// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 * Copyright 2005-2006 Ian Kent <raven@themaw.net>
 */

#include <linux/seq_file.h>
#include <linux/pagemap.h>

#include "autofs_i.h"

struct autofs_info *autofs_new_ino(struct autofs_sb_info *sbi)
{
        struct autofs_info *ino;

        ino = kzalloc_obj(*ino);
        if (ino) {
                INIT_LIST_HEAD(&ino->active);
                INIT_LIST_HEAD(&ino->expiring);
                ino->last_used = jiffies;
                ino->sbi = sbi;
                ino->exp_timeout = -1;
                ino->count = 1;
        }
        return ino;
}

void autofs_clean_ino(struct autofs_info *ino)
{
        ino->uid = GLOBAL_ROOT_UID;
        ino->gid = GLOBAL_ROOT_GID;
        ino->exp_timeout = -1;
        ino->last_used = jiffies;
}

void autofs_free_ino(struct autofs_info *ino)
{
        kfree_rcu(ino, rcu);
}

void autofs_kill_sb(struct super_block *sb)
{
        struct autofs_sb_info *sbi = autofs_sbi(sb);

        /*
         * In the event of a failure in get_sb_nodev the superblock
         * info is not present so nothing else has been setup, so
         * just call kill_anon_super when we are called from
         * deactivate_super.
         */
        if (sbi) {
                /* Free wait queues, close pipe */
                autofs_catatonic_mode(sbi);
                put_pid(sbi->oz_pgrp);
        }

        pr_debug("shutting down\n");
        kill_anon_super(sb);
        if (sbi)
                kfree_rcu(sbi, rcu);
}

static int autofs_show_options(struct seq_file *m, struct dentry *root)
{
        struct autofs_sb_info *sbi = autofs_sbi(root->d_sb);
        struct inode *root_inode = d_inode(root->d_sb->s_root);

        if (!sbi)
                return 0;

        seq_printf(m, ",fd=%d", sbi->pipefd);
        if (!uid_eq(root_inode->i_uid, GLOBAL_ROOT_UID))
                seq_printf(m, ",uid=%u",
                        from_kuid_munged(&init_user_ns, root_inode->i_uid));
        if (!gid_eq(root_inode->i_gid, GLOBAL_ROOT_GID))
                seq_printf(m, ",gid=%u",
                        from_kgid_munged(&init_user_ns, root_inode->i_gid));
        seq_printf(m, ",pgrp=%d", pid_vnr(sbi->oz_pgrp));
        seq_printf(m, ",timeout=%lu", sbi->exp_timeout/HZ);
        seq_printf(m, ",minproto=%d", sbi->min_proto);
        seq_printf(m, ",maxproto=%d", sbi->max_proto);

        if (autofs_type_offset(sbi->type))
                seq_puts(m, ",offset");
        else if (autofs_type_direct(sbi->type))
                seq_puts(m, ",direct");
        else
                seq_puts(m, ",indirect");
        if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE)
                seq_puts(m, ",strictexpire");
        if (sbi->flags & AUTOFS_SBI_IGNORE)
                seq_puts(m, ",ignore");
#ifdef CONFIG_CHECKPOINT_RESTORE
        if (sbi->pipe)
                seq_printf(m, ",pipe_ino=%ld", file_inode(sbi->pipe)->i_ino);
        else
                seq_puts(m, ",pipe_ino=-1");
#endif
        return 0;
}

static void autofs_evict_inode(struct inode *inode)
{
        clear_inode(inode);
        kfree(inode->i_private);
}

static const struct super_operations autofs_sops = {
        .statfs         = simple_statfs,
        .show_options   = autofs_show_options,
        .evict_inode    = autofs_evict_inode,
};

enum {
        Opt_direct,
        Opt_fd,
        Opt_gid,
        Opt_ignore,
        Opt_indirect,
        Opt_maxproto,
        Opt_minproto,
        Opt_offset,
        Opt_pgrp,
        Opt_strictexpire,
        Opt_uid,
};

const struct fs_parameter_spec autofs_param_specs[] = {
        fsparam_flag    ("direct",              Opt_direct),
        fsparam_fd      ("fd",                  Opt_fd),
        fsparam_gid     ("gid",                 Opt_gid),
        fsparam_flag    ("ignore",              Opt_ignore),
        fsparam_flag    ("indirect",            Opt_indirect),
        fsparam_u32     ("maxproto",            Opt_maxproto),
        fsparam_u32     ("minproto",            Opt_minproto),
        fsparam_flag    ("offset",              Opt_offset),
        fsparam_u32     ("pgrp",                Opt_pgrp),
        fsparam_flag    ("strictexpire",        Opt_strictexpire),
        fsparam_uid     ("uid",                 Opt_uid),
        {}
};

struct autofs_fs_context {
        kuid_t  uid;
        kgid_t  gid;
        int     pgrp;
        bool    pgrp_set;
};

/*
 * Open the fd.  We do it here rather than in get_tree so that it's done in the
 * context of the system call that passed the data and not the one that
 * triggered the superblock creation, lest the fd gets reassigned.
 */
static int autofs_parse_fd(struct fs_context *fc, struct autofs_sb_info *sbi,
                           struct fs_parameter *param,
                           struct fs_parse_result *result)
{
        struct file *pipe;
        int ret;

        if (param->type == fs_value_is_file) {
                /* came through the new api */
                pipe = param->file;
                param->file = NULL;
        } else {
                pipe = fget(result->uint_32);
        }
        if (!pipe) {
                errorf(fc, "could not open pipe file descriptor");
                return -EBADF;
        }

        ret = autofs_check_pipe(pipe);
        if (ret < 0) {
                errorf(fc, "Invalid/unusable pipe");
                fput(pipe);
                return -EBADF;
        }

        autofs_set_packet_pipe_flags(pipe);

        if (sbi->pipe)
                fput(sbi->pipe);

        sbi->pipefd = result->uint_32;
        sbi->pipe = pipe;

        return 0;
}

static int autofs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
        struct autofs_fs_context *ctx = fc->fs_private;
        struct autofs_sb_info *sbi = fc->s_fs_info;
        struct fs_parse_result result;
        int opt;

        opt = fs_parse(fc, autofs_param_specs, param, &result);
        if (opt < 0)
                return opt;

        switch (opt) {
        case Opt_fd:
                return autofs_parse_fd(fc, sbi, param, &result);
        case Opt_uid:
                ctx->uid = result.uid;
                break;
        case Opt_gid:
                ctx->gid = result.gid;
                break;
        case Opt_pgrp:
                ctx->pgrp = result.uint_32;
                ctx->pgrp_set = true;
                break;
        case Opt_minproto:
                sbi->min_proto = result.uint_32;
                break;
        case Opt_maxproto:
                sbi->max_proto = result.uint_32;
                break;
        case Opt_indirect:
                set_autofs_type_indirect(&sbi->type);
                break;
        case Opt_direct:
                set_autofs_type_direct(&sbi->type);
                break;
        case Opt_offset:
                set_autofs_type_offset(&sbi->type);
                break;
        case Opt_strictexpire:
                sbi->flags |= AUTOFS_SBI_STRICTEXPIRE;
                break;
        case Opt_ignore:
                sbi->flags |= AUTOFS_SBI_IGNORE;
        }

        return 0;
}

static struct autofs_sb_info *autofs_alloc_sbi(void)
{
        struct autofs_sb_info *sbi;

        sbi = kzalloc_obj(*sbi);
        if (!sbi)
                return NULL;

        sbi->magic = AUTOFS_SBI_MAGIC;
        sbi->flags = AUTOFS_SBI_CATATONIC;
        sbi->min_proto = AUTOFS_MIN_PROTO_VERSION;
        sbi->max_proto = AUTOFS_MAX_PROTO_VERSION;
        sbi->pipefd = -1;
        sbi->mnt_ns_id = to_ns_common(current->nsproxy->mnt_ns)->ns_id;

        set_autofs_type_indirect(&sbi->type);
        mutex_init(&sbi->wq_mutex);
        mutex_init(&sbi->pipe_mutex);
        spin_lock_init(&sbi->fs_lock);
        spin_lock_init(&sbi->lookup_lock);
        INIT_LIST_HEAD(&sbi->active_list);
        INIT_LIST_HEAD(&sbi->expiring_list);

        return sbi;
}

static int autofs_validate_protocol(struct fs_context *fc)
{
        struct autofs_sb_info *sbi = fc->s_fs_info;

        /* Test versions first */
        if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
            sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) {
                errorf(fc, "kernel does not match daemon version "
                       "daemon (%d, %d) kernel (%d, %d)\n",
                       sbi->min_proto, sbi->max_proto,
                       AUTOFS_MIN_PROTO_VERSION, AUTOFS_MAX_PROTO_VERSION);
                return -EINVAL;
        }

        /* Establish highest kernel protocol version */
        if (sbi->max_proto > AUTOFS_MAX_PROTO_VERSION)
                sbi->version = AUTOFS_MAX_PROTO_VERSION;
        else
                sbi->version = sbi->max_proto;

        switch (sbi->version) {
        case 4:
                sbi->sub_version = 7;
                break;
        case 5:
                sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
                break;
        default:
                sbi->sub_version = 0;
        }

        return 0;
}

static int autofs_fill_super(struct super_block *s, struct fs_context *fc)
{
        struct autofs_fs_context *ctx = fc->fs_private;
        struct autofs_sb_info *sbi = s->s_fs_info;
        struct inode *root_inode;
        struct autofs_info *ino;

        pr_debug("starting up, sbi = %p\n", sbi);

        sbi->sb = s;
        s->s_blocksize = 1024;
        s->s_blocksize_bits = 10;
        s->s_magic = AUTOFS_SUPER_MAGIC;
        s->s_op = &autofs_sops;
        set_default_d_op(s, &autofs_dentry_operations);
        s->s_time_gran = 1;

        /*
         * Get the root inode and dentry, but defer checking for errors.
         */
        ino = autofs_new_ino(sbi);
        if (!ino)
                return -ENOMEM;

        root_inode = autofs_get_inode(s, S_IFDIR | 0755);
        if (!root_inode)
                return -ENOMEM;

        root_inode->i_uid = ctx->uid;
        root_inode->i_gid = ctx->gid;
        root_inode->i_fop = &autofs_root_operations;
        root_inode->i_op = &autofs_dir_inode_operations;

        s->s_root = d_make_root(root_inode);
        if (unlikely(!s->s_root)) {
                autofs_free_ino(ino);
                return -ENOMEM;
        }
        s->s_root->d_fsdata = ino;

        if (ctx->pgrp_set) {
                sbi->oz_pgrp = find_get_pid(ctx->pgrp);
                if (!sbi->oz_pgrp)
                        return invalf(fc, "Could not find process group %d",
                                      ctx->pgrp);
        } else
                sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID);

        if (autofs_type_trigger(sbi->type))
                /* s->s_root won't be contended so there's little to
                 * be gained by not taking the d_lock when setting
                 * d_flags, even when a lot mounts are being done.
                 */
                managed_dentry_set_managed(s->s_root);

        pr_debug("pipe fd = %d, pgrp = %u\n",
                 sbi->pipefd, pid_nr(sbi->oz_pgrp));

        sbi->flags &= ~AUTOFS_SBI_CATATONIC;
        return 0;
}

/*
 * Validate the parameters and then request a superblock.
 */
static int autofs_get_tree(struct fs_context *fc)
{
        struct autofs_sb_info *sbi = fc->s_fs_info;
        int ret;

        ret = autofs_validate_protocol(fc);
        if (ret)
                return ret;

        if (sbi->pipefd < 0)
                return invalf(fc, "No control pipe specified");

        return get_tree_nodev(fc, autofs_fill_super);
}

static void autofs_free_fc(struct fs_context *fc)
{
        struct autofs_fs_context *ctx = fc->fs_private;
        struct autofs_sb_info *sbi = fc->s_fs_info;

        if (sbi) {
                if (sbi->pipe)
                        fput(sbi->pipe);
                kfree(sbi);
        }
        kfree(ctx);
}

static const struct fs_context_operations autofs_context_ops = {
        .free           = autofs_free_fc,
        .parse_param    = autofs_parse_param,
        .get_tree       = autofs_get_tree,
};

/*
 * Set up the filesystem mount context.
 */
int autofs_init_fs_context(struct fs_context *fc)
{
        struct autofs_fs_context *ctx;
        struct autofs_sb_info *sbi;

        ctx = kzalloc_obj(struct autofs_fs_context);
        if (!ctx)
                goto nomem;

        ctx->uid = current_uid();
        ctx->gid = current_gid();

        sbi = autofs_alloc_sbi();
        if (!sbi)
                goto nomem_ctx;

        fc->fs_private = ctx;
        fc->s_fs_info = sbi;
        fc->ops = &autofs_context_ops;
        return 0;

nomem_ctx:
        kfree(ctx);
nomem:
        return -ENOMEM;
}

struct inode *autofs_get_inode(struct super_block *sb, umode_t mode)
{
        struct inode *inode = new_inode(sb);

        if (inode == NULL)
                return NULL;

        inode->i_mode = mode;
        if (sb->s_root) {
                inode->i_uid = d_inode(sb->s_root)->i_uid;
                inode->i_gid = d_inode(sb->s_root)->i_gid;
        }
        simple_inode_init_ts(inode);
        inode->i_ino = get_next_ino();

        if (S_ISDIR(mode)) {
                set_nlink(inode, 2);
                inode->i_op = &autofs_dir_inode_operations;
                inode->i_fop = &autofs_dir_operations;
        } else if (S_ISLNK(mode)) {
                inode->i_op = &autofs_symlink_inode_operations;
        } else
                WARN_ON(1);

        return inode;
}