This system call is only available on the 32- and 64-bit PowerPC, it is
used by modern programming language implementations (such as gcc-go) to
implement coroutine features through userspace context switches.
Other container environment, such as Systemd nspawn already whitelist
this system call in their seccomp profile [1] [2]. As such, it would be
nice to also whitelist it in moby.
This issue was encountered on Alpine Linux GitLab CI system, which uses
moby, when attempting to execute gcc-go compiled software on ppc64le.
[1]: https://github.com/systemd/systemd/pull/9487
[2]: https://github.com/systemd/systemd/issues/9485
Signed-off-by: Sören Tempel <soeren+git@soeren-tempel.net>
The io/ioutil package has been deprecated in Go 1.16. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Since commit "seccomp: Sync fields with runtime-spec fields"
(5d244675bd) we support to specify the
DefaultErrnoRet to be used.
Before that commit it was not specified and EPERM was used by default.
This commit keeps the same behaviour but just makes it explicit that the
default is EPERM.
Signed-off-by: Rodrigo Campos <rodrigo@kinvolk.io>
If no seccomp policy is requested, then the built-in default policy in
dockerd applies. This has no rule for "clone3" defined, nor any default
errno defined. So when runc receives the config it attempts to determine
a default errno, using logic defined in its commit:
7a8d7162f9
As explained in the above commit message, runc uses a heuristic to
decide which errno to return by default:
[quote]
The solution applied here is to prepend a "stub" filter which returns
-ENOSYS if the requested syscall has a larger syscall number than any
syscall mentioned in the filter. The reason for this specific rule is
that syscall numbers are (roughly) allocated sequentially and thus newer
syscalls will (usually) have a larger syscall number -- thus causing our
filters to produce -ENOSYS if the filter was written before the syscall
existed.
[/quote]
Unfortunately clone3 appears to one of the edge cases that does not
result in use of ENOSYS, instead ending up with the historical EPERM
errno.
Latest glibc (2.33.9000, in Fedora 35 rawhide) will attempt to use
clone3 by default. If it sees ENOSYS then it will automatically
fallback to using clone. Any other errno is treated as a fatal
error. Thus when docker seccomp policy triggers EPERM from clone3,
no fallback occurs and programs are thus unable to spawn threads.
The clone3 syscall is much more complicated than clone, most notably its
flags are not exposed as a directly argument any more. Instead they are
hidden inside a struct. This means that seccomp filters are unable to
apply policy based on values seen in flags. Thus we can't directly
replicate the current "clone" filtering for "clone3". We can at least
ensure "clone3" returns ENOSYS errno, to trigger fallback to "clone"
at which point we can filter on flags.
Fixes: https://github.com/moby/moby/issues/42680
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This patch, similar to d92739713c, embeds the
`LinuxSeccomp` type of the runtime-spec, so that we can support all options
provided by the spec, and decorates it with our own fields.
With this, profiles can make use of the recently added "Flags" field, to
specify flags that must be passed to seccomp(2) when installing the filter.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Make the error message slightly more informative, and remove the redundant
`len(config.ArchMap) != 0` check, as iterating over an empty, or 'nil' slice
is a no-op already. This allows to use a slightly more idiomatic "if ok := xx; ok"
condition.
Also move validation to the start of the loop (early return), and explicitly create
a new slice for "names" if the legacy "Name" field is used.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Add test to verify profile validation, and to verify that the legacy
format actually loads the profile as expected (instead of only verifying
it doesn't produce an error).
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The runtime spec we are using has support for these 3 fields[1], but
moby doesn't have them in its seccomp struct. This patch just adds and
copies them when they are in the profile.
DefaultErrnoRet is implemented in the runc version moby is using (it is
implemented since runc-rc95[2]) but if we create a container without
this moby patch, we don't see an error nor the expected behavior. This
is not clear for the user (the profile they specify is valid, the syntax
is ok, but the wrong behavior is seen).
This is because the DefaultErrnoRet field is not copied to the config
passed ultimately to runc (i.e. is like the field was not specified).
With this patch, we see the expected behavior.
The other two fileds are in the runtime-spec but not yet in runc (a PR
is open and targets 1.1.0 milestone). However, I took the liberty to
copy them now too for two reasons:
1. If we don't add them now and end up using a runc version that
supports them, then the error that the user will see is not clear at
all:
docker: Error response from daemon: OCI runtime create failed: container_linux.go:380: starting container process caused: listenerPath is not set: unknown.
And it is not obvious to debug for the user, as the field _is_ set in
the profile they specify (just not copied by moby to the profile moby
specifies ultimately to runc).
2. When using a runc without seccomp notify support (like today), the
error we see is the same with and without this moby patch (when using a
seccomp profile with the new fields):
docker: Error response from daemon: OCI runtime create failed: string SCMP_ACT_NOTIFY is not a valid action for seccomp: unknown.
Then, it seems like a clear win to add them now: we don't have to do it
later (that implies not clear errors to the user if we forget, like we
did with DefaultErrnoRet) and the user sees the exact same error when
using a runc version that doesn't support these fields.
[1]: Note we are vendoring version 1c3f411f041711bbeecf35ff7e93461ea6789220 and this version has these 3 fields 1c3f411f04/config-linux.md (seccomp)
[2]: https://github.com/opencontainers/runc/pull/2954/
[3]: https://github.com/opencontainers/runc/pull/2682
Signed-off-by: Rodrigo Campos <rodrigo@kinvolk.io>
This makes the type better reflect the difference with the "runtime" profile;
our local type is used to generate a runtime-spec seccomp profile and extends
the runtime-spec type with additional fields; adding a "Name" field for backward
compatibility with older JSON representations, additional "Comment" metadata,
and conditional rules ("Includes", "Excludes") used during generation to adjust
the profile based on the container (capabilities) and host's (architecture, kernel)
configuration.
This change introduces one change in the type; the "runtime-spec" type uses a
`[]LinuxSeccompArg` for the `Args` field, whereas the local type used pointers;
`[]*LinuxSeccompArg`.
In addition, the runtime-spec Syscall type brings a new `ErrnoRet` field, allowing
the profile to specify the errno code returned for the syscall, which allows
changing the default EPERM for specific syscalls.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
These syscalls were disabled in #18971
due to them requiring CAP_PTRACE. CAP_PTRACE was blocked by default due
to a ptrace related exploit. This has been patched in the Linux kernel
(version 4.8) and thus `ptrace` has been re-enabled. However, these
associated syscalls seem to have been left behind. This commit brings
them in line with `ptrace`, and re-enables it for kernel > 4.8.
Signed-off-by: clubby789 <jamie@hill-daniel.co.uk>
These syscalls (some of which have been in Linux for a while but were
missing from the profile) fall into a few buckets:
* close_range(2), epoll_pwait2(2) are just extensions of existing "safe
for everyone" syscalls.
* The mountv2 API syscalls (fs*(2), move_mount(2), open_tree(2)) are
all equivalent to aspects of mount(2) and thus go into the
CAP_SYS_ADMIN category.
* process_madvise(2) is similar to the other process_*(2) syscalls and
thus goes in the CAP_SYS_PTRACE category.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
This removes the dependency on the `pkg/parsers/kernel` package, because secomp
only needs to consider Linux (and no parsing is needed for Windows or Darwin kernel
versions).
This patch implements the minimum requirements for this implementation:
- only `kernel` and `major` versions are considered
- `minor` version, `flavor`, and `-rcXX` suffixes are ignored
So, for example:
- `3.4.54.longterm-1` => `kernel: 3`, `major: 4`
- `3.8.0-19-generic` => `kernel: 3`, `major: 8`
- `3.10.0-862.2.3.el7.x86_64` => `kernel: 3`, `major: 10`
Some systems also omit the `minor` and/or have odd-formatted versions. In context
of generating seccomp profiles, both versions below are considered equal;
- `3.12.25-gentoo` => `kernel: 3`, `major: 12`
- `3.12-1-amd64` => `kernel: 3`, `major: 12`
Note that `-rcX` suffixes are also not considered, and thus (e.g.) kernel `5.9-rc1`,
`5.9-rc6` and `5.9` are all considered equal.
The motivation for ignoring "minor" versions and "flavors" is that;
- The upstream kernel only does "kernel.major" releases
- While release-candidates exists for kernel (e.g. 5.9-rc5), we don't expect users
to write profiles that target a specific release-candidate, and therefore consider
(e.g.) kernel `5.9-rc1`, `5.9-rc6` and `5.9` to be equal.
- Generally, a seccomp-profile should either be portable, or written for a specific
infrastructure (in which case the writer of the profile would know if the kernel-flavors
used does/does not support certain things.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Commit 5ff21add06 changed the (JSON) format that's
used for seccomp profiles, but keeping the code backward compatible to allow both
the old or new format.
This patch adds a new test, which loads the old format. It takes the default seccomp
profile before the format was changed.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
These types were not used in the API, so could not come up with
a reason why they were in that package.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This was just using libseccomp to get the right arch, but we can use
GOARCH to get this.
The nativeToSeccomp map needed to be adjusted a bit for mipsle vs mipsel
since that's go how refers to it. Also added some other arches to it.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Otherwise if you try to kill a container process from the host directly,
you get EACCES. Also add a comment to make sure that the profile code
(which has been replicated by several projects) doesn't get out of sync.
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Restartable Sequences (rseq) are a kernel-based mechanism for fast
update operations on per-core data in user-space. Some libraries, like
the newest version of Google's TCMalloc, depend on it [1].
This also makes dockers default seccomp profile on par with systemd's,
which enabled 'rseq' in early 2019 [2].
1: https://google.github.io/tcmalloc/design.html
2: 6fee3be0b4
Signed-off-by: Florian Schmaus <flo@geekplace.eu>
Add the membarrier syscall to the default seccomp profile.
It is for example used in the implementation of dlopen() in
the musl libc of Alpine images.
Signed-off-by: Julio Guerra <julio@sqreen.com>
Relates to https://patchwork.kernel.org/patch/10756415/
Added to whitelist:
- `clock_getres_time64` (equivalent of `clock_getres`, which was whitelisted)
- `clock_gettime64` (equivalent of `clock_gettime`, which was whitelisted)
- `clock_nanosleep_time64` (equivalent of `clock_nanosleep`, which was whitelisted)
- `futex_time64` (equivalent of `futex`, which was whitelisted)
- `io_pgetevents_time64` (equivalent of `io_pgetevents`, which was whitelisted)
- `mq_timedreceive_time64` (equivalent of `mq_timedreceive`, which was whitelisted)
- `mq_timedsend_time64 ` (equivalent of `mq_timedsend`, which was whitelisted)
- `ppoll_time64` (equivalent of `ppoll`, which was whitelisted)
- `pselect6_time64` (equivalent of `pselect6`, which was whitelisted)
- `recvmmsg_time64` (equivalent of `recvmmsg`, which was whitelisted)
- `rt_sigtimedwait_time64` (equivalent of `rt_sigtimedwait`, which was whitelisted)
- `sched_rr_get_interval_time64` (equivalent of `sched_rr_get_interval`, which was whitelisted)
- `semtimedop_time64` (equivalent of `semtimedop`, which was whitelisted)
- `timer_gettime64` (equivalent of `timer_gettime`, which was whitelisted)
- `timer_settime64` (equivalent of `timer_settime`, which was whitelisted)
- `timerfd_gettime64` (equivalent of `timerfd_gettime`, which was whitelisted)
- `timerfd_settime64` (equivalent of `timerfd_settime`, which was whitelisted)
- `utimensat_time64` (equivalent of `utimensat`, which was whitelisted)
Not added to whitelist:
- `clock_adjtime64` (equivalent of `clock_adjtime`, which was not whitelisted)
- `clock_settime64` (equivalent of `clock_settime`, which was not whitelisted)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
When translating seccomp profile to opencontainers format, a single
group with multiple syscalls is converted to individual syscall rules.
I am not sure why it is done that way, but suspect it might have
performance implications as the number of rules grows.
Change this to pass a groups of syscalls as a group.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
All clone flags for namespace should be denied.
Based-on-patch-by: Kenta Tada <Kenta.Tada@sony.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
io_pgetevents() is a new Linux system call. It is similar to io_getevents()
that is already whitelisted, and adds no special abilities over that system call.
Allow that system call to enable applications that use it.
Fixes#38894.
Signed-off-by: Avi Kivity <avi@scylladb.com>
