RE: [PATCH] checkpolicy: add support for using last path component in type transition rules

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> How do we handle the case when filename component contains whitespaces?
> Or multibyte characters?
>
Right now, I don't think this issue has higher priority, because it is hard
to imagine actual case we need to set up special cases in TYPE_TRANSITON on
files with whitespace or multibyte names.
(So, my two patches I sent does not handle these cases right now.)

Thanks,
--
NEC Europe Ltd, SAP Global Competence Center
KaiGai Kohei <kohei.kaigai@xxxxxxxxxx>


> -----Original Message-----
> From: owner-selinux@xxxxxxxxxxxxx [mailto:owner-selinux@xxxxxxxxxxxxx] On
> Behalf Of Kohei Kaigai
> Sent: 31. MÃrz 2011 12:46
> To: Eric Paris; selinux@xxxxxxxxxxxxx
> Cc: method@xxxxxxxxxxxxxxx; sds@xxxxxxxxxxxxx
> Subject: RE: [PATCH] checkpolicy: add support for using last path component
> in type transition rules
>
> I have a question in a corner case.
>
> How do we handle the case when filename component contains whitespaces?
> Or multibyte characters?
>
> Rught now, policy_scan.l of checkpolicy defines IDENTIFIER element as follows:
>
>   {letter}({alnum}|[_\-])*([\.]?({alnum}|[_\-]))* { return(IDENTIFIER); }
>
> I think it is an issue in corner case, however, to be considered.
>
> IMO, it is not a good idea to handle multibyte support by ourselves.
> The security policy should have same character set with other stuffs.
>
> Regarding to whitespaces, is it possible to define a syntax without conflicts
> to the existing syntax?
>
> Thanks,
> --
> NEC Europe Ltd, Global Competence Center
> KaiGai Kohei <kohei.kaigai@xxxxxxxxxx>
>
>
> > -----Original Message-----
> > From: owner-selinux@xxxxxxxxxxxxx [mailto:owner-selinux@xxxxxxxxxxxxx] On
> > Behalf Of Eric Paris
> > Sent: 28. MÃrz 2011 19:00
> > To: selinux@xxxxxxxxxxxxx
> > Cc: method@xxxxxxxxxxxxxxx; sds@xxxxxxxxxxxxx
> > Subject: [PATCH] checkpolicy: add support for using last path component in
> > type transition rules
> >
> > This patch adds support for using the last path component as part of the
> > information in making labeling decisions for new objects.  A example
> > rule looks like so:
> >
> > type_transition unconfined_t etc_t:file system_conf_t eric;
> >
> > This rule says if unconfined_t creates a file in a directory labeled
> > etc_t and the last path component is "eric" (no globbing, no matching
> > magic, just exact strcmp) it should be labeled system_conf_t.
> >
> > The kernel and policy representation does not have support for such
> > rules in conditionals, and thus policy explicitly notes that fact if
> > such a rule is added to a conditional.
> >
> > Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>
> > ---
> >
> > diff -up checkpolicy-2.0.23/module_compiler.c.eparis2
> > checkpolicy-2.0.23/module_compiler.c
> > --- checkpolicy-2.0.23/module_compiler.c.eparis2      2010-12-21
> > 16:35:45.000000000 -0500
> > +++ checkpolicy-2.0.23/module_compiler.c      2011-03-23
> 14:19:51.152530839
> > -0400
> > @@ -1313,6 +1313,18 @@ void append_role_allow(role_allow_rule_t
> >  }
> >
> >  /* this doesn't actually append, but really prepends it */
> > +void append_filename_trans(filename_trans_rule_t * filename_trans_rules)
> > +{
> > +     avrule_decl_t *decl = stack_top->decl;
> > +
> > +     /* filename transitions are not allowed within conditionals */
> > +     assert(stack_top->type == 1);
> > +
> > +     filename_trans_rules->next = decl->filename_trans_rules;
> > +     decl->filename_trans_rules = filename_trans_rules;
> > +}
> > +
> > +/* this doesn't actually append, but really prepends it */
> >  void append_range_trans(range_trans_rule_t * range_tr_rules)
> >  {
> >       avrule_decl_t *decl = stack_top->decl;
> > diff -up checkpolicy-2.0.23/module_compiler.h.eparis2
> > checkpolicy-2.0.23/module_compiler.h
> > --- checkpolicy-2.0.23/module_compiler.h.eparis2      2010-12-21
> > 16:35:45.000000000 -0500
> > +++ checkpolicy-2.0.23/module_compiler.h      2011-03-23
> 14:19:51.154531123
> > -0400
> > @@ -80,6 +80,7 @@ void append_avrule(avrule_t * avrule);
> >  void append_role_trans(role_trans_rule_t * role_tr_rules);
> >  void append_role_allow(role_allow_rule_t * role_allow_rules);
> >  void append_range_trans(range_trans_rule_t * range_tr_rules);
> > +void append_filename_trans(filename_trans_rule_t *
> filename_trans_rules);
> >
> >  /* Create a new optional block and add it to the global policy.
> >   * During the second pass resolve the block's requirements.  Return 0
> > diff -up checkpolicy-2.0.23/policy_define.c.eparis2
> > checkpolicy-2.0.23/policy_define.c
> > --- checkpolicy-2.0.23/policy_define.c.eparis2        2010-12-21
> > 16:35:45.000000000 -0500
> > +++ checkpolicy-2.0.23/policy_define.c        2011-03-28
> 13:50:57.667710915
> > -0400
> > @@ -2196,6 +2196,190 @@ int define_role_allow(void)
> >       return 0;
> >  }
> >
> > +avrule_t *define_cond_filename_trans(void)
> > +{
> > +     yyerror("type transitions with a filename not allowed inside "
> > +             "conditionals\n");
> > +     return COND_ERR;
> > +}
> > +
> > +int define_filename_trans(void)
> > +{
> > +     char *id, *name = NULL;
> > +     type_set_t stypes, ttypes;
> > +     ebitmap_t e_stypes, e_ttypes;
> > +     ebitmap_t e_tclasses;
> > +     ebitmap_node_t *snode, *tnode, *cnode;
> > +     filename_trans_t *ft;
> > +     filename_trans_rule_t *ftr;
> > +     class_datum_t *cladatum;
> > +     type_datum_t *typdatum;
> > +     uint32_t otype;
> > +     unsigned int c, s, t;
> > +     int add;
> > +
> > +     if (pass == 1) {
> > +             /* stype */
> > +             while ((id = queue_remove(id_queue)))
> > +                     free(id);
> > +             /* ttype */
> > +             while ((id = queue_remove(id_queue)))
> > +                     free(id);
> > +             /* tclass */
> > +             while ((id = queue_remove(id_queue)))
> > +                     free(id);
> > +             /* otype */
> > +             id = queue_remove(id_queue);
> > +             free(id);
> > +             /* name */
> > +             id = queue_remove(id_queue);
> > +             free(id);
> > +             return 0;
> > +     }
> > +
> > +
> > +     add = 1;
> > +     type_set_init(&stypes);
> > +     while ((id = queue_remove(id_queue))) {
> > +             if (set_types(&stypes, id, &add, 0))
> > +                     goto bad;
> > +     }
> > +
> > +     add =1;
> > +     type_set_init(&ttypes);
> > +     while ((id = queue_remove(id_queue))) {
> > +             if (set_types(&ttypes, id, &add, 0))
> > +                     goto bad;
> > +     }
> > +
> > +     ebitmap_init(&e_tclasses);
> > +     while ((id = queue_remove(id_queue))) {
> > +             if (!is_id_in_scope(SYM_CLASSES, id)) {
> > +                     yyerror2("class %s is not within scope", id);
> > +                     free(id);
> > +                     goto bad;
> > +             }
> > +             cladatum = hashtab_search(policydbp->p_classes.table, id);
> > +             if (!cladatum) {
> > +                     yyerror2("unknown class %s", id);
> > +                     goto bad;
> > +             }
> > +             if (ebitmap_set_bit(&e_tclasses, cladatum->s.value - 1,
> > TRUE)) {
> > +                     yyerror("Out of memory");
> > +                     goto bad;
> > +             }
> > +             free(id);
> > +     }
> > +
> > +     id = (char *)queue_remove(id_queue);
> > +     if (!id) {
> > +             yyerror("no otype in transition definition?");
> > +             goto bad;
> > +     }
> > +     if (!is_id_in_scope(SYM_TYPES, id)) {
> > +             yyerror2("type %s is not within scope", id);
> > +             free(id);
> > +             goto bad;
> > +     }
> > +     typdatum = hashtab_search(policydbp->p_types.table, id);
> > +     if (!typdatum) {
> > +             yyerror2("unknown type %s used in transition definition",
> > id);
> > +             goto bad;
> > +     }
> > +     free(id);
> > +     otype = typdatum->s.value;
> > +
> > +     name = queue_remove(id_queue);
> > +     if (!name) {
> > +             yyerror("no pathname specified in filename_trans
> > definition?");
> > +             goto bad;
> > +     }
> > +
> > +     /* We expand the class set into seperate rules.  We expand the types
> > +      * just to make sure there are not duplicates.  They will get turned
> > +      * into seperate rules later */
> > +     ebitmap_init(&e_stypes);
> > +     if (type_set_expand(&stypes, &e_stypes, policydbp, 1))
> > +             goto bad;
> > +
> > +     ebitmap_init(&e_ttypes);
> > +     if (type_set_expand(&ttypes, &e_ttypes, policydbp, 1))
> > +             goto bad;
> > +
> > +     ebitmap_for_each_bit(&e_tclasses, cnode, c) {
> > +             if (!ebitmap_node_get_bit(cnode, c))
> > +                     continue;
> > +             ebitmap_for_each_bit(&e_stypes, snode, s) {
> > +                     if (!ebitmap_node_get_bit(snode, s))
> > +                             continue;
> > +                     ebitmap_for_each_bit(&e_ttypes, tnode, t) {
> > +                             if (!ebitmap_node_get_bit(tnode, t))
> > +                                     continue;
> > +
> > +                             for (ft = policydbp->filename_trans; ft;
> > ft = ft->next) {
> > +                                     if (ft->stype == (s + 1) &&
> > +                                         ft->ttype == (t + 1) &&
> > +                                         ft->tclass == (c + 1) &&
> > +                                         !strcmp(ft->name, name)) {
> > +                                             yyerror2("duplicate
> > filename transition for: filename_trans %s %s %s:%s",
> > +                                                      name,
> > +
> > policydbp->p_type_val_to_name[s],
> > +
> > policydbp->p_type_val_to_name[t],
> > +
> > policydbp->p_class_val_to_name[c]);
> > +                                             goto bad;
> > +                                     }
> > +                             }
> > +
> > +                             ft = malloc(sizeof(*ft));
> > +                             if (!ft) {
> > +                                     yyerror("out of memory");
> > +                                     goto bad;
> > +                             }
> > +                             memset(ft, 0, sizeof(*ft));
> > +
> > +                             ft->next = policydbp->filename_trans;
> > +                             policydbp->filename_trans = ft;
> > +
> > +                             ft->name = strdup(name);
> > +                             if (!ft->name) {
> > +                                     yyerror("out of memory");
> > +                                     goto bad;
> > +                             }
> > +                             ft->stype = s + 1;
> > +                             ft->ttype = t + 1;
> > +                             ft->tclass = c + 1;
> > +                             ft->otype = otype;
> > +                     }
> > +             }
> > +
> > +             /* Now add the real rule since we didn't find any duplicates
> > */
> > +             ftr = malloc(sizeof(*ftr));
> > +             if (!ftr) {
> > +                     yyerror("out of memory");
> > +                     goto bad;
> > +             }
> > +             filename_trans_rule_init(ftr);
> > +             append_filename_trans(ftr);
> > +
> > +             ftr->name = strdup(name);
> > +             ftr->stypes = stypes;
> > +             ftr->ttypes = ttypes;
> > +             ftr->tclass = c + 1;
> > +             ftr->otype = otype;
> > +     }
> > +
> > +     free(name);
> > +     ebitmap_destroy(&e_stypes);
> > +     ebitmap_destroy(&e_ttypes);
> > +     ebitmap_destroy(&e_tclasses);
> > +
> > +     return 0;
> > +
> > +bad:
> > +     free(name);
> > +     return -1;
> > +}
> > +
> >  static constraint_expr_t *constraint_expr_clone(constraint_expr_t *
> expr)
> >  {
> >       constraint_expr_t *h = NULL, *l = NULL, *e, *newe;
> > diff -up checkpolicy-2.0.23/policy_define.h.eparis2
> > checkpolicy-2.0.23/policy_define.h
> > --- checkpolicy-2.0.23/policy_define.h.eparis2        2010-12-21
> > 16:35:45.000000000 -0500
> > +++ checkpolicy-2.0.23/policy_define.h        2011-03-28
> 13:50:05.489297128
> > -0400
> > @@ -16,6 +16,7 @@
> >  avrule_t *define_cond_compute_type(int which);
> >  avrule_t *define_cond_pol_list(avrule_t *avlist, avrule_t *stmt);
> >  avrule_t *define_cond_te_avtab(int which);
> > +avrule_t *define_cond_filename_trans(void);
> >  cond_expr_t *define_cond_expr(uint32_t expr_type, void *arg1, void*
> arg2);
> >  int define_attrib(void);
> >  int define_av_perms(int inherits);
> > @@ -47,6 +48,7 @@ int define_range_trans(int class_specifi
> >  int define_role_allow(void);
> >  int define_role_trans(void);
> >  int define_role_types(void);
> > +int define_filename_trans(void);
> >  int define_sens(void);
> >  int define_te_avtab(int which);
> >  int define_typealias(void);
> > diff -up checkpolicy-2.0.23/policy_parse.y.eparis2
> > checkpolicy-2.0.23/policy_parse.y
> > --- checkpolicy-2.0.23/policy_parse.y.eparis2 2011-03-23
> > 14:19:51.133528148 -0400
> > +++ checkpolicy-2.0.23/policy_parse.y 2011-03-28 13:49:03.489482156
> > -0400
> > @@ -342,7 +342,10 @@ cond_rule_def           : cond_transitio
> >                       | require_block
> >                       { $$ = NULL; }
> >                          ;
> > -cond_transition_def  : TYPE_TRANSITION names names ':' names identifier
> > ';'
> > +cond_transition_def  : TYPE_TRANSITION names names ':' names identifier
> > identifier ';'
> > +                        { $$ = define_cond_filename_trans() ;
> > +                          if ($$ == COND_ERR) return -1;}
> > +                     | TYPE_TRANSITION names names ':' names identifier
> > ';'
> >                          { $$ =
> > define_cond_compute_type(AVRULE_TRANSITION) ;
> >                            if ($$ == COND_ERR) return -1;}
> >                          | TYPE_MEMBER names names ':' names identifier ';'
> > @@ -377,7 +380,10 @@ cond_dontaudit_def       : DONTAUDIT names nam
> >                       { $$ = define_cond_te_avtab(AVRULE_DONTAUDIT);
> >                            if ($$ == COND_ERR) return -1; }
> >                       ;
> > -transition_def               : TYPE_TRANSITION names names ':' names
> identifier
> > ';'
> > +                     ;
> > +transition_def               : TYPE_TRANSITION  names names ':' names
> identifier
> > identifier ';'
> > +                     {if (define_filename_trans()) return -1; }
> > +                     | TYPE_TRANSITION names names ':' names identifier
> > ';'
> >                          {if (define_compute_type(AVRULE_TRANSITION))
> > return -1;}
> >                          | TYPE_MEMBER names names ':' names identifier ';'
> >                          {if (define_compute_type(AVRULE_MEMBER)) return
> > -1;}
> > diff -up checkpolicy-2.0.23/test/dismod.c.eparis2
> > checkpolicy-2.0.23/test/dismod.c
> > --- checkpolicy-2.0.23/test/dismod.c.eparis2  2011-03-23
> > 14:19:51.142529423 -0400
> > +++ checkpolicy-2.0.23/test/dismod.c  2011-03-23 14:19:51.160531973
> > -0400
> > @@ -52,6 +52,7 @@
> >  #define DISPLAY_AVBLOCK_ROLE_ALLOW   4
> >  #define DISPLAY_AVBLOCK_REQUIRES     5
> >  #define DISPLAY_AVBLOCK_DECLARES     6
> > +#define DISPLAY_AVBLOCK_FILENAME_TRANS       7
> >
> >  static policydb_t policydb;
> >  extern unsigned int ss_initialized;
> > @@ -480,6 +481,18 @@ void display_role_allow(role_allow_rule_
> >       }
> >  }
> >
> > +void display_filename_trans(filename_trans_rule_t * tr, policydb_t * p,
> FILE
> > * fp)
> > +{
> > +     for (; tr; tr = tr->next) {
> > +             fprintf(fp, "filename transition %s", tr->name);
> > +             display_type_set(&tr->stypes, 0, p, fp);
> > +             display_type_set(&tr->ttypes, 0, p, fp);
> > +             display_id(p, fp, SYM_CLASSES, tr->tclass - 1, ":");
> > +             display_id(p, fp, SYM_TYPES, tr->otype - 1, "");
> > +             fprintf(fp, "\n");
> > +     }
> > +}
> > +
> >  int role_display_callback(hashtab_key_t key, hashtab_datum_t datum, void
> > *data)
> >  {
> >       role_datum_t *role;
> > @@ -647,6 +660,11 @@ int display_avdecl(avrule_decl_t * decl,
> >                       }
> >                       break;
> >               }
> > +     case DISPLAY_AVBLOCK_FILENAME_TRANS:
> > +             display_filename_trans(decl->filename_trans_rules,
> > policy,
> > +                                    out_fp);
> > +                     return -1;
> > +             break;
> >       default:{
> >                       assert(0);
> >               }
> > @@ -812,6 +830,7 @@ int menu()
> >       printf("c)  Display policy capabilities\n");
> >       printf("l)  Link in a module\n");
> >       printf("u)  Display the unknown handling setting\n");
> > +     printf("F)  Display filename_trans rules\n");
> >       printf("\n");
> >       printf("f)  set output file\n");
> >       printf("m)  display menu\n");
> > @@ -947,6 +966,11 @@ int main(int argc, char **argv)
> >                       if (out_fp != stdout)
> >                               printf("\nOutput to file: %s\n",
> > OutfileName);
> >                       break;
> > +             case 'F':
> > +                     fprintf(out_fp, "filename_trans rules:\n");
> > +                     display_avblock(DISPLAY_AVBLOCK_FILENAME_TRANS,
> > +                                     0, &policydb, out_fp);
> > +                     break;
> >               case 'l':
> >                       link_module(&policydb, out_fp);
> >                       break;
> > diff -up checkpolicy-2.0.23/test/dispol.c.eparis2
> > checkpolicy-2.0.23/test/dispol.c
> > --- checkpolicy-2.0.23/test/dispol.c.eparis2  2010-12-21
> > 16:35:45.000000000 -0500
> > +++ checkpolicy-2.0.23/test/dispol.c  2011-03-23 14:19:51.162532256
> > -0400
> > @@ -341,6 +341,21 @@ static void display_permissive(policydb_
> >       }
> >  }
> >
> > +static void display_filename_trans(policydb_t *p, FILE *fp)
> > +{
> > +     filename_trans_t *ft;
> > +
> > +     fprintf(fp, "filename_trans rules:\n");
> > +     for (ft = p->filename_trans; ft; ft = ft->next) {
> > +             fprintf(fp, "%s\n", ft->name);
> > +             display_id(p, fp, SYM_TYPES, ft->stype - 1, "");
> > +             display_id(p, fp, SYM_TYPES, ft->ttype - 1, "");
> > +             display_id(p, fp, SYM_CLASSES, ft->tclass - 1, ":");
> > +             display_id(p, fp, SYM_TYPES, ft->otype - 1, "");
> > +             fprintf(fp, "\n");
> > +     }
> > +}
> > +
> >  int menu()
> >  {
> >       printf("\nSelect a command:\n");
> > @@ -355,6 +370,8 @@ int menu()
> >       printf("c)  display policy capabilities\n");
> >       printf("p)  display the list of permissive types\n");
> >       printf("u)  display unknown handling setting\n");
> > +     printf("F)  display filename_trans rules\n");
> > +     printf("\n");
> >       printf("f)  set output file\n");
> >       printf("m)  display menu\n");
> >       printf("q)  quit\n");
> > @@ -492,6 +509,9 @@ int main(int argc, char **argv)
> >                       if (out_fp != stdout)
> >                               printf("\nOutput to file: %s\n",
> > OutfileName);
> >                       break;
> > +             case 'F':
> > +                     display_filename_trans(&policydb, out_fp);
> > +                     break;
> >               case 'q':
> >                       policydb_destroy(&policydb);
> >                       exit(0);
> >
> >
> >
> > --
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