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Add memmap.MMapOpts.RequirePlatformEffect and use where appropriate.

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Per the comment for vfs.GenericProxyDeviceConfigureMMap(), this ensures that if
invalid arguments are provided to application mmap() for a proxy device file,
then an error is returned immediately (from host mmap()) rather than when
demand paging causes host mmap() to be invoked.

PiperOrigin-RevId: 680733678
This commit is contained in:
Jamie Liu
2024-09-30 15:13:16 -07:00
committed by gVisor bot
parent a15559c56c
commit a5459a26cb
9 changed files with 69 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
pkg/sentry/devices/nvproxy/frontend_mmap.go
+1 -4
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@@ -26,10 +26,7 @@ func (fd *frontendFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts)
// Nvidia kernel driver: kernel-open/nvidia/nv-mmap.c:nvidia_mmap_helper()
// requires vm_pgoff == 0, so trying to lazily fault any subset of the
// mapping that doesn't include the beginning will fail.
if opts.PlatformEffect < memmap.PlatformEffectPopulate {
opts.PlatformEffect = memmap.PlatformEffectPopulate
}
return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
return vfs.GenericProxyDeviceConfigureMMap(&fd.vfsfd, fd, opts)
}
// AddMapping implements memmap.Mappable.AddMapping.
pkg/sentry/devices/nvproxy/uvm_mmap.go
+1 -4
View File
@@ -27,10 +27,7 @@ func (fd *uvmFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error
// UVM_VALIDATE_VA_RANGE, and probably other ioctls, expect that
// application mmaps of /dev/nvidia-uvm are immediately visible to the
// driver.
if opts.PlatformEffect < memmap.PlatformEffectPopulate {
opts.PlatformEffect = memmap.PlatformEffectPopulate
}
return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
return vfs.GenericProxyDeviceConfigureMMap(&fd.vfsfd, fd, opts)
}
// AddMapping implements memmap.Mappable.AddMapping.
pkg/sentry/devices/tpuproxy/accel/accel_fd_mmap.go
+1 -1
View File
@@ -26,7 +26,7 @@ import (
// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
func (fd *accelFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
return vfs.GenericProxyDeviceConfigureMMap(&fd.vfsfd, fd, opts)
}
// AddMapping implements memmap.Mappable.AddMapping.
pkg/sentry/devices/tpuproxy/vfio/pci_device_fd_mmap.go
+1 -1
View File
@@ -25,7 +25,7 @@ import (
// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
func (fd *pciDeviceFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
return vfs.GenericProxyDeviceConfigureMMap(&fd.vfsfd, fd, opts)
}
// AddMapping implements memmap.Mappable.AddMapping.
pkg/sentry/devices/tpuproxy/vfio/tpu_fd_mmap.go
+1 -1
View File
@@ -26,7 +26,7 @@ import (
// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
func (fd *tpuFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
return vfs.GenericProxyDeviceConfigureMMap(&fd.vfsfd, fd, opts)
}
// AddMapping implements memmap.Mappable.AddMapping.
pkg/sentry/devices/tpuproxy/vfio/vfio_fd_mmap.go
+1 -1
View File
@@ -26,7 +26,7 @@ import (
// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
func (fd *vfioFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
return vfs.GenericConfigureMMap(&fd.vfsfd, fd, opts)
return vfs.GenericProxyDeviceConfigureMMap(&fd.vfsfd, fd, opts)
}
// AddMapping implements memmap.Mappable.AddMapping.
pkg/sentry/memmap/memmap.go
+9
View File
@@ -360,6 +360,8 @@ type MMapOpts struct {
// Linux.
Stack bool
// PlatformEffect controls the synchronous effect of this call on the
// underlying platform.AddressSpace.
PlatformEffect MMapPlatformEffect
// MLockMode specifies the memory locking behavior of the mapping.
@@ -378,6 +380,13 @@ type MMapOpts struct {
// If Force is true, Unmap and Fixed must be true.
Force bool
// If RequirePlatformEffect is false, PlatformEffect is best-effort;
// failure to create mappings in the platform.AddressSpace are silently
// ignored. If RequirePlatformEffect is true, failure to create mappings in
// the platform.AddressSpace cause MMap() to fail. (If PlatformEffect is
// PlatformEffectDefault, RequirePlatformEffect is ignored.)
RequirePlatformEffect bool
// SentryOwnedContent indicates the sentry exclusively controls the
// underlying memory backing the mapping thus the memory content is
// guaranteed not to be modified outside the sentry's purview.
pkg/sentry/mm/syscalls.go
+41 -30
View File
@@ -114,12 +114,16 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (hostar
}
// Get the new vma.
var droppedIDs []memmap.MappingIdentity
mm.mappingMu.Lock()
if opts.MLockMode < mm.defMLockMode {
opts.MLockMode = mm.defMLockMode
}
vseg, ar, droppedIDs, err := mm.createVMALocked(ctx, opts, droppedIDs)
vseg, ar, droppedIDs, err := mm.createVMALocked(ctx, opts, nil /* droppedIDs */)
defer func() {
for _, id := range droppedIDs {
id.DecRef(ctx)
}
}()
if err != nil {
mm.mappingMu.Unlock()
return 0, err
@@ -131,7 +135,19 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (hostar
// mm/util.c:vm_mmap_pgoff() => mm/gup.c:__mm_populate() =>
// populate_vma_page_range(). Confirm this behavior.
switch {
case opts.PlatformEffect >= memmap.PlatformEffectPopulate || opts.MLockMode == memmap.MLockEager:
case opts.PlatformEffect >= memmap.PlatformEffectPopulate:
if opts.RequirePlatformEffect {
if err := mm.populateVMA(ctx, vseg, ar, opts.PlatformEffect); err != nil {
_, droppedIDs = mm.unmapLocked(ctx, ar, droppedIDs)
mm.mappingMu.Unlock()
return 0, err
}
mm.mappingMu.Unlock()
break
}
fallthrough
case opts.MLockMode == memmap.MLockEager:
// Get pmas and map as requested.
mm.populateVMAAndUnlock(ctx, vseg, ar, opts.PlatformEffect)
@@ -148,10 +164,6 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (hostar
mm.mappingMu.Unlock()
}
for _, id := range droppedIDs {
id.DecRef(ctx)
}
return ar.Start, nil
}
@@ -161,11 +173,11 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (hostar
// Preconditions:
// - mm.mappingMu must be locked.
// - vseg.Range().IsSupersetOf(ar).
func (mm *MemoryManager) populateVMA(ctx context.Context, vseg vmaIterator, ar hostarch.AddrRange, platformEffect memmap.MMapPlatformEffect) {
func (mm *MemoryManager) populateVMA(ctx context.Context, vseg vmaIterator, ar hostarch.AddrRange, platformEffect memmap.MMapPlatformEffect) error {
if !vseg.ValuePtr().effectivePerms.Any() {
// Linux doesn't populate inaccessible pages. See
// mm/gup.c:populate_vma_page_range.
return
// mm.mapASLocked() will no-op due to platform.AddressSpace.MapFile()
// precondition.
return nil
}
mm.activeMu.Lock()
@@ -175,32 +187,29 @@ func (mm *MemoryManager) populateVMA(ctx context.Context, vseg vmaIterator, ar h
// AddressSpace.
if mm.as == nil {
mm.activeMu.Unlock()
return
return nil
}
// Ensure that we have usable pmas.
pseg, _, err := mm.getPMAsLocked(ctx, vseg, ar, hostarch.NoAccess, platformEffect == memmap.PlatformEffectCommit)
if err != nil {
// mm/util.c:vm_mmap_pgoff() ignores the error, if any, from
// mm/gup.c:mm_populate(). If it matters, we'll get it again when
// userspace actually tries to use the failing page.
mm.activeMu.Unlock()
return
return err
}
// Downgrade to a read-lock on activeMu since we don't need to mutate pmas
// anymore.
mm.activeMu.DowngradeLock()
// As above, errors are silently ignored.
mm.mapASLocked(pseg, ar, platformEffect)
err = mm.mapASLocked(pseg, ar, platformEffect)
mm.activeMu.RUnlock()
return err
}
// populateVMAAndUnlock is equivalent to populateVMA, but also unconditionally
// unlocks mm.mappingMu. In cases where populateVMAAndUnlock is usable, it is
// preferable to populateVMA since it unlocks mm.mappingMu before performing
// expensive operations that don't require it to be locked.
// unlocks mm.mappingMu and discards errors. In cases where
// populateVMAAndUnlock is usable, it is preferable to populateVMA since it
// unlocks mm.mappingMu before performing expensive operations that don't
// require it to be locked.
//
// Preconditions:
// - mm.mappingMu must be locked for writing.
@@ -209,13 +218,15 @@ func (mm *MemoryManager) populateVMA(ctx context.Context, vseg vmaIterator, ar h
// Postconditions: mm.mappingMu will be unlocked.
// +checklocksrelease:mm.mappingMu
func (mm *MemoryManager) populateVMAAndUnlock(ctx context.Context, vseg vmaIterator, ar hostarch.AddrRange, platformEffect memmap.MMapPlatformEffect) {
// See populateVMA above for commentary.
if !vseg.ValuePtr().effectivePerms.Any() {
// Linux doesn't populate inaccessible pages. See
// mm/gup.c:populate_vma_page_range.
mm.mappingMu.Unlock()
return
}
mm.activeMu.Lock()
// Can't defer mm.activeMu.Unlock(); see below.
if mm.as == nil {
mm.activeMu.Unlock()
@@ -229,10 +240,14 @@ func (mm *MemoryManager) populateVMAAndUnlock(ctx context.Context, vseg vmaItera
pseg, _, err := mm.getPMAsLocked(ctx, vseg, ar, hostarch.NoAccess, platformEffect == memmap.PlatformEffectCommit)
mm.mappingMu.RUnlock()
if err != nil {
// mm/util.c:vm_mmap_pgoff() ignores the error, if any, from
// mm/gup.c:mm_populate(). If it matters, we'll get it again when
// userspace actually tries to use the failing page.
mm.activeMu.Unlock()
return
}
// As above, errors are silently ignored.
mm.activeMu.DowngradeLock()
mm.mapASLocked(pseg, ar, platformEffect)
mm.activeMu.RUnlock()
@@ -268,11 +283,8 @@ func (mm *MemoryManager) MapStack(ctx context.Context) (hostarch.AddrRange, erro
return hostarch.AddrRange{}, linuxerr.ENOMEM
}
stackStart := stackEnd - szaddr
var droppedIDs []memmap.MappingIdentity
var ar hostarch.AddrRange
var err error
mm.mappingMu.Lock()
_, ar, droppedIDs, err = mm.createVMALocked(ctx, memmap.MMapOpts{
_, ar, droppedIDs, err := mm.createVMALocked(ctx, memmap.MMapOpts{
Length: sz,
Addr: stackStart,
Perms: hostarch.ReadWrite,
@@ -281,7 +293,7 @@ func (mm *MemoryManager) MapStack(ctx context.Context) (hostarch.AddrRange, erro
GrowsDown: true,
MLockMode: mm.defMLockMode,
Hint: "[stack]",
}, droppedIDs)
}, nil /* droppedIDs */)
mm.mappingMu.Unlock()
for _, id := range droppedIDs {
id.DecRef(ctx)
@@ -306,9 +318,8 @@ func (mm *MemoryManager) MUnmap(ctx context.Context, addr hostarch.Addr, length
return linuxerr.EINVAL
}
var droppedIDs []memmap.MappingIdentity
mm.mappingMu.Lock()
_, droppedIDs = mm.unmapLocked(ctx, ar, droppedIDs)
_, droppedIDs := mm.unmapLocked(ctx, ar, nil /* droppedIDs */)
mm.mappingMu.Unlock()
for _, id := range droppedIDs {
pkg/sentry/vfs/file_description_impl_util.go
+13
View File
@@ -426,6 +426,19 @@ func GenericConfigureMMap(fd *FileDescription, m memmap.Mappable, opts *memmap.M
return nil
}
// GenericProxyDeviceConfigureMMap may be used by most implementations of
// FileDescriptionImpl.ConfigureMMap for which the underlying memmap.File is a
// host device file, whose implementation of mmap() may have unusual
// requirements and so should be called immediately (during application mmap())
// to propagate any errors.
func GenericProxyDeviceConfigureMMap(fd *FileDescription, m memmap.Mappable, opts *memmap.MMapOpts) error {
if opts.PlatformEffect < memmap.PlatformEffectPopulate {
opts.PlatformEffect = memmap.PlatformEffectPopulate
}
opts.RequirePlatformEffect = true
return GenericConfigureMMap(fd, m, opts)
}
// LockFD may be used by most implementations of FileDescriptionImpl.Lock*
// functions. Caller must call Init().
//