From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-5.9 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 93AE21FF40 for ; Wed, 14 Dec 2016 20:13:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933267AbcLNUNa (ORCPT ); Wed, 14 Dec 2016 15:13:30 -0500 Received: from mail-pg0-f44.google.com ([74.125.83.44]:32944 "EHLO mail-pg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933260AbcLNUN1 (ORCPT ); Wed, 14 Dec 2016 15:13:27 -0500 Received: by mail-pg0-f44.google.com with SMTP id 3so11419725pgd.0 for ; Wed, 14 Dec 2016 12:13:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=fCgu6/io3FJwYyzV5f94ANf+O5W+H0XvH4ayNuMf1r4=; b=siedeY6zThMR8ve09yIc5wB5rjODVq+wbOEGvjWSk2ByT5RmBWkkcArVheufO+SWAL B4Cbj4hvPNUBRCKf9t99aw0jkG9Q3pDWUyrwus4VOqvZN1Bczg5bFgTbSXHRHJyMbNgS mkJ06+POYfiXL3fxNtBBCSOK3NBMFJZowtbHPvs6jWo8hegBxUF7QwT+URL01OLK4dhQ Dtw50sUYbQUB/y3vuUSPN3agfk/TAah8+ylgRTOCdATqbOdSFkGgf3Naci9lAJqqJAqb ffKsRaWDQ0uGVSNts3LayyJbXZrMBOZN479YH4bz8okmysQ0U55qupOPXHWxL8dqw/BD hq8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=fCgu6/io3FJwYyzV5f94ANf+O5W+H0XvH4ayNuMf1r4=; b=O/AegBY6oD3ztYpiiem6dc1yA+VBzkBNV3fKofbJlkEwo9sZzyH1sZovqKvH4AfQ8c +nMCOUxx7uYLAY5e7uN8qh0pfhoFejO5NGjjsV605yEUMkDU2E4fo0ZDTbfd1Qyjk5rD YGbI5jYIv6c+z+DbCtYgwr47qNp3aGyITsq6/L6I9qkUPejA3lX0IgaBrzRt7m9EvX0f 5WIY0P7YC6sgG45V2ijTC7dljrPYBvdtC3AL2Ni5yvsOopboQPikzjL9NIwteoDc0Vi+ bAGIg84fi0uwaoM55/5ONHG7cEz1+99Omvp7cw/1OPvhtp8YbL9hyuBM29Bl9wuqtasu 8HEQ== X-Gm-Message-State: AKaTC01huHTd2e9KpJTq3enE05dsO42SQ0+zbzNgiDT6nR3fFKpaM9WFfUeZVqeoZFauEvIy X-Received: by 10.98.163.71 with SMTP id s68mr108438871pfe.60.1481746406004; Wed, 14 Dec 2016 12:13:26 -0800 (PST) Received: from google.com ([2620:0:1000:5b00:a0bd:b7d6:4331:46ad]) by smtp.gmail.com with ESMTPSA id h185sm48176728pfg.90.2016.12.14.12.13.24 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Wed, 14 Dec 2016 12:13:24 -0800 (PST) Date: Wed, 14 Dec 2016 12:13:23 -0800 From: Brandon Williams To: Jeff King 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 Message-ID: <20161214201323.GC20063@google.com> References: <1480636862-40489-1-git-send-email-bmwill@google.com> <1481679637-133137-1-git-send-email-bmwill@google.com> <1481679637-133137-6-git-send-email-bmwill@google.com> <20161214164050.uxk434kzhw6au4c2@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161214164050.uxk434kzhw6au4c2@sigill.intra.peff.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org 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 > > --- > > 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. -- Brandon Williams