#include <linux/slab.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/swap.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/perf_event.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/key.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/coredump.h>
#include <linux/utsname.h>
#include <linux/pid_namespace.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/tsacct_kern.h>
#include <linux/cn_proc.h>
#include <linux/audit.h>
#include <linux/tracehook.h>
#include <linux/kmod.h>
#include <linux/fsnotify.h>
#include <linux/fs_struct.h>
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
#include <linux/compat.h>

#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>
#include <asm/exec.h>

#include <trace/events/task.h>
#include "internal.h"
#include "coredump.h"

#include <trace/events/sched.h>

int core_uses_pid;
char core_pattern[CORENAME_MAX_SIZE] = "core";
unsigned int core_pipe_limit;

struct core_name {
        char *corename;
        int used, size;
};
static atomic_t call_count = ATOMIC_INIT(1);

/* The maximal length of core_pattern is also specified in sysctl.c */

static int expand_corename(struct core_name *cn)
{
        char *old_corename = cn->corename;

        cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
        cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);

        if (!cn->corename) {
                kfree(old_corename);
                return -ENOMEM;
        }

        return 0;
}

static int cn_printf(struct core_name *cn, const char *fmt, ...)
{
        char *cur;
        int need;
        int ret;
        va_list arg;

        va_start(arg, fmt);
        need = vsnprintf(NULL, 0, fmt, arg);
        va_end(arg);

        if (likely(need < cn->size - cn->used - 1))
                goto out_printf;

        ret = expand_corename(cn);
        if (ret)
                goto expand_fail;

out_printf:
        cur = cn->corename + cn->used;
        va_start(arg, fmt);
        vsnprintf(cur, need + 1, fmt, arg);
        va_end(arg);
        cn->used += need;
        return 0;

expand_fail:
        return ret;
}

static void cn_escape(char *str)
{
        for (; *str; str++)
                if (*str == '/')
                        *str = '!';
}

static int cn_print_exe_file(struct core_name *cn)
{
        struct file *exe_file;
        char *pathbuf, *path;
        int ret;

        exe_file = get_mm_exe_file(current->mm);
        if (!exe_file) {
                char *commstart = cn->corename + cn->used;
                ret = cn_printf(cn, "%s (path unknown)", current->comm);
                cn_escape(commstart);
                return ret;
        }

        pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
        if (!pathbuf) {
                ret = -ENOMEM;
                goto put_exe_file;
        }

        path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
        if (IS_ERR(path)) {
                ret = PTR_ERR(path);
                goto free_buf;
        }

        cn_escape(path);

        ret = cn_printf(cn, "%s", path);

free_buf:
        kfree(pathbuf);
put_exe_file:
        fput(exe_file);
        return ret;
}

/* format_corename will inspect the pattern parameter, and output a
 * name into corename, which must have space for at least
 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
 */
static int format_corename(struct core_name *cn, struct coredump_params *cprm)
{
        const struct cred *cred = current_cred();
        const char *pat_ptr = core_pattern;
        int ispipe = (*pat_ptr == '|');
        int pid_in_pattern = 0;
        int err = 0;

        cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
        cn->corename = kmalloc(cn->size, GFP_KERNEL);
        cn->used = 0;

        if (!cn->corename)
                return -ENOMEM;

        /* Repeat as long as we have more pattern to process and more output
           space */
        while (*pat_ptr) {
                if (*pat_ptr != '%') {
                        if (*pat_ptr == 0)
                                goto out;
                        err = cn_printf(cn, "%c", *pat_ptr++);
                } else {
                        switch (*++pat_ptr) {
                        /* single % at the end, drop that */
                        case 0:
                                goto out;
                        /* Double percent, output one percent */
                        case '%':
                                err = cn_printf(cn, "%c", '%');
                                break;
                        /* pid */
                        case 'p':
                                pid_in_pattern = 1;
                                err = cn_printf(cn, "%d",
                                              task_tgid_vnr(current));
                                break;
                        /* global pid */
                        case 'P':
                                err = cn_printf(cn, "%d",
                                              task_tgid_nr(current));
                                break;
                        case 'i':
                                err = cn_printf(cn, "%d",
                                              task_pid_vnr(current));
                                break;
                        case 'I':
                                err = cn_printf(cn, "%d",
                                              task_pid_nr(current));
                                break;
                        /* uid */
                        case 'u':
                                err = cn_printf(cn, "%d", cred->uid);
                                break;
                        /* gid */
                        case 'g':
                                err = cn_printf(cn, "%d", cred->gid);
                                break;
                        case 'd':
                                err = cn_printf(cn, "%d",
                                        __get_dumpable(cprm->mm_flags));
                                break;
                        /* signal that caused the coredump */
                        case 's':
                                err = cn_printf(cn, "%ld", cprm->siginfo->si_signo);
                                break;
                        /* UNIX time of coredump */
                        case 't': {
                                struct timeval tv;
                                do_gettimeofday(&tv);
                                err = cn_printf(cn, "%lu", tv.tv_sec);
                                break;
                        }
                        /* hostname */
                        case 'h': {
                                char *namestart = cn->corename + cn->used;
                                down_read(&uts_sem);
                                err = cn_printf(cn, "%s",
                                              utsname()->nodename);
                                up_read(&uts_sem);
                                cn_escape(namestart);
                                break;
                        }
                        /* executable */
                        case 'e': {
                                char *commstart = cn->corename + cn->used;
                                err = cn_printf(cn, "%s", current->comm);
                                cn_escape(commstart);
                                break;
                        }
                        case 'E':
                                err = cn_print_exe_file(cn);
                                break;
                        /* core limit size */
                        case 'c':
                                err = cn_printf(cn, "%lu",
                                              rlimit(RLIMIT_CORE));
                                break;
                        default:
                                break;
                        }
                        ++pat_ptr;
                }

                if (err)
                        return err;
        }

        /* Backward compatibility with core_uses_pid:
         *
         * If core_pattern does not include a %p (as is the default)
         * and core_uses_pid is set, then .%pid will be appended to
         * the filename. Do not do this for piped commands. */
        if (!ispipe && !pid_in_pattern && core_uses_pid) {
                err = cn_printf(cn, ".%d", task_tgid_vnr(current));
                if (err)
                        return err;
        }
out:
        return ispipe;
}

static int zap_process(struct task_struct *start, int exit_code)
{
        struct task_struct *t;
        int nr = 0;

        start->signal->group_exit_code = exit_code;
        start->signal->group_stop_count = 0;

        t = start;
        do {
                task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
                if (t != current && t->mm) {
                        sigaddset(&t->pending.signal, SIGKILL);
                        signal_wake_up(t, 1);
                        nr++;
                }
        } while_each_thread(start, t);

        return nr;
}

static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
                        struct core_state *core_state, int exit_code)
{
        struct task_struct *g, *p;
        unsigned long flags;
        int nr = -EAGAIN;

        spin_lock_irq(&tsk->sighand->siglock);
        if (!signal_group_exit(tsk->signal)) {
                mm->core_state = core_state;
                nr = zap_process(tsk, exit_code);
                tsk->signal->group_exit_task = tsk;
                /* ignore all signals except SIGKILL, see prepare_signal() */
                tsk->signal->flags = SIGNAL_GROUP_COREDUMP;
                clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
        }
        spin_unlock_irq(&tsk->sighand->siglock);
        if (unlikely(nr < 0))
                return nr;

        tsk->flags |= PF_DUMPCORE;
        if (atomic_read(&mm->mm_users) == nr + 1)
                goto done;
        /*
         * We should find and kill all tasks which use this mm, and we should
         * count them correctly into ->nr_threads. We don't take tasklist
         * lock, but this is safe wrt:
         *
         * fork:
         *      None of sub-threads can fork after zap_process(leader). All
         *      processes which were created before this point should be
         *      visible to zap_threads() because copy_process() adds the new
         *      process to the tail of init_task.tasks list, and lock/unlock
         *      of ->siglock provides a memory barrier.
         *
         * do_exit:
         *      The caller holds mm->mmap_sem. This means that the task which
         *      uses this mm can't pass exit_mm(), so it can't exit or clear
         *      its ->mm.
         *
         * de_thread:
         *      It does list_replace_rcu(&leader->tasks, &current->tasks),
         *      we must see either old or new leader, this does not matter.
         *      However, it can change p->sighand, so lock_task_sighand(p)
         *      must be used. Since p->mm != NULL and we hold ->mmap_sem
         *      it can't fail.
         *
         *      Note also that "g" can be the old leader with ->mm == NULL
         *      and already unhashed and thus removed from ->thread_group.
         *      This is OK, __unhash_process()->list_del_rcu() does not
         *      clear the ->next pointer, we will find the new leader via
         *      next_thread().
         */
        rcu_read_lock();
        for_each_process(g) {
                if (g == tsk->group_leader)
                        continue;
                if (g->flags & PF_KTHREAD)
                        continue;
                p = g;
                do {
                        if (p->mm) {
                                if (unlikely(p->mm == mm)) {
                                        lock_task_sighand(p, &flags);
                                        nr += zap_process(p, exit_code);
                                        p->signal->flags = SIGNAL_GROUP_EXIT;
                                        unlock_task_sighand(p, &flags);
                                }
                                break;
                        }
                } while_each_thread(g, p);
        }
        rcu_read_unlock();
done:
        atomic_set(&core_state->nr_threads, nr);
        return nr;
}

static int coredump_wait(int exit_code, struct core_state *core_state)
{
        struct task_struct *tsk = current;
        struct mm_struct *mm = tsk->mm;
        int core_waiters = -EBUSY;

        init_completion(&core_state->startup);
        core_state->dumper.task = tsk;
        core_state->dumper.next = NULL;

        down_write(&mm->mmap_sem);
        if (!mm->core_state)
                core_waiters = zap_threads(tsk, mm, core_state, exit_code);
        up_write(&mm->mmap_sem);

        if (core_waiters > 0) {
                struct core_thread *ptr;

                wait_for_completion(&core_state->startup);
                /*
                 * Wait for all the threads to become inactive, so that
                 * all the thread context (extended register state, like
                 * fpu etc) gets copied to the memory.
                 */
                ptr = core_state->dumper.next;
                while (ptr != NULL) {
                        wait_task_inactive(ptr->task, 0);
                        ptr = ptr->next;
                }
        }

        return core_waiters;
}

static void coredump_finish(struct mm_struct *mm, bool core_dumped)
{
        struct core_thread *curr, *next;
        struct task_struct *task;

        spin_lock_irq(&current->sighand->siglock);
        if (core_dumped && !__fatal_signal_pending(current))
                current->signal->group_exit_code |= 0x80;
        current->signal->group_exit_task = NULL;
        current->signal->flags = SIGNAL_GROUP_EXIT;
        spin_unlock_irq(&current->sighand->siglock);

        next = mm->core_state->dumper.next;
        while ((curr = next) != NULL) {
                next = curr->next;
                task = curr->task;
                /*
                 * see exit_mm(), curr->task must not see
                 * ->task == NULL before we read ->next.
                 */
                smp_mb();
                curr->task = NULL;
                wake_up_process(task);
        }

        mm->core_state = NULL;
}

static bool dump_interrupted(void)
{
        /*
         * SIGKILL or freezing() interrupt the coredumping. Perhaps we
         * can do try_to_freeze() and check __fatal_signal_pending(),
         * but then we need to teach dump_write() to restart and clear
         * TIF_SIGPENDING.
         */
        return signal_pending(current);
}

static void wait_for_dump_helpers(struct file *file)
{
        struct pipe_inode_info *pipe = file->private_data;

        pipe_lock(pipe);
        pipe->readers++;
        pipe->writers--;
        wake_up_interruptible_sync(&pipe->wait);
        kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
        pipe_unlock(pipe);

        /*
         * We actually want wait_event_freezable() but then we need
         * to clear TIF_SIGPENDING and improve dump_interrupted().
         */
        wait_event_interruptible(pipe->wait, pipe->readers == 1);

        pipe_lock(pipe);
        pipe->readers--;
        pipe->writers++;
        pipe_unlock(pipe);
}

/*
 * umh_pipe_setup
 * helper function to customize the process used
 * to collect the core in userspace.  Specifically
 * it sets up a pipe and installs it as fd 0 (stdin)
 * for the process.  Returns 0 on success, or
 * PTR_ERR on failure.
 * Note that it also sets the core limit to 1.  This
 * is a special value that we use to trap recursive
 * core dumps
 */
static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
{
        struct file *files[2];
        struct coredump_params *cp = (struct coredump_params *)info->data;
        int err = create_pipe_files(files, 0);
        if (err)
                return err;

        cp->file = files[1];

        err = replace_fd(0, files[0], 0);
        fput(files[0]);
        /* and disallow core files too */
        current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};

        return err;
}

void do_coredump(siginfo_t *siginfo)
{
        struct core_state core_state;
        struct core_name cn;
        struct mm_struct *mm = current->mm;
        struct linux_binfmt * binfmt;
        const struct cred *old_cred;
        struct cred *cred;
        int retval = 0;
        int flag = 0;
        int ispipe;
        struct files_struct *displaced;
        bool need_nonrelative = false;
        bool core_dumped = false;
        static atomic_t core_dump_count = ATOMIC_INIT(0);
        struct coredump_params cprm = {
                .siginfo = siginfo,
                .regs = signal_pt_regs(),
                .limit = rlimit(RLIMIT_CORE),
                /*
                 * We must use the same mm->flags while dumping core to avoid
                 * inconsistency of bit flags, since this flag is not protected
                 * by any locks.
                 */
                .mm_flags = mm->flags,
        };

        audit_core_dumps(siginfo->si_signo);

        binfmt = mm->binfmt;
        if (!binfmt || !binfmt->core_dump)
                goto fail;
        if (!__get_dumpable(cprm.mm_flags))
                goto fail;

        cred = prepare_creds();
        if (!cred)
                goto fail;
        /*
         * We cannot trust fsuid as being the "true" uid of the process
         * nor do we know its entire history. We only know it was tainted
         * so we dump it as root in mode 2, and only into a controlled
         * environment (pipe handler or fully qualified path).
         */
        if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
                /* Setuid core dump mode */
                flag = O_EXCL;          /* Stop rewrite attacks */
                cred->fsuid = GLOBAL_ROOT_UID;  /* Dump root private */
                need_nonrelative = true;
        }

        retval = coredump_wait(siginfo->si_signo, &core_state);
        if (retval < 0)
                goto fail_creds;

        old_cred = override_creds(cred);

        ispipe = format_corename(&cn, &cprm);

        if (ispipe) {
                int dump_count;
                char **helper_argv;
                struct subprocess_info *sub_info;

                if (ispipe < 0) {
                        printk(KERN_WARNING "format_corename failed\n");
                        printk(KERN_WARNING "Aborting core\n");
                        goto fail_corename;
                }

                if (cprm.limit == 1) {
                        /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
                         *
                         * Normally core limits are irrelevant to pipes, since
                         * we're not writing to the file system, but we use
                         * cprm.limit of 1 here as a speacial value, this is a
                         * consistent way to catch recursive crashes.
                         * We can still crash if the core_pattern binary sets
                         * RLIM_CORE = !1, but it runs as root, and can do
                         * lots of stupid things.
                         *
                         * Note that we use task_tgid_vnr here to grab the pid
                         * of the process group leader.  That way we get the
                         * right pid if a thread in a multi-threaded
                         * core_pattern process dies.
                         */
                        printk(KERN_WARNING
                                "Process %d(%s) has RLIMIT_CORE set to 1\n",
                                task_tgid_vnr(current), current->comm);
                        printk(KERN_WARNING "Aborting core\n");
                        goto fail_unlock;
                }
                cprm.limit = RLIM_INFINITY;

                dump_count = atomic_inc_return(&core_dump_count);
                if (core_pipe_limit && (core_pipe_limit < dump_count)) {
                        printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
                               task_tgid_vnr(current), current->comm);
                        printk(KERN_WARNING "Skipping core dump\n");
                        goto fail_dropcount;
                }

                helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
                if (!helper_argv) {
                        printk(KERN_WARNING "%s failed to allocate memory\n",
                               __func__);
                        goto fail_dropcount;
                }

                retval = -ENOMEM;
                sub_info = call_usermodehelper_setup(helper_argv[0],
                                                helper_argv, NULL, GFP_KERNEL,
                                                umh_pipe_setup, NULL, &cprm);
                if (sub_info)
                        retval = call_usermodehelper_exec(sub_info,
                                                          UMH_WAIT_EXEC);

                argv_free(helper_argv);
                if (retval) {
                        printk(KERN_INFO "Core dump to %s pipe failed\n",
                               cn.corename);
                        goto close_fail;
                }
        } else {
                struct inode *inode;

                if (cprm.limit < binfmt->min_coredump)
                        goto fail_unlock;

                if (need_nonrelative && cn.corename[0] != '/') {
                        printk(KERN_WARNING "Pid %d(%s) can only dump core "\
                                "to fully qualified path!\n",
                                task_tgid_vnr(current), current->comm);
                        printk(KERN_WARNING "Skipping core dump\n");
                        goto fail_unlock;
                }

                cprm.file = filp_open(cn.corename,
                                 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
                                 0600);
                if (IS_ERR(cprm.file))
                        goto fail_unlock;

                inode = file_inode(cprm.file);
                if (inode->i_nlink > 1)
                        goto close_fail;
                if (d_unhashed(cprm.file->f_path.dentry))
                        goto close_fail;
                /*
                 * AK: actually i see no reason to not allow this for named
                 * pipes etc, but keep the previous behaviour for now.
                 */
                if (!S_ISREG(inode->i_mode))
                        goto close_fail;
                /*
                 * Dont allow local users get cute and trick others to coredump
                 * into their pre-created files.
                 */
                if (!uid_eq(inode->i_uid, current_fsuid()))
                        goto close_fail;
                if (!cprm.file->f_op || !cprm.file->f_op->write)
                        goto close_fail;
                if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
                        goto close_fail;
        }

        /* get us an unshared descriptor table; almost always a no-op */
        retval = unshare_files(&displaced);
        if (retval)
                goto close_fail;
        if (displaced)
                put_files_struct(displaced);
        if (!dump_interrupted()) {
                file_start_write(cprm.file);
                core_dumped = binfmt->core_dump(&cprm);
                file_end_write(cprm.file);
        }
        if (ispipe && core_pipe_limit)
                wait_for_dump_helpers(cprm.file);
close_fail:
        if (cprm.file)
                filp_close(cprm.file, NULL);
fail_dropcount:
        if (ispipe)
                atomic_dec(&core_dump_count);
fail_unlock:
        kfree(cn.corename);
fail_corename:
        coredump_finish(mm, core_dumped);
        revert_creds(old_cred);
fail_creds:
        put_cred(cred);
fail:
        return;
}

/*
 * Core dumping helper functions.  These are the only things you should
 * do on a core-file: use only these functions to write out all the
 * necessary info.
 */
int dump_write(struct file *file, const void *addr, int nr)
{
        return !dump_interrupted() &&
                access_ok(VERIFY_READ, addr, nr) &&
                file->f_op->write(file, addr, nr, &file->f_pos) == nr;
}
EXPORT_SYMBOL(dump_write);

int dump_seek(struct file *file, loff_t off)
{
        int ret = 1;

        if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
                if (dump_interrupted() ||
                    file->f_op->llseek(file, off, SEEK_CUR) < 0)
                        return 0;
        } else {
                char *buf = (char *)get_zeroed_page(GFP_KERNEL);

                if (!buf)
                        return 0;
                while (off > 0) {
                        unsigned long n = off;

                        if (n > PAGE_SIZE)
                                n = PAGE_SIZE;
                        if (!dump_write(file, buf, n)) {
                                ret = 0;
                                break;
                        }
                        off -= n;
                }
                free_page((unsigned long)buf);
        }
        return ret;
}
EXPORT_SYMBOL(dump_seek);