libsepol: implement new module binary format of avrule

Implement a new module policy format that closely matches the new
internal representation of avrule introduced in the previous patch.

This patch bumps the maximum module policy version and implements
reading/writing functions such that the module binary policy structure
matches its internal representation, namely, the object name attribute
used for the filename transition rules.

These changes have no significant effect on the size of the module
policy file (tested with Fedora policy).

Signed-off-by: Juraj Marcin <[email protected]>

libsepol/include/sepol/policydb/policydb.h

@@ -748,9 +748,10 @@ extern int policydb_set_target_platform(policydb_t *p, int platform);
 #define MOD_POLICYDB_VERSION_INFINIBAND		19
 #define MOD_POLICYDB_VERSION_GLBLUB		20
 #define MOD_POLICYDB_VERSION_SELF_TYPETRANS	21
+#define MOD_POLICYDB_VERSION_AVRULE_FTRANS	22
 
 #define MOD_POLICYDB_VERSION_MIN MOD_POLICYDB_VERSION_BASE
-#define MOD_POLICYDB_VERSION_MAX MOD_POLICYDB_VERSION_SELF_TYPETRANS
+#define MOD_POLICYDB_VERSION_MAX MOD_POLICYDB_VERSION_AVRULE_FTRANS
 
 #define POLICYDB_CONFIG_MLS    1
 

libsepol/src/policydb.c

@@ -341,6 +341,13 @@ static const struct policydb_compat_info policydb_compat[] = {
 	 .ocon_num = OCON_IBENDPORT + 1,
 	 .target_platform = SEPOL_TARGET_SELINUX,
 	},
+	{
+	 .type = POLICY_BASE,
+	 .version = MOD_POLICYDB_VERSION_AVRULE_FTRANS,
+	 .sym_num = SYM_NUM,
+	 .ocon_num = OCON_IBENDPORT + 1,
+	 .target_platform = SEPOL_TARGET_SELINUX,
+	},
 	{
 	 .type = POLICY_MOD,
 	 .version = MOD_POLICYDB_VERSION_BASE,
@@ -467,6 +474,13 @@ static const struct policydb_compat_info policydb_compat[] = {
 	 .ocon_num = 0,
 	 .target_platform = SEPOL_TARGET_SELINUX,
 	},
+	{
+	 .type = POLICY_MOD,
+	 .version = MOD_POLICYDB_VERSION_AVRULE_FTRANS,
+	 .sym_num = SYM_NUM,
+	 .ocon_num = 0,
+	 .target_platform = SEPOL_TARGET_SELINUX,
+	},
 };
 
 #if 0
@@ -3203,6 +3217,19 @@ static avrule_t *avrule_read(policydb_t * p, struct policy_file *fp)
 		tail = cur;
 	}
 
+	if (p->policyvers >= MOD_POLICYDB_VERSION_AVRULE_FTRANS &&
+	    avrule->specified & AVRULE_TRANSITION) {
+		rc = next_entry(buf, fp, sizeof(uint32_t));
+		if (rc < 0)
+			goto bad;
+		len = le32_to_cpu(*buf);
+		if (len) {
+			rc = str_read(&avrule->object_name, fp, len);
+			if (rc < 0)
+				goto bad;
+		}
+	}
+
 	if (avrule->specified & AVRULE_XPERMS) {
 		uint8_t buf8;
 		size_t nel = ARRAY_SIZE(avrule->xperms->perms);
@@ -3639,6 +3666,7 @@ static int avrule_decl_read(policydb_t * p, avrule_decl_t * decl,
 	}
 
 	if (p->policyvers >= MOD_POLICYDB_VERSION_FILENAME_TRANS &&
+	    p->policyvers < MOD_POLICYDB_VERSION_AVRULE_FTRANS &&
 	    filename_trans_rule_read(p, &decl->avrules, fp))
 		return -1;
 

libsepol/src/write.c

@@ -2008,8 +2008,9 @@ static int avrule_write(policydb_t *p, avrule_t * avrule,
 	uint32_t buf[32], len;
 	class_perm_node_t *cur;
 
-	/* skip filename transitions for now */
-	if (avrule->specified & AVRULE_TRANSITION && avrule->object_name)
+	/* skip filename transitions if writing older version without name */
+	if (p->policyvers < MOD_POLICYDB_VERSION_AVRULE_FTRANS &&
+	    avrule->specified & AVRULE_TRANSITION && avrule->object_name)
 		return POLICYDB_SUCCESS;
 
 	if (p->policyvers < MOD_POLICYDB_VERSION_SELF_TYPETRANS &&
@@ -2056,6 +2057,21 @@ static int avrule_write(policydb_t *p, avrule_t * avrule,
 		cur = cur->next;
 	}
 
+	if (p->policyvers >= MOD_POLICYDB_VERSION_AVRULE_FTRANS &&
+	    avrule->specified & AVRULE_TRANSITION) {
+		len = avrule->object_name ? strlen(avrule->object_name) : 0;
+		*buf = cpu_to_le32(len);
+		items = put_entry(buf, sizeof(uint32_t), 1, fp);
+		if (items != 1)
+			return POLICYDB_ERROR;
+		if (avrule->object_name) {
+			items = put_entry(avrule->object_name, sizeof(char),
+					  len, fp);
+			if (items != len)
+				return POLICYDB_ERROR;
+		}
+	}
+
 	if (avrule->specified & AVRULE_XPERMS) {
 		size_t nel = ARRAY_SIZE(avrule->xperms->perms);
 		uint32_t buf32[nel];
@@ -2105,7 +2121,8 @@ static int avrule_write_list(policydb_t *p, avrule_t * avrules,
 	avrule = avrules;
 	len = 0;
 	while (avrule) {
-		if (!(avrule->specified & AVRULE_TRANSITION &&
+		if (p->policyvers >= MOD_POLICYDB_VERSION_AVRULE_FTRANS ||
+		    !(avrule->specified & AVRULE_TRANSITION &&
 		      avrule->object_name))
 			len++;
 		avrule = avrule->next;
@@ -2340,6 +2357,7 @@ static int avrule_decl_write(avrule_decl_t * decl, int num_scope_syms,
 	}
 
 	if (p->policyvers >= MOD_POLICYDB_VERSION_FILENAME_TRANS &&
+	    p->policyvers < MOD_POLICYDB_VERSION_AVRULE_FTRANS &&
 	    filename_trans_rule_write(p, decl->avrules, fp))
 		return POLICYDB_ERROR;