diff options
Diffstat (limited to 'pkg')
| -rw-r--r-- | pkg/abi/linux/xattr.go | 3 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/overlay/filesystem.go | 2 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/tmpfs/tmpfs.go | 68 |
3 files changed, 46 insertions, 27 deletions
diff --git a/pkg/abi/linux/xattr.go b/pkg/abi/linux/xattr.go index 99180b208..8ef837f27 100644 --- a/pkg/abi/linux/xattr.go +++ b/pkg/abi/linux/xattr.go @@ -23,6 +23,9 @@ const ( XATTR_CREATE = 1 XATTR_REPLACE = 2 + XATTR_TRUSTED_PREFIX = "trusted." + XATTR_TRUSTED_PREFIX_LEN = len(XATTR_TRUSTED_PREFIX) + XATTR_USER_PREFIX = "user." XATTR_USER_PREFIX_LEN = len(XATTR_USER_PREFIX) ) diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go index a3cee4047..e720bfb0b 100644 --- a/pkg/sentry/fsimpl/overlay/filesystem.go +++ b/pkg/sentry/fsimpl/overlay/filesystem.go @@ -30,7 +30,7 @@ import ( // _OVL_XATTR_OPAQUE is an extended attribute key whose value is set to "y" for // opaque directories. // Linux: fs/overlayfs/overlayfs.h:OVL_XATTR_OPAQUE -const _OVL_XATTR_OPAQUE = "trusted.overlay.opaque" +const _OVL_XATTR_OPAQUE = linux.XATTR_TRUSTED_PREFIX + "overlay.opaque" func isWhiteout(stat *linux.Statx) bool { return stat.Mode&linux.S_IFMT == linux.S_IFCHR && stat.RdevMajor == 0 && stat.RdevMinor == 0 diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go index a7fdf19ca..c4cec4130 100644 --- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go +++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go @@ -631,49 +631,65 @@ func (i *inode) listxattr(size uint64) ([]string, error) { } func (i *inode) getxattr(creds *auth.Credentials, opts *vfs.GetxattrOptions) (string, error) { - if err := i.checkPermissions(creds, vfs.MayRead); err != nil { + if err := i.checkXattrPermissions(creds, opts.Name, vfs.MayRead); err != nil { return "", err } - if !strings.HasPrefix(opts.Name, linux.XATTR_USER_PREFIX) { - return "", syserror.EOPNOTSUPP - } - if !i.userXattrSupported() { - return "", syserror.ENODATA - } return i.xattrs.Getxattr(opts) } func (i *inode) setxattr(creds *auth.Credentials, opts *vfs.SetxattrOptions) error { - if err := i.checkPermissions(creds, vfs.MayWrite); err != nil { + if err := i.checkXattrPermissions(creds, opts.Name, vfs.MayWrite); err != nil { return err } - if !strings.HasPrefix(opts.Name, linux.XATTR_USER_PREFIX) { - return syserror.EOPNOTSUPP - } - if !i.userXattrSupported() { - return syserror.EPERM - } return i.xattrs.Setxattr(opts) } func (i *inode) removexattr(creds *auth.Credentials, name string) error { - if err := i.checkPermissions(creds, vfs.MayWrite); err != nil { + if err := i.checkXattrPermissions(creds, name, vfs.MayWrite); err != nil { return err } - if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) { - return syserror.EOPNOTSUPP - } - if !i.userXattrSupported() { - return syserror.EPERM - } return i.xattrs.Removexattr(name) } -// Extended attributes in the user.* namespace are only supported for regular -// files and directories. -func (i *inode) userXattrSupported() bool { - filetype := linux.S_IFMT & atomic.LoadUint32(&i.mode) - return filetype == linux.S_IFREG || filetype == linux.S_IFDIR +func (i *inode) checkXattrPermissions(creds *auth.Credentials, name string, ats vfs.AccessTypes) error { + switch { + case ats&vfs.MayRead == vfs.MayRead: + if err := i.checkPermissions(creds, vfs.MayRead); err != nil { + return err + } + case ats&vfs.MayWrite == vfs.MayWrite: + if err := i.checkPermissions(creds, vfs.MayWrite); err != nil { + return err + } + default: + panic(fmt.Sprintf("checkXattrPermissions called with impossible AccessTypes: %v", ats)) + } + + switch { + case strings.HasPrefix(name, linux.XATTR_TRUSTED_PREFIX): + // The trusted.* namespace can only be accessed by privileged + // users. + if creds.HasCapability(linux.CAP_SYS_ADMIN) { + return nil + } + if ats&vfs.MayWrite == vfs.MayWrite { + return syserror.EPERM + } + return syserror.ENODATA + case strings.HasPrefix(name, linux.XATTR_USER_PREFIX): + // Extended attributes in the user.* namespace are only + // supported for regular files and directories. + filetype := linux.S_IFMT & atomic.LoadUint32(&i.mode) + if filetype == linux.S_IFREG || filetype == linux.S_IFDIR { + return nil + } + if ats&vfs.MayWrite == vfs.MayWrite { + return syserror.EPERM + } + return syserror.ENODATA + + } + return syserror.EOPNOTSUPP } // fileDescription is embedded by tmpfs implementations of |