Since the recent CVE fixes, TestFdLeaksSystemd sometimes fails:
=== RUN TestFdLeaksSystemd
exec_test.go:1750: extra fd 9 -> /12224/task/13831/fd
exec_test.go:1753: found 1 extra fds after container.Run
--- FAIL: TestFdLeaksSystemd (0.10s)
It might have been caused by the change to the test code in commit
ff6fe13 ("utils: use safe procfs for /proc/self/fd loop code") -- we are
now opening a file descriptor during the logic to get a list of file
descriptors. If the file descriptor happens to be allocated to a
different number, you'll get an error.
Let's try to filter out the fd used to read a directory.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
On some systems (e.g., AlmaLinux 8), systemd automatically removes cgroup paths
when they become empty (i.e., contain no processes). To prevent this, we spawn
a dummy process to pin the cgroup in place.
Fix: https://github.com/opencontainers/runc/issues/5003
Signed-off-by: lifubang <lifubang@acmcoder.com>
This is to ensure that Go version in Dockerfile (which is used to build
release binaries) is:
- currently supported;
- used in CI tests.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
For some reason, some jobs in .github/workflows/validate.yml
have "fetch-depth: 0" argument to actions/checkout, meaning
"all history for all branches and tags". Obviously this is
not needed here.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
The main update is actually in github.com/opencontainers/cgroups, but we
need to also update runtime-spec to a newer pre-release version to get
the updates from there as well.
In short, the behaviour change is now that "0" is treated as a valid
value to set in "pids.max", "-1" means "max" and unset/nil means "do
nothing". As described in the opencontainers/cgroups PR, this change is
actually backwards compatible because our internal state.json stores
PidsLimit, and that entry is marked as "omitempty". So, an old runc
would omit PidsLimit=0 in state.json, and this will be parsed by a new
runc as being "nil" -- and both would treat this case as "do not set
anything".
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Commit b2f8a74d "clothed" the naked return as inflicted by gofumpt
v0.9.0. Since gofumpt v0.9.2 this rule was moved to "extra" category,
not enabled by default. The only other "extra" rule is to group adjacent
parameters with the same type, which also makes sense.
Enable gofumpt "extra" rules, and reformat the code accordingly.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This is mostly a mechanical change, but we also need to change some
types to match the "mode int" argument that golang.org/x/sys/unix
decided to use.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
This was always the intended behaviour but commit 72fbb34f50 ("rootfs:
switch to fd-based handling of mountpoint targets") regressed it when
adding a mechanism to create a file handle to the target if it didn't
already exist (causing the later stat to always succeed).
A lot of people depend on this functionality, so add some tests to make
sure we don't break it in the future.
Fixes: 72fbb34f50 ("rootfs: switch to fd-based handling of mountpoint targets")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
This new version includes the fixes for CVE-2025-52881, so we can remove
the internal/third_party copy of the library we added in commit
ed6b1693b8 ("selinux: use safe procfs API for labels") as well as the
"replace" directive in go.mod (which is problematic for "go get"
installs).
Fixes: ed6b1693b8 ("selinux: use safe procfs API for labels")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
This will result in slower runs but we are having issues with
golangci-lint (false positives) that are most probably related
to caching.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
On MIPS arches, Rdev is uint32 so we have to convert it.
Fixes issue 4962.
Fixes: 8476df83 ("libct: add/use isDevNull, verifyDevNull")
Fixes: de87203e ("console: verify /dev/pts/ptmx before use")
Fixes: 398955bc ("console: add fallback for pre-TIOCGPTPEER kernels")
Reported-by: Tianon Gravi <admwiggin@gmail.com>
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Aleksa Sarai (21):
rootfs: re-allow dangling symlinks in mount targets
openat2: improve resilience on busy systems
selinux: use safe procfs API for labels
rootfs: switch to fd-based handling of mountpoint targets
libct/system: use securejoin for /proc/$pid/stat
init: use securejoin for /proc/self/setgroups
init: write sysctls using safe procfs API
utils: remove unneeded EnsureProcHandle
utils: use safe procfs for /proc/self/fd loop code
apparmor: use safe procfs API for labels
ci: add lint to forbid the usage of os.Create
rootfs: avoid using os.Create for new device inodes
internal: add wrappers for securejoin.Proc*
go.mod: update to github.com/cyphar/filepath-securejoin@v0.5.0
console: verify /dev/pts/ptmx before use
console: avoid trivial symlink attacks for /dev/console
console: add fallback for pre-TIOCGPTPEER kernels
console: use TIOCGPTPEER when allocating peer PTY
*: switch to safer securejoin.Reopen
internal: move utils.MkdirAllInRoot to internal/pathrs
internal/sys: add VerifyInode helper
Li Fubang (1):
libct: align param type for mountCgroupV1/V2 functions
Kir Kolyshkin (3):
libct: maskPaths: don't rely on ENOTDIR for mount
libct: maskPaths: only ignore ENOENT on mount dest
libct: add/use isDevNull, verifyDevNull
Fixes: CVE-2025-31133 GHSA-9493-h29p-rfm2
Fixes: CVE-2025-52565 GHSA-qw9x-cqr3-wc7r
Fixes: CVE-2025-52881 GHSA-cgrx-mc8f-2prm
Reported-by: Lei Wang <ssst0n3@gmail.com>
Reported-by: Li Fubang <lifubang@acmcoder.com>
Reported-by: Tõnis Tiigi <tonistiigi@gmail.com>
Reported-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
It seems there are a fair few images where dangling symlinks are used as
path components for mount targets, which pathrs-lite does not support
(and it would be difficult to fully support this in a race-free way).
This was actually meant to be blocked by commit 63c2908164 ("rootfs:
try to scope MkdirAll to stay inside the rootfs"), followed by commit
dd827f7b71 ("utils: switch to securejoin.MkdirAllHandle"). However, we
still used SecureJoin to construct mountpoint targets, which means that
dangling symlinks were "resolved" before reaching pathrs-lite.
This patch basically re-adds this hack in order to reduce the breakages
we've seen so far.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Previously, we would see a ~3% failure rate when starting containers
with mounts that contain ".." (which can trigger -EAGAIN). To counteract
this, filepath-securejoin v0.5.1 includes a bump of the internal retry
limit from 32 to 128, which lowers the failure rate to 0.12%.
However, there is still a risk of spurious failure on regular systems.
In order to try to provide more resilience (while avoiding DoS attacks),
this patch also includes an additional retry loop that terminates based
on a deadline rather than retry count. The deadline is 2ms, as my
testing found that ~800us for a single pathrs operation was the longest
latency due to -EAGAIN retries, and that was an outlier compared to the
more common ~400us latencies -- so 2ms should be more than enough for
any real system.
The failure rates above were based on more 50k runs of runc with an
attack script (from libpathrs) running a rename attack on all cores of a
16-core system, which is arguably a worst-case but heavily utilised
servers could likely approach similar results.
Tested-by: Phil Estes <estesp@gmail.com>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Due to the sensitive nature of these fixes, it was not possible to
submit these upstream and vendor the upstream library. Instead, this
patch uses a fork of github.com/opencontainers/selinux, branched at
commit opencontainers/selinux@879a755db5.
In order to permit downstreams to build with this patched version, a
snapshot of the forked version has been included in
internal/third_party/selinux. Note that since we use "go mod vendor",
the patched code is usable even without being "go get"-able. Once the
embargo for this issue is lifted we can submit the patches upstream and
switch back to a proper upstream go.mod entry.
Also, this requires us to temporarily disable the CI job we have that
disallows "replace" directives.
Fixes: GHSA-cgrx-mc8f-2prm CVE-2025-52881
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
An attacker could race with us during mount configuration in order to
trick us into mounting over an unexpected path. This would bypass
checkProcMount() and would allow for security profiles to be left
unapplied by mounting over /proc/self/attr/... (or even more serious
outcomes such as killing the entire system by tricking runc into writing
strings to /proc/sysrq-trigger).
This is a larger issue with our current mount infrastructure, and the
ideal solution would be to rewrite it all to be fd-based (which would
also allow us to support the "new" mount API, which also avoids a bunch
of other issues with mount(8)). However, such a rewrite is not really
workable as a security fix, so this patch is a bit of a compromise
approach to fix the issue while also moving us a bit towards that
eventual end-goal.
The core issue in CVE-2025-52881 is that we currently use the (insecure)
SecureJoin to re-resolve mountpoint target paths multiple times during
mounting. Rather than generating a string from createMountpoint(), we
instead open an *os.File handle to the target mountpoint directly and
then operate on that handle. This will make it easier to remove
utils.WithProcfd() and rework mountViaFds() in the future.
The only real issue we need to work around is that we need to re-open
the mount target after doing the mount in order to get a handle to the
mountpoint -- pathrs.Reopen() doesn't work in this case (it just
re-opens the inode under the mountpoint) so we need to do a naive
re-open using the full path. Note that if we used move_mount(2) this
wouldn't be a problem because we would have a handle to the mountpoint
itself.
Note that this is still somewhat of a temporary solution -- ideally
mountViaFds would use *os.File directly to let us avoid some other
issues with using bare /proc/... paths, as well as also letting us more
easily use the new mount API on modern kernels.
Fixes: GHSA-cgrx-mc8f-2prm CVE-2025-52881
Co-developed-by: lifubang <lifubang@acmcoder.com>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Aleksa Sarai