There is no need to explicitly add `cgo` build tag, it is set by
by go tools if cgo is enabled.
Fixes: ecd6463101
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Commit fe898e7862 (PR #1350) enables kernel memory accounting
for all cgroups created by libcontainer -- even if kmem limit is
not configured.
Kernel memory accounting is known to be broken in some kernels,
specifically the ones from RHEL7 (including RHEL 7.5). Those
kernels do not support kernel memory reclaim, and are prone to
oopses. Unconditionally enabling kmem acct on such kernels lead
to bugs, such as
* https://github.com/opencontainers/runc/issues/1725
* https://github.com/kubernetes/kubernetes/issues/61937
* https://github.com/moby/moby/issues/29638
This commit gives a way to compile runc without kernel memory setting
support. To do so, use something like
make BUILDTAGS="seccomp nokmem"
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This is a regression from 06f789cf26
when the user namespace was configured without a privileged helper.
To allow a single mapping in an user namespace, it is necessary to set
/proc/self/setgroups to "deny".
For a simple reproducer, the user namespace can be created with
"unshare -r".
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Linux kernel v4.15 introduces better diagnostics for Intel RDT operation
errors. If any error returns when making new directories or writing to
any of the control file in resctrl filesystem, reading file
/sys/fs/resctrl/info/last_cmd_status could provide more information that
can be conveyed in the error returns from file operations.
Some examples:
echo "L3:0=f3;1=ff" > /sys/fs/resctrl/container_id/schemata
-bash: echo: write error: Invalid argument
cat /sys/fs/resctrl/info/last_cmd_status
mask f3 has non-consecutive 1-bits
echo "MB:0=0;1=110" > /sys/fs/resctrl/container_id/schemata
-bash: echo: write error: Invalid argument
cat /sys/fs/resctrl/info/last_cmd_status
MB value 0 out of range [10,100]
cd /sys/fs/resctrl
mkdir 1 2 3 4 5 6 7 8
mkdir: cannot create directory '8': No space left on device
cat /sys/fs/resctrl/info/last_cmd_status
out of CLOSIDs
See 'last_cmd_status' for more details in kernel documentation:
https://www.kernel.org/doc/Documentation/x86/intel_rdt_ui.txt
In runc, we could append the diagnostics information to the error
message of Intel RDT operation errors to provide more user-friendly
information.
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Double check if Intel RDT sub-features are available in "resource
control" filesystem. Intel RDT sub-features can be selectively disabled
or enabled by kernel command line (e.g., rdt=!l3cat,mba) in 4.14 and
newer kernel.
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Memory Bandwidth Allocation (MBA) is a resource allocation sub-feature
of Intel Resource Director Technology (RDT) which is supported on some
Intel Xeon platforms. Intel RDT/MBA provides indirect and approximate
throttle over memory bandwidth for the software. A user controls the
resource by indicating the percentage of maximum memory bandwidth.
Hardware details of Intel RDT/MBA can be found in section 17.18 of
Intel Software Developer Manual:
https://software.intel.com/en-us/articles/intel-sdm
In Linux 4.12 kernel and newer, Intel RDT/MBA is enabled by kernel
config CONFIG_INTEL_RDT. If hardware support, CPU flags `rdt_a` and
`mba` will be set in /proc/cpuinfo.
Intel RDT "resource control" filesystem hierarchy:
mount -t resctrl resctrl /sys/fs/resctrl
tree /sys/fs/resctrl
/sys/fs/resctrl/
|-- info
| |-- L3
| | |-- cbm_mask
| | |-- min_cbm_bits
| | |-- num_closids
| |-- MB
| |-- bandwidth_gran
| |-- delay_linear
| |-- min_bandwidth
| |-- num_closids
|-- ...
|-- schemata
|-- tasks
|-- <container_id>
|-- ...
|-- schemata
|-- tasks
For MBA support for `runc`, we will reuse the infrastructure and code
base of Intel RDT/CAT which implemented in #1279. We could also make
use of `tasks` and `schemata` configuration for memory bandwidth
resource constraints.
The file `tasks` has a list of tasks that belongs to this group (e.g.,
<container_id>" group). Tasks can be added to a group by writing the
task ID to the "tasks" file (which will automatically remove them from
the previous group to which they belonged). New tasks created by
fork(2) and clone(2) are added to the same group as their parent.
The file `schemata` has a list of all the resources available to this
group. Each resource (L3 cache, memory bandwidth) has its own line and
format.
Memory bandwidth schema:
It has allocation values for memory bandwidth on each socket, which
contains L3 cache id and memory bandwidth percentage.
Format: "MB:<cache_id0>=bandwidth0;<cache_id1>=bandwidth1;..."
The minimum bandwidth percentage value for each CPU model is predefined
and can be looked up through "info/MB/min_bandwidth". The bandwidth
granularity that is allocated is also dependent on the CPU model and
can be looked up at "info/MB/bandwidth_gran". The available bandwidth
control steps are: min_bw + N * bw_gran. Intermediate values are
rounded to the next control step available on the hardware.
For more information about Intel RDT kernel interface:
https://www.kernel.org/doc/Documentation/x86/intel_rdt_ui.txt
An example for runc:
Consider a two-socket machine with two L3 caches where the minimum
memory bandwidth of 10% with a memory bandwidth granularity of 10%.
Tasks inside the container may use a maximum memory bandwidth of 20%
on socket 0 and 70% on socket 1.
"linux": {
"intelRdt": {
"memBwSchema": "MB:0=20;1=70"
}
}
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Update runtime-spec to get Intel RDT/MBA Linux configs which will be
used in successive commits.
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
make sure epollConsole is closed before returning an error. It solves
a hang when using these commands with a container that uses a
terminal:
runc run foo &
ssh root@localhost runc exec foo echo hello
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Fix duplicate entries and missing entries in getCgroupMountsHelper
Add test for testing cgroup mounts on bedrock linux
Stop relying on number of subsystems for cgroups
LGTMs: @crosbymichael @cyphar
Closes#1817
While all modern kernels (and I do mean _all_ of them -- this syscall
was added in 2.6.10 before git had begun development!) have support for
this syscall, LXC has a default seccomp profile that returns ENOSYS for
this syscall. For most syscalls this would be a deal-breaker, and our
use of session keyrings is security-based there are a few mitigating
factors that make this change not-completely-insane:
* We already have a flag that disables the use of session keyrings
(for older kernels that had system-wide keyring limits and so
on). So disabling it is not a new idea.
* While the primary justification of using session keys *is*
security-based, it's more of a security-by-obscurity protection.
The main defense keyrings have is VFS credentials -- which is
something that users already have better security tools for
(setuid(2) and user namespaces).
* Given the security justification you might argue that we
shouldn't silently ignore this. However, the only way for the
kernel to return -ENOSYS is either being ridiculously old (at
which point we wouldn't work anyway) or that there is a seccomp
profile in place blocking it.
Given that the seccomp profile (if malicious) could very easily
just return 0 or a silly return code (or something even more
clever with seccomp-bpf) and trick us without this patch, there
isn't much of a significant change in how much seccomp can trick
us with or without this patch.
Given all of that over-analysis, I'm pretty convinced there isn't a
security problem in this very specific case and it will help out the
ChromeOS folks by allowing Docker to run inside their LXC container
setup. I'd be happy to be proven wrong.
Ref: https://bugs.chromium.org/p/chromium/issues/detail?id=860565
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This PR decomposes `libcontainer/configs.Config.Rootless bool` into `RootlessEUID bool` and
`RootlessCgroups bool`, so as to make "runc-in-userns" to be more compatible with "rootful" runc.
`RootlessEUID` denotes that runc is being executed as a non-root user (euid != 0) in
the current user namespace. `RootlessEUID` is almost identical to the former `Rootless`
except cgroups stuff.
`RootlessCgroups` denotes that runc is unlikely to have the full access to cgroups.
`RootlessCgroups` is set to false if runc is executed as the root (euid == 0) in the initial namespace.
Otherwise `RootlessCgroups` is set to true.
(Hint: if `RootlessEUID` is true, `RootlessCgroups` becomes true as well)
When runc is executed as the root (euid == 0) in an user namespace (e.g. by Docker-in-LXD, Podman, Usernetes),
`RootlessEUID` is set to false but `RootlessCgroups` is set to true.
So, "runc-in-userns" behaves almost same as "rootful" runc except that cgroups errors are ignored.
This PR does not have any impact on CLI flags and `state.json`.
Note about CLI:
* Now `runc --rootless=(auto|true|false)` CLI flag is only used for setting `RootlessCgroups`.
* Now `runc spec --rootless` is only required when `RootlessEUID` is set to true.
For runc-in-userns, `runc spec` without `--rootless` should work, when sufficient numbers of
UID/GID are mapped.
Note about `$XDG_RUNTIME_DIR` (e.g. `/run/user/1000`):
* `$XDG_RUNTIME_DIR` is ignored if runc is being executed as the root (euid == 0) in the initial namespace, for backward compatibility.
(`/run/runc` is used)
* If runc is executed as the root (euid == 0) in an user namespace, `$XDG_RUNTIME_DIR` is honored if `$USER != "" && $USER != "root"`.
This allows unprivileged users to allow execute runc as the root in userns, without mounting writable `/run/runc`.
Note about `state.json`:
* `rootless` is set to true when `RootlessEUID == true && RootlessCgroups == true`.
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Michael Crosby
Aleksa Sarai
Ace-Tang
Mrunal Patel
Kir Kolyshkin
Chris Aniszczyk
Giuseppe Scrivano
Harald Nordgren
Xiaochen Shen
Adrian Reber
Mike Brown
Jonathan Marler
Akihiro Suda
Yan Zhu