Create a helper function for filesystems do the checks required for
casefold directories and strict encoding.
Suggested-by: Gabriel Krisman Bertazi <gabriel@xxxxxxxxxx>
Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
---
Changes from v2:
- Moved function to libfs and adpated its name
- Wrapped at 72 chars column
- Decomposed the big if (...) to be more clear
---
fs/libfs.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 1 +
2 files changed, 39 insertions(+)
diff --git a/fs/libfs.c b/fs/libfs.c
index 8aa34870449f..99fb36b48708 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1928,6 +1928,44 @@ int generic_ci_match(const struct inode *parent,
return !res;
}
EXPORT_SYMBOL(generic_ci_match);
+
+/**
+ * generic_ci_validate_strict_name - Check if a given name is suitable
+ * for a directory
+ *
+ * This functions checks if the proposed filename is valid for the
+ * parent directory. That means that only valid UTF-8 filenames will be
+ * accepted for casefold directories from filesystems created with the
+ * strict encoding flag. That also means that any name will be
+ * accepted for directories that doesn't have casefold enabled, or
+ * aren't being strict with the encoding.
+ *
+ * @dir: inode of the directory where the new file will be created
+ * @name: name of the new file
+ *
+ * Return:
+ * * True if the filename is suitable for this directory. It can be
+ * true if a given name is not suitable for a strict encoding
+ * directory, but the directory being used isn't strict
+ * * False if the filename isn't suitable for this directory. This only
+ * happens when a directory is casefolded and the filesystem is strict
+ * about its encoding.
+ */
+bool generic_ci_validate_strict_name(struct inode *dir, struct qstr *name)
+{
+ if (!IS_CASEFOLDED(dir) || !sb_has_strict_encoding(dir->i_sb))
+ return true;
+
+ /*
+ * A casefold dir must have a encoding set, unless the filesystem
+ * is corrupted
+ */
+ if (WARN_ON_ONCE(!dir->i_sb->s_encoding))
+ return true;
+
+ return utf8_validate(dir->i_sb->s_encoding, name);
+}
+EXPORT_SYMBOL(generic_ci_validate_strict_name);
#endif
#ifdef CONFIG_FS_ENCRYPTION
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd34b5755c0b..937142950dfe 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3385,6 +3385,7 @@ extern int generic_ci_match(const struct inode *parent,
const struct qstr *name,
const struct qstr *folded_name,
const u8 *de_name, u32 de_name_len);
+bool generic_ci_validate_strict_name(struct inode *dir, struct qstr *name);
static inline bool sb_has_encoding(const struct super_block *sb)
{
--
2.46.0
