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-rw-r--r--pkg/sentry/fs/fsutil/README.md17
-rw-r--r--pkg/sentry/fs/fsutil/host_mappable.go10
-rw-r--r--pkg/sentry/fs/fsutil/inode_cached.go28
-rw-r--r--pkg/sentry/fs/tmpfs/inode_file.go16
-rw-r--r--pkg/sentry/memmap/memmap.go14
-rw-r--r--pkg/sentry/mm/address_space.go2
-rw-r--r--pkg/sentry/mm/mm.go3
-rw-r--r--pkg/sentry/platform/filemem/filemem.go65
-rw-r--r--pkg/sentry/platform/kvm/BUILD24
-rw-r--r--pkg/sentry/platform/kvm/address_space.go104
-rw-r--r--pkg/sentry/platform/kvm/host_map.go184
-rw-r--r--pkg/sentry/platform/platform.go95
-rw-r--r--pkg/sentry/platform/ptrace/subprocess.go4
13 files changed, 139 insertions, 427 deletions
diff --git a/pkg/sentry/fs/fsutil/README.md b/pkg/sentry/fs/fsutil/README.md
index d3780e9fa..6e677890c 100644
--- a/pkg/sentry/fs/fsutil/README.md
+++ b/pkg/sentry/fs/fsutil/README.md
@@ -108,9 +108,9 @@ The host then sends a `SIGSEGV` to the sentry because the address range [`A`,
`A`+8) is not mapped on the host. The `SIGSEGV` indicates that the memory was
accessed writable. The sentry looks up the vma associated with [`A`, `A`+8),
finds the file that was mapped and its `CachingInodeOperations`. It then calls
-`CachingInodeOperations.MapInto` which allocates memory to back [`A`, `A`+8). It
-may choose to allocate more memory (i.e. do "readahead") to minimize subsequent
-faults.
+`CachingInodeOperations.Translate` which allocates memory to back [`A`, `A`+8).
+It may choose to allocate more memory (i.e. do "readahead") to minimize
+subsequent faults.
Memory that is allocated comes from a host tmpfs file (see `filemem.FileMem`).
The host tmpfs file memory is brought up to date with the contents of the mapped
@@ -138,12 +138,11 @@ memcpy(A, buffer, 4);
```
Since the first process has already mapped and accessed the same region of the
-file writable, `CachingInodeOperations.MapInto` is called but re-maps the memory
-that has already been allocated (because the host mapping can be invalidated at
-any time) rather than allocating new memory. The address range [`A`, `A`+0x1000)
-reflects the same cached view of the file as the first process sees. For
-example, reading 8 bytes from the file from either process via read(2) starting
-at offset 0 returns a consistent "bbbbaaaa".
+file writable, `CachingInodeOperations.Translate` is called but returns the
+memory that has already been allocated rather than allocating new memory. The
+address range [`A`, `A`+0x1000) reflects the same cached view of the file as the
+first process sees. For example, reading 8 bytes from the file from either
+process via read(2) starting at offset 0 returns a consistent "bbbbaaaa".
When this process no longer needs the shared memory, it may do:
diff --git a/pkg/sentry/fs/fsutil/host_mappable.go b/pkg/sentry/fs/fsutil/host_mappable.go
index 340f8d288..1bb5c6b6e 100644
--- a/pkg/sentry/fs/fsutil/host_mappable.go
+++ b/pkg/sentry/fs/fsutil/host_mappable.go
@@ -106,16 +106,16 @@ func (h *HostMappable) InvalidateUnsavable(ctx context.Context) error {
return nil
}
-// MapInto implements platform.File.MapInto.
-func (h *HostMappable) MapInto(as platform.AddressSpace, addr usermem.Addr, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
- return as.MapFile(addr, h.backingFile.FD(), fr, at, precommit)
-}
-
// MapInternal implements platform.File.MapInternal.
func (h *HostMappable) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
return h.hostFileMapper.MapInternal(fr, h.backingFile.FD(), at.Write)
}
+// FD implements platform.File.FD.
+func (h *HostMappable) FD() int {
+ return h.backingFile.FD()
+}
+
// IncRef implements platform.File.IncRef.
func (h *HostMappable) IncRef(fr platform.FileRange) {
mr := memmap.MappableRange{Start: fr.Start, End: fr.End}
diff --git a/pkg/sentry/fs/fsutil/inode_cached.go b/pkg/sentry/fs/fsutil/inode_cached.go
index e3b52e943..ef11676b8 100644
--- a/pkg/sentry/fs/fsutil/inode_cached.go
+++ b/pkg/sentry/fs/fsutil/inode_cached.go
@@ -835,20 +835,6 @@ func (c *CachingInodeOperations) InvalidateUnsavable(ctx context.Context) error
return nil
}
-// MapInto implements platform.File.MapInto. This is used when we directly map
-// an underlying host fd and CachingInodeOperations is used as the platform.File
-// during translation.
-func (c *CachingInodeOperations) MapInto(as platform.AddressSpace, addr usermem.Addr, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
- return as.MapFile(addr, c.backingFile.FD(), fr, at, precommit)
-}
-
-// MapInternal implements platform.File.MapInternal. This is used when we
-// directly map an underlying host fd and CachingInodeOperations is used as the
-// platform.File during translation.
-func (c *CachingInodeOperations) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
- return c.hostFileMapper.MapInternal(fr, c.backingFile.FD(), at.Write)
-}
-
// IncRef implements platform.File.IncRef. This is used when we directly map an
// underlying host fd and CachingInodeOperations is used as the platform.File
// during translation.
@@ -900,3 +886,17 @@ func (c *CachingInodeOperations) DecRef(fr platform.FileRange) {
c.dataMu.Unlock()
}
+
+// MapInternal implements platform.File.MapInternal. This is used when we
+// directly map an underlying host fd and CachingInodeOperations is used as the
+// platform.File during translation.
+func (c *CachingInodeOperations) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+ return c.hostFileMapper.MapInternal(fr, c.backingFile.FD(), at.Write)
+}
+
+// FD implements platform.File.FD. This is used when we directly map an
+// underlying host fd and CachingInodeOperations is used as the platform.File
+// during translation.
+func (c *CachingInodeOperations) FD() int {
+ return c.backingFile.FD()
+}
diff --git a/pkg/sentry/fs/tmpfs/inode_file.go b/pkg/sentry/fs/tmpfs/inode_file.go
index 5648ff8f4..13d06684d 100644
--- a/pkg/sentry/fs/tmpfs/inode_file.go
+++ b/pkg/sentry/fs/tmpfs/inode_file.go
@@ -39,20 +39,8 @@ var (
)
// fileInodeOperations implements fs.InodeOperations for a regular tmpfs file.
-// These files are backed by FrameRegions allocated from a platform.Memory,
-// and may be directly mapped.
-//
-// The tmpfs file memory is backed by FrameRegions, each of which is reference
-// counted. frames maintains a single reference on each of the FrameRegions.
-// Since these contain the contents of the file, the reference may only be
-// decremented once this file is both deleted and all handles to the file have
-// been closed.
-//
-// Mappable users may also call IncRefOn/DecRefOn, generally to indicate that
-// they plan to use MapInto to map the file into an AddressSpace. These calls
-// include an InvalidatorRegion associated with that reference. When the
-// referenced portion of the file is removed (with Truncate), the associated
-// InvalidatorRegion is invalidated.
+// These files are backed by pages allocated from a platform.Memory, and may be
+// directly mapped.
//
// +stateify savable
type fileInodeOperations struct {
diff --git a/pkg/sentry/memmap/memmap.go b/pkg/sentry/memmap/memmap.go
index cf20b11e3..70cdf428b 100644
--- a/pkg/sentry/memmap/memmap.go
+++ b/pkg/sentry/memmap/memmap.go
@@ -70,11 +70,13 @@ type Mappable interface {
// of offsets specified by required, and at most the range of offsets
// specified by optional. at is the set of access types that may be
// performed using the returned Translations. If not all required offsets
- // are translated, it returns a non-nil error explaining why. Returned
- // translations, and any mappings returned by platform.File.MapInternal for
- // translated platform.Files, are valid until invalidated by a call back to
+ // are translated, it returns a non-nil error explaining why.
+ //
+ // Translations are valid until invalidated by a callback to
// MappingSpace.Invalidate or until the caller removes its mapping of the
- // translated range.
+ // translated range. Mappable implementations must ensure that at least one
+ // reference is held on all pages in a platform.File that may be the result
+ // of a valid Translation.
//
// Preconditions: required.Length() > 0. optional.IsSupersetOf(required).
// required and optional must be page-aligned. The caller must have
@@ -98,9 +100,7 @@ type Translation struct {
// Source is the translated range in the Mappable.
Source MappableRange
- // File is the mapped file. When the Translation is invalidated, pages
- // mapped by File.MapInto must be unmapped, and pages mapped by
- // File.MapInternal become invalid.
+ // File is the mapped file.
File platform.File
// Offset is the offset into File at which this Translation begins.
diff --git a/pkg/sentry/mm/address_space.go b/pkg/sentry/mm/address_space.go
index e7aa24c69..90cfef746 100644
--- a/pkg/sentry/mm/address_space.go
+++ b/pkg/sentry/mm/address_space.go
@@ -183,7 +183,7 @@ func (mm *MemoryManager) mapASLocked(pseg pmaIterator, ar usermem.AddrRange, pre
if pma.needCOW {
perms.Write = false
}
- if err := pma.file.MapInto(mm.as, pmaMapAR.Start, pseg.fileRangeOf(pmaMapAR), perms, precommit); err != nil {
+ if err := mm.as.MapFile(pmaMapAR.Start, pma.file, pseg.fileRangeOf(pmaMapAR), perms, precommit); err != nil {
return err
}
pseg = pseg.NextSegment()
diff --git a/pkg/sentry/mm/mm.go b/pkg/sentry/mm/mm.go
index a69b8c7be..e2c636f38 100644
--- a/pkg/sentry/mm/mm.go
+++ b/pkg/sentry/mm/mm.go
@@ -24,7 +24,8 @@
// mm.MemoryManager.activeMu
// Locks taken by memmap.Mappable.Translate
// mm.privateRefs.mu
-// platform.File locks
+// platform.AddressSpace locks
+// platform.File locks
// mm.aioManager.mu
// mm.AIOContext.mu
//
diff --git a/pkg/sentry/platform/filemem/filemem.go b/pkg/sentry/platform/filemem/filemem.go
index 97da31e70..f41c70ba5 100644
--- a/pkg/sentry/platform/filemem/filemem.go
+++ b/pkg/sentry/platform/filemem/filemem.go
@@ -32,7 +32,6 @@ import (
"time"
"gvisor.googlesource.com/gvisor/pkg/log"
- "gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/memutil"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
"gvisor.googlesource.com/gvisor/pkg/sentry/safemem"
@@ -504,39 +503,6 @@ func (f *FileMem) markReclaimed(fr platform.FileRange) {
}
}
-// MapInto implements platform.File.MapInto.
-func (f *FileMem) MapInto(as platform.AddressSpace, addr usermem.Addr, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
- if !fr.WellFormed() || fr.Length() == 0 || fr.Start%usermem.PageSize != 0 || fr.End%usermem.PageSize != 0 {
- panic(fmt.Sprintf("invalid range: %v", fr))
- }
- return as.MapFile(addr, int(f.file.Fd()), fr, at, precommit)
-}
-
-// MapInternal implements platform.File.MapInternal.
-func (f *FileMem) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
- if !fr.WellFormed() || fr.Length() == 0 {
- panic(fmt.Sprintf("invalid range: %v", fr))
- }
- if at.Execute {
- return safemem.BlockSeq{}, syserror.EACCES
- }
-
- chunks := ((fr.End + chunkMask) >> chunkShift) - (fr.Start >> chunkShift)
- if chunks == 1 {
- // Avoid an unnecessary slice allocation.
- var seq safemem.BlockSeq
- err := f.forEachMappingSlice(fr, func(bs []byte) {
- seq = safemem.BlockSeqOf(safemem.BlockFromSafeSlice(bs))
- })
- return seq, err
- }
- blocks := make([]safemem.Block, 0, chunks)
- err := f.forEachMappingSlice(fr, func(bs []byte) {
- blocks = append(blocks, safemem.BlockFromSafeSlice(bs))
- })
- return safemem.BlockSeqFromSlice(blocks), err
-}
-
// IncRef implements platform.File.IncRef.
func (f *FileMem) IncRef(fr platform.FileRange) {
if !fr.WellFormed() || fr.Length() == 0 || fr.Start%usermem.PageSize != 0 || fr.End%usermem.PageSize != 0 {
@@ -596,9 +562,29 @@ func (f *FileMem) DecRef(fr platform.FileRange) {
}
}
-// Flush implements platform.Mappable.Flush.
-func (f *FileMem) Flush(ctx context.Context) error {
- return nil
+// MapInternal implements platform.File.MapInternal.
+func (f *FileMem) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
+ if !fr.WellFormed() || fr.Length() == 0 {
+ panic(fmt.Sprintf("invalid range: %v", fr))
+ }
+ if at.Execute {
+ return safemem.BlockSeq{}, syserror.EACCES
+ }
+
+ chunks := ((fr.End + chunkMask) >> chunkShift) - (fr.Start >> chunkShift)
+ if chunks == 1 {
+ // Avoid an unnecessary slice allocation.
+ var seq safemem.BlockSeq
+ err := f.forEachMappingSlice(fr, func(bs []byte) {
+ seq = safemem.BlockSeqOf(safemem.BlockFromSafeSlice(bs))
+ })
+ return seq, err
+ }
+ blocks := make([]safemem.Block, 0, chunks)
+ err := f.forEachMappingSlice(fr, func(bs []byte) {
+ blocks = append(blocks, safemem.BlockFromSafeSlice(bs))
+ })
+ return safemem.BlockSeqFromSlice(blocks), err
}
// forEachMappingSlice invokes fn on a sequence of byte slices that
@@ -653,6 +639,11 @@ func (f *FileMem) getChunkMapping(chunk int) ([]uintptr, uintptr, error) {
return mappings, m, nil
}
+// FD implements platform.File.FD.
+func (f *FileMem) FD() int {
+ return int(f.file.Fd())
+}
+
// UpdateUsage implements platform.Memory.UpdateUsage.
func (f *FileMem) UpdateUsage() error {
f.mu.Lock()
diff --git a/pkg/sentry/platform/kvm/BUILD b/pkg/sentry/platform/kvm/BUILD
index 6e40b3177..b7bf88249 100644
--- a/pkg/sentry/platform/kvm/BUILD
+++ b/pkg/sentry/platform/kvm/BUILD
@@ -2,28 +2,6 @@ load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
package(licenses = ["notice"])
-load("//tools/go_generics:defs.bzl", "go_template_instance")
-
-go_template_instance(
- name = "host_map_set",
- out = "host_map_set.go",
- consts = {
- "minDegree": "15",
- },
- imports = {
- "usermem": "gvisor.googlesource.com/gvisor/pkg/sentry/usermem",
- },
- package = "kvm",
- prefix = "hostMap",
- template = "//pkg/segment:generic_set",
- types = {
- "Key": "usermem.Addr",
- "Range": "usermem.AddrRange",
- "Value": "uintptr",
- "Functions": "hostMapSetFunctions",
- },
-)
-
go_library(
name = "kvm",
srcs = [
@@ -36,8 +14,6 @@ go_library(
"bluepill_fault.go",
"bluepill_unsafe.go",
"context.go",
- "host_map.go",
- "host_map_set.go",
"kvm.go",
"kvm_amd64.go",
"kvm_amd64_unsafe.go",
diff --git a/pkg/sentry/platform/kvm/address_space.go b/pkg/sentry/platform/kvm/address_space.go
index 72e897a9a..6d8d8e65b 100644
--- a/pkg/sentry/platform/kvm/address_space.go
+++ b/pkg/sentry/platform/kvm/address_space.go
@@ -15,7 +15,6 @@
package kvm
import (
- "reflect"
"sync"
"sync/atomic"
@@ -88,11 +87,6 @@ type addressSpace struct {
// dirtySet is the set of dirty vCPUs.
dirtySet *dirtySet
-
- // files contains files mapped in the host address space.
- //
- // See host_map.go for more information.
- files hostMap
}
// invalidate is the implementation for Invalidate.
@@ -118,6 +112,11 @@ func (as *addressSpace) Touch(c *vCPU) bool {
return as.dirtySet.mark(c)
}
+type hostMapEntry struct {
+ addr uintptr
+ length uintptr
+}
+
func (as *addressSpace) mapHost(addr usermem.Addr, m hostMapEntry, at usermem.AccessType) (inv bool) {
for m.length > 0 {
physical, length, ok := translateToPhysical(m.addr)
@@ -158,100 +157,57 @@ func (as *addressSpace) mapHost(addr usermem.Addr, m hostMapEntry, at usermem.Ac
return inv
}
-func (as *addressSpace) mapHostFile(addr usermem.Addr, fd int, fr platform.FileRange, at usermem.AccessType) error {
- // Create custom host mappings.
- ms, err := as.files.CreateMappings(usermem.AddrRange{
- Start: addr,
- End: addr + usermem.Addr(fr.End-fr.Start),
- }, at, fd, fr.Start)
- if err != nil {
- return err
- }
-
- inv := false
- for _, m := range ms {
- // The host mapped slices are guaranteed to be aligned.
- prev := as.mapHost(addr, m, at)
- inv = inv || prev
- addr += usermem.Addr(m.length)
- }
- if inv {
- as.invalidate()
- }
-
- return nil
-}
+// MapFile implements platform.AddressSpace.MapFile.
+func (as *addressSpace) MapFile(addr usermem.Addr, f platform.File, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
+ as.mu.Lock()
+ defer as.mu.Unlock()
-func (as *addressSpace) mapFilemem(addr usermem.Addr, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
- // TODO: Lock order at the platform level is not sufficiently
- // well-defined to guarantee that the caller (FileMem.MapInto) is not
- // holding any locks that FileMem.MapInternal may take.
-
- // Retrieve mappings for the underlying filemem. Note that the
- // permissions here are largely irrelevant, since it corresponds to
- // physical memory for the guest. We enforce the given access type
- // below, in the guest page tables.
- bs, err := as.filemem.MapInternal(fr, usermem.AccessType{
- Read: true,
- Write: true,
+ // Get mappings in the sentry's address space, which are guaranteed to be
+ // valid as long as a reference is held on the mapped pages (which is in
+ // turn required by AddressSpace.MapFile precondition).
+ //
+ // If precommit is true, we will touch mappings to commit them, so ensure
+ // that mappings are readable from sentry context.
+ //
+ // We don't execute from application file-mapped memory, and guest page
+ // tables don't care if we have execute permission (but they do need pages
+ // to be readable).
+ bs, err := f.MapInternal(fr, usermem.AccessType{
+ Read: at.Read || at.Execute || precommit,
+ Write: at.Write,
})
if err != nil {
return err
}
- // Save the original range for invalidation.
- orig := usermem.AddrRange{
- Start: addr,
- End: addr + usermem.Addr(fr.End-fr.Start),
- }
-
+ // Map the mappings in the sentry's address space (guest physical memory)
+ // into the application's address space (guest virtual memory).
inv := false
for !bs.IsEmpty() {
b := bs.Head()
bs = bs.Tail()
// Since fr was page-aligned, b should also be page-aligned. We do the
// lookup in our host page tables for this translation.
- s := b.ToSlice()
if precommit {
+ s := b.ToSlice()
for i := 0; i < len(s); i += usermem.PageSize {
_ = s[i] // Touch to commit.
}
}
prev := as.mapHost(addr, hostMapEntry{
- addr: reflect.ValueOf(&s[0]).Pointer(),
- length: uintptr(len(s)),
+ addr: b.Addr(),
+ length: uintptr(b.Len()),
}, at)
inv = inv || prev
- addr += usermem.Addr(len(s))
+ addr += usermem.Addr(b.Len())
}
if inv {
as.invalidate()
- as.files.DeleteMapping(orig)
}
return nil
}
-// MapFile implements platform.AddressSpace.MapFile.
-func (as *addressSpace) MapFile(addr usermem.Addr, fd int, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
- as.mu.Lock()
- defer as.mu.Unlock()
-
- // Create an appropriate mapping. If this is filemem, we don't create
- // custom mappings for each in-application mapping. For files however,
- // we create distinct mappings for each address space. Unfortunately,
- // there's not a better way to manage this here. The file underlying
- // this fd can change at any time, so we can't actually index the file
- // and share between address space. Oh well. It's all referring to the
- // same physical pages, hopefully we don't run out of address space.
- if fd != int(as.filemem.File().Fd()) {
- // N.B. precommit is ignored for host files.
- return as.mapHostFile(addr, fd, fr, at)
- }
-
- return as.mapFilemem(addr, fr, at, precommit)
-}
-
// Unmap unmaps the given range by calling pagetables.PageTables.Unmap.
func (as *addressSpace) Unmap(addr usermem.Addr, length uint64) {
as.mu.Lock()
@@ -264,10 +220,6 @@ func (as *addressSpace) Unmap(addr usermem.Addr, length uint64) {
})
if prev {
as.invalidate()
- as.files.DeleteMapping(usermem.AddrRange{
- Start: addr,
- End: addr + usermem.Addr(length),
- })
// Recycle any freed intermediate pages.
as.pageTables.Allocator.Recycle()
diff --git a/pkg/sentry/platform/kvm/host_map.go b/pkg/sentry/platform/kvm/host_map.go
deleted file mode 100644
index ee6a1a42d..000000000
--- a/pkg/sentry/platform/kvm/host_map.go
+++ /dev/null
@@ -1,184 +0,0 @@
-// Copyright 2018 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package kvm
-
-import (
- "fmt"
- "sync"
- "syscall"
-
- "gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
-)
-
-type hostMap struct {
- // mu protects below.
- mu sync.RWMutex
-
- // set contains host mappings.
- set hostMapSet
-}
-
-type hostMapEntry struct {
- addr uintptr
- length uintptr
-}
-
-// forEach iterates over all mappings in the given range.
-//
-// Precondition: segFn and gapFn must be non-nil.
-func (hm *hostMap) forEach(
- r usermem.AddrRange,
- segFn func(offset uint64, m hostMapEntry),
- gapFn func(offset uint64, length uintptr) (uintptr, bool)) {
-
- seg, gap := hm.set.Find(r.Start)
- for {
- if seg.Ok() && seg.Start() < r.End {
- // A valid segment: pass information.
- overlap := seg.Range().Intersect(r)
- segOffset := uintptr(overlap.Start - seg.Start())
- mapOffset := uint64(overlap.Start - r.Start)
- segFn(mapOffset, hostMapEntry{
- addr: seg.Value() + segOffset,
- length: uintptr(overlap.Length()),
- })
- seg, gap = seg.NextNonEmpty()
- } else if gap.Ok() && gap.Start() < r.End {
- // A gap: pass gap information.
- overlap := gap.Range().Intersect(r)
- mapOffset := uint64(overlap.Start - r.Start)
- addr, ok := gapFn(mapOffset, uintptr(overlap.Length()))
- if ok {
- seg = hm.set.Insert(gap, overlap, addr)
- seg, gap = seg.NextNonEmpty()
- } else {
- seg = gap.NextSegment()
- gap = hostMapGapIterator{} // Invalid.
- }
- } else {
- // Terminal.
- break
- }
- }
-}
-
-func (hm *hostMap) createMappings(r usermem.AddrRange, at usermem.AccessType, fd int, offset uint64) (ms []hostMapEntry, err error) {
- hm.forEach(r, func(mapOffset uint64, m hostMapEntry) {
- // Replace any existing mappings.
- _, _, errno := syscall.RawSyscall6(
- syscall.SYS_MMAP,
- m.addr,
- m.length,
- uintptr(at.Prot()),
- syscall.MAP_FIXED|syscall.MAP_SHARED,
- uintptr(fd),
- uintptr(offset+mapOffset))
- if errno != 0 && err == nil {
- err = errno
- }
- }, func(mapOffset uint64, length uintptr) (uintptr, bool) {
- // Create a new mapping.
- addr, _, errno := syscall.RawSyscall6(
- syscall.SYS_MMAP,
- 0,
- length,
- uintptr(at.Prot()),
- syscall.MAP_SHARED,
- uintptr(fd),
- uintptr(offset+mapOffset))
- if errno != 0 {
- err = errno
- return 0, false
- }
- return addr, true
- })
- if err != nil {
- return nil, err
- }
-
- // Collect all entries.
- //
- // We do this after the first iteration because some segments may have
- // been merged in the above, and we'll return the simplest form. This
- // also provides a basic sanity check in the form of no gaps.
- hm.forEach(r, func(_ uint64, m hostMapEntry) {
- ms = append(ms, m)
- }, func(uint64, uintptr) (uintptr, bool) {
- // Should not happen: we just mapped this above.
- panic("unexpected gap")
- })
-
- return ms, nil
-}
-
-// CreateMappings creates a new set of host mapping entries.
-func (hm *hostMap) CreateMappings(r usermem.AddrRange, at usermem.AccessType, fd int, offset uint64) (ms []hostMapEntry, err error) {
- hm.mu.Lock()
- ms, err = hm.createMappings(r, at, fd, offset)
- hm.mu.Unlock()
- return
-}
-
-func (hm *hostMap) deleteMapping(r usermem.AddrRange) {
- // Remove all the existing mappings.
- hm.forEach(r, func(_ uint64, m hostMapEntry) {
- _, _, errno := syscall.RawSyscall(
- syscall.SYS_MUNMAP,
- m.addr,
- m.length,
- 0)
- if errno != 0 {
- // Should never happen.
- panic(fmt.Sprintf("unmap error: %v", errno))
- }
- }, func(uint64, uintptr) (uintptr, bool) {
- // Sometimes deleteMapping will be called on a larger range
- // than physical mappings are defined. That's okay.
- return 0, false
- })
-
- // Knock the entire range out.
- hm.set.RemoveRange(r)
-}
-
-// DeleteMapping deletes the given range.
-func (hm *hostMap) DeleteMapping(r usermem.AddrRange) {
- hm.mu.Lock()
- hm.deleteMapping(r)
- hm.mu.Unlock()
-}
-
-// hostMapSetFunctions is used in the implementation of mapSet.
-type hostMapSetFunctions struct{}
-
-func (hostMapSetFunctions) MinKey() usermem.Addr { return 0 }
-func (hostMapSetFunctions) MaxKey() usermem.Addr { return ^usermem.Addr(0) }
-func (hostMapSetFunctions) ClearValue(val *uintptr) { *val = 0 }
-
-func (hostMapSetFunctions) Merge(r1 usermem.AddrRange, addr1 uintptr, r2 usermem.AddrRange, addr2 uintptr) (uintptr, bool) {
- if addr1+uintptr(r1.Length()) != addr2 {
- return 0, false
- }
-
- // Since the two regions are contiguous in both the key space and the
- // value space, we can just store a single segment with the first host
- // virtual address; the logic above operates based on the size of the
- // segments.
- return addr1, true
-}
-
-func (hostMapSetFunctions) Split(r usermem.AddrRange, hostAddr uintptr, split usermem.Addr) (uintptr, uintptr) {
- return hostAddr, hostAddr + uintptr(split-r.Start)
-}
diff --git a/pkg/sentry/platform/platform.go b/pkg/sentry/platform/platform.go
index a9e76bd45..b2ce851da 100644
--- a/pkg/sentry/platform/platform.go
+++ b/pkg/sentry/platform/platform.go
@@ -52,11 +52,11 @@ type Platform interface {
DetectsCPUPreemption() bool
// MapUnit returns the alignment used for optional mappings into this
- // platform's AddressSpaces. Higher values indicate lower per-page
- // costs for AddressSpace.MapInto. As a special case, a MapUnit of 0
- // indicates that the cost of AddressSpace.MapInto is effectively
- // independent of the number of pages mapped. If MapUnit is non-zero,
- // it must be a power-of-2 multiple of usermem.PageSize.
+ // platform's AddressSpaces. Higher values indicate lower per-page costs
+ // for AddressSpace.MapFile. As a special case, a MapUnit of 0 indicates
+ // that the cost of AddressSpace.MapFile is effectively independent of the
+ // number of pages mapped. If MapUnit is non-zero, it must be a power-of-2
+ // multiple of usermem.PageSize.
MapUnit() uint64
// MinUserAddress returns the minimum mappable address on this
@@ -194,17 +194,17 @@ const SignalInterrupt = linux.SIGCHLD
// AddressSpace represents a virtual address space in which a Context can
// execute.
type AddressSpace interface {
- // MapFile creates a shared mapping of offsets in fr, from the file
- // with file descriptor fd, at address addr. Any existing overlapping
- // mappings are silently replaced.
+ // MapFile creates a shared mapping of offsets fr from f at address addr.
+ // Any existing overlapping mappings are silently replaced.
//
- // If precommit is true, host memory should be committed to the mapping
- // when MapFile returns when possible. The precommit flag is advisory
- // and implementations may choose to ignore it.
+ // If precommit is true, the platform should eagerly commit resources (e.g.
+ // physical memory) to the mapping. The precommit flag is advisory and
+ // implementations may choose to ignore it.
//
- // Preconditions: addr and fr must be page-aligned. length > 0.
- // at.Any() == true.
- MapFile(addr usermem.Addr, fd int, fr FileRange, at usermem.AccessType, precommit bool) error
+ // Preconditions: addr and fr must be page-aligned. fr.Length() > 0.
+ // at.Any() == true. At least one reference must be held on all pages in
+ // fr, and must continue to be held as long as pages are mapped.
+ MapFile(addr usermem.Addr, f File, fr FileRange, at usermem.AccessType, precommit bool) error
// Unmap unmaps the given range.
//
@@ -309,44 +309,39 @@ func (f SegmentationFault) Error() string {
// File represents a host file that may be mapped into an AddressSpace.
type File interface {
- // MapInto maps fr into as, starting at addr, for accesses of type at.
- //
- // If precommit is true, the platform should eagerly commit resources (e.g.
- // physical memory) to the mapping. The precommit flag is advisory and
- // implementations may choose to ignore it.
+ // All pages in a File are reference-counted.
+
+ // IncRef increments the reference count on all pages in fr.
//
- // Note that there is no File.Unmap; clients should use as.Unmap directly.
+ // Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() >
+ // 0. At least one reference must be held on all pages in fr. (The File
+ // interface does not provide a way to acquire an initial reference;
+ // implementors may define mechanisms for doing so.)
+ IncRef(fr FileRange)
+
+ // DecRef decrements the reference count on all pages in fr.
//
- // Preconditions: fr.Start and fr.End must be page-aligned.
- // fr.Length() > 0. at.Any() == true. Implementors may define
- // additional requirements.
- MapInto(as AddressSpace, addr usermem.Addr, fr FileRange, at usermem.AccessType, precommit bool) error
+ // Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() >
+ // 0. At least one reference must be held on all pages in fr.
+ DecRef(fr FileRange)
// MapInternal returns a mapping of the given file offsets in the invoking
- // process' address space for reading and writing. The returned mapping is
- // valid as long as a reference is held on the mapped range.
+ // process' address space for reading and writing.
//
// Note that fr.Start and fr.End need not be page-aligned.
//
- // Preconditions: fr.Length() > 0. Implementors may define additional
- // requirements.
- MapInternal(fr FileRange, at usermem.AccessType) (safemem.BlockSeq, error)
-
- // IncRef signals that a region in the file is actively referenced through a
- // memory map. Implementors must ensure that the contents of a referenced
- // region remain consistent. Specifically, mappings returned by MapInternal
- // must refer to the same underlying contents. If the implementor also
- // implements the Memory interface, the file range must not be reused in a
- // different allocation while it has active references.
+ // Preconditions: fr.Length() > 0. At least one reference must be held on
+ // all pages in fr.
//
- // Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() > 0.
- IncRef(fr FileRange)
+ // Postconditions: The returned mapping is valid as long as at least one
+ // reference is held on the mapped pages.
+ MapInternal(fr FileRange, at usermem.AccessType) (safemem.BlockSeq, error)
- // DecRef reduces the frame ref count on the range specified by fr.
+ // FD returns the file descriptor represented by the File.
//
- // Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() >
- // 0. DecRef()s on a region must match earlier IncRef()s.
- DecRef(fr FileRange)
+ // The only permitted operation on the returned file descriptor is to map
+ // pages from it consistent with the requirements of AddressSpace.MapFile.
+ FD() int
}
// FileRange represents a range of uint64 offsets into a File.
@@ -361,19 +356,13 @@ func (fr FileRange) String() string {
// Memory represents an allocatable File that may be mapped into any
// AddressSpace associated with the same Platform.
type Memory interface {
- // Memory implements File methods with the following properties:
- //
- // - Pages mapped by MapInto must be allocated, and must be unmapped from
- // all AddressSpaces before they are freed.
- //
- // - Pages mapped by MapInternal must be allocated. Returned mappings are
- // guaranteed to be valid until the mapped pages are freed.
File
- // Allocate returns a range of pages of the given length, owned by the
- // caller and with the given accounting kind. Allocated memory initially has
- // a single reference and will automatically be freed when no references to
- // them remain. See File.IncRef and File.DecRef.
+ // Allocate returns a range of initially-zeroed pages of the given length
+ // with the given accounting kind and a single reference held by the
+ // caller. When the last reference on an allocated page is released,
+ // ownership of the page is returned to the Memory, allowing it to be
+ // returned by a future call to Allocate.
//
// Preconditions: length must be page-aligned and non-zero.
Allocate(length uint64, kind usage.MemoryKind) (FileRange, error)
diff --git a/pkg/sentry/platform/ptrace/subprocess.go b/pkg/sentry/platform/ptrace/subprocess.go
index a9d083f5a..82f125073 100644
--- a/pkg/sentry/platform/ptrace/subprocess.go
+++ b/pkg/sentry/platform/ptrace/subprocess.go
@@ -563,7 +563,7 @@ func (s *subprocess) syscall(sysno uintptr, args ...arch.SyscallArgument) (uintp
}
// MapFile implements platform.AddressSpace.MapFile.
-func (s *subprocess) MapFile(addr usermem.Addr, fd int, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
+func (s *subprocess) MapFile(addr usermem.Addr, f platform.File, fr platform.FileRange, at usermem.AccessType, precommit bool) error {
var flags int
if precommit {
flags |= syscall.MAP_POPULATE
@@ -574,7 +574,7 @@ func (s *subprocess) MapFile(addr usermem.Addr, fd int, fr platform.FileRange, a
arch.SyscallArgument{Value: uintptr(fr.Length())},
arch.SyscallArgument{Value: uintptr(at.Prot())},
arch.SyscallArgument{Value: uintptr(flags | syscall.MAP_SHARED | syscall.MAP_FIXED)},
- arch.SyscallArgument{Value: uintptr(fd)},
+ arch.SyscallArgument{Value: uintptr(f.FD())},
arch.SyscallArgument{Value: uintptr(fr.Start)})
return err
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-02 07:32:51 +0000