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Diffstat (limited to 'pkg/sentry/kernel/fd_table.go')
-rw-r--r--pkg/sentry/kernel/fd_table.go196
1 files changed, 96 insertions, 100 deletions
diff --git a/pkg/sentry/kernel/fd_table.go b/pkg/sentry/kernel/fd_table.go
index 8786a70b5..eff556a0c 100644
--- a/pkg/sentry/kernel/fd_table.go
+++ b/pkg/sentry/kernel/fd_table.go
@@ -18,10 +18,10 @@ import (
"fmt"
"math"
"strings"
- "sync/atomic"
"golang.org/x/sys/unix"
"gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/bitmap"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/sentry/fs"
@@ -84,13 +84,8 @@ type FDTable struct {
// mu protects below.
mu sync.Mutex `state:"nosave"`
- // next is start position to find fd.
- next int32
-
- // used contains the number of non-nil entries. It must be accessed
- // atomically. It may be read atomically without holding mu (but not
- // written).
- used int32
+ // fdBitmap shows which fds are already in use.
+ fdBitmap bitmap.Bitmap `state:"nosave"`
// descriptorTable holds descriptors.
descriptorTable `state:".(map[int32]descriptor)"`
@@ -98,6 +93,8 @@ type FDTable struct {
func (f *FDTable) saveDescriptorTable() map[int32]descriptor {
m := make(map[int32]descriptor)
+ f.mu.Lock()
+ defer f.mu.Unlock()
f.forEach(context.Background(), func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
m[fd] = descriptor{
file: file,
@@ -111,12 +108,16 @@ func (f *FDTable) saveDescriptorTable() map[int32]descriptor {
func (f *FDTable) loadDescriptorTable(m map[int32]descriptor) {
ctx := context.Background()
f.initNoLeakCheck() // Initialize table.
- f.used = 0
+ f.fdBitmap = bitmap.New(uint32(math.MaxUint16))
for fd, d := range m {
+ if fd < 0 {
+ panic(fmt.Sprintf("FD is not supposed to be negative. FD: %d", fd))
+ }
+
if file, fileVFS2 := f.setAll(ctx, fd, d.file, d.fileVFS2, d.flags); file != nil || fileVFS2 != nil {
panic("VFS1 or VFS2 files set")
}
-
+ f.fdBitmap.Add(uint32(fd))
// Note that we do _not_ need to acquire a extra table reference here. The
// table reference will already be accounted for in the file, so we drop the
// reference taken by set above.
@@ -189,8 +190,10 @@ func (f *FDTable) DecRef(ctx context.Context) {
func (f *FDTable) forEach(ctx context.Context, fn func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags)) {
// retries tracks the number of failed TryIncRef attempts for the same FD.
retries := 0
- fd := int32(0)
- for {
+ fds := f.fdBitmap.ToSlice()
+ // Iterate through the fdBitmap.
+ for _, ufd := range fds {
+ fd := int32(ufd)
file, fileVFS2, flags, ok := f.getAll(fd)
if !ok {
break
@@ -218,7 +221,6 @@ func (f *FDTable) forEach(ctx context.Context, fn func(fd int32, file *fs.File,
fileVFS2.DecRef(ctx)
}
retries = 0
- fd++
}
}
@@ -226,6 +228,8 @@ func (f *FDTable) forEach(ctx context.Context, fn func(fd int32, file *fs.File,
func (f *FDTable) String() string {
var buf strings.Builder
ctx := context.Background()
+ f.mu.Lock()
+ defer f.mu.Unlock()
f.forEach(ctx, func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
switch {
case file != nil:
@@ -250,10 +254,10 @@ func (f *FDTable) String() string {
}
// NewFDs allocates new FDs guaranteed to be the lowest number available
-// greater than or equal to the fd parameter. All files will share the set
+// greater than or equal to the minFD parameter. All files will share the set
// flags. Success is guaranteed to be all or none.
-func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags FDFlags) (fds []int32, err error) {
- if fd < 0 {
+func (f *FDTable) NewFDs(ctx context.Context, minFD int32, files []*fs.File, flags FDFlags) (fds []int32, err error) {
+ if minFD < 0 {
// Don't accept negative FDs.
return nil, unix.EINVAL
}
@@ -267,31 +271,48 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags
if lim.Cur != limits.Infinity {
end = int32(lim.Cur)
}
- if fd >= end {
+ if minFD+int32(len(files)) > end {
return nil, unix.EMFILE
}
}
f.mu.Lock()
- // From f.next to find available fd.
- if fd < f.next {
- fd = f.next
+ // max is used as the largest number in fdBitmap + 1.
+ max := int32(0)
+
+ if !f.fdBitmap.IsEmpty() {
+ max = int32(f.fdBitmap.Maximum())
+ max++
}
+ // Adjust max in case it is less than minFD.
+ if max < minFD {
+ max = minFD
+ }
// Install all entries.
- for i := fd; i < end && len(fds) < len(files); i++ {
- if d, _, _ := f.get(i); d == nil {
- // Set the descriptor.
- f.set(ctx, i, files[len(fds)], flags)
- fds = append(fds, i) // Record the file descriptor.
+ for len(fds) < len(files) {
+ // Try to use free bit in fdBitmap.
+ // If all bits in fdBitmap are used, expand fd to the max.
+ fd := f.fdBitmap.FirstZero(uint32(minFD))
+ if fd == math.MaxInt32 {
+ fd = uint32(max)
+ max++
+ }
+ if fd >= uint32(end) {
+ break
}
+ f.fdBitmap.Add(fd)
+ f.set(ctx, int32(fd), files[len(fds)], flags)
+ fds = append(fds, int32(fd))
+ minFD = int32(fd)
}
// Failure? Unwind existing FDs.
if len(fds) < len(files) {
for _, i := range fds {
f.set(ctx, i, nil, FDFlags{})
+ f.fdBitmap.Remove(uint32(i))
}
f.mu.Unlock()
@@ -305,20 +326,15 @@ func (f *FDTable) NewFDs(ctx context.Context, fd int32, files []*fs.File, flags
return nil, unix.EMFILE
}
- if fd == f.next {
- // Update next search start position.
- f.next = fds[len(fds)-1] + 1
- }
-
f.mu.Unlock()
return fds, nil
}
// NewFDsVFS2 allocates new FDs guaranteed to be the lowest number available
-// greater than or equal to the fd parameter. All files will share the set
+// greater than or equal to the minFD parameter. All files will share the set
// flags. Success is guaranteed to be all or none.
-func (f *FDTable) NewFDsVFS2(ctx context.Context, fd int32, files []*vfs.FileDescription, flags FDFlags) (fds []int32, err error) {
- if fd < 0 {
+func (f *FDTable) NewFDsVFS2(ctx context.Context, minFD int32, files []*vfs.FileDescription, flags FDFlags) (fds []int32, err error) {
+ if minFD < 0 {
// Don't accept negative FDs.
return nil, unix.EINVAL
}
@@ -332,31 +348,47 @@ func (f *FDTable) NewFDsVFS2(ctx context.Context, fd int32, files []*vfs.FileDes
if lim.Cur != limits.Infinity {
end = int32(lim.Cur)
}
- if fd >= end {
+ if minFD >= end {
return nil, unix.EMFILE
}
}
f.mu.Lock()
- // From f.next to find available fd.
- if fd < f.next {
- fd = f.next
+ // max is used as the largest number in fdBitmap + 1.
+ max := int32(0)
+
+ if !f.fdBitmap.IsEmpty() {
+ max = int32(f.fdBitmap.Maximum())
+ max++
}
- // Install all entries.
- for i := fd; i < end && len(fds) < len(files); i++ {
- if d, _, _ := f.getVFS2(i); d == nil {
- // Set the descriptor.
- f.setVFS2(ctx, i, files[len(fds)], flags)
- fds = append(fds, i) // Record the file descriptor.
- }
+ // Adjust max in case it is less than minFD.
+ if max < minFD {
+ max = minFD
}
+ for len(fds) < len(files) {
+ // Try to use free bit in fdBitmap.
+ // If all bits in fdBitmap are used, expand fd to the max.
+ fd := f.fdBitmap.FirstZero(uint32(minFD))
+ if fd == math.MaxInt32 {
+ fd = uint32(max)
+ max++
+ }
+ if fd >= uint32(end) {
+ break
+ }
+ f.fdBitmap.Add(fd)
+ f.setVFS2(ctx, int32(fd), files[len(fds)], flags)
+ fds = append(fds, int32(fd))
+ minFD = int32(fd)
+ }
// Failure? Unwind existing FDs.
if len(fds) < len(files) {
for _, i := range fds {
f.setVFS2(ctx, i, nil, FDFlags{})
+ f.fdBitmap.Remove(uint32(i))
}
f.mu.Unlock()
@@ -370,57 +402,19 @@ func (f *FDTable) NewFDsVFS2(ctx context.Context, fd int32, files []*vfs.FileDes
return nil, unix.EMFILE
}
- if fd == f.next {
- // Update next search start position.
- f.next = fds[len(fds)-1] + 1
- }
-
f.mu.Unlock()
return fds, nil
}
-// NewFDVFS2 allocates a file descriptor greater than or equal to minfd for
+// NewFDVFS2 allocates a file descriptor greater than or equal to minFD for
// the given file description. If it succeeds, it takes a reference on file.
-func (f *FDTable) NewFDVFS2(ctx context.Context, minfd int32, file *vfs.FileDescription, flags FDFlags) (int32, error) {
- if minfd < 0 {
- // Don't accept negative FDs.
- return -1, unix.EINVAL
- }
-
- // Default limit.
- end := int32(math.MaxInt32)
-
- // Ensure we don't get past the provided limit.
- if limitSet := limits.FromContext(ctx); limitSet != nil {
- lim := limitSet.Get(limits.NumberOfFiles)
- if lim.Cur != limits.Infinity {
- end = int32(lim.Cur)
- }
- if minfd >= end {
- return -1, unix.EMFILE
- }
- }
-
- f.mu.Lock()
- defer f.mu.Unlock()
-
- // From f.next to find available fd.
- fd := minfd
- if fd < f.next {
- fd = f.next
- }
- for fd < end {
- if d, _, _ := f.getVFS2(fd); d == nil {
- f.setVFS2(ctx, fd, file, flags)
- if fd == f.next {
- // Update next search start position.
- f.next = fd + 1
- }
- return fd, nil
- }
- fd++
+func (f *FDTable) NewFDVFS2(ctx context.Context, minFD int32, file *vfs.FileDescription, flags FDFlags) (int32, error) {
+ files := []*vfs.FileDescription{file}
+ fileSlice, error := f.NewFDsVFS2(ctx, minFD, files, flags)
+ if error != nil {
+ return -1, error
}
- return -1, unix.EMFILE
+ return fileSlice[0], nil
}
// NewFDAt sets the file reference for the given FD. If there is an active
@@ -469,6 +463,11 @@ func (f *FDTable) newFDAt(ctx context.Context, fd int32, file *fs.File, fileVFS2
defer f.mu.Unlock()
df, dfVFS2 := f.setAll(ctx, fd, file, fileVFS2, flags)
+ // Add fd to fdBitmap.
+ if file != nil || fileVFS2 != nil {
+ f.fdBitmap.Add(uint32(fd))
+ }
+
return df, dfVFS2, nil
}
@@ -573,7 +572,9 @@ func (f *FDTable) GetVFS2(fd int32) (*vfs.FileDescription, FDFlags) {
// Precondition: The caller must be running on the task goroutine, or Task.mu
// must be locked.
func (f *FDTable) GetFDs(ctx context.Context) []int32 {
- fds := make([]int32, 0, int(atomic.LoadInt32(&f.used)))
+ f.mu.Lock()
+ defer f.mu.Unlock()
+ fds := make([]int32, 0, int(f.fdBitmap.GetNumOnes()))
f.forEach(ctx, func(fd int32, _ *fs.File, _ *vfs.FileDescription, _ FDFlags) {
fds = append(fds, fd)
})
@@ -583,13 +584,15 @@ func (f *FDTable) GetFDs(ctx context.Context) []int32 {
// Fork returns an independent FDTable.
func (f *FDTable) Fork(ctx context.Context) *FDTable {
clone := f.k.NewFDTable()
-
+ f.mu.Lock()
+ defer f.mu.Unlock()
f.forEach(ctx, func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
// The set function here will acquire an appropriate table
// reference for the clone. We don't need anything else.
if df, dfVFS2 := clone.setAll(ctx, fd, file, fileVFS2, flags); df != nil || dfVFS2 != nil {
panic("VFS1 or VFS2 files set")
}
+ clone.fdBitmap.Add(uint32(fd))
})
return clone
}
@@ -604,11 +607,6 @@ func (f *FDTable) Remove(ctx context.Context, fd int32) (*fs.File, *vfs.FileDesc
f.mu.Lock()
- // Update current available position.
- if fd < f.next {
- f.next = fd
- }
-
orig, orig2, _, _ := f.getAll(fd)
// Add reference for caller.
@@ -621,6 +619,7 @@ func (f *FDTable) Remove(ctx context.Context, fd int32) (*fs.File, *vfs.FileDesc
if orig != nil || orig2 != nil {
orig, orig2 = f.setAll(ctx, fd, nil, nil, FDFlags{}) // Zap entry.
+ f.fdBitmap.Remove(uint32(fd))
}
f.mu.Unlock()
@@ -644,16 +643,13 @@ func (f *FDTable) RemoveIf(ctx context.Context, cond func(*fs.File, *vfs.FileDes
f.forEach(ctx, func(fd int32, file *fs.File, fileVFS2 *vfs.FileDescription, flags FDFlags) {
if cond(file, fileVFS2, flags) {
df, dfVFS2 := f.setAll(ctx, fd, nil, nil, FDFlags{}) // Clear from table.
+ f.fdBitmap.Remove(uint32(fd))
if df != nil {
files = append(files, df)
}
if dfVFS2 != nil {
filesVFS2 = append(filesVFS2, dfVFS2)
}
- // Update current available position.
- if fd < f.next {
- f.next = fd
- }
}
})
f.mu.Unlock()
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 11:00:54 +0000