If someone misconfigures a debuginfod federation to have loops, and
a nonexistent buildid lookup is attempted, bad things will happen,
as is documented.
This patch aims to reduce the risk by adding an option to debuginfod
that functions kind of like an IP packet's TTL: a limit on the length of
XFF: header that debuginfod is willing to process. If X-Forwarded-For:
exceeds N hops, it will not delegate a local lookup miss to upstream
debuginfods.
Commit
ab38d167c40c99 causes federation loops for non-existent resources
to result in multiple temporary deadlocks, each lasting for
$DEBUGINFOD_TIMEOUT seconds. Since concurrent requests for each unique
resource are now serialized, federation loops can result in one server
thread waiting to acquire a lock while the server thread holding the
lock waits for the first thread to respond to an http request.
This PR can help protect against the above multiple temporary deadlocks
behaviour. Ex. if --forwarded-ttl-limit=0 then the timeout behaviour of
local loops should be avoided.
https://sourceware.org/bugzilla/show_bug.cgi?id=27917
Signed-off-by: Di Chen <dichen@redhat.com>
+2021-08-20 Di Chen <dichen@redhat.com>
+
+ * debuginfod.cxx (options): Add ARGP_KEY_FORWARDED_TTL_LIMIT.
+ (forwarded_ttl_limit): New static unsigned.
+ (parse_opt): Handle ARGP_KEY_FORWARDED_TTL_LIMIT.
+ (handle_buildid): Check forwarded_ttl_limit.
+ (main): Log forwarded ttl limit.
+
2021-08-20 Saleem Abdulrasool <abdulras@google.com>
* debuginfod.cxx: Remove error.h include.
#define ARGP_KEY_FDCACHE_PREFETCH_FDS 0x1006
{ "fdcache-prefetch-fds", ARGP_KEY_FDCACHE_PREFETCH_FDS, "NUM", 0,"Number of files allocated to the \
prefetch cache.", 0},
+#define ARGP_KEY_FORWARDED_TTL_LIMIT 0x1007
+ {"forwarded-ttl-limit", ARGP_KEY_FORWARDED_TTL_LIMIT, "NUM", 0, "Limit of X-Forwarded-For hops, default 8.", 0},
{ NULL, 0, NULL, 0, NULL, 0 },
};
static long fdcache_mintmp;
static long fdcache_prefetch_mbs;
static long fdcache_prefetch_fds;
+static unsigned forwarded_ttl_limit = 8;
static string tmpdir;
static void set_metric(const string& key, double value);
if( fdcache_mintmp > 100 || fdcache_mintmp < 0 )
argp_failure(state, 1, EINVAL, "fdcache mintmp percent");
break;
+ case ARGP_KEY_FORWARDED_TTL_LIMIT:
+ forwarded_ttl_limit = (unsigned) atoi(arg);
+ break;
case ARGP_KEY_ARG:
source_paths.insert(string(arg));
break;
if (xff != "")
xff += string(", "); // comma separated list
+ unsigned int xff_count = 0;
+ for (auto&& i : xff){
+ if (i == ',') xff_count++;
+ }
+
+ // if X-Forwarded-For: exceeds N hops,
+ // do not delegate a local lookup miss to upstream debuginfods.
+ if (xff_count >= forwarded_ttl_limit)
+ throw reportable_exception(MHD_HTTP_NOT_FOUND, "not found, --forwared-ttl-limit reached \
+and will not query the upstream servers");
+
// Compute the client's numeric IP address only - so can't merge with conninfo()
const union MHD_ConnectionInfo *u = MHD_get_connection_info (conn,
MHD_CONNECTION_INFO_CLIENT_ADDRESS);
obatched(clog) << "groom time " << groom_s << endl;
obatched(clog) << "prefetch fds " << fdcache_prefetch_fds << endl;
obatched(clog) << "prefetch mbs " << fdcache_prefetch_mbs << endl;
+ obatched(clog) << "forwarded ttl limit " << forwarded_ttl_limit << endl;
if (scan_archives.size()>0)
{
+2021-08-20 Di Chen <dichen@redhat.com>
+
+ * debuginfod.8: Add --forwarded-ttl-limit=NUM documentation.
+
2021-07-28 Alice Zhang <alizhang@redhat.com>
PR27950
can translate to RAM scarcity if the disk happens to be on a RAM
virtual disk. The default threshold is 25%.
+.TP
+.B "\-\-forwarded\-ttl\-limit=NUM"
+Configure limits of X-Forwarded-For hops. if X-Forwarded-For
+exceeds N hops, it will not delegate a local lookup miss to
+upstream debuginfods. The default limit is 8.
+
.TP
.B "\-v"
Increase verbosity of logging to the standard error file descriptor.
+2021-08-20 Di Chen <dichen@redhat.com>
+
+ * run-debuginfod-find.sh: Add test for X-Forwarded-For hops limit.
+
2021-08-04 Mark Wielaard <mark@klomp.org>
PR28190
PID2=0
PID3=0
PID4=0
+PID5=0
+PID6=0
cleanup()
{
if [ $PID2 -ne 0 ]; then kill $PID2; wait $PID2; fi
if [ $PID3 -ne 0 ]; then kill $PID3; wait $PID3; fi
if [ $PID4 -ne 0 ]; then kill $PID4; wait $PID4; fi
+ if [ $PID5 -ne 0 ]; then kill $PID5; wait $PID5; fi
+ if [ $PID6 -ne 0 ]; then kill $PID6; wait $PID6; fi
rm -rf F R D L Z ${PWD}/foobar ${PWD}/mocktree ${PWD}/.client_cache* ${PWD}/tmp*
exit_cleanup
}
errfiles_list=
err() {
echo ERROR REPORTS
- for ports in $PORT1 $PORT2 $PORT3
+ for ports in $PORT1 $PORT2 $PORT3 $PORT4 $PORT5
do
echo ERROR REPORT $port metrics
curl -s http://127.0.0.1:$port/metrics
exit 1;
fi
+########################################################################
+
+# Test when debuginfod hitting X-Forwarded-For hops limit.
+# This test will start two servers (as a loop) with two different hop limits.
+
+while true; do
+ PORT4=`expr '(' $RANDOM % 1000 ')' + 9000`
+ PORT5=`expr '(' $RANDOM % 1000 ')' + 9000`
+ ss -atn | fgrep -e ":$PORT4" -e ":$PORT5"|| break
+done
+
+# Make sure the vlogs are cleaned up after the test
+# and that they are printed on error.
+tempfiles vlog$PORT4 vlog$PORT5
+errfiles vlog$PORT4 vlog$PORT5
+
+env LD_LIBRARY_PATH=$ldpath DEBUGINFOD_URLS=http://127.0.0.1:$PORT5 ${abs_builddir}/../debuginfod/debuginfod $VERBOSE --forwarded-ttl-limit 0 -p $PORT4 > vlog$PORT4 2>&1 &
+PID5=$!
+
+env LD_LIBRARY_PATH=$ldpath DEBUGINFOD_URLS=http://127.0.0.1:$PORT4 ${abs_builddir}/../debuginfod/debuginfod $VERBOSE --forwarded-ttl-limit 1 -p $PORT5 > vlog$PORT5 2>&1 &
+PID6=$!
+
+wait_ready $PORT4 'ready' 1
+wait_ready $PORT5 'ready' 1
+
+export DEBUGINFOD_URLS="http://127.0.0.1:$PORT4/"
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find debuginfo 01234567 || true
+
+# Use a different buildid to avoid using same cache.
+export DEBUGINFOD_URLS="http://127.0.0.1:$PORT5/"
+testrun ${abs_top_builddir}/debuginfod/debuginfod-find debuginfo 11234567 || true
+
+grep "forwared-ttl-limit reached and will not query the upstream servers" vlog$PORT4
+grep -v "forwared-ttl-limit reached and will not query the upstream servers" vlog$PORT5 | grep "not found" vlog$PORT5
+
+kill $PID5 $PID6
+wait $PID5 $PID6
+
+PID5=0
+PID6=0
+
exit 0
projects / thirdparty / elfutils.git / commitdiff
