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@xxxxxxxxxx> > --- > 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
