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Refactor syscall.Fstat calls in hostfs.

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Just call syscall.Fstat directly each time mode/file owner are needed. This
feels more natural than using i.getPermissions().

PiperOrigin-RevId: 308257405
This commit is contained in:
Dean Deng
2020-04-24 08:20:28 -07:00
committed by gVisor bot
parent 21a54adebc
commit 40a712c57c
1 changed files with 13 additions and 22 deletions
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pkg/sentry/fsimpl/host/host.go
+13 -22
View File
@@ -169,31 +169,22 @@ func fileFlagsFromHostFD(fd int) (int, error) {
// CheckPermissions implements kernfs.Inode.
func (i *inode) CheckPermissions(ctx context.Context, creds *auth.Credentials, ats vfs.AccessTypes) error {
mode, uid, gid, err := i.getPermissions()
if err != nil {
var s syscall.Stat_t
if err := syscall.Fstat(i.hostFD, &s); err != nil {
return err
}
return vfs.GenericCheckPermissions(creds, ats, mode, uid, gid)
return vfs.GenericCheckPermissions(creds, ats, linux.FileMode(s.Mode), auth.KUID(s.Uid), auth.KGID(s.Gid))
}
// Mode implements kernfs.Inode.
func (i *inode) Mode() linux.FileMode {
mode, _, _, err := i.getPermissions()
// Retrieving the mode from the host fd using fstat(2) should not fail.
// If the syscall does not succeed, something is fundamentally wrong.
if err != nil {
panic(fmt.Sprintf("failed to retrieve mode from host fd %d: %v", i.hostFD, err))
}
return linux.FileMode(mode)
}
func (i *inode) getPermissions() (linux.FileMode, auth.KUID, auth.KGID, error) {
// Retrieve metadata.
var s syscall.Stat_t
if err := syscall.Fstat(i.hostFD, &s); err != nil {
return 0, 0, 0, err
// Retrieving the mode from the host fd using fstat(2) should not fail.
// If the syscall does not succeed, something is fundamentally wrong.
panic(fmt.Sprintf("failed to retrieve mode from host fd %d: %v", i.hostFD, err))
}
return linux.FileMode(s.Mode), auth.KUID(s.Uid), auth.KGID(s.Gid), nil
return linux.FileMode(s.Mode)
}
// Stat implements kernfs.Inode.
@@ -326,11 +317,11 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
if m&^(linux.STATX_MODE|linux.STATX_SIZE|linux.STATX_ATIME|linux.STATX_MTIME) != 0 {
return syserror.EPERM
}
mode, uid, gid, err := i.getPermissions()
if err != nil {
var hostStat syscall.Stat_t
if err := syscall.Fstat(i.hostFD, &hostStat); err != nil {
return err
}
if err := vfs.CheckSetStat(ctx, creds, &s, mode.Permissions(), uid, gid); err != nil {
if err := vfs.CheckSetStat(ctx, creds, &s, linux.FileMode(hostStat.Mode&linux.PermissionsMask), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil {
return err
}
@@ -374,11 +365,11 @@ func (i *inode) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptio
}
func (i *inode) open(d *vfs.Dentry, mnt *vfs.Mount) (*vfs.FileDescription, error) {
mode, _, _, err := i.getPermissions()
if err != nil {
var s syscall.Stat_t
if err := syscall.Fstat(i.hostFD, &s); err != nil {
return nil, err
}
fileType := mode.FileType()
fileType := s.Mode & linux.FileTypeMask
if fileType == syscall.S_IFSOCK {
if i.isTTY {
return nil, errors.New("cannot use host socket as TTY")