Integrate parts of meta-intel-iot-security

Adds the recipes of the sub layers
 - meta-security-framework
 - meta-security-smack

Change-Id: I618608008a3b3d1d34adb6e38048110f13ac0643
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

2 files changed, 205 insertions, 0 deletions

diff --git a/meta-security/classes/deploy-files.bbclass b/meta-security/classes/deploy-files.bbclass
new file mode 100644
index 000000000..ec19323a3
--- /dev/null
+++ b/meta-security/classes/deploy-files.bbclass
@@ -0,0 +1,68 @@
+DEPLOY_FILES_DIR = "${WORKDIR}/deploy-files-${PN}"
+SSTATETASKS += "do_deploy_files"
+do_deploy_files[sstate-inputdirs] = "${DEPLOY_FILES_DIR}"
+do_deploy_files[sstate-outputdirs] = "${DEPLOY_DIR}/files/"
+
+python do_deploy_files_setscene () {
+    sstate_setscene(d)
+}
+addtask do_deploy_files_setscene
+do_deploy_files[dirs] = "${DEPLOY_FILES_DIR} ${B}"
+
+# Use like this:
+# DEPLOY_FILES = "abc xyz"
+# DEPLOY_FILES_FROM[abc] = "file-ab dir-c"
+# DEPLOY_FILES_TO[abc] = "directory-for-abc"
+# DEPLOY_FILES_FROM[xyz] = "file-xyz"
+# DEPLOY_FILES_TO[xyz] = "directory-for-xyz"
+#
+# The destination directory will be created inside
+# ${DEPLOYDIR}. The source files and directories
+# will be copied such that their name and (for
+# directories) the directory tree below it will
+# be preserved. Shell wildcards are supported.
+#
+# The default DEPLOY_FILES copies files for the native host
+# and the target into two different directories. Use that as follows:
+# DEPLOY_FILES_FROM_native = "native-file"
+# DEPLOY_FILES_FROM_target = "target-file"
+
+DEPLOY_FILES ?= "native target"
+DEPLOY_FILES_FROM[native] ?= ""
+DEPLOY_FILES_TO[native] = "native/${BUILD_ARCH}"
+DEPLOY_FILES_FROM[target] ?= ""
+DEPLOY_FILES_TO[target] = "target/${MACHINE}"
+
+# We have to use a Python function to access variable flags. Because
+# bitbake then does not know about the dependency on these variables,
+# we need to explicitly declare that. DEPLOYDIR may change without
+# invalidating the sstate, therefore it is not listed.
+do_deploy_files[vardeps] = "DEPLOY_FILES DEPLOY_FILES_FROM DEPLOY_FILES_TO"
+python do_deploy_files () {
+    import glob
+    import os
+    import shutil
+
+    for file in (d.getVar('DEPLOY_FILES', True) or '').split():
+        bb.note('file: %s' % file)
+        from_pattern = d.getVarFlag('DEPLOY_FILES_FROM', file, True)
+        bb.note('from: %s' % from_pattern)
+        if from_pattern:
+            to = os.path.join(d.getVar('DEPLOY_FILES_DIR', True), d.getVarFlag('DEPLOY_FILES_TO', file, True))
+            bb.note('to: %s' % to)
+            if not os.path.isdir(to):
+                os.makedirs(to)
+            for from_path in from_pattern.split():
+                for src in (glob.glob(from_path) or [from_path]):
+                    bb.note('Deploying %s to %s' % (src, to))
+                    if os.path.isdir(src):
+                        src_dirname = shutil._basename(src)
+                        to = os.path.join(to, src_dirname)
+                        if os.path.exists(to):
+                            bb.utils.remove(to, True)
+                        shutil.copytree(src, to)
+                    else:
+                        shutil.copy(src, to)
+}
+
+addtask deploy_files before do_build after do_compile
diff --git a/meta-security/classes/xattr-images.bbclass b/meta-security/classes/xattr-images.bbclass
new file mode 100644
index 000000000..565a3fb6e
--- /dev/null
+++ b/meta-security/classes/xattr-images.bbclass
@@ -0,0 +1,137 @@
+# 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 ; "