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authorJeff King <peff@peff.net>2021-09-22 22:11:53 (GMT)
committerJunio C Hamano <gitster@pobox.com>2021-09-23 04:24:58 (GMT)
commitb66c77a64e696eb5e5994a58c0d50073f8e93bf1 (patch)
tree120630b6c5e287e04affd10f2841253b3e133dc6
parent225bc32a989d7a22fa6addafd4ce7dcd04675dbf (diff)
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http: match headers case-insensitively when redacting
When HTTP/2 is in use, we fail to correctly redact "Authorization" (and other) headers in our GIT_TRACE_CURL output. We get the headers in our CURLOPT_DEBUGFUNCTION callback, curl_trace(). It passes them along to curl_dump_header(), which in turn checks redact_sensitive_header(). We see the headers as a text buffer like: Host: ... Authorization: Basic ... After breaking it into lines, we match each header using skip_prefix(). This is case-sensitive, even though HTTP headers are case-insensitive. This has worked reliably in the past because these headers are generated by curl itself, which is predictable in what it sends. But when HTTP/2 is in use, instead we get a lower-case "authorization:" header, and we fail to match it. The fix is simple: we should match with skip_iprefix(). Testing is more complicated, though. We do have a test for the redacting feature, but we don't hit the problem case because our test Apache setup does not understand HTTP/2. You can reproduce the issue by applying this on top of the test change in this patch: diff --git a/t/lib-httpd/apache.conf b/t/lib-httpd/apache.conf index afa91e38b0..19267c7107 100644 --- a/t/lib-httpd/apache.conf +++ b/t/lib-httpd/apache.conf @@ -29,6 +29,9 @@ ErrorLog error.log LoadModule setenvif_module modules/mod_setenvif.so </IfModule> +LoadModule http2_module modules/mod_http2.so +Protocols h2c + <IfVersion < 2.4> LockFile accept.lock </IfVersion> @@ -64,8 +67,8 @@ LockFile accept.lock <IfModule !mod_access_compat.c> LoadModule access_compat_module modules/mod_access_compat.so </IfModule> -<IfModule !mod_mpm_prefork.c> - LoadModule mpm_prefork_module modules/mod_mpm_prefork.so +<IfModule !mod_mpm_event.c> + LoadModule mpm_event_module modules/mod_mpm_event.so </IfModule> <IfModule !mod_unixd.c> LoadModule unixd_module modules/mod_unixd.so diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh index 1c2a444ae7..ff74f0ae8a 100755 --- a/t/t5551-http-fetch-smart.sh +++ b/t/t5551-http-fetch-smart.sh @@ -24,6 +24,10 @@ test_expect_success 'create http-accessible bare repository' ' git push public main:main ' +test_expect_success 'prefer http/2' ' + git config --global http.version HTTP/2 +' + setup_askpass_helper test_expect_success 'clone http repository' ' but this has a few issues: - it's not necessarily portable. The http2 apache module might not be available on all systems. Further, the http2 module isn't compatible with the prefork mpm, so we have to switch to something else. But we don't necessarily know what's available. It would be nice if we could have conditional config, but IfModule only tells us if a module is already loaded, not whether it is available at all. This might be a non-issue. The http tests are already optional, and modern-enough systems may just have both of these. But... - if we do this, then we'd no longer be testing HTTP/1.1 at all. I'm not sure how much that matters since it's all handled by curl under the hood, but I'd worry that some detail leaks through. We'd probably want two scripts running similar tests, one with HTTP/2 and one with HTTP/1.1. - speaking of which, a later test fails with the patch above! The problem is that it is making sure we used a chunked transfer-encoding by looking for that header in the trace. But HTTP/2 doesn't support that, as it has its own streaming mechanisms (the overall operation works fine; we just don't see the header in the trace). Furthermore, even with the changes above, this test still does not detect the current failure, because we see _both_ HTTP/1.1 and HTTP/2 requests, which confuse it. Quoting only the interesting bits from the resulting trace file, we first see: => Send header: GET /auth/smart/repo.git/info/refs?service=git-upload-pack HTTP/1.1 => Send header: Connection: Upgrade, HTTP2-Settings => Send header: Upgrade: h2c => Send header: HTTP2-Settings: AAMAAABkAAQCAAAAAAIAAAAA <= Recv header: HTTP/1.1 401 Unauthorized <= Recv header: Date: Wed, 22 Sep 2021 20:03:32 GMT <= Recv header: Server: Apache/2.4.49 (Debian) <= Recv header: WWW-Authenticate: Basic realm="git-auth" So the client asks for HTTP/2, but Apache does not do the upgrade for the 401 response. Then the client repeats with credentials: => Send header: GET /auth/smart/repo.git/info/refs?service=git-upload-pack HTTP/1.1 => Send header: Authorization: Basic <redacted> => Send header: Connection: Upgrade, HTTP2-Settings => Send header: Upgrade: h2c => Send header: HTTP2-Settings: AAMAAABkAAQCAAAAAAIAAAAA <= Recv header: HTTP/1.1 101 Switching Protocols <= Recv header: Upgrade: h2c <= Recv header: Connection: Upgrade <= Recv header: HTTP/2 200 <= Recv header: content-type: application/x-git-upload-pack-advertisement So the client does properly redact there, because we're speaking HTTP/1.1, and the server indicates it can do the upgrade. And then the client will make further requests using HTTP/2: => Send header: POST /auth/smart/repo.git/git-upload-pack HTTP/2 => Send header: authorization: Basic dXNlckBob3N0OnBhc3NAaG9zdA== => Send header: content-type: application/x-git-upload-pack-request And there we can see that the credential is _not_ redacted. This part of the test is what gets confused: # Ensure that there is no "Basic" followed by a base64 string, but that # the auth details are redacted ! grep "Authorization: Basic [0-9a-zA-Z+/]" trace && grep "Authorization: Basic <redacted>" trace The first grep does not match the un-redacted HTTP/2 header, because it insists on an uppercase "A". And the second one does find the HTTP/1.1 header. So as far as the test is concerned, everything is OK, but it failed to notice the un-redacted lines. We can make this test (and the other related ones) more robust by adding "-i" to grep case-insensitively. This isn't really doing anything for now, since we're not actually speaking HTTP/2, but it future-proofs the tests for a day when we do (either we add explicit HTTP/2 test support, or it's eventually enabled by default by our Apache+curl test setup). And it doesn't hurt in the meantime for the tests to be more careful. The change to use "grep -i", coupled with the changes to use HTTP/2 shown above, causes the test to fail with the current code, and pass after this patch is applied. And finally, there's one other way to demonstrate the issue (and how I actually found it originally). Looking at GIT_TRACE_CURL output against github.com, you'll see the unredacted output, even if you didn't set http.version. That's because setting it is only necessary for curl to send the extra headers in its HTTP/1.1 request that say "Hey, I speak HTTP/2; upgrade if you do, too". But for a production site speaking https, the server advertises via ALPN, a TLS extension, that it supports HTTP/2, and the client can immediately start using it. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--http.c6
-rwxr-xr-xt/t5551-http-fetch-smart.sh24
2 files changed, 15 insertions, 15 deletions
diff --git a/http.c b/http.c
index 8119247..fdb6e22 100644
--- a/http.c
+++ b/http.c
@@ -643,8 +643,8 @@ static void redact_sensitive_header(struct strbuf *header)
const char *sensitive_header;
if (trace_curl_redact &&
- (skip_prefix(header->buf, "Authorization:", &sensitive_header) ||
- skip_prefix(header->buf, "Proxy-Authorization:", &sensitive_header))) {
+ (skip_iprefix(header->buf, "Authorization:", &sensitive_header) ||
+ skip_iprefix(header->buf, "Proxy-Authorization:", &sensitive_header))) {
/* The first token is the type, which is OK to log */
while (isspace(*sensitive_header))
sensitive_header++;
@@ -654,7 +654,7 @@ static void redact_sensitive_header(struct strbuf *header)
strbuf_setlen(header, sensitive_header - header->buf);
strbuf_addstr(header, " <redacted>");
} else if (trace_curl_redact &&
- skip_prefix(header->buf, "Cookie:", &sensitive_header)) {
+ skip_iprefix(header->buf, "Cookie:", &sensitive_header)) {
struct strbuf redacted_header = STRBUF_INIT;
const char *cookie;
diff --git a/t/t5551-http-fetch-smart.sh b/t/t5551-http-fetch-smart.sh
index 4f87d90..4e54226 100755
--- a/t/t5551-http-fetch-smart.sh
+++ b/t/t5551-http-fetch-smart.sh
@@ -196,8 +196,8 @@ test_expect_success 'GIT_TRACE_CURL redacts auth details' '
# Ensure that there is no "Basic" followed by a base64 string, but that
# the auth details are redacted
- ! grep "Authorization: Basic [0-9a-zA-Z+/]" trace &&
- grep "Authorization: Basic <redacted>" trace
+ ! grep -i "Authorization: Basic [0-9a-zA-Z+/]" trace &&
+ grep -i "Authorization: Basic <redacted>" trace
'
test_expect_success 'GIT_CURL_VERBOSE redacts auth details' '
@@ -208,8 +208,8 @@ test_expect_success 'GIT_CURL_VERBOSE redacts auth details' '
# Ensure that there is no "Basic" followed by a base64 string, but that
# the auth details are redacted
- ! grep "Authorization: Basic [0-9a-zA-Z+/]" trace &&
- grep "Authorization: Basic <redacted>" trace
+ ! grep -i "Authorization: Basic [0-9a-zA-Z+/]" trace &&
+ grep -i "Authorization: Basic <redacted>" trace
'
test_expect_success 'GIT_TRACE_CURL does not redact auth details if GIT_TRACE_REDACT=0' '
@@ -219,7 +219,7 @@ test_expect_success 'GIT_TRACE_CURL does not redact auth details if GIT_TRACE_RE
git clone --bare "$HTTPD_URL/auth/smart/repo.git" redact-auth &&
expect_askpass both user@host &&
- grep "Authorization: Basic [0-9a-zA-Z+/]" trace
+ grep -i "Authorization: Basic [0-9a-zA-Z+/]" trace
'
test_expect_success 'disable dumb http on server' '
@@ -474,10 +474,10 @@ test_expect_success 'cookies are redacted by default' '
GIT_TRACE_CURL=true \
git -c "http.cookieFile=$(pwd)/cookies" clone \
$HTTPD_URL/smart/repo.git clone 2>err &&
- grep "Cookie:.*Foo=<redacted>" err &&
- grep "Cookie:.*Bar=<redacted>" err &&
- ! grep "Cookie:.*Foo=1" err &&
- ! grep "Cookie:.*Bar=2" err
+ grep -i "Cookie:.*Foo=<redacted>" err &&
+ grep -i "Cookie:.*Bar=<redacted>" err &&
+ ! grep -i "Cookie:.*Foo=1" err &&
+ ! grep -i "Cookie:.*Bar=2" err
'
test_expect_success 'empty values of cookies are also redacted' '
@@ -486,7 +486,7 @@ test_expect_success 'empty values of cookies are also redacted' '
GIT_TRACE_CURL=true \
git -c "http.cookieFile=$(pwd)/cookies" clone \
$HTTPD_URL/smart/repo.git clone 2>err &&
- grep "Cookie:.*Foo=<redacted>" err
+ grep -i "Cookie:.*Foo=<redacted>" err
'
test_expect_success 'GIT_TRACE_REDACT=0 disables cookie redaction' '
@@ -496,8 +496,8 @@ test_expect_success 'GIT_TRACE_REDACT=0 disables cookie redaction' '
GIT_TRACE_REDACT=0 GIT_TRACE_CURL=true \
git -c "http.cookieFile=$(pwd)/cookies" clone \
$HTTPD_URL/smart/repo.git clone 2>err &&
- grep "Cookie:.*Foo=1" err &&
- grep "Cookie:.*Bar=2" err
+ grep -i "Cookie:.*Foo=1" err &&
+ grep -i "Cookie:.*Bar=2" err
'
test_expect_success 'GIT_TRACE_CURL_NO_DATA prevents data from being traced' '