diff options
Diffstat (limited to 'meta-security/classes/xattr-images.bbclass')
| -rw-r--r-- | meta-security/classes/xattr-images.bbclass | 137 |
1 files changed, 0 insertions, 137 deletions
diff --git a/meta-security/classes/xattr-images.bbclass b/meta-security/classes/xattr-images.bbclass deleted file mode 100644 index 565a3fb6e..000000000 --- a/meta-security/classes/xattr-images.bbclass +++ /dev/null @@ -1,137 +0,0 @@ -# Both Smack and IMA/EVM rely on xattrs. Inheriting this class ensures -# that these xattrs get preserved in tar and jffs2 images. -# -# It also fixes the rootfs so that the content of directories with -# SMACK::TRANSMUTE is correctly labelled. This is because pseudo does -# not know the special semantic of SMACK::TRANSMUTE and omits the -# updating of the Smack label when creating entries inside such a directory, -# for example /etc (see base-files_%.bbappend). Without the fixup, -# files already installed during the image creation would have different (and -# wrong) Smack labels. - -# xattr support is expected to be compiled into mtd-utils. We just need to -# use it. -EXTRA_IMAGECMD_jffs2_append = " --with-xattr" - -# By default, OE-core uses tar from the host, which may or may not have the -# --xattrs parameter which was introduced in 1.27. For image building we -# use a recent enough tar instead. -# -# The GNU documentation does not specify whether --xattrs-include is necessary. -# In practice, it turned out to be not needed when creating archives and -# required when extracting, but it seems prudent to use it in both cases. -IMAGE_DEPENDS_tar_append = " tar-replacement-native" -EXTRANATIVEPATH += "tar-native" -IMAGE_CMD_TAR = "tar --xattrs --xattrs-include=*" - -xattr_images_fix_transmute[dirs] = "${IMAGE_ROOTFS}" -python xattr_images_fix_transmute () { - # The recursive updating of the Smack label ensures that each entry - # has the label set for its parent directories if one of those was - # marked as transmuting. - # - # In addition, "_" is set explicitly on everything that would not - # have a label otherwise. This is a workaround for tools like swupd - # which transfers files from a rootfs onto a target device where Smack - # is active: on the target, each file gets assigned a label, typically - # the one from the process which creates it. swupd (or rather, the tools - # it is currently built on) knows how to set security.SMACK64="_" when - # it is set on the original files, but it does not know that it needs - # to remove that xattr when not set. - import os - import errno - - if getattr(os, 'getxattr', None): - # Python 3: os has xattr support. - def lgetxattr(f, attr): - try: - value = os.getxattr(f, attr, follow_symlinks=False) - return value.decode('utf8') - except OSError as ex: - if ex.errno == errno.ENODATA: - return None - - def lsetxattr(f, attr, value): - os.setxattr(f, attr.encode('utf8'), value.encode('utf8'), follow_symlinks=False) - else: - # Python 2: xattr support only in xattr module. - # - # Cannot use the 'xattr' module, it is not part of a standard Python - # installation. Instead re-implement using ctypes. Only has to be good - # enough for xattrs that are strings. Always operates on the symlinks themselves, - # not what they point to. - import ctypes - - # We cannot look up the xattr functions inside libc. That bypasses - # pseudo, which overrides these functions via LD_PRELOAD. Instead we have to - # find the function address and then create a ctypes function from it. - libdl = ctypes.CDLL("libdl.so.2") - _dlsym = libdl.dlsym - _dlsym.restype = ctypes.c_void_p - RTLD_DEFAULT = ctypes.c_void_p(0) - _lgetxattr = ctypes.CFUNCTYPE(ctypes.c_ssize_t, ctypes.c_char_p, ctypes.c_char_p, ctypes.c_void_p, ctypes.c_size_t, - use_errno=True)(_dlsym(RTLD_DEFAULT, 'lgetxattr')) - _lsetxattr = ctypes.CFUNCTYPE(ctypes.c_int, ctypes.c_char_p, ctypes.c_char_p, ctypes.c_void_p, ctypes.c_size_t, ctypes.c_int, - use_errno=True)(_dlsym(RTLD_DEFAULT, 'lsetxattr')) - - def lgetxattr(f, attr): - len = 32 - while True: - buffer = ctypes.create_string_buffer('\000' * len) - res = _lgetxattr(f, attr, buffer, ctypes.c_size_t(len)) - if res >= 0: - return buffer.value - else: - error = ctypes.get_errno() - if ctypes.get_errno() == errno.ERANGE: - len *= 2 - elif error == errno.ENODATA: - return None - else: - raise IOError(error, 'lgetxattr(%s, %s): %d = %s = %s' % - (f, attr, error, errno.errorcode[error], os.strerror(error))) - - def lsetxattr(f, attr, value): - res = _lsetxattr(f, attr, value, ctypes.c_size_t(len(value)), ctypes.c_int(0)) - if res != 0: - error = ctypes.get_errno() - raise IOError(error, 'lsetxattr(%s, %s, %s): %d = %s = %s' % - (f, attr, value, error, errno.errorcode[error], os.strerror(error))) - - def visit(path, deflabel, deftransmute): - isrealdir = os.path.isdir(path) and not os.path.islink(path) - curlabel = lgetxattr(path, 'security.SMACK64') - transmute = lgetxattr(path, 'security.SMACK64TRANSMUTE') == 'TRUE' - - if not curlabel: - # Since swupd doesn't remove the label from an updated file assigned by - # the target device's kernel upon unpacking the file from an update, - # we have to set the floor label explicitly even though it is the default label - # and thus adding it would create additional overhead. Otherwise this - # would result in hash mismatches reported by `swupd verify`. - lsetxattr(path, 'security.SMACK64', deflabel) - if not transmute and deftransmute and isrealdir: - lsetxattr(path, 'security.SMACK64TRANSMUTE', 'TRUE') - - # Identify transmuting directories and change the default Smack - # label inside them. In addition, directories themselves must become - # transmuting. - if isrealdir: - if transmute: - deflabel = lgetxattr(path, 'security.SMACK64') - deftransmute = True - if deflabel is None: - raise RuntimeError('%s: transmuting directory without Smack label' % path) - elif curlabel: - # Directory with explicit label set and not transmuting => do not - # change the content unless we run into another transmuting directory. - deflabel = '_' - deftransmute = False - - for entry in os.listdir(path): - visit(os.path.join(path, entry), deflabel, deftransmute) - - visit('.', '_', False) -} -# Same logic as in ima-evm-rootfs.bbclass: try to run as late as possible. -IMAGE_PREPROCESS_COMMAND_append_with-lsm-smack = " xattr_images_fix_transmute ; " |