auth: add rwlock to AuthClientHandler to prevent races
For cephx, build_authorizer reads a bunch of state (especially the
current session_key) which can be updated by the MonClient. With no
locks held, Pipe::connect() calls SimpleMessenger::get_authorizer()
which ends up calling RadosClient::get_authorizer() and then
AuthClientHandler::bulid_authorizer(). This unsafe usage can lead to
crashes like:
Program terminated with signal 11, Segmentation fault.
0x00007fa0d2ddb7cb in ceph::buffer::ptr::release (this=0x7f987a5e3070) at common/buffer.cc:370
370 common/buffer.cc: No such file or directory.
in common/buffer.cc
(gdb) bt
0x00007fa0d2ddb7cb in ceph::buffer::ptr::release (this=0x7f987a5e3070) at common/buffer.cc:370
0x00007fa0d2ddec00 in ~ptr (this=0x7f989c03b830) at ./include/buffer.h:171
ceph::buffer::list::rebuild (this=0x7f989c03b830) at common/buffer.cc:817
0x00007fa0d2ddecb9 in ceph::buffer::list::c_str (this=0x7f989c03b830) at common/buffer.cc:1045
0x00007fa0d2ea4dc2 in Pipe::connect (this=0x7fa0c4307340) at msg/Pipe.cc:907
0x00007fa0d2ea7d73 in Pipe::writer (this=0x7fa0c4307340) at msg/Pipe.cc:1518
0x00007fa0d2eb44dd in Pipe::Writer::entry (this=<value optimized out>) at msg/Pipe.h:59
0x00007fa0e0f5f9d1 in start_thread (arg=0x7f987a5e4700) at pthread_create.c:301
0x00007fa0de560b6d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115
Fix this by adding an rwlock to AuthClientHandler. A simpler fix would
be to move RadosClient::get_authorizer() into the MonClient() under
the MonClient lock, but this would not catch all uses of other
Authorizer, e.g. for verify_authorizer() and it would serialize
independent connection attempts.
This mainly matters for cephx, but none and unknown can have the
global_id reset as well.