Return-Path: Received: from mail-io0-f195.google.com ([209.85.223.195]:33281 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753242AbdFPPVL (ORCPT ); Fri, 16 Jun 2017 11:21:11 -0400 Subject: [PATCH v2 06/19] svcrdma: Improve Write chunk sanity checking From: Chuck Lever To: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org Date: Fri, 16 Jun 2017 11:21:09 -0400 Message-ID: <20170616152109.14210.88247.stgit@klimt.1015granger.net> In-Reply-To: <20170616151535.14210.34926.stgit@klimt.1015granger.net> References: <20170616151535.14210.34926.stgit@klimt.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Identify malformed transport headers and unsupported chunk combinations as early as possible. - Reject RPC-over-RDMA messages that contain more than one Write chunk, since this implementation does not support more than one per message. - Ensure that segment lengths are not crazy. - Ensure that the chunk's segment count is not crazy. With a 1KB inline threshold, the largest number of Write segments that can be conveyed is about 60 (for a RDMA_NOMSG Reply message). Signed-off-by: Chuck Lever --- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 52 ++++++++++++++++++++++++++++--- 1 file changed, 47 insertions(+), 5 deletions(-) diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index 885ad95..cf8be18 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -117,6 +117,11 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp, rqstp->rq_arg.tail[0].iov_len = 0; } +/* This accommodates the largest possible Write chunk, + * in one segment. + */ +#define MAX_BYTES_WRITE_SEG ((u32)(RPCSVC_MAXPAGES << PAGE_SHIFT)) + /* This accommodates the largest possible Position-Zero * Read chunk or Reply chunk, in one segment. */ @@ -162,15 +167,52 @@ static __be32 *xdr_check_read_list(__be32 *p, const __be32 *end) return p; } -static __be32 *xdr_check_write_list(__be32 *p, __be32 *end) +/* The segment count is limited to how many segments can + * fit in the transport header without overflowing the + * buffer. That's about 60 Write segments for a 1KB inline + * threshold. + */ +static __be32 *xdr_check_write_chunk(__be32 *p, const __be32 *end, + u32 maxlen) { - __be32 *next; + u32 i, segcount; + + segcount = be32_to_cpup(p++); + for (i = 0; i < segcount; i++) { + p++; /* handle */ + if (be32_to_cpup(p++) > maxlen) + return NULL; + p += 2; /* offset */ + + if (p > end) + return NULL; + } + + return p; +} +/* Sanity check the Write list. + * + * Implementation limits: + * - This implementation supports only one Write chunk. + * + * Sanity checks: + * - Write list does not overflow buffer. + * - Segment size limited by largest NFS data payload. + * + * Returns pointer to the following Reply chunk. + */ +static __be32 *xdr_check_write_list(__be32 *p, const __be32 *end) +{ + u32 chcount; + + chcount = 0; while (*p++ != xdr_zero) { - next = p + 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz; - if (next > end) + p = xdr_check_write_chunk(p, end, MAX_BYTES_WRITE_SEG); + if (!p) + return NULL; + if (chcount++ > 1) return NULL; - p = next; } return p; }