Avoid netlink socket address conflict
NetlinkManager previously bound all netlink sockets with nl_pid =
getpid(). Unfortunately only the first such socket is allowed to claim
nl_pid = getpid(). The kernel is happy to assign this value
automatically if nl_pid = 0. For more information on nl_pid see "man 7
netlink".
When NFLogListener was added, it created a socket with a kernel assigned
nl_pid, unfortunately the kernel assigns getpid() to the first such
socket and listener was initialized earlier in the startup process than
NetlinkManager.
This change alters NetlinkManager to request a kernel assigned nl_pid and
defensively moves the initialization of NFLogListener later in the
startup sequence to favor proper operation of existing code in
NetlinkManager. Error logging is also slightly improved.
Test: as follows
- built
- flashed
- booted
- "runtest -x .../netd_unit_test.cpp" passes
- "cts-tradefed run commandAndExit cts-dev -m CtsOsTestCases -t
android.os.cts.StrictModeTest" passes
Bug: 62353125
Change-Id: I9c1c76e5769de75ff624bf43634ac4061c447a72
diff --git a/server/NetlinkManager.cpp b/server/NetlinkManager.cpp
index 7a7627a..698de9f 100644
--- a/server/NetlinkManager.cpp
+++ b/server/NetlinkManager.cpp
@@ -77,7 +77,8 @@
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
- nladdr.nl_pid = getpid();
+ // Kernel will assign a unique nl_pid if set to zero.
+ nladdr.nl_pid = 0;
nladdr.nl_groups = groups;
if ((*sock = socket(PF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, netlinkFamily)) < 0) {