From: Brandon Williams <bmwill@google.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, sbeller@google.com, bburky@bburky.com,
gitster@pobox.com, jrnieder@gmail.com
Subject: Re: [PATCH v9 5/5] transport: add from_user parameter to is_transport_allowed
Date: Wed, 14 Dec 2016 12:37:52 -0800 [thread overview]
Message-ID: <20161214203752.GD20063@google.com> (raw)
In-Reply-To: <20161214201323.GC20063@google.com>
On 12/14, Brandon Williams wrote:
> On 12/14, Jeff King wrote:
> > On Tue, Dec 13, 2016 at 05:40:37PM -0800, Brandon Williams wrote:
> >
> > > Add the from_user parameter to the 'is_transport_allowed' function.
> > > This allows callers to query if a transport protocol is allowed, given
> > > that the caller knows that the protocol is coming from the user (1) or
> > > not from the user (0) such as redirects in libcurl. If unknown a -1
> > > should be provided which falls back to reading `GIT_PROTOCOL_FROM_USER`
> > > to determine if the protocol came from the user.
> >
> > I think your commit message is upside-down with respect to the purpose
> > of the patch. The end goal we want is for http to distinguish between
> > protocol restrictions for redirects versus initial requests. The rest is
> > an implementation detail. It's definitely still worth discussing that
> > implementation detail (though I think your in-code comments may be
> > sufficient), but I don't see the rationale discussed here at all.
>
> I'll fix the commit message to better discuss the reasoning behind the
> change.
>
> > > Signed-off-by: Brandon Williams <bmwill@google.com>
> > > ---
> > > http.c | 14 +++++++-------
> > > transport.c | 8 +++++---
> > > transport.h | 13 ++++++++++---
> > > 3 files changed, 22 insertions(+), 13 deletions(-)
> >
> > I'm trying to think of a way to test this. I guess the case we are
> > covering here is when a server redirects, but the protocol is only
> > allowed from the user. So:
> >
> > diff --git a/t/t5812-proto-disable-http.sh b/t/t5812-proto-disable-http.sh
> > index 044cc152f..d911afd24 100755
> > --- a/t/t5812-proto-disable-http.sh
> > +++ b/t/t5812-proto-disable-http.sh
> > @@ -30,5 +30,12 @@ test_expect_success 'curl limits redirects' '
> > test_must_fail git clone "$HTTPD_URL/loop-redir/smart/repo.git"
> > '
> >
> > +test_expect_success 'http can be limited to from-user' '
> > + git -c protocol.http.allow=user \
> > + clone "$HTTPD_URL/smart/repo.git" plain.git &&
> > + test_must_fail git -c protocol.http.allow=user \
> > + clone "$HTTPD_URL/smart-redir-perm/repo.git" redir.git
> > +'
> > +
> > stop_httpd
> > test_done
> >
> > It's an oddball configuration, and you'd probably just set
> > http.followRedirects=false in practice, but it does correctly check this
> > case.
>
> K I'll add this in as a test.
>
> > > @@ -588,9 +588,9 @@ static CURL *get_curl_handle(void)
> > > #endif
> > > #if LIBCURL_VERSION_NUM >= 0x071304
> > > curl_easy_setopt(result, CURLOPT_REDIR_PROTOCOLS,
> > > - get_curl_allowed_protocols());
> > > + get_curl_allowed_protocols(0));
> > > curl_easy_setopt(result, CURLOPT_PROTOCOLS,
> > > - get_curl_allowed_protocols());
> > > + get_curl_allowed_protocols(-1));
> >
> > This covers internal redirects done by libcurl, but not the dumb-walker
> > http-alternates nonsense. We have to feed the URL from http-alternates
> > back to curl ourselves, so it uses CURLOPT_PROTOCOLS even though it
> > should count as "not from the user".
> >
> > To fix that, I think we'd need something like:
> >
> > - get_curl_handle() stops setting these options, as it is done only
> > once when the curl handle is initialized. Instead, the protocol
> > restrictions should go into get_active_slot(), which is called for
> > each request. The values set would remain the same, and be the
> > baseline.
> >
> > - the http-walker.c code would need to know when it's requesting from
> > the base URL, and when it's an alternate. I think this would depend
> > on the position of the "alt" in in the linked list it keeps.
> >
> > - when requesting from an alternate, http-walker would set
> > CURLOPT_PROTOCOLS with get_curl_allowed_protocols(0)
> >
> > I have to admit that it sounds like a fair bit of work for a pretty
> > obscure case. You'd have to:
> >
> > 1. Turn http.allowRedirects to "true", to allow redirects even for
> > non-initial contact.
> >
> > 2. Turn one of protocol.{http,https,ftp,ftps}.allow to "user" to
> > restrict it from being used in a redirect.
> >
> > I'm tempted to punt on it and just do:
> >
> > if (http_follow_config == HTTP_FOLLOW_ALWAYS &&
> > get_curl_allowed_protocols(0) != get_curl_allowed_protocols(-1))
> > die("user-only protocol restrictions not implemented for http-alternates");
> >
> > which errs on the safe side. We could even shove that down into the case
> > where we actually see some alternates, like:
> >
> > diff --git a/http-walker.c b/http-walker.c
> > index c2f81cd6a..5bcc850b1 100644
> > --- a/http-walker.c
> > +++ b/http-walker.c
> > @@ -160,6 +160,12 @@ static void prefetch(struct walker *walker, unsigned char *sha1)
> > #endif
> > }
> >
> > +static void check_alternates_protocol_restrictions(void)
> > +{
> > + if (get_curl_allowed_protocols(0) != get_curl_allowed_protocol(-1))
> > + die("user-only protocol restrictions not implemented for http alternates");
> > +}
> > +
> > static void process_alternates_response(void *callback_data)
> > {
> > struct alternates_request *alt_req =
> > @@ -272,6 +278,7 @@ static void process_alternates_response(void *callback_data)
> > /* skip "objects\n" at end */
> > if (okay) {
> > struct strbuf target = STRBUF_INIT;
> > + check_alternates_protocol_restrictions();
> > strbuf_add(&target, base, serverlen);
> > strbuf_add(&target, data + i, posn - i - 7);
> > warning("adding alternate object store: %s",
> >
> > I find it unlikely that anybody would ever care, but at least we'd do
> > the safe thing. I dunno. Maybe I am just being lazy.
>
> Well, that's unfortunate! It does sound like a more full-proof solution
> to these dumb http alternates could be involved. I don't think your
> simple "lazy" solution may be enough to not just die by default.
>
> By default ftp/ftps will have a policy of "user only" which means they
> will be set by the call to get_curl_allowed_protocol(-1) but not set by
> get_curl_allowed_protocol(0). This would result in the call to
> check_alternates_protocol_restrictions failing all the time unless the
> user explicitly sets ftp/ftps to "always" or "never". If that is the
> desired behavior then your proposed solution would be fine, otherwise we
> may have to do the more involved approach.
Naively looking at the code (and your longer suggestion), is there a
reason why we couldn't simply have http-walker set CURLOPT_PROTOCOLS
with get_curl_allowed_protocols(0) in the fetch_alternates() function?
That way we just override the CURLOPT_PROTOCOLS value when alternates
are involved.
Like so:
diff --git a/http-walker.c b/http-walker.c
index c2f81cd..b284cec 100644
--- a/http-walker.c
+++ b/http-walker.c
@@ -339,6 +339,8 @@ static void fetch_alternates(struct walker *walker, const char *base)
curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
curl_easy_setopt(slot->curl, CURLOPT_URL, url.buf);
+ curl_easy_setopt(slot->curl, CURLOPT_PROTOCOLS,
+ get_curl_allowed_protocols(0));
alt_req.base = base;
alt_req.url = &url;
--
Brandon Williams
next prev parent reply other threads:[~2016-12-14 20:37 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-02 22:20 [PATCH] transport: add core.allowProtocol config option Brandon Williams
2016-11-02 22:41 ` Stefan Beller
2016-11-02 22:47 ` Brandon Williams
2016-11-02 23:05 ` Jeff King
2016-11-02 23:08 ` Jeff King
2016-11-02 23:34 ` Brandon Williams
2016-11-02 23:33 ` Brandon Williams
2016-11-02 23:46 ` Brandon Williams
2016-11-03 0:08 ` Jeff King
2016-11-03 0:22 ` Jonathan Nieder
2016-11-03 0:41 ` Blake Burkhart
2016-11-03 2:44 ` Junio C Hamano
2016-11-03 14:38 ` Jeff King
2016-11-03 17:25 ` Brandon Williams
2016-11-03 17:39 ` Stefan Beller
2016-11-03 17:51 ` Brandon Williams
2016-11-03 18:02 ` Jeff King
2016-11-03 18:08 ` Brandon Williams
2016-11-03 18:00 ` Jeff King
2016-11-03 17:53 ` Jeff King
2016-11-03 18:19 ` Brandon Williams
2016-11-03 18:25 ` Jeff King
2016-11-03 18:24 ` Jeff King
2016-11-03 18:45 ` Brandon Williams
2016-11-03 18:50 ` Jeff King
2016-11-03 18:56 ` Brandon Williams
2016-11-03 0:50 ` [PATCH v2] " Brandon Williams
2016-11-04 20:55 ` [PATCH v3] transport: add protocol policy " Brandon Williams
2016-11-04 20:58 ` Brandon Williams
2016-11-04 21:35 ` Stefan Beller
2016-11-04 23:09 ` Jeff King
2016-11-05 0:18 ` Brandon Williams
2016-11-04 22:38 ` Stefan Beller
2016-11-07 18:14 ` Brandon Williams
2016-11-04 23:06 ` Jeff King
2016-11-07 19:17 ` Brandon Williams
2016-11-07 19:35 ` [PATCH v4 1/2] lib-proto-disable: variable name fix Brandon Williams
2016-11-07 19:35 ` [PATCH v4 2/2] transport: add protocol policy config option Brandon Williams
2016-11-07 20:44 ` Jeff King
2016-11-07 21:02 ` Brandon Williams
2016-11-07 20:26 ` [PATCH v4 1/2] lib-proto-disable: variable name fix Jeff King
2016-11-07 20:40 ` Brandon Williams
2016-11-07 20:48 ` Jeff King
2016-11-08 3:32 ` Jacob Keller
2016-11-08 20:52 ` Junio C Hamano
2016-11-07 21:51 ` [PATCH v5 " Brandon Williams
2016-11-07 21:51 ` [PATCH v5 2/2] transport: add protocol policy config option Brandon Williams
2016-11-08 22:04 ` Jeff King
2016-11-08 22:05 ` Brandon Williams
2016-12-01 19:44 ` [PATCH v6 0/4] transport protocol policy configuration Brandon Williams
2016-12-01 19:44 ` [PATCH v6 1/4] lib-proto-disable: variable name fix Brandon Williams
2016-12-01 19:44 ` [PATCH v6 2/4] transport: add protocol policy config option Brandon Williams
2016-12-01 19:44 ` [PATCH v6 3/4] http: always warn if libcurl version is too old Brandon Williams
2016-12-01 19:44 ` [PATCH v6 4/4] transport: check if protocol can be used on a redirect Brandon Williams
2016-12-01 19:48 ` Brandon Williams
2016-12-01 19:49 ` Brandon Williams
2016-12-01 19:50 ` Jeff King
2016-12-01 19:54 ` Junio C Hamano
2016-12-01 19:59 ` Jeff King
2016-12-01 20:01 ` Brandon Williams
2016-12-01 20:25 ` [PATCH v7 0/4] transport protocol policy configuration Brandon Williams
2016-12-01 20:25 ` [PATCH v7 1/4] lib-proto-disable: variable name fix Brandon Williams
2016-12-01 20:25 ` [PATCH v7 2/4] transport: add protocol policy config option Brandon Williams
2016-12-01 20:25 ` [PATCH v7 3/4] http: always warn if libcurl version is too old Brandon Williams
2016-12-01 20:25 ` [PATCH v7 4/4] transport: add from_user parameter to is_transport_allowed Brandon Williams
2016-12-01 21:40 ` Jeff King
2016-12-01 22:25 ` Junio C Hamano
2016-12-01 23:07 ` Brandon Williams
2016-12-01 23:26 ` Brandon Williams
2016-12-02 0:13 ` Jeff King
2016-12-02 17:33 ` Brandon Williams
2016-12-01 23:34 ` Junio C Hamano
2016-12-01 23:58 ` Brandon Williams
2016-12-05 20:04 ` Junio C Hamano
2016-12-05 22:22 ` Brandon Williams
2016-12-05 23:19 ` Junio C Hamano
2016-12-05 23:22 ` Brandon Williams
2016-12-06 13:51 ` Jeff King
2016-12-06 17:53 ` Junio C Hamano
2016-12-06 18:10 ` Jeff King
2016-12-06 18:24 ` [PATCH v2] jk/http-walker-limit-redirect rebased to maint-2.9 Jeff King
2016-12-06 18:24 ` [PATCH v2 1/6] http: simplify update_url_from_redirect Jeff King
2016-12-06 18:24 ` [PATCH v2 2/6] http: always update the base URL for redirects Jeff King
2016-12-06 18:24 ` [PATCH v2 3/6] remote-curl: rename shadowed options variable Jeff King
2016-12-06 18:24 ` [PATCH v2 4/6] http: make redirects more obvious Jeff King
2016-12-06 18:24 ` [PATCH v2 5/6] http: treat http-alternates like redirects Jeff King
2016-12-06 18:25 ` [PATCH v2 6/6] http-walker: complain about non-404 loose object errors Jeff King
2016-12-06 22:24 ` [PATCH v7 4/4] transport: add from_user parameter to is_transport_allowed Brandon Williams
2016-12-02 0:00 ` [PATCH v8 0/5] transport protocol policy configuration Brandon Williams
2016-12-02 0:00 ` [PATCH v8 1/5] lib-proto-disable: variable name fix Brandon Williams
2016-12-02 0:00 ` [PATCH v8 2/5] transport: add protocol policy config option Brandon Williams
2016-12-02 0:01 ` [PATCH v8 3/5] http: always warn if libcurl version is too old Brandon Williams
2016-12-02 0:01 ` [PATCH v8 4/5] http: create function to get curl allowed protocols Brandon Williams
2016-12-02 0:01 ` [PATCH v8 5/5] transport: add from_user parameter to is_transport_allowed Brandon Williams
2016-12-14 1:40 ` [PATCH v9 0/5] transport protocol policy configuration Brandon Williams
2016-12-14 1:40 ` [PATCH v9 1/5] lib-proto-disable: variable name fix Brandon Williams
2016-12-14 1:40 ` [PATCH v9 2/5] transport: add protocol policy config option Brandon Williams
2016-12-14 1:40 ` [PATCH v9 3/5] http: always warn if libcurl version is too old Brandon Williams
2016-12-14 16:01 ` Jeff King
2016-12-14 17:56 ` Brandon Williams
2016-12-14 1:40 ` [PATCH v9 4/5] http: create function to get curl allowed protocols Brandon Williams
2016-12-14 16:03 ` Jeff King
2016-12-14 18:00 ` Brandon Williams
2016-12-14 1:40 ` [PATCH v9 5/5] transport: add from_user parameter to is_transport_allowed Brandon Williams
2016-12-14 16:40 ` Jeff King
2016-12-14 20:13 ` Brandon Williams
2016-12-14 20:33 ` Jeff King
2016-12-14 21:12 ` Jeff King
2016-12-14 21:58 ` Brandon Williams
[not found] ` <CAP3OtXiOPbAkr5Mn+5tEmZZAZzJXQ4CvtpHCg=wt+k-bi6K2vA@mail.gmail.com>
[not found] ` <CAP3OtXhH++szRws20MaHt-ftLBMUJuYiTmfL50mOFP4FA4Mn6Q@mail.gmail.com>
2016-12-14 22:52 ` Jeff King
2016-12-14 20:37 ` Brandon Williams [this message]
2016-12-14 20:41 ` Jeff King
2016-12-14 20:50 ` Brandon Williams
2016-12-14 22:39 ` [PATCH v10 0/6] transport protocol policy configuration Brandon Williams
2016-12-14 22:39 ` [PATCH v10 1/6] lib-proto-disable: variable name fix Brandon Williams
2016-12-14 22:39 ` [PATCH v10 2/6] http: always warn if libcurl version is too old Brandon Williams
2016-12-15 0:21 ` Jeff King
2016-12-15 17:29 ` Junio C Hamano
2016-12-14 22:39 ` [PATCH v10 3/6] transport: add protocol policy config option Brandon Williams
2016-12-14 22:39 ` [PATCH v10 4/6] http: create function to get curl allowed protocols Brandon Williams
2016-12-14 22:39 ` [PATCH v10 5/6] transport: add from_user parameter to is_transport_allowed Brandon Williams
2016-12-14 22:39 ` [PATCH v10 6/6] http: respect protocol.*.allow=user for http-alternates Brandon Williams
2016-12-14 23:25 ` [PATCH v10 0/6] transport protocol policy configuration Junio C Hamano
2016-12-15 0:22 ` Jeff King
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