67 lines
2.0 KiB
Go
67 lines
2.0 KiB
Go
// Copyright 2018 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mm
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import (
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/shm"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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)
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// DetachShm unmaps a sysv shared memory segment.
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func (mm *MemoryManager) DetachShm(ctx context.Context, addr usermem.Addr) error {
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if addr != addr.RoundDown() {
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// "... shmaddr is not aligned on a page boundary." - man shmdt(2)
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return syserror.EINVAL
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}
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var detached *shm.Shm
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mm.mappingMu.Lock()
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defer mm.mappingMu.Unlock()
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// Find and remove the first vma containing an address >= addr that maps a
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// segment originally attached at addr.
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vseg := mm.vmas.LowerBoundSegment(addr)
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for vseg.Ok() {
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vma := vseg.ValuePtr()
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if shm, ok := vma.mappable.(*shm.Shm); ok && vseg.Start() >= addr && uint64(vseg.Start()-addr) == vma.off {
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detached = shm
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vseg = mm.unmapLocked(ctx, vseg.Range()).NextSegment()
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break
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} else {
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vseg = vseg.NextSegment()
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}
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}
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if detached == nil {
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// There is no shared memory segment attached at addr.
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return syserror.EINVAL
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}
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// Remove all vmas that could have been created by the same attach.
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end := addr + usermem.Addr(detached.EffectiveSize())
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for vseg.Ok() && vseg.End() <= end {
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vma := vseg.ValuePtr()
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if vma.mappable == detached && uint64(vseg.Start()-addr) == vma.off {
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vseg = mm.unmapLocked(ctx, vseg.Range()).NextSegment()
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} else {
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vseg = vseg.NextSegment()
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}
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}
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return nil
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}
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