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 4DAF8C7EE29 for ; Fri, 9 Jun 2023 21:12:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229586AbjFIVMd (ORCPT ); Fri, 9 Jun 2023 17:12:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229517AbjFIVMd (ORCPT ); Fri, 9 Jun 2023 17:12:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9913035A2; Fri, 9 Jun 2023 14:12:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 36BE260F4D; Fri, 9 Jun 2023 21:12:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C035C433EF; Fri, 9 Jun 2023 21:12:29 +0000 (UTC) Date: Fri, 9 Jun 2023 17:12:27 -0400 From: Steven Rostedt To: Alan Maguire Cc: mhiramat@kernel.org, corbet@lwn.net, shuah@kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 tracing 3/6] tracing: support IPv6 filter predicates Message-ID: <20230609171227.56dc45b6@gandalf.local.home> In-Reply-To: <1682696089-27937-4-git-send-email-alan.maguire@oracle.com> References: <1682696089-27937-1-git-send-email-alan.maguire@oracle.com> <1682696089-27937-4-git-send-email-alan.maguire@oracle.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org BTW, the subjects for the tracing subsystem should always start with a capital letter. "tracing: Support IPv6 filter predicates" But that's not why I'm replying here. On Fri, 28 Apr 2023 16:34:46 +0100 Alan Maguire wrote: > Support '==' and '!=' predicates for IPv6 addresses; > for example > > cd /sys/kernel/debug/tracing/events/tcp/tcp_receive_reset > echo "saddr_v6 == ::1" > filter > > or equivalently > > echo "saddr_v6 == 0:0:0:0:0:0:0:1" > filter > > Signed-off-by: Alan Maguire > --- > kernel/trace/trace_events_filter.c | 73 ++++++++++++++++++++++++++++++ > 1 file changed, 73 insertions(+) > > diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c > index d8e08d3c3594..e2521574f3c4 100644 > --- a/kernel/trace/trace_events_filter.c > +++ b/kernel/trace/trace_events_filter.c > @@ -1665,6 +1665,79 @@ static int parse_pred(const char *str, void *data, > if (pred->op == OP_NE) > pred->not = 1; > > + } else if (field->size == 16 && > + (str[i] == ':' || > + (isalnum(str[i]) && tolower(str[i + 1]) != 'x'))) { > + u8 j, gap_size, gap = 0, gap_count = 0, index = 0; > + u16 tmp_v6addr[8] = {}; > + u16 v6addr[8] = {}; > + > + /* For IPv6 addresses, only '==' or '!=' are supported. */ > + if (pred->op != OP_EQ && pred->op != OP_NE) { > + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i); > + goto err_free; > + } > + /* Store the u16s in the address string consecutively in > + * tmp_v6addr while tracking the presence of a "::" (if any) > + * in the IPv6 address string; we will use its location > + * to determine how many u16s it represents (the gap_size > + * below). Only one "::" is allowed in an IPv6 address > + * string. > + */ > + while (isalnum(str[i]) || str[i] == ':') { > + switch (str[i]) { > + case ':': > + i++; > + /* mark "::" index by setting gap */ > + if (str[i] == ':') { > + gap = index; > + gap_count++; > + i++; > + } > + if (gap_count > 1) { > + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, > + pos + s); > + goto err_free; > + } > + break; > + default: > + if (sscanf(&str[i], "%hx", &tmp_v6addr[index]) != 1) { > + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, > + pos + s); > + goto err_free; > + } > + index++; > + while (isalnum(str[i])) > + i++; > + break; > + } > + } There appears to be no limit to the above loop. I panic'd my machine with: # echo 'saddr_v6 == 0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef:0123:4567:89ab:cdef' > /sys/kernel/tracing/events/sock/inet_sk_error_report/filter -- Steve > + /* The gap_size here represents the number of u16s the "::" > + * represents; for ::1 the gap size is 7, for feed::face > + * it is 6, etc. > + */ > + gap_size = 8 - index; > + index = 0; > + for (j = 0; j < 8; ) { > + if (gap_size > 0 && j == gap) { > + j += gap_size; > + } else { > +#ifdef __BIG_ENDIAN > + v6addr[j++] = tmp_v6addr[index]; > +#else > + v6addr[j++] = ((tmp_v6addr[index] & 0xff) << 8) + > + ((tmp_v6addr[index] & 0xff00) >> 8); > +#endif > + index++; > + } > + } > + pred_val = kzalloc(field->size, GFP_KERNEL); > + memcpy(pred_val, v6addr, field->size); > + pred->val = (u64)pred_val; > + pred->fn_num = FILTER_PRED_FN_MEMCMP; > + if (pred->op == OP_NE) > + pred->not = 1; > + > } else if (str[i] == '0' && tolower(str[i + 1]) == 'x' && > field->size > 8) { > /* For sizes > 8 bytes, we store hex bytes for comparison;