// SPDX-License-Identifier: GPL-2.0
#include <linux/syscalls.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/statfs.h>
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/compat.h>
#include "internal.h"

static int flags_by_mnt(int mnt_flags)
{
        int flags = 0;

        if (mnt_flags & MNT_READONLY)
                flags |= ST_RDONLY;
        if (mnt_flags & MNT_NOSUID)
                flags |= ST_NOSUID;
        if (mnt_flags & MNT_NODEV)
                flags |= ST_NODEV;
        if (mnt_flags & MNT_NOEXEC)
                flags |= ST_NOEXEC;
        if (mnt_flags & MNT_NOATIME)
                flags |= ST_NOATIME;
        if (mnt_flags & MNT_NODIRATIME)
                flags |= ST_NODIRATIME;
        if (mnt_flags & MNT_RELATIME)
                flags |= ST_RELATIME;
        if (mnt_flags & MNT_NOSYMFOLLOW)
                flags |= ST_NOSYMFOLLOW;
        return flags;
}

static int flags_by_sb(int s_flags)
{
        int flags = 0;
        if (s_flags & SB_SYNCHRONOUS)
                flags |= ST_SYNCHRONOUS;
        if (s_flags & SB_MANDLOCK)
                flags |= ST_MANDLOCK;
        if (s_flags & SB_RDONLY)
                flags |= ST_RDONLY;
        return flags;
}

static int calculate_f_flags(struct vfsmount *mnt)
{
        return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
                flags_by_sb(mnt->mnt_sb->s_flags);
}

static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
{
        int retval;

        if (!dentry->d_sb->s_op->statfs)
                return -ENOSYS;

        memset(buf, 0, sizeof(*buf));
        retval = security_sb_statfs(dentry);
        if (retval)
                return retval;
        retval = dentry->d_sb->s_op->statfs(dentry, buf);
        if (retval == 0 && buf->f_frsize == 0)
                buf->f_frsize = buf->f_bsize;
        return retval;
}

int vfs_get_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
{
        struct kstatfs st;
        int error;

        error = statfs_by_dentry(dentry, &st);
        if (error)
                return error;

        *fsid = st.f_fsid;
        return 0;
}
EXPORT_SYMBOL(vfs_get_fsid);

int vfs_statfs(const struct path *path, struct kstatfs *buf)
{
        int error;

        error = statfs_by_dentry(path->dentry, buf);
        if (!error)
                buf->f_flags = calculate_f_flags(path->mnt);
        return error;
}
EXPORT_SYMBOL(vfs_statfs);

int user_statfs(const char __user *pathname, struct kstatfs *st)
{
        struct path path;
        int error;
        unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT;
        CLASS(filename, name)(pathname);
retry:
        error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL);
        if (!error) {
                error = vfs_statfs(&path, st);
                path_put(&path);
                if (retry_estale(error, lookup_flags)) {
                        lookup_flags |= LOOKUP_REVAL;
                        goto retry;
                }
        }
        return error;
}

int fd_statfs(int fd, struct kstatfs *st)
{
        CLASS(fd_raw, f)(fd);

        if (fd_empty(f))
                return -EBADF;
        return vfs_statfs(&fd_file(f)->f_path, st);
}

static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
{
        struct statfs buf;

        if (sizeof(buf) == sizeof(*st))
                memcpy(&buf, st, sizeof(*st));
        else {
                memset(&buf, 0, sizeof(buf));
                if (sizeof buf.f_blocks == 4) {
                        if ((st->f_blocks | st->f_bfree | st->f_bavail |
                             st->f_bsize | st->f_frsize) &
                            0xffffffff00000000ULL)
                                return -EOVERFLOW;
                        /*
                         * f_files and f_ffree may be -1; it's okay to stuff
                         * that into 32 bits
                         */
                        if (st->f_files != -1 &&
                            (st->f_files & 0xffffffff00000000ULL))
                                return -EOVERFLOW;
                        if (st->f_ffree != -1 &&
                            (st->f_ffree & 0xffffffff00000000ULL))
                                return -EOVERFLOW;
                }

                buf.f_type = st->f_type;
                buf.f_bsize = st->f_bsize;
                buf.f_blocks = st->f_blocks;
                buf.f_bfree = st->f_bfree;
                buf.f_bavail = st->f_bavail;
                buf.f_files = st->f_files;
                buf.f_ffree = st->f_ffree;
                buf.f_fsid = st->f_fsid;
                buf.f_namelen = st->f_namelen;
                buf.f_frsize = st->f_frsize;
                buf.f_flags = st->f_flags;
        }
        if (copy_to_user(p, &buf, sizeof(buf)))
                return -EFAULT;
        return 0;
}

static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
{
        struct statfs64 buf;
        if (sizeof(buf) == sizeof(*st))
                memcpy(&buf, st, sizeof(*st));
        else {
                memset(&buf, 0, sizeof(buf));
                buf.f_type = st->f_type;
                buf.f_bsize = st->f_bsize;
                buf.f_blocks = st->f_blocks;
                buf.f_bfree = st->f_bfree;
                buf.f_bavail = st->f_bavail;
                buf.f_files = st->f_files;
                buf.f_ffree = st->f_ffree;
                buf.f_fsid = st->f_fsid;
                buf.f_namelen = st->f_namelen;
                buf.f_frsize = st->f_frsize;
                buf.f_flags = st->f_flags;
        }
        if (copy_to_user(p, &buf, sizeof(buf)))
                return -EFAULT;
        return 0;
}

SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
{
        struct kstatfs st;
        int error = user_statfs(pathname, &st);
        if (!error)
                error = do_statfs_native(&st, buf);
        return error;
}

SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
{
        struct kstatfs st;
        int error;
        if (sz != sizeof(*buf))
                return -EINVAL;
        error = user_statfs(pathname, &st);
        if (!error)
                error = do_statfs64(&st, buf);
        return error;
}

SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
{
        struct kstatfs st;
        int error = fd_statfs(fd, &st);
        if (!error)
                error = do_statfs_native(&st, buf);
        return error;
}

SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
{
        struct kstatfs st;
        int error;

        if (sz != sizeof(*buf))
                return -EINVAL;

        error = fd_statfs(fd, &st);
        if (!error)
                error = do_statfs64(&st, buf);
        return error;
}

static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
{
        struct super_block *s = user_get_super(dev, false);
        int err;
        if (!s)
                return -EINVAL;

        err = statfs_by_dentry(s->s_root, sbuf);
        drop_super(s);
        return err;
}

SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
{
        struct ustat tmp;
        struct kstatfs sbuf;
        int err = vfs_ustat(new_decode_dev(dev), &sbuf);
        if (err)
                return err;

        memset(&tmp,0,sizeof(struct ustat));
        tmp.f_tfree = sbuf.f_bfree;
        if (IS_ENABLED(CONFIG_ARCH_32BIT_USTAT_F_TINODE))
                tmp.f_tinode = min_t(u64, sbuf.f_ffree, UINT_MAX);
        else
                tmp.f_tinode = sbuf.f_ffree;

        return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
}

#ifdef CONFIG_COMPAT
static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
{
        struct compat_statfs buf;
        if (sizeof ubuf->f_blocks == 4) {
                if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
                     kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
                        return -EOVERFLOW;
                /* f_files and f_ffree may be -1; it's okay
                 * to stuff that into 32 bits */
                if (kbuf->f_files != 0xffffffffffffffffULL
                 && (kbuf->f_files & 0xffffffff00000000ULL))
                        return -EOVERFLOW;
                if (kbuf->f_ffree != 0xffffffffffffffffULL
                 && (kbuf->f_ffree & 0xffffffff00000000ULL))
                        return -EOVERFLOW;
        }
        memset(&buf, 0, sizeof(struct compat_statfs));
        buf.f_type = kbuf->f_type;
        buf.f_bsize = kbuf->f_bsize;
        buf.f_blocks = kbuf->f_blocks;
        buf.f_bfree = kbuf->f_bfree;
        buf.f_bavail = kbuf->f_bavail;
        buf.f_files = kbuf->f_files;
        buf.f_ffree = kbuf->f_ffree;
        buf.f_namelen = kbuf->f_namelen;
        buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
        buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
        buf.f_frsize = kbuf->f_frsize;
        buf.f_flags = kbuf->f_flags;
        if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
                return -EFAULT;
        return 0;
}

/*
 * The following statfs calls are copies of code from fs/statfs.c and
 * should be checked against those from time to time
 */
COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
{
        struct kstatfs tmp;
        int error = user_statfs(pathname, &tmp);
        if (!error)
                error = put_compat_statfs(buf, &tmp);
        return error;
}

COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
{
        struct kstatfs tmp;
        int error = fd_statfs(fd, &tmp);
        if (!error)
                error = put_compat_statfs(buf, &tmp);
        return error;
}

static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
{
        struct compat_statfs64 buf;

        if ((kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
                return -EOVERFLOW;

        memset(&buf, 0, sizeof(struct compat_statfs64));
        buf.f_type = kbuf->f_type;
        buf.f_bsize = kbuf->f_bsize;
        buf.f_blocks = kbuf->f_blocks;
        buf.f_bfree = kbuf->f_bfree;
        buf.f_bavail = kbuf->f_bavail;
        buf.f_files = kbuf->f_files;
        buf.f_ffree = kbuf->f_ffree;
        buf.f_namelen = kbuf->f_namelen;
        buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
        buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
        buf.f_frsize = kbuf->f_frsize;
        buf.f_flags = kbuf->f_flags;
        if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
                return -EFAULT;
        return 0;
}

int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
{
        struct kstatfs tmp;
        int error;

        if (sz != sizeof(*buf))
                return -EINVAL;

        error = user_statfs(pathname, &tmp);
        if (!error)
                error = put_compat_statfs64(buf, &tmp);
        return error;
}

COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
{
        return kcompat_sys_statfs64(pathname, sz, buf);
}

int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
{
        struct kstatfs tmp;
        int error;

        if (sz != sizeof(*buf))
                return -EINVAL;

        error = fd_statfs(fd, &tmp);
        if (!error)
                error = put_compat_statfs64(buf, &tmp);
        return error;
}

COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
{
        return kcompat_sys_fstatfs64(fd, sz, buf);
}

/*
 * This is a copy of sys_ustat, just dealing with a structure layout.
 * Given how simple this syscall is that apporach is more maintainable
 * than the various conversion hacks.
 */
COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
{
        struct compat_ustat tmp;
        struct kstatfs sbuf;
        int err = vfs_ustat(new_decode_dev(dev), &sbuf);
        if (err)
                return err;

        memset(&tmp, 0, sizeof(struct compat_ustat));
        tmp.f_tfree = sbuf.f_bfree;
        tmp.f_tinode = sbuf.f_ffree;
        if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
                return -EFAULT;
        return 0;
}
#endif