lkml.org 
[lkml]   [2024]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RESEND PATCH v9 1/3] libfs: Introduce case-insensitive string comparison helper
    Date
    From: Gabriel Krisman Bertazi <krisman@collabora.com>

    generic_ci_match can be used by case-insensitive filesystems to compare
    strings under lookup with dirents in a case-insensitive way. This
    function is currently reimplemented by each filesystem supporting
    casefolding, so this reduces code duplication in filesystem-specific
    code.

    Reviewed-by: Eric Biggers <ebiggers@google.com>
    Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
    Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com>
    ---
    fs/libfs.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/fs.h | 4 +++
    2 files changed, 72 insertions(+)

    diff --git a/fs/libfs.c b/fs/libfs.c
    index bb18884ff20e..f80cb982ac89 100644
    --- a/fs/libfs.c
    +++ b/fs/libfs.c
    @@ -1773,6 +1773,74 @@ static const struct dentry_operations generic_ci_dentry_ops = {
    .d_hash = generic_ci_d_hash,
    .d_compare = generic_ci_d_compare,
    };
    +
    +/**
    + * generic_ci_match() - Match a name (case-insensitively) with a dirent.
    + * @parent: Inode of the parent of the dirent under comparison
    + * @name: name under lookup.
    + * @folded_name: Optional pre-folded name under lookup
    + * @de_name: Dirent name.
    + * @de_name_len: dirent name length.
    + *
    + *
    + * Test whether a case-insensitive directory entry matches the filename
    + * being searched. If @folded_name is provided, it is used instead of
    + * recalculating the casefold of @name.
    + *
    + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or
    + * < 0 on error.
    + */
    +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)
    +{
    + const struct super_block *sb = parent->i_sb;
    + const struct unicode_map *um = sb->s_encoding;
    + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
    + struct qstr dirent = QSTR_INIT(de_name, de_name_len);
    + int res, match = false;
    +
    + if (IS_ENCRYPTED(parent)) {
    + const struct fscrypt_str encrypted_name =
    + FSTR_INIT((u8 *) de_name, de_name_len);
    +
    + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent)))
    + return -EINVAL;
    +
    + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
    + if (!decrypted_name.name)
    + return -ENOMEM;
    + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name,
    + &decrypted_name);
    + if (res < 0)
    + goto out;
    + dirent.name = decrypted_name.name;
    + dirent.len = decrypted_name.len;
    + }
    +
    + if (folded_name->name)
    + res = utf8_strncasecmp_folded(um, folded_name, &dirent);
    + else
    + res = utf8_strncasecmp(um, name, &dirent);
    +
    + if (!res)
    + match = true;
    + else if (res < 0 && !sb_has_strict_encoding(sb)) {
    + /*
    + * In non-strict mode, fallback to a byte comparison if
    + * the names have invalid characters.
    + */
    + res = 0;
    + match = ((name->len == dirent.len) &&
    + !memcmp(name->name, dirent.name, dirent.len));
    + }
    +
    +out:
    + kfree(decrypted_name.name);
    + return (res >= 0) ? match : res;
    +}
    +EXPORT_SYMBOL(generic_ci_match);
    #endif

    #ifdef CONFIG_FS_ENCRYPTION
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index 820b93b2917f..7af691ff8d44 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -3296,6 +3296,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
    extern int generic_check_addressable(unsigned, u64);

    extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry);
    +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);

    static inline bool sb_has_encoding(const struct super_block *sb)
    {
    --
    2.34.1

    \
     
     \ /
      Last update: 2024-05-27 14:54    [W:7.796 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site