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ensure the path is a sub-cgroup path #3381

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Merged
AkihiroSuda merged 1 commit into from
Mar 7, 2022
Merged

ensure the path is a sub-cgroup path #3381

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12 changes: 10 additions & 2 deletions libcontainer/container_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -632,7 +632,11 @@ func (c *linuxContainer) newSetnsProcess(p *Process, cmd *exec.Cmd, messageSockP
// cgroup v1: using the same path for all controllers.
// cgroup v2: the only possible way.
for k := range proc.cgroupPaths {
proc.cgroupPaths[k] = path.Join(proc.cgroupPaths[k], add)
subPath := path.Join(proc.cgroupPaths[k], add)
if !strings.HasPrefix(subPath, proc.cgroupPaths[k]) {
return nil, fmt.Errorf("%s is not a sub cgroup path", add)
}
proc.cgroupPaths[k] = subPath
}
// cgroup v2: do not try to join init process's cgroup
// as a fallback (see (*setnsProcess).start).
Expand All @@ -641,7 +645,11 @@ func (c *linuxContainer) newSetnsProcess(p *Process, cmd *exec.Cmd, messageSockP
// Per-controller paths.
for ctrl, add := range p.SubCgroupPaths {
if val, ok := proc.cgroupPaths[ctrl]; ok {
proc.cgroupPaths[ctrl] = path.Join(val, add)
subPath := path.Join(val, add)
if !strings.HasPrefix(subPath, val) {
return nil, fmt.Errorf("%s is not a sub cgroup path", add)
}
proc.cgroupPaths[ctrl] = subPath
} else {
return nil, fmt.Errorf("unknown controller %s in SubCgroupPaths", ctrl)
}
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10 changes: 10 additions & 0 deletions tests/integration/exec.bats
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Expand Up @@ -197,6 +197,11 @@ function check_exec_debug() {
__runc run -d --console-socket "$CONSOLE_SOCKET" test_busybox
testcontainer test_busybox running

# Check we can't join parent cgroup.
runc exec --cgroup ".." test_busybox cat /proc/self/cgroup
[ "$status" -ne 0 ]
[[ "$output" == *" .. is not a sub cgroup path"* ]]

# Check we can't join non-existing subcgroup.
runc exec --cgroup nonexistent test_busybox cat /proc/self/cgroup
[ "$status" -ne 0 ]
Expand Down Expand Up @@ -243,6 +248,11 @@ function check_exec_debug() {
__runc run -d --console-socket "$CONSOLE_SOCKET" test_busybox
testcontainer test_busybox running

# Check we can't join parent cgroup.
runc exec --cgroup ".." test_busybox cat /proc/self/cgroup
[ "$status" -ne 0 ]
[[ "$output" == *" .. is not a sub cgroup path"* ]]

# Check we can't join non-existing subcgroup.
runc exec --cgroup nonexistent test_busybox cat /proc/self/cgroup
[ "$status" -ne 0 ]
Expand Down