                                  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,
                        fd_offset);

                if (error != N_TXTADDR(ex))
                        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,
                                fd_offset + ex.a_text);
                if (error != N_DATADDR(ex))
                        return error;
        }
beyond_if:
        set_binfmt(&aout_format);

        retval = set_brk(current->mm->start_brk, current->mm->brk);
        if (retval < 0)
                return retval;

        current->mm->start_stack =
                (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
#ifdef __alpha__
        regs->gp = ex.a_gpvalue;
#endif
        start_thread(regs, ex.a_entry, current->mm->start_stack);
        return 0;
}

static int load_aout_library(struct file *file)
{
        struct inode * inode;
        unsigned long bss, start_addr, len;
        unsigned long error;
        int retval;
        struct exec ex;
        loff_t pos = 0;

        inode = file_inode(file);

        retval = -ENOEXEC;
        error = kernel_read(file, &ex, sizeof(ex), &pos);
        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;
        }

        /*
         * Requires a mmap handler. This prevents people from using a.out
         * as part of an exploit attack against /proc-related vulnerabilities.
         */
        if (!file->f_op->mmap)
                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) {
                if (printk_ratelimit())
                {
                        printk(KERN_WARNING 
                               "N_TXTOFF is not page aligned. Please convert library: %pD\n",
                               file);
                }
                retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
                if (retval)
                        goto out;

                read_code(file, start_addr, N_TXTOFF(ex),
                          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,
                        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) {
                retval = vm_brk(start_addr + len, bss - len);
                if (retval)
                        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);
}

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