This is an additional mitigation for CVE-2019-16884. The primary problem
is that Docker can be coerced into bind-mounting a file system on top of
/proc (resulting in label-related writes to /proc no longer happening).
While we are working on mitigations against permitting the mounts, this
helps avoid our code from being tricked into writing to non-procfs
files. This is not a perfect solution (after all, there might be a
bind-mount of a different procfs file over the target) but in order to
exploit that you would need to be able to tweak a config.json pretty
specifically (which thankfully Docker doesn't allow).
Specifically this stops AppArmor from not labeling a process silently
due to /proc/self/attr/... being incorrectly set, and stops any
accidental fd leaks because /proc/self/fd/... is not real.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This moves all console code to use github.com/containerd/console library to
handle console I/O. Also move to use EpollConsole by default when user requests
a terminal so we can still cope when the other side temporarily goes away.
Signed-off-by: Daniel Dao <dqminh89@gmail.com>
Since syscall is outdated and broken for some architectures,
use x/sys/unix instead.
There are still some dependencies on the syscall package that will
remain in syscall for the forseeable future:
Errno
Signal
SysProcAttr
Additionally:
- os still uses syscall, so it needs to be kept for anything
returning *os.ProcessState, such as process.Wait.
Signed-off-by: Christy Perez <christy@linux.vnet.ibm.com>
The original implementation is in C, which increases cognitive load and
possibly might cause us problems in the future. Since sys/unix is better
maintained than the syscall standard library switching makes more sense.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
POSIX mandates that `cmsg_len` in `struct cmsghdr` is a `socklen_t`,
which is an `unsigned int`. Musl libc as used in Alpine implements
this; Glibc ignores the spec and makes it a `size_t` ie `unsigned long`.
To avoid the `-Wformat=` warning from the `%lu` on Alpine, cast this
to an `unsigned long` always.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
This adds C wrappers for sendmsg and recvmsg, specifically used for
passing around file descriptors in Go. The wrappers (sendfd, recvfd)
expect to be called in a context where it makes sense (where the other
side is carrying out the corresponding action).
This patch is part of the console rewrite patchset.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Ensure that path safety is maintained, this essentially reapplies
c0cad6aa5e ("cgroups: fs: fix cgroup.Parent path sanitisation"), which
was accidentally removed in 256f3a8ebc ("Add support for CgroupsPath
field").
Signed-off-by: Aleksa Sarai <asarai@suse.com>
Marshall the raw objects for the sync pipes so that no new line chars
are left behind in the pipe causing errors.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
