From: Emily Shaffer <nasamuffin@google.com>
To: Glen Choo via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Glen Choo <chooglen@google.com>
Subject: Re: [PATCH] http: redact curl h2h3 headers in info
Date: Thu, 10 Nov 2022 13:57:35 -0800 [thread overview]
Message-ID: <Y21zz1HYXzyyfwqy@google.com> (raw)
In-Reply-To: <pull.1377.git.git.1667955151994.gitgitgadget@gmail.com>
On Wed, Nov 09, 2022 at 12:52:31AM +0000, Glen Choo via GitGitGadget wrote:
>
> With GIT_TRACE_CURL=1 or GIT_CURL_VERBOSE=1, sensitive headers like
> "Authorization" and "Cookie" get redacted. However, since [1], curl's
> h2h3 module also prints headers in its "info", which don't get redacted.
> For example,
>
> echo 'github.com TRUE / FALSE 1698960413304 o foo=bar' >cookiefile &&
> GIT_TRACE_CURL=1 GIT_TRACE_CURL_NO_DATA=1 git \
> -c 'http.cookiefile=cookiefile' \
> -c 'http.version=' \
> ls-remote https://github.com/git/git refs/heads/main 2>output &&
> grep 'cookie' output
>
> produces output like:
>
> 23:04:16.920495 http.c:678 == Info: h2h3 [cookie: o=foo=bar]
> 23:04:16.920562 http.c:637 => Send header: cookie: o=<redacted>
>
> Teach http.c to check for h2h3 headers in info and redact them using the
> existing header redaction logic.
>
> [1] https://github.com/curl/curl/commit/f8c3724aa90472c0e617ddbbc420aa199971eb77
>
> Signed-off-by: Glen Choo <chooglen@google.com>
> ---
> http: redact curl h2h3 headers in info
>
> I initially sent this to the security list, but the general impression
> is that this isn't sensitive enough for an embargoed fix, so this is
> better discussed in the open instead.
>
> Since this comes from curl's HTTP2.0/3.0 module, this can be mitigated
> by setting http.version to 1.X, e.g. "git -c http.version=HTTP/1.1".
>
> According to [1], the susceptible curl versions appear to be 7.86.0,
> 7.85.0, 7.84.0, 7.83.1, 7.83.0, 7.82.0, but I'm not sure which platforms
> are vulnerable.
>
> This patch fixes the issue on my machine running curl 7.85.0, so I think
> it is okay to merge as-is. That said, I would strongly prefer to add
> tests, but I haven't figured out how. In particular:
>
> * Do we have a way of using HTTP/2.0 in our tests? A cursory glance at
> our httpd config suggests that we only use HTTP/1.1.
> * How could we set up end-to-end tests to ensure that we're testing
> this against affected versions of curl? To avoid regressions, I'd
> also prefer to test against future versions of curl too.
>
> [1]
> https://github.com/curl/curl/commit/f8c3724aa90472c0e617ddbbc420aa199971eb77
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1377%2Fchooglen%2Fhttp%2Fredact-h2h3-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1377/chooglen/http/redact-h2h3-v1
> Pull-Request: https://github.com/git/git/pull/1377
>
> http.c | 40 ++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 38 insertions(+), 2 deletions(-)
>
> diff --git a/http.c b/http.c
> index 5d0502f51fd..cbcc7c3f5b6 100644
> --- a/http.c
> +++ b/http.c
> @@ -560,8 +560,10 @@ static void set_curl_keepalive(CURL *c)
> }
> #endif
>
> -static void redact_sensitive_header(struct strbuf *header)
> +/* Return 0 if redactions been made, 1 otherwise. */
Does it make sense to reverse the retval here?
`if (!redact_sensitive_header())` sounds like "if not redacted, ..." -
but here it means the opposite, right?
> +static int redact_sensitive_header(struct strbuf *header)
> {
> + int ret = 1;
> const char *sensitive_header;
>
> if (trace_curl_redact &&
> @@ -575,6 +577,7 @@ static void redact_sensitive_header(struct strbuf *header)
> /* Everything else is opaque and possibly sensitive */
> strbuf_setlen(header, sensitive_header - header->buf);
> strbuf_addstr(header, " <redacted>");
> + ret = 0;
> } else if (trace_curl_redact &&
> skip_iprefix(header->buf, "Cookie:", &sensitive_header)) {
> struct strbuf redacted_header = STRBUF_INIT;
> @@ -612,6 +615,27 @@ static void redact_sensitive_header(struct strbuf *header)
>
> strbuf_setlen(header, sensitive_header - header->buf);
> strbuf_addbuf(header, &redacted_header);
> + ret = 0;
> + }
> + return ret;
> +}
> +
> +/* Redact headers in info */
> +static void redact_sensitive_info_header(struct strbuf *header)
> +{
> + const char *sensitive_header;
> +
> + if (trace_curl_redact &&
> + skip_iprefix(header->buf, "h2h3 [", &sensitive_header)) {
> + struct strbuf inner = STRBUF_INIT;
> +
> + /* Drop the trailing "]" */
> + strbuf_add(&inner, sensitive_header, strlen(sensitive_header) - 1);
> + if (!redact_sensitive_header(&inner)) {
> + strbuf_setlen(header, strlen("h2h3 ["));
> + strbuf_addbuf(header, &inner);
> + strbuf_addch(header, ']');
I'd really like some more comments in this function - even just one
describing the string we're trying to redact, or showing a sample line.
Navigating string parsing is always a bit difficult.
> + }
> }
> }
>
> @@ -668,6 +692,18 @@ static void curl_dump_data(const char *text, unsigned char *ptr, size_t size)
> strbuf_release(&out);
> }
>
> +static void curl_print_info(char *data, size_t size)
Nit: Every other helper in this file calls it _dump_, so should this
also say _dump_ instead of _print_?
> +{
> + struct strbuf buf = STRBUF_INIT;
> +
> + strbuf_add(&buf, data, size);
> +
> + redact_sensitive_info_header(&buf);
> + trace_printf_key(&trace_curl, "== Info: %s", buf.buf);
> +
> + strbuf_release(&buf);
> +}
> +
> static int curl_trace(CURL *handle, curl_infotype type, char *data, size_t size, void *userp)
> {
> const char *text;
> @@ -675,7 +711,7 @@ static int curl_trace(CURL *handle, curl_infotype type, char *data, size_t size,
>
> switch (type) {
> case CURLINFO_TEXT:
> - trace_printf_key(&trace_curl, "== Info: %s", data);
> + curl_print_info(data, size);
> break;
> case CURLINFO_HEADER_OUT:
> text = "=> Send header";
>
> base-commit: c03801e19cb8ab36e9c0d17ff3d5e0c3b0f24193
Otherwise functionally it seems fine to me. case CURLINFO_TEXT is the
one case that's not already using a curl_dump_* helper, so we're adding
one, and to that helper we're adding a call out to
redact_sensitive_header().
Thanks.
- Emily
> --
> gitgitgadget
next prev parent reply other threads:[~2022-11-10 21:57 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-09 0:52 [PATCH] http: redact curl h2h3 headers in info Glen Choo via GitGitGadget
2022-11-10 2:52 ` Taylor Blau
2022-11-10 17:48 ` Glen Choo
2022-11-10 21:50 ` Jeff King
2022-11-10 22:53 ` Glen Choo
2022-11-11 2:29 ` Jeff King
2022-11-11 2:31 ` Taylor Blau
2022-11-11 14:49 ` [PATCH] t: run t5551 tests with both HTTP and HTTP/2 Jeff King
2022-11-11 15:06 ` Ævar Arnfjörð Bjarmason
2022-11-11 15:19 ` Jeff King
2022-11-11 15:20 ` Jeff King
2022-11-10 21:57 ` Emily Shaffer [this message]
2022-11-10 22:14 ` [PATCH] http: redact curl h2h3 headers in info Glen Choo
2022-11-11 2:35 ` Taylor Blau
2022-11-10 22:57 ` [PATCH v2] " Glen Choo via GitGitGadget
2022-11-11 2:36 ` Taylor Blau
2022-11-11 2:38 ` Jeff King
2022-11-11 2:39 ` Taylor Blau
2022-11-11 17:55 ` Glen Choo
2022-11-11 22:35 ` [PATCH v3 0/2] " Glen Choo via GitGitGadget
2022-11-11 22:35 ` [PATCH v3 1/2] t: run t5551 tests with both HTTP and HTTP/2 Jeff King via GitGitGadget
2022-11-11 22:35 ` [PATCH v3 2/2] http: redact curl h2h3 headers in info Glen Choo via GitGitGadget
2022-11-14 22:33 ` [PATCH v3 0/2] " Jeff King
2022-11-14 22:43 ` Taylor Blau
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
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Y21zz1HYXzyyfwqy@google.com \
--to=nasamuffin@google.com \
--cc=chooglen@google.com \
--cc=git@vger.kernel.org \
--cc=gitgitgadget@gmail.com \
/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.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
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).