source: fedd/access_to_abac.py @ 09b1e9d

#!/usr/local/bin/python

import sys, os
import re
import subprocess

from string import join
from federation.fedid import fedid
from optparse import OptionParser, OptionValueError


class attribute:
    '''
    Encapculate a principal/attribute/link tuple.
    '''
    bad_attr = re.compile('[^a-zA-Z0-9_]+')
    def __init__(self, p, a, l=None):
        self.principal = p
        self.attr = attribute.bad_attr.sub('_', a)
        if l: self.link = attribute.bad_attr.sub('_', l)
        else: self.link = None

    def __str__(self):
        if self.link:
            return "%s.%s.%s" % (self.principal, self.attr, self.link)
        elif self.attr:
            return "%s.%s" % (self.principal, self.attr)
        else:
            return "%s" % self.principal

class credential:
    '''
    A Credential, that is the requisites (as attributes) and the assigned
    attribute (as principal, attr).   If req is iterable, the requirements are
    an intersection/conjunction.
    '''
    bad_attr = re.compile('[^a-zA-Z0-9_]+')
    def __init__(self, p, a, req):
        self.principal = p
        if isinstance(a, (tuple, list, set)) and len(a) == 1:
            self.attr = credential.bad_attr.sub('_', a[0])
        else:
            self.attr = credential.bad_attr.sub('_', a)
        self.req = req

    def __str__(self):
        if isinstance(self.req, (tuple, list, set)):
            return "%s.%s <- %s" % (self.principal, self.attr, 
                    join(["%s" % r for r in self.req], ' & '))
        else:
            return "%s.%s <- %s" % (self.principal, self.attr, self.req)

# Mappinng generation functiona and the access parser throw these when there is
# a parsing problem.
class parse_error(RuntimeError): pass

# Error creating a credential
class credential_error(RuntimeError): pass

# Functions to parse the individual access maps as well as an overall function
# to parse generic ones.  The specific ones create a credential to local
# attributes mapping and the global one creates the access policy credentials.

#  All the local parsing functions get the unparsed remainder of the line
#  (after the three-name and the attribute it maps to), the credential list to
#  add the new ABAC credential(s) that will be mapped into the loacl
#  credentials, the fedid of this entity, a dict mapping the local credentials
#  to ABAC credentials that are required to exercise those local rights and the
#  three-name (p, gp, gu) that is being mapped.
def parse_emulab(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the emulab (project, allocation_user, access_user) format.  Access
    users are deprecates and allocation users used for both.  This fuction
    collapses them.
    '''
    right_side_str = '\s*,\s*\(\s*%s\s*,\s*%s\s*,\s*%s\s*\)' % \
            (id_same_str, id_same_str,id_same_str)

    m = re.match(right_side_str, l)
    if m:
        project, user = m.group(1,2)
        # Resolve "<same>"s in project and user
        if project == '<same>':
            if gp  is not None:
                project = gp 
            else:
                raise parse_error("Project cannot be decisively mapped: %s" % l)
        if user == '<same>':
            if gu is not None:
                project = gu 
            else:
                raise parse_error("User cannot be decisively mapped: %s" % l)

        # Create a semi-mnemonic name for the destination credential (the one
        # that will be mapped to the local attributes
        if project and user:
            a = 'project_%s_user_%s' % (project, user)
        elif project:
            a = 'project_%s' % project
        elif user:
            a = 'user_%s' % user
        else:
            raise parse_error("No mapping for %s/%s!?" % (gp, gu))

        # Store the creds and map entries
        c = credential(me, a, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if (project, user) in to_id: to_id[(project,user)].append(c)
        else: to_id[(project,user)] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)


def parse_protogeni(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the protoGENI (cert, user, user_key, cert_pw) format.
    '''
    right_side_str = '\s*,\s*\(\s*(%s)\s*,\s*(%s)\s*,\s*(%s)\s*,\s*(%s)\s*\)' \
            % (path_str, id_str, path_str, id_str)

    m = re.match(right_side_str, l)
    if m:
        cert, user, key, pw = m.group(1,2,3,4)
        # The credential is formed from just the path (with / mapped to _) and
        # the username.
        acert = re.sub('/', '_', cert)

        a = "cert_%s_user_%s" % (acert, user)

        # Store em
        c = credential(me, a, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if (cert, user, key, pw) in to_id: 
            to_id[(cert, user, key, pw)].append(c)
        else: 
            to_id[(cert, user, key, pw)] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)

def parse_dragon(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the dragon (repository_name) version.
    '''
    right_side_str = '\s*,\s*\(\s*(%s)\s*\)' % \
            (id_str)

    m = re.match(right_side_str, l)
    if m:
        repo= m.group(1)
        c = credential(me, 'repo_%s' % repo, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if repo in to_id: to_id[repo].append(c)
        else: to_id[repo] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)

def parse_skel(l, creds, me, to_id, p, gp, gu, lr):
    '''
    Parse the skeleton (local_attr) version.
    '''
    right_side_str = '\s*,\s*\(\s*(%s)\s*\)' % \
            (id_str)

    m = re.match(right_side_str, l)
    if m:
        lattr = m.group(1)
        c = credential(me, 'lattr_%s' % lattr, 
                [attribute(p, x, lr) for x in (gp, gu) if x is not None])
        creds.add(c)
        if lattr in to_id: to_id[lattr].append(c)
        else: to_id[lattr] = [ c ]
    else:
        raise parse_error("Badly formatted local mapping: %s" % l)

# internal plug-ins have no local attributes.
def parse_internal(l, creds, me, to_id, p, gp, gu, lr): pass


class access_opts(OptionParser):
    '''
    Parse the options for this program.  Most are straightforward, but the
    mapper uses a callback to convert from a string to a local mapper function.
    '''
    # Valid mappers
    mappers = { 
            'emulab': parse_emulab, 
            'dragon': parse_dragon,
            'internal': parse_internal,
            'skel': parse_skel,
            'protogeni': parse_protogeni,
            }

    @staticmethod
    def parse_mapper(opt, s, val, parser, dest):
        if val in access_opts.mappers:
            setattr(parser.values, dest, access_opts.mappers[val])
        else:
            raise OptionValueError('%s must be one of %s' % \
                    (s, join(access_opts.mappers.keys(), ', ')))

    def __init__(self):
        OptionParser.__init__(self, usage='%prog [opts] file [...]')
        self.add_option('--cert', dest='cert', default=None,
                help='my fedid as an X.509 certificate')
        self.add_option('--key', dest='key', default=None,
                help='key for the certificate')
        self.add_option('--dir', dest='dir', default=None,
                help='Output directory for credentials')
        self.add_option('--type', action='callback', nargs=1, type='str',
                callback=access_opts.parse_mapper, 
                callback_kwargs = { 'dest': 'mapper'}, 
                help='Type of access file to parse.  One of %s. ' %\
                        join(access_opts.mappers.keys(), ', ') + \
                        'Omit for generic parsing.')
        self.add_option('--quiet', dest='quiet', action='store_true', 
                default=False,
                help='Do not print credential to local attribute map')
        self.add_option('--create-creds', action='store_true', 
                dest='create_creds', default=False,
                help='create credentials for rules.  Requires ' + \
                        '--cert, --key, and --dir to be given.')
        self.add_option('--file', dest='file', default=None,
                help='Access DB to parse.  If this is present, ' + \
                        'omit the positional filename')
        self.add_option('--mapfile', dest='map', default=None,
                help='File for the attribute to local authorization data')
        self.add_option('--no-delegate', action='store_false', dest='delegate',
                default=True,
                help='do not accept delegated attributes with the ' +\
                        'acting_for linking role')
        self.add_option('--debug', action='store_true', dest='debug', 
                default=False, help='Just print actions')
        self.set_defaults(mapper=None)

def create_creds(creds, cert, key, dir, debug=False, 
        creddy='/usr/local/bin/creddy'):
    '''
    Make the creddy calls to create the attributes from the list of credential
    objects in the creds parameter.
    '''
    def attrs(r):
        '''
        Convert an attribute into creddy --subject-id and --subject-role
        parameters
        '''
        if r.principal and r.link and r.attr:
            return ['--subject-id=%s' % r.principal, 
                    '--subject-role=%s.%s' % (r.attr, r.link),
                    ]
        elif r.principal and r.attr:
            return ['--subject-id=%s' % r.principal, 
                    '--subject-role=%s' %r.attr]
        elif r.principal:
            return ['--subject-id=%s' % r.prinicpal]
        else:
            raise parse_error('Attribute without a principal?')

    # main line of create_creds
    for i, c in enumerate(creds):
        cmd = [creddy, '--attribute', '--issuer=%s' % cert, '--key=%s' % key,
                '--role=%s' % c.attr, '--out=%s/cred%d' % (dir, i)]
        for r in c.req:
            cmd.extend(attrs(r))
        if debug:
            print join(cmd)
        else:
            rv = subprocess.call(cmd)
            if rv != 0:
                raise credential_error("%s: %d" % (join(cmd), rv))

# Regular expressions and parts thereof for parsing
comment_re = re.compile('^\s*#|^$')
fedid_str = 'fedid:([0-9a-fA-F]{40})'
id_str = '[a-zA-Z][\w_-]*'
path_str = '[a-zA-Z_/\.-]+'
id_any_str = '(%s|<any>)' % id_str
id_same_str = '(%s|<same>)' % id_str
left_side_str = '\(\s*%s\s*,\s*%s\s*,\s*%s\s*\)' % \
        (fedid_str, id_any_str, id_any_str)
right_side_str = '(%s)(\s*,\s*\(.*\))?' % (id_str)
line_re = re.compile('%s\s*->\s*%s' % (left_side_str, right_side_str))

p = access_opts()
opts, args = p.parse_args()

if opts.file:
    args.append(opts.file)

# Validate arguments
if len(args) < 1:
    sys.exit('No filenames given to parse')

if opts.cert: 
    try:
        me = fedid(file=opts.cert) 
    except EnvironmentError, e:
        sys.exit('Bad --cert: %s (%s)' % (e.strerror, e.filename or '?!'))
else: 
    print >>sys.stderr, 'No --cert, using dummy fedid'
    me = fedid(hexstr='0123456789012345678901234567890123456789')

if opts.key and not os.access(opts.key, os.R_OK):
    sys.exit('Cannot read key (%s)' % opts.key)

if opts.dir:
    if not os.path.isdir(opts.dir):
        sys.exit('%s is not a directory' % opts.dir)
    elif not os.access(opts.dir, os.W_OK):
        sys.exit('%s is not writable' % opts.dir)

if opts.delegate: delegation_link = 'acting_for'
else: delegation_link = None

mapper = opts.mapper

# Do the parsing
for fn in args:
    creds = set()
    to_id = { }
    try:
        f = open(fn, "r")
        for i, l in enumerate(f):
            try:
                if comment_re.match(l):
                    continue
                else:
                    m =  line_re.match(l)
                    if m:
                        p, da = m.group(1, 4)
                        gp, gu = m.group(2, 3)
                        if gp == '<any>': gp = None
                        if gu == '<any>': gu = None

                        creds.add(credential(me, da, 
                                [attribute(p, x, delegation_link) \
                                        for x in (gp, gu) \
                                            if x is not None]))
                        if m.group(5) and mapper:
                            mapper(m.group(5), creds, me, to_id, p, gp, gu,
                                    delegation_link)
                    else:
                        raise parse_error('Syntax error')
            except parse_error, e:
                f.close()
                raise parse_error('Error on line %d of %s: %s' % \
                        (i, fn, e.message))
                
        f.close()
    except parse_error, e:
        print >> sys.stderr, "%s" % e
        continue

    except EnvironmentError, e:
        print >>sys.stderr, "File error %s: %s" % \
                (e.filename or '!?', e.strerror) 
        continue

    # Credential output
    if opts.create_creds:
        if all([opts.cert, opts.key, opts.dir]):
            try:
                create_creds([c for c in creds if c.principal == me],
                        opts.cert, opts.key, opts.dir, opts.debug)
            except credential_error, e:
                sys.exit('Credential creation failed: %s' % e)
        else:
            print >>sys.stderr, 'Cannot create credentials.  Missing parameter'

    # Local map output
    if opts.map or opts.debug:
        try:
            if opts.map and opts.map != '-' and not opts.debug:
                f = open(opts.map, 'w')
            else:
                f = sys.stdout
            for k, c in to_id.items():
                for a in set(["%s.%s" % (x.principal, x.attr) for x in c]):
                    print >>f, "%s -> (%s)" % ( a, join(k, ', '))
        except EnvironmentError, e:
            sys.exit("Cannot open %s: %s" % (e.filename or '!?', e.strerror))