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  1. 11 8月, 2017 1 次提交
  3. 10 8月, 2017 4 次提交
  5. 15 7月, 2017 1 次提交
    • J
      sparc64: Measure receiver forward progress to avoid send mondo timeout · 9d53caec
      由 Jane Chu 提交于 
      A large sun4v SPARC system may have moments of intensive xcall activities,
usually caused by unmapping many pages on many CPUs concurrently. This can
flood receivers with CPU mondo interrupts for an extended period, causing
some unlucky senders to hit send-mondo timeout. This problem gets worse
as cpu count increases because sometimes mappings must be invalidated on
all CPUs, and sometimes all CPUs may gang up on a single CPU.

But a busy system is not a broken system. In the above scenario, as long
as the receiver is making forward progress processing mondo interrupts,
the sender should continue to retry.

This patch implements the receiver's forward progress meter by introducing
a per cpu counter 'cpu_mondo_counter[cpu]' where 'cpu' is in the range
of 0..NR_CPUS. The receiver increments its counter as soon as it receives
a mondo and the sender tracks the receiver's counter. If the receiver has
stopped making forward progress when the retry limit is reached, the sender
declares send-mondo-timeout and panic; otherwise, the receiver is allowed
to keep making forward progress.

In addition, it's been observed that PCIe hotplug events generate Correctable
Errors that are handled by hypervisor and then OS. Hypervisor 'borrows'
a guest cpu strand briefly to provide the service. If the cpu strand is
simultaneously the only cpu targeted by a mondo, it may not be available
for the mondo in 20msec, causing SUN4V mondo timeout. It appears that 1 second
is the agreed wait time between hypervisor and guest OS, this patch makes
the adjustment.

Orabug: 25476541
Orabug: 26417466
Signed-off-by: NJane Chu <jane.chu@oracle.com>
Reviewed-by: NSteve Sistare <steven.sistare@oracle.com>
Reviewed-by: NAnthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: NRob Gardner <rob.gardner@oracle.com>
Reviewed-by: NThomas Tai <thomas.tai@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9d53caec
  7. 13 7月, 2017 1 次提交
  9. 11 7月, 2017 1 次提交
  11. 04 7月, 2017 1 次提交
  13. 29 6月, 2017 1 次提交
  15. 28 6月, 2017 3 次提交
  17. 26 6月, 2017 5 次提交
  19. 21 6月, 2017 1 次提交
    • D
      net: introduce SO_PEERGROUPS getsockopt · 28b5ba2a
      由 David Herrmann 提交于 
      This adds the new getsockopt(2) option SO_PEERGROUPS on SOL_SOCKET to
retrieve the auxiliary groups of the remote peer. It is designed to
naturally extend SO_PEERCRED. That is, the underlying data is from the
same credentials. Regarding its syntax, it is based on SO_PEERSEC. That
is, if the provided buffer is too small, ERANGE is returned and @optlen
is updated. Otherwise, the information is copied, @optlen is set to the
actual size, and 0 is returned.

While SO_PEERCRED (and thus `struct ucred') already returns the primary
group, it lacks the auxiliary group vector. However, nearly all access
controls (including kernel side VFS and SYSVIPC, but also user-space
polkit, DBus, ...) consider the entire set of groups, rather than just
the primary group. But this is currently not possible with pure
SO_PEERCRED. Instead, user-space has to work around this and query the
system database for the auxiliary groups of a UID retrieved via
SO_PEERCRED.

Unfortunately, there is no race-free way to query the auxiliary groups
of the PID/UID retrieved via SO_PEERCRED. Hence, the current user-space
solution is to use getgrouplist(3p), which itself falls back to NSS and
whatever is configured in nsswitch.conf(3). This effectively checks
which groups we *would* assign to the user if it logged in *now*. On
normal systems it is as easy as reading /etc/group, but with NSS it can
resort to quering network databases (eg., LDAP), using IPC or network
communication.

Long story short: Whenever we want to use auxiliary groups for access
checks on IPC, we need further IPC to talk to the user/group databases,
rather than just relying on SO_PEERCRED and the incoming socket. This
is unfortunate, and might even result in dead-locks if the database
query uses the same IPC as the original request.

So far, those recursions / dead-locks have been avoided by using
primitive IPC for all crucial NSS modules. However, we want to avoid
re-inventing the wheel for each NSS module that might be involved in
user/group queries. Hence, we would preferably make DBus (and other IPC
that supports access-management based on groups) work without resorting
to the user/group database. This new SO_PEERGROUPS ioctl would allow us
to make dbus-daemon work without ever calling into NSS.

Cc: Michal Sekletar <msekleta@redhat.com>
Cc: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: NTom Gundersen <teg@jklm.no>
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      28b5ba2a
  21. 20 6月, 2017 1 次提交
  23. 13 6月, 2017 4 次提交
  25. 11 6月, 2017 1 次提交
  27. 09 6月, 2017 1 次提交
    • A
      tty: add TIOCGPTPEER ioctl · 54ebbfb1
      由 Aleksa Sarai 提交于 
      When opening the slave end of a PTY, it is not possible for userspace to
safely ensure that /dev/pts/$num is actually a slave (in cases where the
mount namespace in which devpts was mounted is controlled by an
untrusted process). In addition, there are several unresolvable
race conditions if userspace were to attempt to detect attacks through
stat(2) and other similar methods [in addition it is not clear how
userspace could detect attacks involving FUSE].

Resolve this by providing an interface for userpace to safely open the
"peer" end of a PTY file descriptor by using the dentry cached by
devpts. Since it is not possible to have an open master PTY without
having its slave exposed in /dev/pts this interface is safe. This
interface currently does not provide a way to get the master pty (since
it is not clear whether such an interface is safe or even useful).

Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Valentin Rothberg <vrothberg@suse.com>
Signed-off-by: NAleksa Sarai <asarai@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      54ebbfb1
  29. 07 6月, 2017 5 次提交
  31. 04 6月, 2017 2 次提交
  33. 26 5月, 2017 5 次提交
  35. 22 5月, 2017 1 次提交
  37. 18 5月, 2017 1 次提交