From: Steven Rostedt <rostedt@goodmis.org>
To: Alan Maguire <alan.maguire@oracle.com>
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
Date: Fri, 9 Jun 2023 17:12:27 -0400 [thread overview]
Message-ID: <20230609171227.56dc45b6@gandalf.local.home> (raw)
In-Reply-To: <1682696089-27937-4-git-send-email-alan.maguire@oracle.com>
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 <alan.maguire@oracle.com> 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 <alan.maguire@oracle.com>
> ---
> 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;
next prev parent reply other threads:[~2023-06-09 21:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-28 15:34 [PATCH v2 tracing 0/6] tracing: additional filter predicates Alan Maguire
2023-04-28 15:34 ` [PATCH v2 tracing 1/6] tracing: support > 8 byte array " Alan Maguire
2023-04-28 15:34 ` [PATCH v2 tracing 2/6] tracing: support IPv4 address filter predicate Alan Maguire
2023-04-28 15:34 ` [PATCH v2 tracing 3/6] tracing: support IPv6 filter predicates Alan Maguire
2023-06-09 21:12 ` Steven Rostedt [this message]
2023-06-09 21:15 ` Steven Rostedt
2023-04-28 15:34 ` [PATCH v2 tracing 4/6] tracing: support MAC address " Alan Maguire
2023-04-28 15:34 ` [PATCH v2 tracing 5/6] selftests/ftrace: add test coverage for " Alan Maguire
2023-04-28 15:34 ` [PATCH v2 tracing 6/6] tracing: document IPv4, IPv6, MAC address and > 8 byte numeric filtering support Alan Maguire
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230609171227.56dc45b6@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=alan.maguire@oracle.com \
--cc=corbet@lwn.net \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=shuah@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).