This fix tries to address the issue raised in #24374 where
`docker info` outputs seccomp support in Ubuntu 14.04 but
the seccomp wass not actually supported.
The issue is that in the current docker implementation, seccomp
support is only checked against the kernel by inspect CONFIG_SECCOMP
and CONFIG_SECCOMP_FILTER. However, seccomp might not be enabled
when building docker (through golang build flag).
This fix adds a supportSeccomp boolean variable. The supportSeccomp
is only set to true when seccomp is enabled when building docker.
This fix fixes#24374.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Currently the default seccomp profile is fixed. This changes it
so that it varies depending on the Linux capabilities selected with
the --cap-add and --cap-drop options. Without this, if a user adds
privileges, eg to allow ptrace with --cap-add sys_ptrace then still
cannot actually use ptrace as it is still blocked by seccomp, so
they will probably disable seccomp or use --privileged. With this
change the syscalls that are needed for the capability are also
allowed by the seccomp profile based on the selected capabilities.
While this patch makes it easier to do things with for example
cap_sys_admin enabled, as it will now allow creating new namespaces
and use of mount, it still allows less than --cap-add cap_sys_admin
--security-opt seccomp:unconfined would have previously. It is not
recommended that users run containers with cap_sys_admin as this does
give full access to the host machine.
It also cleans up some architecture specific system calls to be
only selected when needed.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
