From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A78DAC433EF for ; Wed, 16 Mar 2022 11:00:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355225AbiCPLBo (ORCPT ); Wed, 16 Mar 2022 07:01:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343563AbiCPLBl (ORCPT ); Wed, 16 Mar 2022 07:01:41 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFEBC60077; Wed, 16 Mar 2022 04:00:26 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 7C1961F390; Wed, 16 Mar 2022 11:00:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1647428425; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sM70Iz/zzL8rdDARgecMacKzOr4IAgxW59+OOfyajuQ=; b=uU0cZRVlBKXUf/R+jLICWslqJDd9nE4DVFsBsr85qy8VMNx8Y3oGHNSslldU0n6fDRb389 +Hoc6bOUghHybUFl3OHytyDkNj2ulIGCObYx1y2wmsyGRwj0oJpoaChl9GzAo61zNwUNhV aXL7WpVovZFQBeGQAW8nrGJujmi4FiY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1647428425; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sM70Iz/zzL8rdDARgecMacKzOr4IAgxW59+OOfyajuQ=; b=Ik1zk3N8Zy8woyUX6ule6XPSOFHo8qUlysfb/Q/VRWocIJpxc7Sy1VW8P3tw8Xfgcx/Fw1 +dy1sQ8LP+X8X3Bw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 1C125139FE; Wed, 16 Mar 2022 11:00:25 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 75vxA0nDMWLCKwAAMHmgww (envelope-from ); Wed, 16 Mar 2022 11:00:25 +0000 Received: from localhost (brahms.olymp [local]) by brahms.olymp (OpenSMTPD) with ESMTPA id 0a1379f3; Wed, 16 Mar 2022 11:00:42 +0000 (UTC) From: =?utf-8?Q?Lu=C3=ADs_Henriques?= To: Xiubo Li Cc: Jeff Layton , Ilya Dryomov , ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 2/3] ceph: add support for handling encrypted snapshot names References: <20220315161959.19453-1-lhenriques@suse.de> <20220315161959.19453-3-lhenriques@suse.de> <972eafc3-93a3-b523-4ad2-e234b3664635@redhat.com> Date: Wed, 16 Mar 2022 11:00:42 +0000 In-Reply-To: <972eafc3-93a3-b523-4ad2-e234b3664635@redhat.com> (Xiubo Li's message of "Wed, 16 Mar 2022 08:47:43 +0800") Message-ID: <87r172i2lh.fsf@brahms.olymp> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Xiubo Li writes: > On 3/16/22 12:19 AM, Lu=C3=ADs Henriques wrote: >> When creating a snapshot, the .snap directories for every subdirectory w= ill >> show the snapshot name in the "long format": >> >> # mkdir .snap/my-snap >> # ls my-dir/.snap/ >> _my-snap_1099511627782 >> >> Encrypted snapshots will need to be able to handle these snapshot names = by >> encrypting/decrypting only the snapshot part of the string ('my-snap'). >> >> Also, since the MDS prevents snapshot names to be bigger than 240 charac= ters >> it is necessary to adapt CEPH_NOHASH_NAME_MAX to accommodate this extra >> limitation. >> >> Signed-off-by: Lu=C3=ADs Henriques >> --- >> fs/ceph/crypto.c | 158 +++++++++++++++++++++++++++++++++++++++++------ >> fs/ceph/crypto.h | 11 ++-- >> 2 files changed, 145 insertions(+), 24 deletions(-) >> >> diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c >> index c125a79019b3..06a4b918201c 100644 >> --- a/fs/ceph/crypto.c >> +++ b/fs/ceph/crypto.c >> @@ -128,18 +128,95 @@ void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_re= quest *req, struct ceph_acl_se >> swap(req->r_fscrypt_auth, as->fscrypt_auth); >> } >> -int ceph_encode_encrypted_dname(const struct inode *parent, struct qs= tr >> *d_name, char *buf) >> +/* >> + * User-created snapshots can't start with '_'. Snapshots that start w= ith this >> + * character are special (hint: there aren't real snapshots) and use the >> + * following format: >> + * >> + * __ >> + * >> + * where: >> + * - - the real snapshot name that may need to be decr= ypted, >> + * - - the inode number for the actual snapshot >> + * >> + * This function parses these snapshot names and returns the inode >> + * . 'name_len' will also bet set with the >> + * length. >> + */ >> +static struct inode *parse_longname(const struct inode *parent, const c= har *name, >> + int *name_len) >> { >> + struct inode *dir =3D NULL; >> + struct ceph_vino vino =3D { .snap =3D CEPH_NOSNAP }; >> + char *inode_number; >> + char *name_end; >> + int orig_len =3D *name_len; >> + int ret =3D -EIO; >> + >> + /* Skip initial '_' */ >> + name++; >> + name_end =3D strrchr(name, '_'); >> + if (!name_end) { >> + dout("Failed to parse long snapshot name: %s\n", name); >> + return ERR_PTR(-EIO); >> + } >> + *name_len =3D (name_end - name); >> + if (*name_len <=3D 0) { >> + pr_err("Failed to parse long snapshot name\n"); >> + return ERR_PTR(-EIO); >> + } >> + >> + /* Get the inode number */ >> + inode_number =3D kmemdup_nul(name_end + 1, >> + orig_len - *name_len - 2, >> + GFP_KERNEL); >> + if (!inode_number) >> + return ERR_PTR(-ENOMEM); >> + ret =3D kstrtou64(inode_number, 0, &vino.ino); >> + if (ret) { >> + dout("Failed to parse inode number: %s\n", name); >> + dir =3D ERR_PTR(ret); >> + goto out; >> + } >> + >> + /* And finally the inode */ >> + dir =3D ceph_get_inode(parent->i_sb, vino, NULL); > > Maybe you should use ceph_find_inode() here ? We shouldn't insert a new o= ne > here. And IMO the parent dir inode must be in the cache... Right, that makes sense. I'll swap it for the ceph_find_inode(). >> + if (IS_ERR(dir)) >> + dout("Can't find inode %s (%s)\n", inode_number, name); >> + >> +out: >> + kfree(inode_number); >> + return dir; >> +} > > Here I think you have missed one case, not all the long snap names are ne= eded to > be dencrypted if they are from the parent snap realms, who are not encryp= ted, > for example: > > mkdir dir1 > > fscrypt encrypt dir1 > > mkdir dir1/dir2 > > mkdir .snap/root_snap > > mkdir dir1/.snap/dir1_snap > > ls dir1/dir2/.snap/ > > _root_snap_1=C2=A0 _dir1_snap_1099511628283 > > You shouldn't encrypt the "_root_snap_1" long name. Ah! Good catch! Yes, this case isn't being covered. I'll fix it with by following your suggestion bellow. >> + >> +int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_na= me, char *buf) >> +{ >> + struct inode *dir =3D parent; >> + struct qstr iname; >> u32 len; >> + int name_len; >> int elen; >> int ret; >> - u8 *cryptbuf; >> + u8 *cryptbuf =3D NULL; >> if (!fscrypt_has_encryption_key(parent)) { >> memcpy(buf, d_name->name, d_name->len); >> return d_name->len; >> } >> + iname.name =3D d_name->name; >> + name_len =3D d_name->len; >> + >> + /* Handle the special case of snapshot names that start with '_' */ >> + if ((ceph_snap(dir) =3D=3D CEPH_SNAPDIR) && (name_len > 0) && >> + (iname.name[0] =3D=3D '_')) { >> + dir =3D parse_longname(parent, iname.name, &name_len); >> + if (IS_ERR(dir)) >> + return PTR_ERR(dir); >> + iname.name++; /* skip initial '_' */ >> + } >> + iname.len =3D name_len; >> + > > Maybe you can do this just before checking the fscrypt_has_encryption_key= () to > fix the issue mentioned above ? > > >> /* >> * convert cleartext d_name to ciphertext >> * if result is longer than CEPH_NOKEY_NAME_MAX, >> @@ -147,18 +224,22 @@ int ceph_encode_encrypted_dname(const struct inode= *parent, struct qstr *d_name, >> * >> * See: fscrypt_setup_filename >> */ >> - if (!fscrypt_fname_encrypted_size(parent, d_name->len, NAME_MAX, &len)) >> - return -ENAMETOOLONG; >> + if (!fscrypt_fname_encrypted_size(dir, iname.len, NAME_MAX, &len)) { >> + elen =3D -ENAMETOOLONG; >> + goto out; >> + } >> /* Allocate a buffer appropriate to hold the result */ >> cryptbuf =3D kmalloc(len > CEPH_NOHASH_NAME_MAX ? NAME_MAX : len, GFP= _KERNEL); >> - if (!cryptbuf) >> - return -ENOMEM; >> + if (!cryptbuf) { >> + elen =3D -ENOMEM; >> + goto out; >> + } >> - ret =3D fscrypt_fname_encrypt(parent, d_name, cryptbuf, len); >> + ret =3D fscrypt_fname_encrypt(dir, &iname, cryptbuf, len); >> if (ret) { >> - kfree(cryptbuf); >> - return ret; >> + elen =3D ret; >> + goto out; >> } >> /* hash the end if the name is long enough */ >> @@ -174,12 +255,24 @@ int ceph_encode_encrypted_dname(const struct inode= *parent, struct qstr *d_name, >> /* base64 encode the encrypted name */ >> elen =3D fscrypt_base64url_encode(cryptbuf, len, buf); >> - kfree(cryptbuf); >> dout("base64-encoded ciphertext name =3D %.*s\n", elen, buf); >> + >> + if ((elen > 0) && (dir !=3D parent)) { >> + char tmp_buf[FSCRYPT_BASE64URL_CHARS(NAME_MAX)]; >> + > > Do we really need FSCRYPT_BASE64URL_CHARS(NAME_MAX) ? Since you have fix = the > 189->180 code, then the encrypted long snap name shouldn't exceed 255. > > I think the NAME_MAX is enough. Yes, correct. I'll change that too. > And also you should check the elen here it shouldn't exceed 240 after enc= rypted, > or should we fail it here directly with a warning log ? Right, that should probably be logged. I'll had that check. Thanks a lot for your review, Xiubo. Cheers, --=20 Lu=C3=ADs >> + elen =3D snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld", >> + elen, buf, dir->i_ino); >> + memcpy(buf, tmp_buf, elen); >> + } >> + >> +out: >> + kfree(cryptbuf); >> + if (dir !=3D parent) >> + iput(dir); >> return elen; >> } >> -int ceph_encode_encrypted_fname(const struct inode *parent, struct de= ntry >> *dentry, char *buf) >> +int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *de= ntry, char *buf) >> { >> WARN_ON_ONCE(!fscrypt_has_encryption_key(parent)); >> @@ -204,11 +297,14 @@ int ceph_encode_encrypted_fname(const struct ino= de >> *parent, struct dentry *dentr >> int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_s= tr *tname, >> struct fscrypt_str *oname, bool *is_nokey) >> { >> - int ret; >> + struct inode *dir =3D fname->dir; >> struct fscrypt_str _tname =3D FSTR_INIT(NULL, 0); >> struct fscrypt_str iname; >> + char *name =3D fname->name; >> + int name_len =3D fname->name_len; >> + int ret; >> - if (!IS_ENCRYPTED(fname->dir)) { >> + if (!IS_ENCRYPTED(dir)) { >> oname->name =3D fname->name; >> oname->len =3D fname->name_len; >> return 0; >> @@ -218,15 +314,24 @@ int ceph_fname_to_usr(const struct ceph_fname *fna= me, struct fscrypt_str *tname, >> if (fname->name_len > NAME_MAX || fname->ctext_len > NAME_MAX) >> return -EIO; >> - ret =3D __fscrypt_prepare_readdir(fname->dir); >> + /* Handle the special case of snapshot names that start with '_' */ >> + if ((ceph_snap(dir) =3D=3D CEPH_SNAPDIR) && (name_len > 0) && >> + (name[0] =3D=3D '_')) { >> + dir =3D parse_longname(dir, name, &name_len); >> + if (IS_ERR(dir)) >> + return PTR_ERR(dir); >> + name++; /* skip initial '_' */ >> + } >> + >> + ret =3D __fscrypt_prepare_readdir(dir); >> if (ret) >> - return ret; >> + goto out_inode; >> /* >> * Use the raw dentry name as sent by the MDS instead of >> * generating a nokey name via fscrypt. >> */ >> - if (!fscrypt_has_encryption_key(fname->dir)) { >> + if (!fscrypt_has_encryption_key(dir)) { >> if (fname->no_copy) >> oname->name =3D fname->name; >> else >> @@ -234,7 +339,8 @@ int ceph_fname_to_usr(const struct ceph_fname *fname= , struct fscrypt_str *tname, >> oname->len =3D fname->name_len; >> if (is_nokey) >> *is_nokey =3D true; >> - return 0; >> + ret =3D 0; >> + goto out_inode; >> } >> if (fname->ctext_len =3D=3D 0) { >> @@ -243,11 +349,11 @@ int ceph_fname_to_usr(const struct ceph_fname *fna= me, struct fscrypt_str *tname, >> if (!tname) { >> ret =3D fscrypt_fname_alloc_buffer(NAME_MAX, &_tname); >> if (ret) >> - return ret; >> + goto out_inode; >> tname =3D &_tname; >> } >> - declen =3D fscrypt_base64url_decode(fname->name, fname->name_len, >> tname->name); >> + declen =3D fscrypt_base64url_decode(name, name_len, tname->name); >> if (declen <=3D 0) { >> ret =3D -EIO; >> goto out; >> @@ -259,9 +365,21 @@ int ceph_fname_to_usr(const struct ceph_fname *fnam= e, struct fscrypt_str *tname, >> iname.len =3D fname->ctext_len; >> } >> - ret =3D fscrypt_fname_disk_to_usr(fname->dir, 0, 0, &iname, oname); >> + ret =3D fscrypt_fname_disk_to_usr(dir, 0, 0, &iname, oname); >> + if (!ret && (dir !=3D fname->dir)) { >> + char tmp_buf[FSCRYPT_BASE64URL_CHARS(NAME_MAX)]; >> + >> + name_len =3D snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld", >> + oname->len, oname->name, dir->i_ino); >> + memcpy(oname->name, tmp_buf, name_len); >> + oname->len =3D name_len; >> + } >> + >> out: >> fscrypt_fname_free_buffer(&_tname); >> +out_inode: >> + if ((dir !=3D fname->dir) && !IS_ERR(dir)) >> + iput(dir); >> return ret; >> } >> diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h >> index 185fb4799a6d..e38a842e02a6 100644 >> --- a/fs/ceph/crypto.h >> +++ b/fs/ceph/crypto.h >> @@ -76,13 +76,16 @@ static inline u32 ceph_fscrypt_auth_len(struct ceph_= fscrypt_auth *fa) >> * smaller size. If the ciphertext name is longer than the value below= , then >> * sha256 hash the remaining bytes. >> * >> - * 189 bytes =3D> 252 bytes base64-encoded, which is <=3D NAME_MAX (255) >> + * 180 bytes =3D> 240 bytes base64-encoded, which is <=3D NAME_MAX (255) >> + * >> + * (Note: 240 bytes is the maximum size allowed for snapshot names to t= ake into >> + * account the format: '__') >> * >> * Note that for long names that end up having their tail portion hash= ed, we >> * must also store the full encrypted name (in the dentry's alternate_= name >> * field). >> */ >> -#define CEPH_NOHASH_NAME_MAX (189 - SHA256_DIGEST_SIZE) >> +#define CEPH_NOHASH_NAME_MAX (180 - SHA256_DIGEST_SIZE) >> void ceph_fscrypt_set_ops(struct super_block *sb); >> @@ -91,8 +94,8 @@ void ceph_fscrypt_free_dummy_policy(struct ceph_fs_c= lient >> *fsc); >> int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inod= e, >> struct ceph_acl_sec_ctx *as); >> void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, struct c= eph_acl_sec_ctx *as); >> -int ceph_encode_encrypted_dname(const struct inode *parent, struct qstr= *d_name, char *buf); >> -int ceph_encode_encrypted_fname(const struct inode *parent, struct dent= ry *dentry, char *buf); >> +int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_na= me, char *buf); >> +int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *de= ntry, char *buf); >> static inline int ceph_fname_alloc_buffer(struct inode *parent, stru= ct >> fscrypt_str *fname) >> { >> >