// 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; retry: error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); 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) { struct fd f = fdget_raw(fd); int error = -EBADF; if (f.file) { error = vfs_statfs(&f.file->f_path, st); fdput(f); } return error; } 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