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![Stephen Smalley](/assets/img/avatar_default.png)
Modify SELinux to dynamically discover class and permission values upon policy load, based on the dynamic object class/perm discovery logic from libselinux. A mapping is created between kernel-private class and permission indices used outside the security server and the policy values used within the security server. The mappings are only applied upon kernel-internal computations; similar mappings for the private indices of userspace object managers is handled on a per-object manager basis by the userspace AVC. The interfaces for compute_av and transition_sid are split for kernel vs. userspace; the userspace functions are distinguished by a _user suffix. The kernel-private class indices are no longer tied to the policy values and thus do not need to skip indices for userspace classes; thus the kernel class index values are compressed. The flask.h definitions were regenerated by deleting the userspace classes from refpolicy's definitions and then regenerating the headers. Going forward, we can just maintain the flask.h, av_permissions.h, and classmap.h definitions separately from policy as they are no longer tied to the policy values. The next patch introduces a utility to automate generation of flask.h and av_permissions.h from the classmap.h definitions. The older kernel class and permission string tables are removed and replaced by a single security class mapping table that is walked at policy load to generate the mapping. The old kernel class validation logic is completely replaced by the mapping logic. The handle unknown logic is reworked. reject_unknown=1 is handled when the mappings are computed at policy load time, similar to the old handling by the class validation logic. allow_unknown=1 is handled when computing and mapping decisions - if the permission was not able to be mapped (i.e. undefined, mapped to zero), then it is automatically added to the allowed vector. If the class was not able to be mapped (i.e. undefined, mapped to zero), then all permissions are allowed for it if allow_unknown=1. avc_audit leverages the new security class mapping table to lookup the class and permission names from the kernel-private indices. The mdp program is updated to use the new table when generating the class definitions and allow rules for a minimal boot policy for the kernel. It should be noted that this policy will not include any userspace classes, nor will its policy index values for the kernel classes correspond with the ones in refpolicy (they will instead match the kernel-private indices). Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: James Morris <jmorris@namei.org>
147 lines
4.3 KiB
C
147 lines
4.3 KiB
C
/*
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*
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* mdp - make dummy policy
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*
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* When pointed at a kernel tree, builds a dummy policy for that kernel
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* with exactly one type with full rights to itself.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2006
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*
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* Authors: Serge E. Hallyn <serue@us.ibm.com>
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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static void usage(char *name)
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{
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printf("usage: %s [-m] policy_file context_file\n", name);
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exit(1);
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}
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/* Class/perm mapping support */
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struct security_class_mapping {
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const char *name;
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const char *perms[sizeof(unsigned) * 8 + 1];
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};
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#include "classmap.h"
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#include "initial_sid_to_string.h"
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int main(int argc, char *argv[])
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{
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int i, j, mls = 0;
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int initial_sid_to_string_len;
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char **arg, *polout, *ctxout;
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FILE *fout;
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if (argc < 3)
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usage(argv[0]);
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arg = argv+1;
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if (argc==4 && strcmp(argv[1], "-m") == 0) {
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mls = 1;
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arg++;
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}
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polout = *arg++;
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ctxout = *arg;
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fout = fopen(polout, "w");
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if (!fout) {
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printf("Could not open %s for writing\n", polout);
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usage(argv[0]);
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}
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/* print out the classes */
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for (i = 0; secclass_map[i].name; i++)
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fprintf(fout, "class %s\n", secclass_map[i].name);
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fprintf(fout, "\n");
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initial_sid_to_string_len = sizeof(initial_sid_to_string) / sizeof (char *);
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/* print out the sids */
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for (i = 1; i < initial_sid_to_string_len; i++)
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fprintf(fout, "sid %s\n", initial_sid_to_string[i]);
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fprintf(fout, "\n");
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/* print out the class permissions */
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for (i = 0; secclass_map[i].name; i++) {
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struct security_class_mapping *map = &secclass_map[i];
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fprintf(fout, "class %s\n", map->name);
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fprintf(fout, "{\n");
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for (j = 0; map->perms[j]; j++)
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fprintf(fout, "\t%s\n", map->perms[j]);
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fprintf(fout, "}\n\n");
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}
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fprintf(fout, "\n");
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/* NOW PRINT OUT MLS STUFF */
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if (mls) {
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printf("MLS not yet implemented\n");
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exit(1);
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}
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/* types, roles, and allows */
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fprintf(fout, "type base_t;\n");
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fprintf(fout, "role base_r types { base_t };\n");
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for (i = 0; secclass_map[i].name; i++)
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fprintf(fout, "allow base_t base_t:%s *;\n",
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secclass_map[i].name);
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fprintf(fout, "user user_u roles { base_r };\n");
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fprintf(fout, "\n");
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/* default sids */
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for (i = 1; i < initial_sid_to_string_len; i++)
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fprintf(fout, "sid %s user_u:base_r:base_t\n", initial_sid_to_string[i]);
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fprintf(fout, "\n");
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fprintf(fout, "fs_use_xattr ext2 user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr ext3 user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr ext4 user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr jfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr xfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr reiserfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr jffs2 user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr gfs2 user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_xattr lustre user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_task eventpollfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_task pipefs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_task sockfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_trans mqueue user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_trans devpts user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_trans hugetlbfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_trans tmpfs user_u:base_r:base_t;\n");
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fprintf(fout, "fs_use_trans shm user_u:base_r:base_t;\n");
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fprintf(fout, "genfscon proc / user_u:base_r:base_t\n");
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fclose(fout);
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fout = fopen(ctxout, "w");
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if (!fout) {
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printf("Wrote policy, but cannot open %s for writing\n", ctxout);
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usage(argv[0]);
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}
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fprintf(fout, "/ user_u:base_r:base_t\n");
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fprintf(fout, "/.* user_u:base_r:base_t\n");
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fclose(fout);
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return 0;
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}
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