commit f9c654c703af9623d0b64f116288ea81986ffa56
author Lorenzo Colitti <lorenzo@google.com> Thu Mar 01 18:02:15 2018 +0900
committer Lorenzo Colitti <lorenzo@google.com> Thu Mar 01 18:11:40 2018 +0900
tree c6dd298142d959159ebbdb82705b373a7fee98e9
parent e5763b48eee9fc8613fac5279e917a65ca2874ce

Temporarily open BPF maps with no access flags.

Some device kernels have not yet picked up the commit that adds
support for BPF file open flags. Make userspace always use 0
until the kernels are fixed.

Also fix the log tag (it's currently empty).

Bug: 30950746
Test: "adb shell dumpsys netstats detail" returns data on device with 4.9 kernel
Change-Id: Icbab37e0bc9376d2c23e70eaa290a367bc804498

libbpf/BpfNetworkStats.cpp

diff --git a/libbpf/BpfNetworkStats.cpp b/libbpf/BpfNetworkStats.cpp
index bbe4c30..31ba606 100644
--- a/libbpf/BpfNetworkStats.cpp
+++ b/libbpf/BpfNetworkStats.cpp
@@ -28,11 +28,20 @@
 #include "bpf/BpfNetworkStats.h"
 #include "bpf/BpfUtils.h"
 
+#ifdef LOG_TAG
+#undef LOG_TAG
+#endif
+
+#define LOG_TAG "BpfNetworkStats"
+
 namespace android {
 namespace bpf {
 
 static const char* BPF_IFACE_STATS = "/proc/net/dev";
 
+// TODO: change this to BPF_F_RDONLY as soon as device kernels have been updated.
+static constexpr uint32_t BPF_OPEN_FLAGS = 0;
+
 int bpfGetUidStatsInternal(uid_t uid, Stats* stats, const base::unique_fd& map_fd) {
     struct StatsKey curKey, nextKey;
     curKey = NONEXISTENT_STATSKEY;
@@ -55,10 +64,10 @@
 }
 
 int bpfGetUidStats(uid_t uid, Stats* stats) {
-    base::unique_fd uidStatsMap(bpf::mapRetrieve(UID_STATS_MAP_PATH, BPF_F_RDONLY));
+    base::unique_fd uidStatsMap(bpf::mapRetrieve(UID_STATS_MAP_PATH, BPF_OPEN_FLAGS));
     if (uidStatsMap < 0) {
         int ret = -errno;
-        ALOGE("get map fd failed from %s: %s", UID_STATS_MAP_PATH, strerror(errno));
+        ALOGE("Opening map fd from %s failed: %s", UID_STATS_MAP_PATH, strerror(errno));
         return ret;
     }
     return bpfGetUidStatsInternal(uid, stats, uidStatsMap);
@@ -184,7 +193,7 @@
 int parseBpfNetworkStatsDetail(std::vector<stats_line>* lines,
                                const std::vector<std::string>& limitIfaces, int limitTag,
                                int limitUid) {
-    base::unique_fd tagStatsMap(bpf::mapRetrieve(TAG_STATS_MAP_PATH, 0));
+    base::unique_fd tagStatsMap(bpf::mapRetrieve(TAG_STATS_MAP_PATH, BPF_OPEN_FLAGS));
     int ret = 0;
     if (tagStatsMap < 0) {
         ret = -errno;
@@ -195,10 +204,10 @@
     if (ret) return ret;
 
     if (limitTag == TAG_ALL) {
-        base::unique_fd uidStatsMap(bpf::mapRetrieve(UID_STATS_MAP_PATH, BPF_F_RDONLY));
+        base::unique_fd uidStatsMap(bpf::mapRetrieve(UID_STATS_MAP_PATH, BPF_OPEN_FLAGS));
         if (uidStatsMap < 0) {
             ret = -errno;
-            ALOGE("get map fd failed: %s", strerror(errno));
+            ALOGE("Opening map fd from %s failed: %s", UID_STATS_MAP_PATH, strerror(errno));
             return ret;
         }
         ret = parseBpfUidStatsDetail(lines, limitIfaces, limitUid, uidStatsMap);
@@ -263,7 +272,7 @@
 }
 
 int cleanStatsMap() {
-    base::unique_fd cookieTagMap(bpf::mapRetrieve(COOKIE_UID_MAP_PATH, BPF_F_RDONLY));
+    base::unique_fd cookieTagMap(bpf::mapRetrieve(COOKIE_UID_MAP_PATH, BPF_OPEN_FLAGS));
     int ret = 0;
     if (cookieTagMap < 0) {
         ret = -errno;
@@ -271,7 +280,7 @@
         return ret;
     }
 
-    base::unique_fd tagStatsMap(bpf::mapRetrieve(TAG_STATS_MAP_PATH, 0));
+    base::unique_fd tagStatsMap(bpf::mapRetrieve(TAG_STATS_MAP_PATH, BPF_OPEN_FLAGS));
     if (tagStatsMap < 0) {
         ret = -errno;
         ALOGE("get tagStats map fd failed: %s", strerror(errno));