From patchwork Sat Jun 14 06:22:57 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 896929 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 13BE01DC07D; Sat, 14 Jun 2025 06:22:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749882180; cv=none; b=EltcouEIy2nI79osdWkNnwwqKIaar9LUVWykp8/baOEQ++KIbHSb9PZaEv/fyeWig1z/2pdasYN1D5Mp+tZf5qBwP42OKiBXlwDMdgTRaIxQDVZMZ7hrt4lfheJUjNlqAKpsgXv0HXvRe+DFIX36Ya2pO3PpRERle0xiGp5/kSk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749882180; c=relaxed/simple; bh=s8ncKfbjoUuaFvFWw1MFGMiB1D/9Qfk0QPSyrvn+kUg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jm2uBcobn8T2vR+UkhKMqP/gd+WJANAf2wNw5NV/aZd0M9znjRC1GsiNx9HTeHfeSWh0RLjHrNvzqYgjsMRf1ENvHPCC/hJlMiLuO1TeQj0oqwGH2WoNtMwAPcaomd23RtVu5Q45qP2rF2NiZV0O2F21ll8bxcOygbMd8nqGz9s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=s9ryv4WW; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="s9ryv4WW" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=ZTfConObul4qVY0QSdQ7t8u8m7+yP1EN+rWNBepTobg=; b=s9ryv4WWeeeCNVc20SjsBha5/i cJNrg8Qtve64SrfFmowo9PWwiUvc2RyasTgn8L69BXec1doOAgdrDMfYVkPpPYDL25IbMwbnjGVfl hZeRTbR6LzaLts3hTFTQNGA4pKN6qpGY2hW9gC0WbnXMPIJfQjxALcE5g8G7/LonjF09eJqwJeE4V 3kVDuf8NWkbhcYah+ffe0uCADp2jBxKeu9k8kjH0VVQe57LOYOt0CTZL0JRmx+tIoZJRAwGCm9Ulj ImQtTM24I+pe1Q4UzO9ZMWsmPk4MX7EYb4DGdDA1x5Lz/bY70qbiQ8+QurBtwxz9blDqTVnSCEoO7 Hr3KCnSQ==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uQKI5-00000002FL6-2QzN; Sat, 14 Jun 2025 06:22:57 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Slava.Dubeyko@ibm.com, ceph-devel@vger.kernel.org Subject: [PATCH 3/3] ceph: fix a race with rename() in ceph_mdsc_build_path() Date: Sat, 14 Jun 2025 07:22:57 +0100 Message-ID: <20250614062257.535594-3-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250614062257.535594-1-viro@zeniv.linux.org.uk> References: <20250614062051.GC1880847@ZenIV> <20250614062257.535594-1-viro@zeniv.linux.org.uk> Precedence: bulk X-Mailing-List: ceph-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: Al Viro Lift copying the name into callers of ceph_encode_encrypted_dname() that do not have it already copied; ceph_encode_encrypted_fname() disappears. That fixes a UAF in ceph_mdsc_build_path() - while the initial copy of plaintext into buf is done under ->d_lock, we access the original name again in ceph_encode_encrypted_fname() and that is done without any locking. With ceph_encode_encrypted_dname() using the stable copy the problem goes away. Signed-off-by: Al Viro Tested-by: Viacheslav Dubeyko Reviewed-by: Viacheslav Dubeyko --- fs/ceph/caps.c | 18 +++++++----------- fs/ceph/crypto.c | 19 ++----------------- fs/ceph/crypto.h | 18 ++++-------------- fs/ceph/dir.c | 7 +++---- fs/ceph/mds_client.c | 4 ++-- 5 files changed, 18 insertions(+), 48 deletions(-) diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index a8d8b56cf9d2..b1a8ff612c41 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -4957,24 +4957,20 @@ int ceph_encode_dentry_release(void **p, struct dentry *dentry, cl = ceph_inode_to_client(dir); spin_lock(&dentry->d_lock); if (ret && di->lease_session && di->lease_session->s_mds == mds) { + int len = dentry->d_name.len; doutc(cl, "%p mds%d seq %d\n", dentry, mds, (int)di->lease_seq); rel->dname_seq = cpu_to_le32(di->lease_seq); __ceph_mdsc_drop_dentry_lease(dentry); + memcpy(*p, dentry->d_name.name, len); spin_unlock(&dentry->d_lock); if (IS_ENCRYPTED(dir) && fscrypt_has_encryption_key(dir)) { - int ret2 = ceph_encode_encrypted_fname(dir, dentry, *p); - - if (ret2 < 0) - return ret2; - - rel->dname_len = cpu_to_le32(ret2); - *p += ret2; - } else { - rel->dname_len = cpu_to_le32(dentry->d_name.len); - memcpy(*p, dentry->d_name.name, dentry->d_name.len); - *p += dentry->d_name.len; + len = ceph_encode_encrypted_dname(dir, *p, len); + if (len < 0) + return len; } + rel->dname_len = cpu_to_le32(len); + *p += len; } else { spin_unlock(&dentry->d_lock); } diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c index 2aef56fc6275..e312f52f48e4 100644 --- a/fs/ceph/crypto.c +++ b/fs/ceph/crypto.c @@ -253,23 +253,16 @@ static struct inode *parse_longname(const struct inode *parent, return dir; } -int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name, - char *buf) +int ceph_encode_encrypted_dname(struct inode *parent, char *buf, int elen) { struct ceph_client *cl = ceph_inode_to_client(parent); struct inode *dir = parent; char *p = buf; u32 len; - int name_len; - int elen; + int name_len = elen; int ret; u8 *cryptbuf = NULL; - memcpy(buf, d_name->name, d_name->len); - elen = d_name->len; - - name_len = elen; - /* Handle the special case of snapshot names that start with '_' */ if (ceph_snap(dir) == CEPH_SNAPDIR && *p == '_') { dir = parse_longname(parent, p, &name_len); @@ -342,14 +335,6 @@ int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name, return elen; } -int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry, - char *buf) -{ - WARN_ON_ONCE(!fscrypt_has_encryption_key(parent)); - - return ceph_encode_encrypted_dname(parent, &dentry->d_name, buf); -} - /** * ceph_fname_to_usr - convert a filename for userland presentation * @fname: ceph_fname to be converted diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h index d0768239a1c9..f752bbb2eb06 100644 --- a/fs/ceph/crypto.h +++ b/fs/ceph/crypto.h @@ -102,10 +102,7 @@ int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode, struct ceph_acl_sec_ctx *as); void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, struct ceph_acl_sec_ctx *as); -int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name, - char *buf); -int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry, - char *buf); +int ceph_encode_encrypted_dname(struct inode *parent, char *buf, int len); static inline int ceph_fname_alloc_buffer(struct inode *parent, struct fscrypt_str *fname) @@ -194,17 +191,10 @@ static inline void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, { } -static inline int ceph_encode_encrypted_dname(struct inode *parent, - struct qstr *d_name, char *buf) +static inline int ceph_encode_encrypted_dname(struct inode *parent, char *buf, + int len) { - memcpy(buf, d_name->name, d_name->len); - return d_name->len; -} - -static inline int ceph_encode_encrypted_fname(struct inode *parent, - struct dentry *dentry, char *buf) -{ - return -EOPNOTSUPP; + return len; } static inline int ceph_fname_alloc_buffer(struct inode *parent, diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index a321aa6d0ed2..8478e7e75df6 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -423,17 +423,16 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx) req->r_inode_drop = CEPH_CAP_FILE_EXCL; } if (dfi->last_name) { - struct qstr d_name = { .name = dfi->last_name, - .len = strlen(dfi->last_name) }; + int len = strlen(dfi->last_name); req->r_path2 = kzalloc(NAME_MAX + 1, GFP_KERNEL); if (!req->r_path2) { ceph_mdsc_put_request(req); return -ENOMEM; } + memcpy(req->r_path2, dfi->last_name, len); - err = ceph_encode_encrypted_dname(inode, &d_name, - req->r_path2); + err = ceph_encode_encrypted_dname(inode, req->r_path2, len); if (err < 0) { ceph_mdsc_put_request(req); return err; diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 230e0c3f341f..0f497c39ff82 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -2766,8 +2766,8 @@ char *ceph_mdsc_build_path(struct ceph_mds_client *mdsc, struct dentry *dentry, } if (fscrypt_has_encryption_key(d_inode(parent))) { - len = ceph_encode_encrypted_fname(d_inode(parent), - cur, buf); + len = ceph_encode_encrypted_dname(d_inode(parent), + buf, len); if (len < 0) { dput(parent); dput(cur);