ceph: handle fscrypt fields in cap messages from MDS

Handle the new fscrypt_file and fscrypt_auth fields in cap messages. Use
them to populate new fields in cap_extra_info and update the inode with
those values.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-and-tested-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: jtlayton

fs/ceph/caps.c

@@ -3383,6 +3383,9 @@ struct cap_extra_info {
 	/* currently issued */
 	int issued;
 	struct timespec64 btime;
+	u8 *fscrypt_auth;
+	u32 fscrypt_auth_len;
+	u64 fscrypt_file_size;
 };
 
 /*
@@ -3415,6 +3418,14 @@ static void handle_cap_grant(struct inode *inode,
 	bool deleted_inode = false;
 	bool fill_inline = false;
 
+	/*
+	 * If there is at least one crypto block then we'll trust
+	 * fscrypt_file_size. If the real length of the file is 0, then
+	 * ignore it (it has probably been truncated down to 0 by the MDS).
+	 */
+	if (IS_ENCRYPTED(inode) && size)
+		size = extra_info->fscrypt_file_size;
+
 	dout("handle_cap_grant inode %p cap %p mds%d seq %d %s\n",
 	     inode, cap, session->s_mds, seq, ceph_cap_string(newcaps));
 	dout(" size %llu max_size %llu, i_size %llu\n", size, max_size,
@@ -3481,6 +3492,14 @@ static void handle_cap_grant(struct inode *inode,
 		dout("%p mode 0%o uid.gid %d.%d\n", inode, inode->i_mode,
 		     from_kuid(&init_user_ns, inode->i_uid),
 		     from_kgid(&init_user_ns, inode->i_gid));
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+		if (ci->fscrypt_auth_len != extra_info->fscrypt_auth_len ||
+		    memcmp(ci->fscrypt_auth, extra_info->fscrypt_auth,
+			   ci->fscrypt_auth_len))
+			pr_warn_ratelimited("%s: cap grant attempt to change fscrypt_auth on non-I_NEW inode (old len %d new len %d)\n",
+				__func__, ci->fscrypt_auth_len,
+				extra_info->fscrypt_auth_len);
+#endif
 	}
 
 	if ((newcaps & CEPH_CAP_LINK_SHARED) &&
@@ -3897,7 +3916,8 @@ static void handle_cap_flushsnap_ack(struct inode *inode, u64 flush_tid,
  */
 static bool handle_cap_trunc(struct inode *inode,
 			     struct ceph_mds_caps *trunc,
-			     struct ceph_mds_session *session)
+			     struct ceph_mds_session *session,
+			     struct cap_extra_info *extra_info)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int mds = session->s_mds;
@@ -3914,6 +3934,14 @@ static bool handle_cap_trunc(struct inode *inode,
 
 	issued |= implemented | dirty;
 
+	/*
+	 * If there is at least one crypto block then we'll trust
+	 * fscrypt_file_size. If the real length of the file is 0, then
+	 * ignore it (it has probably been truncated down to 0 by the MDS).
+	 */
+	if (IS_ENCRYPTED(inode) && size)
+		size = extra_info->fscrypt_file_size;
+
 	dout("handle_cap_trunc inode %p mds%d seq %d to %lld seq %d\n",
 	     inode, mds, seq, truncate_size, truncate_seq);
 	queue_trunc = ceph_fill_file_size(inode, issued,
@@ -4135,6 +4163,52 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 	*target_cap = cap;
 }
 
+#ifdef CONFIG_FS_ENCRYPTION
+static int parse_fscrypt_fields(void **p, void *end,
+				struct cap_extra_info *extra)
+{
+	u32 len;
+
+	ceph_decode_32_safe(p, end, extra->fscrypt_auth_len, bad);
+	if (extra->fscrypt_auth_len) {
+		ceph_decode_need(p, end, extra->fscrypt_auth_len, bad);
+		extra->fscrypt_auth = kmalloc(extra->fscrypt_auth_len,
+					      GFP_KERNEL);
+		if (!extra->fscrypt_auth)
+			return -ENOMEM;
+		ceph_decode_copy_safe(p, end, extra->fscrypt_auth,
+					extra->fscrypt_auth_len, bad);
+	}
+
+	ceph_decode_32_safe(p, end, len, bad);
+	if (len >= sizeof(u64)) {
+		ceph_decode_64_safe(p, end, extra->fscrypt_file_size, bad);
+		len -= sizeof(u64);
+	}
+	ceph_decode_skip_n(p, end, len, bad);
+	return 0;
+bad:
+	return -EIO;
+}
+#else
+static int parse_fscrypt_fields(void **p, void *end,
+				struct cap_extra_info *extra)
+{
+	u32 len;
+
+	/* Don't care about these fields unless we're encryption-capable */
+	ceph_decode_32_safe(p, end, len, bad);
+	if (len)
+		ceph_decode_skip_n(p, end, len, bad);
+	ceph_decode_32_safe(p, end, len, bad);
+	if (len)
+		ceph_decode_skip_n(p, end, len, bad);
+	return 0;
+bad:
+	return -EIO;
+}
+#endif
+
 /*
  * Handle a caps message from the MDS.
  *
@@ -4255,6 +4329,11 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 		ceph_decode_64_safe(&p, end, extra_info.nsubdirs, bad);
 	}
 
+	if (msg_version >= 12) {
+		if (parse_fscrypt_fields(&p, end, &extra_info))
+			goto bad;
+	}
+
 	/* lookup ino */
 	inode = ceph_find_inode(mdsc->fsc->sb, vino);
 	dout(" op %s ino %llx.%llx inode %p\n", ceph_cap_op_name(op), vino.ino,
@@ -4352,7 +4431,8 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 		break;
 
 	case CEPH_CAP_OP_TRUNC:
-		queue_trunc = handle_cap_trunc(inode, h, session);
+		queue_trunc = handle_cap_trunc(inode, h, session,
+						&extra_info);
 		spin_unlock(&ci->i_ceph_lock);
 		if (queue_trunc)
 			ceph_queue_vmtruncate(inode);
@@ -4375,6 +4455,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 	if (close_sessions)
 		ceph_mdsc_close_sessions(mdsc);
 
+	kfree(extra_info.fscrypt_auth);
 	return;
 
 flush_cap_releases: