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  1. 03 Jun, 2019 1 commit
  3. 29 May, 2019 4 commits
  5. 28 May, 2019 2 commits
  7. 21 May, 2019 2 commits
  9. 17 May, 2019 2 commits
  11. 16 May, 2019 3 commits
  13. 15 May, 2019 8 commits
    • network: Fixes bug that stopped down hook from running for phys netdevs · b3259dc6
      Thomas Parrott authored 
      Signed-off-by: 's avatarThomas Parrott <thomas.parrott@canonical.com>
    • Merge pull request #3005 from tomponline/tp-phys-ns-restore · e2f2d86a
      Christian Brauner authored 
      network: move phys netdevs back to monitor's net ns rather than pid 1's
    • network: move phys netdevs back to monitor's net ns rather than pid 1's · 0037ab49
      Thomas Parrott authored 
      Updates lxc_restore_phys_nics_to_netns() to move phys netdevs back to the monitor's network namespace rather than the previously hardcoded PID 1 net ns.

This is to fix instances where LXC is started inside a net ns different from PID 1 and physical devices are moved back to a different net ns when the container is shutdown than the net ns than where the container was started from.
Signed-off-by: 's avatarThomas Parrott <thomas.parrott@canonical.com>
    • Merge pull request #3004 from brauner/master · 8f06ff54
      Stéphane Graber authored 
      configure: handle checks when cross-compiling
    • lxc_clone: get rid of some indirection · 5e7b4b3c
      Tycho Andersen authored 
      We have a do_clone(), which just calls a void f(void *) that it gets
passed. We build up a struct consisting of two args that are just the
actual arg and actual function. Let's just have the syscall do this for us.
Signed-off-by: 's avatarTycho Andersen <tycho@tycho.ws>
    • doc: add a little note about shared ns + LSMs · 8de90384
      Tycho Andersen authored 
      We should add a little not about the race in the previous patch.
Signed-off-by: 's avatarTycho Andersen <tycho@tycho.ws>
    • lxc_clone: pass non-stack allocated stack to clone · c74e9217
      Tycho Andersen authored 
      There are two problems with this code:

1. The math is wrong. We allocate a char *foo[__LXC_STACK_SIZE]; which
   means it's really sizeof(char *) * __LXC_STACK_SIZE, instead of just
   __LXC_STACK SIZE.

2. We can't actually allocate it on our stack. When we use CLONE_VM (which
   we do in the shared ns case) that means that the new thread is just
   running one page lower on the stack, but anything that allocates a page
   on the stack may clobber data. This is a pretty short race window since
   we just do the shared ns stuff and then do a clone without CLONE_VM.

However, it does point out an interesting possible privilege escalation if
things aren't configured correctly: do_share_ns() sets up namespaces while
it shares the address space of the task that spawned it; once it enters the
pid ns of the thing it's sharing with, the thing it's sharing with can
ptrace it and write stuff into the host's address space. Since the function
that does the clone() is lxc_spawn(), it has a struct cgroup_ops* on the
stack, which itself has function pointers called later in the function, so
it's possible to allocate shellcode in the address space of the host and
run it fairly easily.

ASLR doesn't mitigate this since we know exactly the stack offsets; however
this patch has the kernel allocate a new stack, which will help. Of course,
the attacker could just check /proc/pid/maps to find the location of the
stack, but they'd still have to guess where to write stuff in.

The thing that does prevent this is the default configuration of apparmor.
Since the apparmor profile is set in the second clone, and apparmor
prevents ptracing things under a different profile, attackers confined by
apparmor can't do this. However, if users are using a custom configuration
with shared namespaces, care must be taken to avoid this race.

Shared namespaces aren't widely used now, so perhaps this isn't a problem,
but with the advent of crio-lxc for k8s, this functionality will be used
more.
Signed-off-by: 's avatarTycho Andersen <tycho@tycho.ws>
    • configure: handle checks when cross-compiling · 4e900c18
      Christian Brauner authored 
      Signed-off-by: 's avatarChristian Brauner <christian.brauner@ubuntu.com>
  15. 13 May, 2019 7 commits
  17. 12 May, 2019 1 commit
  19. 11 May, 2019 3 commits
  21. 10 May, 2019 7 commits