Re: [PATCH] fs/ntfs3: Add windows_names mount option

From: Kari Argillander
Date: Sun Oct 09 2022 - 08:24:55 EST

On Fri, 7 Oct 2022 at 14:55, Daniel Pinto <danielpinto52@xxxxxxxxx> wrote:
>
> When enabled, the windows_names mount option prevents the creation
> of files or directories with names not allowed by Windows. Use
> the same option name as NTFS-3G for compatibility.

Can you also add this mount option to documentation.

> Signed-off-by: Daniel Pinto <danielpinto52@xxxxxxxxx>
> ---
> fs/ntfs3/frecord.c | 7 ++-
> fs/ntfs3/fsntfs.c | 104 +++++++++++++++++++++++++++++++++++++++++++++
> fs/ntfs3/inode.c | 7 +++
> fs/ntfs3/ntfs_fs.h | 2 +
> fs/ntfs3/super.c | 7 +++
> 5 files changed, 126 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ntfs3/frecord.c b/fs/ntfs3/frecord.c
> index 70a80f9412f7..ce5e8f3b1aca 100644
> --- a/fs/ntfs3/frecord.c
> +++ b/fs/ntfs3/frecord.c
> @@ -3011,6 +3011,7 @@ int ni_add_name(struct ntfs_inode *dir_ni, struct ntfs_inode *ni,
> struct NTFS_DE *de)
> {
> int err;
> + struct ntfs_sb_info *sbi = ni->mi.sbi;
> struct ATTRIB *attr;
> struct ATTR_LIST_ENTRY *le;
> struct mft_inode *mi;
> @@ -3018,6 +3019,10 @@ int ni_add_name(struct ntfs_inode *dir_ni, struct ntfs_inode *ni,
> struct ATTR_FILE_NAME *de_name = (struct ATTR_FILE_NAME *)(de + 1);
> u16 de_key_size = le16_to_cpu(de->key_size);
>
> + if (sbi->options->windows_names &&
> + !valid_windows_name(sbi, (struct le_str *)&de_name->name_len))
> + return -EINVAL;
> +
> mi_get_ref(&ni->mi, &de->ref);
> mi_get_ref(&dir_ni->mi, &de_name->home);
>
> @@ -3036,7 +3041,7 @@ int ni_add_name(struct ntfs_inode *dir_ni, struct ntfs_inode *ni,
> memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), de_name, de_key_size);
>
> /* Insert new name into directory. */
> - err = indx_insert_entry(&dir_ni->dir, dir_ni, de, ni->mi.sbi, NULL, 0);
> + err = indx_insert_entry(&dir_ni->dir, dir_ni, de, sbi, NULL, 0);
> if (err)
> ni_remove_attr_le(ni, attr, mi, le);
>
> diff --git a/fs/ntfs3/fsntfs.c b/fs/ntfs3/fsntfs.c
> index 4ed15f64b17f..674b644e1070 100644
> --- a/fs/ntfs3/fsntfs.c
> +++ b/fs/ntfs3/fsntfs.c
> @@ -98,6 +98,30 @@ const __le16 WOF_NAME[17] = {
> };
> #endif
>
> +static const __le16 CON_NAME[3] = {
> + cpu_to_le16('C'), cpu_to_le16('O'), cpu_to_le16('N'),
> +};
> +
> +static const __le16 NUL_NAME[3] = {
> + cpu_to_le16('N'), cpu_to_le16('U'), cpu_to_le16('L'),
> +};
> +
> +static const __le16 AUX_NAME[3] = {
> + cpu_to_le16('A'), cpu_to_le16('U'), cpu_to_le16('X'),
> +};
> +
> +static const __le16 PRN_NAME[3] = {
> + cpu_to_le16('P'), cpu_to_le16('R'), cpu_to_le16('N'),
> +};
> +
> +static const __le16 COM_NAME[3] = {
> + cpu_to_le16('C'), cpu_to_le16('O'), cpu_to_le16('M'),
> +};
> +
> +static const __le16 LPT_NAME[3] = {
> + cpu_to_le16('L'), cpu_to_le16('P'), cpu_to_le16('T'),
> +};
> +
> // clang-format on
>
> /*
> @@ -2502,3 +2526,83 @@ int run_deallocate(struct ntfs_sb_info *sbi, struct runs_tree *run, bool trim)
>
> return 0;
> }
> +
> +static inline bool name_has_forbidden_chars(const struct le_str *fname)
> +{
> + int i, ch;
> +
> + /* check for forbidden chars */
> + for (i = 0; i < fname->len; ++i) {
> + ch = le16_to_cpu(fname->name[i]);
> +
> + /* control chars */
> + if (ch < 0x20)
> + return true;
> +
> + switch (ch) {
> + /* disallowed by Windows */
> + case '\\':
> + case '/':
> + case ':':
> + case '*':
> + case '?':
> + case '<':
> + case '>':
> + case '|':
> + case '\"':
> + return true;
> +
> + default:
> + /* allowed char */
> + break;
> + }
> + }
> +
> + /* file names cannot end with space or . */
> + if (fname->len > 0) {
> + ch = le16_to_cpu(fname->name[fname->len - 1]);
> + if (ch == ' ' || ch == '.')
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static inline bool is_reserved_name(struct ntfs_sb_info *sbi,
> + const struct le_str *fname)
> +{
> + int port_digit;
> + const __le16 *name = fname->name;
> + int len = fname->len;
> + u16 *upcase = sbi->upcase;
> +
> + /* check for 3 chars reserved names (device names) */
> + /* name by itself or with any extension is forbidden */
> + if (len == 3 || (len > 3 && le16_to_cpu(name[3]) == '.'))
> + if (!ntfs_cmp_names(name, 3, CON_NAME, 3, upcase, false) ||
> + !ntfs_cmp_names(name, 3, NUL_NAME, 3, upcase, false) ||
> + !ntfs_cmp_names(name, 3, AUX_NAME, 3, upcase, false) ||
> + !ntfs_cmp_names(name, 3, PRN_NAME, 3, upcase, false))
> + return true;
> +
> + /* check for 4 chars reserved names (port name followed by 1..9) */
> + /* name by itself or with any extension is forbidden */
> + if (len == 4 || (len > 4 && le16_to_cpu(name[4]) == '.')) {
> + port_digit = le16_to_cpu(name[3]);
> + if (port_digit >= '1' && port_digit <= '9')
> + if (!ntfs_cmp_names(name, 3, COM_NAME, 3, upcase, false) ||
> + !ntfs_cmp_names(name, 3, LPT_NAME, 3, upcase, false))
> + return true;
> + }
> +
> + return false;
> +}
> +
> +/*
> + * valid_windows_name - Check if a file name is valid in Windows.
> + */
> +bool valid_windows_name(struct ntfs_sb_info *sbi, const struct le_str *fname)
> +{
> + return !name_has_forbidden_chars(fname) &&
> + !is_reserved_name(sbi, fname);
> +}
> diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
> index e9cf00d14733..4eb298e2ee98 100644
> --- a/fs/ntfs3/inode.c
> +++ b/fs/ntfs3/inode.c
> @@ -1361,6 +1361,13 @@ struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,
> mi_get_ref(&ni->mi, &new_de->ref);
>
> fname = (struct ATTR_FILE_NAME *)(new_de + 1);
> +
> + if (sbi->options->windows_names &&
> + !valid_windows_name(sbi, (struct le_str *)&fname->name_len)) {
> + err = -EINVAL;
> + goto out4;
> + }
> +
> mi_get_ref(&dir_ni->mi, &fname->home);
> fname->dup.cr_time = fname->dup.m_time = fname->dup.c_time =
> fname->dup.a_time = std5->cr_time;
> diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
> index 6c1c7ef3b2d6..ebfb720fc4fd 100644
> --- a/fs/ntfs3/ntfs_fs.h
> +++ b/fs/ntfs3/ntfs_fs.h
> @@ -98,6 +98,7 @@ struct ntfs_mount_options {
> unsigned showmeta : 1; /* Show meta files. */
> unsigned nohidden : 1; /* Do not show hidden files. */
> unsigned hide_dot_files : 1; /* Set hidden flag on dot files. */
> + unsigned windows_names : 1; /* Disallow names forbidden by Windows. */
> unsigned force : 1; /* RW mount dirty volume. */
> unsigned noacsrules : 1; /* Exclude acs rules. */
> unsigned prealloc : 1; /* Preallocate space when file is growing. */
> @@ -645,6 +646,7 @@ int ntfs_remove_reparse(struct ntfs_sb_info *sbi, __le32 rtag,
> const struct MFT_REF *ref);
> void mark_as_free_ex(struct ntfs_sb_info *sbi, CLST lcn, CLST len, bool trim);
> int run_deallocate(struct ntfs_sb_info *sbi, struct runs_tree *run, bool trim);
> +bool valid_windows_name(struct ntfs_sb_info *sbi, const struct le_str *name);
>
> /* Globals from index.c */
> int indx_used_bit(struct ntfs_index *indx, struct ntfs_inode *ni, size_t *bit);
> diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
> index 1e2c04e48f98..6f3485fad417 100644
> --- a/fs/ntfs3/super.c
> +++ b/fs/ntfs3/super.c
> @@ -248,6 +248,7 @@ enum Opt {
> Opt_sparse,
> Opt_nohidden,
> Opt_hide_dot_files,
> + Opt_windows_names,
> Opt_showmeta,
> Opt_acl,
> Opt_iocharset,
> @@ -269,6 +270,7 @@ static const struct fs_parameter_spec ntfs_fs_parameters[] = {
> fsparam_flag_no("sparse", Opt_sparse),
> fsparam_flag_no("hidden", Opt_nohidden),
> fsparam_flag_no("hidedotfiles", Opt_hide_dot_files),
> + fsparam_flag_no("windows_names", Opt_windows_names),
> fsparam_flag_no("acl", Opt_acl),
> fsparam_flag_no("showmeta", Opt_showmeta),
> fsparam_flag_no("prealloc", Opt_prealloc),
> @@ -361,6 +363,9 @@ static int ntfs_fs_parse_param(struct fs_context *fc,
> case Opt_hide_dot_files:
> opts->hide_dot_files = result.negated ? 1 : 0;
> break;
> + case Opt_windows_names:
> + opts->windows_names = result.negated ? 0 : 1;
> + break;
> case Opt_acl:
> if (!result.negated)
> #ifdef CONFIG_NTFS3_FS_POSIX_ACL
> @@ -561,6 +566,8 @@ static int ntfs_show_options(struct seq_file *m, struct dentry *root)
> seq_puts(m, ",showmeta");
> if (opts->nohidden)
> seq_puts(m, ",nohidden");
> + if (opts->windows_names)
> + seq_puts(m, ",windows_names");
> if (opts->force)
> seq_puts(m, ",force");
> if (opts->noacsrules)
>