libsepol: add policy utilities

These are similar to the libselinux utilities but operate on a binary
policy instead of the running kernel.  This allows to run them on
SELinux disabled or even non Linux systems, e.g. for development or
continuous integration.

sepol_check_access:
  (similar to selinux_check_access)
  Check access:

    $ sepol_check_access policy.bin staff_u:staff_r:gpg_t:s0 sysadm_u:sysadm_r:gpg_t:s0 process fork
    requested permission fork denied by constraint; reason:
    constrain process { fork setexec setfscreate setcurrent execmem execstack execheap setkeycreate setsockcreate } ((r1 == r2 -Fail-) ); Constraint DENIED
    constrain process { signull getsched getsession getpgid getcap getattr getrlimit } ((r1 == r2 -Fail-)  or (r1 != { staff_r user_r logadm_r apache2adm_r } -Fail-)  and (t1 == rbacproc_read -Fail-)  or (t1 == rbacproc_full -Fail-)  or (t1 == systemd_user_instance_domain -Fail-)  and (u2 == system_u -Fail-)  and (r2 == system_r -Fail-)  and (t2 == systemd_t -Fail-) ); Constraint DENIED
    constrain process { sigchld sigkill sigstop signal ptrace setsched setpgid setcap share setrlimit } ((r1 == r2 -Fail-)  or (r1 != { staff_r user_r logadm_r apache2adm_r } -Fail-)  and (t1 == rbacproc_full -Fail-)  or (t1 == systemd_user_instance_domain -Fail-)  and (u2 == system_u -Fail-)  and (r2 == system_r -Fail-)  and (t2 == systemd_t -Fail-) ); Constraint DENIED

sepol_compute_av:
  (similar to compute_av)
  Compute access vectors:

    $ sepol_compute_av policy.bin staff_u:staff_r:gpg_t:s0 staff_u:staff_r:gpg_t:s0 process
    allowed:     fork sigchld signull signal getsched setsched setpgid getcap setcap setrlimit
    decided:     fork transition sigchld sigkill sigstop signull signal ptrace getsched setsched getsession getpgid setpgid getcap setcap share getattr setexec setfscreate noatsecure siginh setrlimit rlimitinh dyntransition setcurrent execmem execstack execheap setkeycreate setsockcreate getrlimit
    auditallow:
    auditdeny:   fork transition sigchld sigkill sigstop signull signal ptrace getsched setsched getsession getpgid setpgid getcap setcap share getattr setexec setfscreate noatsecure siginh setrlimit rlimitinh dyntransition setcurrent execmem execstack execheap setkeycreate setsockcreate getrlimit

sepol_compute_member:
  (similar to compute_member)
  Compute a SID to use when selecting a member of a polyinstantiated object:

    $ sepol_compute_member policy.bin staff_u:staff_r:staff_t:s0 system_u:object_r:tmp_t:s0 dir
    system_u:object_r:user_tmp_t:s0

sepol_compute_relabel:
  (similar to compute_relabel)
  Compute a SID to use for relabeling an object:

    $ sepol_compute_relabel policy.bin staff_u:staff_r:staff_t:s0 system_u:object_r:tty_device_t:s0 chr_file
    staff_u:object_r:user_tty_device_t:s0

sepol_validate_transition:
  (similar to validatetrans)
  Compute a validatetrans decision:

  $ sepol_validate_transition policy.bin system_u:object_r:user_tmp_t:s0 system_u:object_r:shadow_t:s0 file staff_u:staff_r:staff_t:s0
  allowed

Acked-by: James Carter <jwcart2@gmail.com>
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>

libsepol/.gitignore

@@ -1,2 +1,7 @@
 utils/chkcon
+utils/sepol_check_access
+utils/sepol_compute_av
+utils/sepol_compute_member
+utils/sepol_compute_relabel
+utils/sepol_validate_transition
 libsepol.map

libsepol/utils/sepol_check_access.c

@@ -0,0 +1,130 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sepol/policydb/services.h>
+#include <sepol/sepol.h>
+
+
+int main(int argc, char *argv[])
+{
+	FILE *fp;
+	sepol_security_id_t ssid, tsid;
+	sepol_security_class_t tclass;
+	const char *permlist;
+	sepol_access_vector_t av;
+	struct sepol_av_decision avd;
+	unsigned int reason;
+	char *reason_buf;
+	int i;
+
+	if (argc != 6) {
+		printf("usage:  %s policy source_context target_context class permission[,permission2[,...]]\n", argv[0]);
+		return 1;
+	}
+
+	fp = fopen(argv[1], "r");
+	if (!fp) {
+		fprintf(stderr, "Can't open policy %s:  %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+	if (sepol_set_policydb_from_file(fp) < 0) {
+		fprintf(stderr, "Error while processing policy %s:  %s\n", argv[1], strerror(errno));
+		fclose(fp);
+		return 1;
+	}
+	fclose(fp);
+
+	if (sepol_context_to_sid(argv[2], strlen(argv[2]), &ssid) < 0) {
+		fprintf(stderr, "Invalid source context %s\n", argv[2]);
+		return 1;
+	}
+
+	if (sepol_context_to_sid(argv[3], strlen(argv[3]), &tsid) < 0) {
+		fprintf(stderr, "Invalid target context %s\n", argv[3]);
+		return 1;
+	}
+
+	if (sepol_string_to_security_class(argv[4], &tclass) < 0) {
+		fprintf(stderr, "Invalid security class %s\n", argv[4]);
+		return 1;
+	}
+
+	permlist = argv[5];
+	do {
+		char *tmp = NULL;
+		const char *perm;
+		const char *delim = strchr(permlist, ',');
+
+		if (delim) {
+			tmp = strndup(permlist, delim - permlist);
+			if (!tmp) {
+				fprintf(stderr, "Failed to allocate memory:  %s\n", strerror(errno));
+				return 1;
+			}
+		}
+
+		perm = tmp ? tmp : permlist;
+
+		if (sepol_string_to_av_perm(tclass, perm, &av) < 0) {
+			fprintf(stderr, "Invalid permission %s for security class %s:  %s\n", perm, argv[4], strerror(errno));
+			free(tmp);
+			return 1;
+		}
+
+		free(tmp);
+
+		permlist = strchr(permlist, ',');
+	} while (permlist++);
+
+	if (av == 0) {
+		fprintf(stderr, "Empty permission set computed from %s\n", argv[5]);
+		return 1;
+	}
+
+	if (sepol_compute_av_reason_buffer(ssid, tsid, tclass, av, &avd, &reason, &reason_buf, 0) < 0) {
+		fprintf(stderr, "Failed to compute av decision:  %s\n", strerror(errno));
+		return 1;
+	}
+
+	if ((avd.allowed & av) == av) {
+		printf("requested permission %s allowed\n", argv[5]);
+		free(reason_buf);
+		return 0;
+	}
+
+	printf("requested permission %s denied by ", argv[5]);
+	i = 0;
+	if (reason & SEPOL_COMPUTEAV_TE) {
+		printf("te-rule");
+		i++;
+	}
+	if (reason & SEPOL_COMPUTEAV_CONS) {
+		if (i > 0)
+			printf(", ");
+		printf("constraint");
+		i++;
+	}
+	if (reason & SEPOL_COMPUTEAV_RBAC) {
+		if (i > 0)
+			printf(", ");
+		printf("transition-constraint");
+		i++;
+	}
+	if (reason & SEPOL_COMPUTEAV_BOUNDS) {
+		if (i > 0)
+			printf(", ");
+		printf("type-bound");
+		//i++;
+	}
+
+	if ((reason & SEPOL_COMPUTEAV_CONS) && reason_buf)
+		printf("; reason:\n%s", reason_buf);
+
+	free(reason_buf);
+
+	printf("\n");
+
+	return 7;
+}

libsepol/utils/sepol_compute_av.c

@@ -0,0 +1,66 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sepol/policydb/services.h>
+#include <sepol/sepol.h>
+
+
+int main(int argc, char *argv[])
+{
+	FILE *fp;
+	sepol_security_id_t ssid, tsid;
+	sepol_security_class_t tclass;
+	struct sepol_av_decision avd;
+	int rc;
+
+	if (argc != 5) {
+		printf("usage:  %s policy scontext tcontext tclass\n", argv[0]);
+		return 1;
+	}
+
+	fp = fopen(argv[1], "r");
+	if (!fp) {
+		fprintf(stderr, "Can't open policy %s:  %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+	if (sepol_set_policydb_from_file(fp) < 0) {
+		fprintf(stderr, "Error while processing policy %s:  %s\n", argv[1], strerror(errno));
+		fclose(fp);
+		return 1;
+	}
+	fclose(fp);
+
+	if (sepol_context_to_sid(argv[2], strlen(argv[2]), &ssid) < 0) {
+		fprintf(stderr, "Invalid source context %s\n", argv[2]);
+		return 1;
+	}
+
+	if (sepol_context_to_sid(argv[3], strlen(argv[3]), &tsid) < 0) {
+		fprintf(stderr, "Invalid target context %s\n", argv[3]);
+		return 1;
+	}
+
+	if (sepol_string_to_security_class(argv[4], &tclass) < 0) {
+		fprintf(stderr, "Invalid security class %s\n", argv[4]);
+		return 1;
+	}
+
+	rc = sepol_compute_av(ssid, tsid, tclass, 0, &avd);
+	switch (rc) {
+	case 0:
+		printf("allowed:    %s\n", sepol_av_perm_to_string(tclass, avd.allowed));
+		printf("decided:    %s\n", sepol_av_perm_to_string(tclass, avd.decided));
+		printf("auditallow: %s\n", sepol_av_perm_to_string(tclass, avd.auditallow));
+		printf("auditdeny:  %s\n", sepol_av_perm_to_string(tclass, avd.auditdeny));
+		break;
+	case -EINVAL:
+		printf("Invalid request\n");
+		break;
+	default:
+		printf("Failed to compute av decision: %d\n", rc);
+	}
+
+	return rc != 0;
+}

libsepol/utils/sepol_compute_member.c

@@ -0,0 +1,64 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sepol/policydb/services.h>
+#include <sepol/sepol.h>
+
+
+int main(int argc, char *argv[])
+{
+	FILE *fp;
+	sepol_security_id_t ssid, tsid, out_sid;
+	sepol_security_class_t tclass;
+	char *context;
+	size_t context_len;
+
+	if (argc != 5) {
+		printf("usage:  %s policy scontext tcontext tclass\n", argv[0]);
+		return 1;
+	}
+
+	fp = fopen(argv[1], "r");
+	if (!fp) {
+		fprintf(stderr, "Can't open policy %s:  %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+	if (sepol_set_policydb_from_file(fp) < 0) {
+		fprintf(stderr, "Error while processing policy %s:  %s\n", argv[1], strerror(errno));
+		fclose(fp);
+		return 1;
+	}
+	fclose(fp);
+
+	if (sepol_context_to_sid(argv[2], strlen(argv[2]), &ssid) < 0) {
+		fprintf(stderr, "Invalid source context %s\n", argv[2]);
+		return 1;
+	}
+
+	if (sepol_context_to_sid(argv[3], strlen(argv[3]), &tsid) < 0) {
+		fprintf(stderr, "Invalid target context %s\n", argv[3]);
+		return 1;
+	}
+
+	if (sepol_string_to_security_class(argv[4], &tclass) < 0) {
+		fprintf(stderr, "Invalid security class %s\n", argv[4]);
+		return 1;
+	}
+
+	if (sepol_member_sid(ssid, tsid, tclass, &out_sid) < 0) {
+		fprintf(stderr, "Failed to compute member sid:  %s\n", strerror(errno));
+		return 1;
+	}
+
+	if (sepol_sid_to_context(out_sid, &context, &context_len) < 0) {
+		fprintf(stderr, "Failed to convert sid %u:  %s\n", out_sid, strerror(errno));
+		return 1;
+	}
+
+	printf("%s\n", context);
+	free(context);
+
+	return 0;
+}

libsepol/utils/sepol_compute_relabel.c

@@ -0,0 +1,64 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sepol/policydb/services.h>
+#include <sepol/sepol.h>
+
+
+int main(int argc, char *argv[])
+{
+	FILE *fp;
+	sepol_security_id_t ssid, tsid, out_sid;
+	sepol_security_class_t tclass;
+	char *context;
+	size_t context_len;
+
+	if (argc != 5) {
+		printf("usage:  %s policy scontext tcontext tclass\n", argv[0]);
+		return 1;
+	}
+
+	fp = fopen(argv[1], "r");
+	if (!fp) {
+		fprintf(stderr, "Can't open policy %s:  %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+	if (sepol_set_policydb_from_file(fp) < 0) {
+		fprintf(stderr, "Error while processing policy %s:  %s\n", argv[1], strerror(errno));
+		fclose(fp);
+		return 1;
+	}
+	fclose(fp);
+
+	if (sepol_context_to_sid(argv[2], strlen(argv[2]), &ssid) < 0) {
+		fprintf(stderr, "Invalid source context %s\n", argv[2]);
+		return 1;
+	}
+
+	if (sepol_context_to_sid(argv[3], strlen(argv[3]), &tsid) < 0) {
+		fprintf(stderr, "Invalid target context %s\n", argv[3]);
+		return 1;
+	}
+
+	if (sepol_string_to_security_class(argv[4], &tclass) < 0) {
+		fprintf(stderr, "Invalid security class %s\n", argv[4]);
+		return 1;
+	}
+
+	if (sepol_change_sid(ssid, tsid, tclass, &out_sid) < 0) {
+		fprintf(stderr, "Failed to compute changed sid:  %s\n", strerror(errno));
+		return 1;
+	}
+
+	if (sepol_sid_to_context(out_sid, &context, &context_len) < 0) {
+		fprintf(stderr, "Failed to convert sid %u:  %s\n", out_sid, strerror(errno));
+		return 1;
+	}
+
+	printf("%s\n", context);
+	free(context);
+
+	return 0;
+}

libsepol/utils/sepol_validate_transition.c

@@ -0,0 +1,74 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sepol/policydb/services.h>
+#include <sepol/sepol.h>
+
+
+int main(int argc, char *argv[])
+{
+	FILE *fp;
+	sepol_security_id_t oldsid, newsid, tasksid;
+	sepol_security_class_t tclass;
+	char *reason = NULL;
+	int ret;
+
+	if (argc != 6) {
+		printf("usage:  %s policy oldcontext newcontext tclass taskcontext\n", argv[0]);
+		return 1;
+	}
+
+	fp = fopen(argv[1], "r");
+	if (!fp) {
+		fprintf(stderr, "Can't open policy %s:  %s\n", argv[1], strerror(errno));
+		return 1;
+	}
+	if (sepol_set_policydb_from_file(fp) < 0) {
+		fprintf(stderr, "Error while processing policy %s:  %s\n", argv[1], strerror(errno));
+		fclose(fp);
+		return 1;
+	}
+	fclose(fp);
+
+	if (sepol_context_to_sid(argv[2], strlen(argv[2]), &oldsid) < 0) {
+		fprintf(stderr, "Invalid old context %s\n", argv[2]);
+		return 1;
+	}
+
+	if (sepol_context_to_sid(argv[3], strlen(argv[3]), &newsid) < 0) {
+		fprintf(stderr, "Invalid new context %s\n", argv[3]);
+		return 1;
+	}
+
+	if (sepol_string_to_security_class(argv[4], &tclass) < 0) {
+		fprintf(stderr, "Invalid security class %s\n", argv[4]);
+		return 1;
+	}
+
+	if (sepol_context_to_sid(argv[5], strlen(argv[5]), &tasksid) < 0) {
+		fprintf(stderr, "Invalid task context %s\n", argv[5]);
+		return 1;
+	}
+
+	ret = sepol_validate_transition_reason_buffer(oldsid, newsid, tasksid, tclass, &reason, SHOW_GRANTED);
+	switch (ret) {
+	case 0:
+		printf("allowed\n");
+		ret = 0;
+		break;
+	case -EPERM:
+		printf("denied\n");
+		printf("%s\n", reason ? reason : "unknown - possible BUG()");
+		ret = 7;
+		break;
+	default:
+		printf("sepol_validate_transition_reason_buffer returned %d errno: %s\n", ret, strerror(errno));
+		ret = 1;
+	}
+
+	free(reason);
+
+	return ret;
+}