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Tue, 4 Jun 2024 19:17:46 +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 mLlRMVpoX2bXYwAAD6G6ig (envelope-from ); Tue, 04 Jun 2024 19:17:46 +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 4/7] ext4: Reuse generic_ci_match for ci comparisons In-Reply-To: <20240529082634.141286-5-eugen.hristev@collabora.com> (Eugen Hristev's message of "Wed, 29 May 2024 11:26:31 +0300") Organization: SUSE References: <20240529082634.141286-1-eugen.hristev@collabora.com> <20240529082634.141286-5-eugen.hristev@collabora.com> Date: Tue, 04 Jun 2024 15:17:41 -0400 Message-ID: <87cyowldpm.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-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]; ARC_NA(0.00)[]; HAS_ORG_HEADER(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_TWELVE(0.00)[15]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_DN_SOME(0.00)[] X-Spam-Score: -4.30 X-Spam-Flag: NO Eugen Hristev writes: > From: Gabriel Krisman Bertazi > > Instead of reimplementing ext4_match_ci, use the new libfs helper. > > It also adds a comment explaining why fname->cf_name.name must be > checked prior to the encryption hash optimization, because that tripped > me before. > > Signed-off-by: Gabriel Krisman Bertazi > Signed-off-by: Eugen Hristev > Reviewed-by: Eric Biggers > --- > fs/ext4/namei.c | 91 +++++++++++++++---------------------------------- > 1 file changed, 27 insertions(+), 64 deletions(-) > > diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c > index ec4c9bfc1057..20668741a23c 100644 > --- a/fs/ext4/namei.c > +++ b/fs/ext4/namei.c > @@ -1390,58 +1390,6 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block) > } > > #if IS_ENABLED(CONFIG_UNICODE) > -/* > - * Test whether a case-insensitive directory entry matches the filename > - * being searched for. If quick is set, assume the name being looked up > - * is already in the casefolded form. > - * > - * Returns: 0 if the directory entry matches, more than 0 if it > - * doesn't match or less than zero on error. > - */ > -static int ext4_ci_compare(const struct inode *parent, const struct qstr *name, > - u8 *de_name, size_t de_name_len, bool quick) > -{ > - 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 entry = QSTR_INIT(de_name, de_name_len); > - int ret; > - > - if (IS_ENCRYPTED(parent)) { > - const struct fscrypt_str encrypted_name = > - FSTR_INIT(de_name, de_name_len); > - > - decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); > - if (!decrypted_name.name) > - return -ENOMEM; > - ret = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, > - &decrypted_name); > - if (ret < 0) > - goto out; > - entry.name = decrypted_name.name; > - entry.len = decrypted_name.len; > - } > - > - if (quick) > - ret = utf8_strncasecmp_folded(um, name, &entry); > - else > - ret = utf8_strncasecmp(um, name, &entry); > - if (ret < 0) { > - /* Handle invalid character sequence as either an error > - * or as an opaque byte sequence. > - */ > - if (sb_has_strict_encoding(sb)) > - ret = -EINVAL; > - else if (name->len != entry.len) > - ret = 1; > - else > - ret = !!memcmp(name->name, entry.name, entry.len); > - } > -out: > - kfree(decrypted_name.name); > - return ret; > -} > - > int ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname, > struct ext4_filename *name) > { > @@ -1503,20 +1451,35 @@ static bool ext4_match(struct inode *parent, > #if IS_ENABLED(CONFIG_UNICODE) > if (IS_CASEFOLDED(parent) && > (!IS_ENCRYPTED(parent) || fscrypt_has_encryption_key(parent))) { > - if (fname->cf_name.name) { > - if (IS_ENCRYPTED(parent)) { > - if (fname->hinfo.hash != EXT4_DIRENT_HASH(de) || > - fname->hinfo.minor_hash != > - EXT4_DIRENT_MINOR_HASH(de)) { > + int ret; > > - return false; > - } > - } > - return !ext4_ci_compare(parent, &fname->cf_name, > - de->name, de->name_len, true); > + /* > + * Just checking IS_ENCRYPTED(parent) below is not > + * sufficient to decide whether one can use the hash for > + * skipping the string comparison, because the key might > + * have been added right after > + * ext4_fname_setup_ci_filename(). In this case, a hash > + * mismatch will be a false negative. Therefore, make > + * sure cf_name was properly initialized before > + * considering the calculated hash. > + */ > + if (IS_ENCRYPTED(parent) && fname->cf_name.name && > + (fname->hinfo.hash != EXT4_DIRENT_HASH(de) || > + fname->hinfo.minor_hash != EXT4_DIRENT_MINOR_HASH(de))) > + return false; > + > + ret = generic_ci_match(parent, fname->usr_fname, > + &fname->cf_name, de->name, > + de->name_len); > + if (ret < 0) { > + /* > + * Treat comparison errors as not a match. The > + * only case where it happens is on a disk > + * corruption or ENOMEM. > + */ > + return false; > } > - return !ext4_ci_compare(parent, fname->usr_fname, de->name, > - de->name_len, false); With the changes to patch 3 in this iteration, This could become: /* * Treat comparison errors as not a match. The * only case where it happens is disk corruption * or ENOMEM. */ return ext4_ci_compare(parent, fname->usr_fname, de->name, de->name_len, false) > 0; -- Gabriel Krisman Bertazi