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Tue, 4 Jun 2024 19:18:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id iATjNJxoX2YjZAAAD6G6ig (envelope-from ); Tue, 04 Jun 2024 19:18:52 +0000 From: Gabriel Krisman Bertazi To: Eugen Hristev Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, jaegeuk@kernel.org, adilger.kernel@dilger.ca, tytso@mit.edu, chao@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, ebiggers@google.com, kernel@collabora.com, Gabriel Krisman Bertazi Subject: Re: [PATCH v17 3/7] libfs: Introduce case-insensitive string comparison helper In-Reply-To: <20240529082634.141286-4-eugen.hristev@collabora.com> (Eugen Hristev's message of "Wed, 29 May 2024 11:26:30 +0300") Organization: SUSE References: <20240529082634.141286-1-eugen.hristev@collabora.com> <20240529082634.141286-4-eugen.hristev@collabora.com> Date: Tue, 04 Jun 2024 15:18:47 -0400 Message-ID: <878qzkldns.fsf@mailhost.krisman.be> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Flag: NO X-Spam-Score: -4.30 X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; FUZZY_BLOCKED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; HAS_ORG_HEADER(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_TWELVE(0.00)[15]; RCVD_COUNT_TWO(0.00)[2]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[] Eugen Hristev writes: > From: Gabriel Krisman Bertazi > > 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. > > Signed-off-by: Gabriel Krisman Bertazi > [eugen.hristev@collabora.com: rework to first test the exact match, cleanup > and add error message] > Signed-off-by: Eugen Hristev Other than the origin of the length in memcmp mentioned by Eric, this patch looks good to me now. Thanks again for picking up this work! > --- > fs/libfs.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 4 +++ > 2 files changed, 78 insertions(+) > > diff --git a/fs/libfs.c b/fs/libfs.c > index b635ee5adbcc..6a6cfa2d7d93 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -1854,6 +1854,80 @@ static const struct dentry_operations generic_ci_dentry_ops = { > .d_revalidate = fscrypt_d_revalidate, > #endif > }; > + > +/** > + * generic_ci_match() - Match a name (case-insensitively) with a dirent. > + * This is a filesystem helper for comparison with directory entries. > + * generic_ci_d_compare should be used in VFS' ->d_compare instead. > + * > + * @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 = 0; > + > + 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) { > + kfree(decrypted_name.name); > + return res; > + } > + dirent.name = decrypted_name.name; > + dirent.len = decrypted_name.len; > + } > + > + /* > + * Attempt a case-sensitive match first. It is cheaper and > + * should cover most lookups, including all the sane > + * applications that expect a case-sensitive filesystem. > + */ > + > + if (dirent.len == (folded_name->name ? folded_name->len : name->len) && > + !memcmp(name->name, dirent.name, dirent.len)) > + goto out; > + > + if (folded_name->name) > + res = utf8_strncasecmp_folded(um, folded_name, &dirent); > + else > + res = utf8_strncasecmp(um, name, &dirent); > + > +out: > + kfree(decrypted_name.name); > + if (res < 0 && sb_has_strict_encoding(sb)) { > + pr_err_ratelimited("Directory contains filename that is invalid UTF-8"); > + return 0; > + } > + return !res; > +} > +EXPORT_SYMBOL(generic_ci_match); > #endif > > #ifdef CONFIG_FS_ENCRYPTION > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 639885621608..f8ca264a0edc 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3367,6 +3367,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); > extern int generic_check_addressable(unsigned, u64); > > extern void generic_set_sb_d_ops(struct super_block *sb); > +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) > { -- Gabriel Krisman Bertazi