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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]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; HAS_ORG_HEADER(0.00)[]; RCPT_COUNT_TWELVE(0.00)[15]; 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)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] X-Headers-End: 1s9v28-0007ax-2D Subject: Re: [f2fs-dev] [PATCH v16 3/9] libfs: Introduce case-insensitive string comparison helper X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: brauner@kernel.org, kernel@collabora.com, tytso@mit.edu, jack@suse.cz, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Eric Biggers , adilger.kernel@dilger.ca, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, jaegeuk@kernel.org, linux-ext4@vger.kernel.org, Gabriel Krisman Bertazi Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net Eugen Hristev writes: > On 5/13/24 00:27, Gabriel Krisman Bertazi wrote: >> Eric Biggers writes: >> >>> On Fri, Apr 05, 2024 at 03:13:26PM +0300, Eugen Hristev wrote: >> >>>> + 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; >>> >>> If fscrypt_fname_disk_to_usr() returns an error and !sb_has_strict_encoding(sb), >>> then this function returns 0 (indicating no match) instead of the error code >>> (indicating an error). Is that the correct behavior? I would think that >>> strict_encoding should only have an effect on the actual name >>> comparison. >> >> No. we *want* this return code to be propagated back to f2fs. In ext4 it >> wouldn't matter since the error is not visible outside of ext4_match, >> but f2fs does the right thing and stops the lookup. > > In the previous version which I sent, you told me that the error should be > propagated only in strict_mode, and if !strict_mode, it should just return no match. > Originally I did not understand that this should be done only for utf8_strncasecmp > errors, and not for all the errors. I will change it here to fix that. Yes, it depends on which error we are talking about. For ENOMEM and whatever error fscrypt_fname_disk_to_usr returns, we surely want to send that back, such that f2fs can handle it (i.e abort the lookup). Unicode casefolding errors don't need to stop the lookup. >> Thinking about it, there is a second problem with this series. >> Currently, if we are on strict_mode, f2fs_match_ci_name does not >> propagate unicode errors back to f2fs. So, once a utf8 invalid sequence >> is found during lookup, it will be considered not-a-match but the lookup >> will continue. This allows some lookups to succeed even in a corrupted >> directory. With this patch, we will abort the lookup on the first >> error, breaking existing semantics. Note that these are different from >> memory allocation failure and fscrypt_fname_disk_to_usr. For those, it >> makes sense to abort. > > So , in the case of f2fs , we must not propagate utf8 errors ? It should just > return no match even in strict mode ? > If this helper is common for both f2fs and ext4, we have to do the same for ext4 ? > Or we are no longer able to commonize the code altogether ? We can have a common handler. It doesn't matter for Ext4 because it ignores all errors. Perhaps ext4 can be improved too in a different patchset. >> My suggestion would be to keep the current behavior. Make >> generic_ci_match only propagate non-unicode related errors back to the >> filesystem. This means that we need to move the error messages in patch >> 6 and 7 into this function, so they only trigger when utf8_strncasecmp* >> itself fails. >> > > So basically unicode errors stop here, and print the error message here in that case. > Am I understanding it correctly ? Yes, that is it. print the error message - only in strict mode - and return not-a-match. Is there any problem with this approach that I'm missing? >>>> + /* >>>> + * 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 (folded_name->name) { >>>> + if (dirent.len == folded_name->len && >>>> + !memcmp(folded_name->name, dirent.name, dirent.len)) >>>> + goto out; >>>> + res = utf8_strncasecmp_folded(um, folded_name, &dirent); >>> >>> Shouldn't the memcmp be done with the original user-specified name, not the >>> casefolded name? I would think that the user-specified name is the one that's >>> more likely to match the on-disk name, because of case preservation. In most >>> cases users will specify the same case on both file creation and later access. >> >> Yes. >> > so the utf8_strncasecmp_folded call here must use name->name instead of folded_name ? No, utf8_strncasecmp_folded requires a casefolded name. Eric's point is that the *memcmp* should always compare against name->name since it's more likely to match the name on disk than the folded version because the user is probably doing a case-exact lookup. This also means the memcmp can be moved outside the "if (folded_name->name)", simplifying the patch! -- Gabriel Krisman Bertazi _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel