Re: [PATCH 1/1] libsepol: cil: Add ability to redeclare types[attributes]

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On 08/17/2017 02:04 PM, Daniel Cashman wrote:
From: Dan Cashman <dcashman@xxxxxxxxxx>

Signed-off-by: Dan Cashman <dcashman@xxxxxxxxxxx>
Change-Id: I5a72f2e6c339baee8ebc07e3e9176296320e2c80
---
  libsepol/cil/include/cil/cil.h   |  1 +
  libsepol/cil/src/cil.c           |  5 +++++
  libsepol/cil/src/cil_build_ast.c | 46 ++++++++++++++++++++++++++++++++++------
  libsepol/cil/src/cil_internal.h  |  1 +
  secilc/secilc.c                  |  9 +++++++-
  5 files changed, 54 insertions(+), 8 deletions(-)

diff --git a/libsepol/cil/include/cil/cil.h b/libsepol/cil/include/cil/cil.h
index 4507892c..4df646a0 100644
--- a/libsepol/cil/include/cil/cil.h
+++ b/libsepol/cil/include/cil/cil.h
@@ -46,6 +46,7 @@ extern int cil_userprefixes_to_string(cil_db_t *db, char **out, size_t *size);
  extern int cil_selinuxusers_to_string(cil_db_t *db, char **out, size_t *size);
  extern int cil_filecons_to_string(cil_db_t *db, char **out, size_t *size);
  extern void cil_set_disable_dontaudit(cil_db_t *db, int disable_dontaudit);
+extern void cil_set_multiple_decls(cil_db_t *db, int multiple_decls);
  extern void cil_set_disable_neverallow(cil_db_t *db, int disable_neverallow);
  extern void cil_set_preserve_tunables(cil_db_t *db, int preserve_tunables);
  extern int cil_set_handle_unknown(cil_db_t *db, int handle_unknown);
diff --git a/libsepol/cil/src/cil.c b/libsepol/cil/src/cil.c
index 9b9ccc36..e8bbbfdf 100644
--- a/libsepol/cil/src/cil.c
+++ b/libsepol/cil/src/cil.c
@@ -1675,6 +1675,11 @@ void cil_set_mls(struct cil_db *db, int mls)
  	db->mls = mls;
  }
+void cil_set_multiple_decls(struct cil_db *db, int multiple_decls)
+{
+	db->multiple_decls = multiple_decls;
+}
+
  void cil_set_target_platform(struct cil_db *db, int target_platform)
  {
  	db->target_platform = target_platform;
diff --git a/libsepol/cil/src/cil_build_ast.c b/libsepol/cil/src/cil_build_ast.c
index 36cc6735..9a2fd0d5 100644
--- a/libsepol/cil/src/cil_build_ast.c
+++ b/libsepol/cil/src/cil_build_ast.c
@@ -82,10 +82,33 @@ exit:
  	return rc;
  }
+/*
+ * Determine whether or not multiple declarations of the same key can share a
+ * datum, given the new datum and the one already present in a given symtab.
+ */
+int cil_is_datum_multiple_decl(__attribute__((unused)) struct cil_symtab_datum *cur,
+                               __attribute__((unused)) struct cil_symtab_datum *old,
+                               enum cil_flavor f)
+{
+	int rc = CIL_FALSE;
+
+	switch (f) {
+	case CIL_TYPE:
+	case CIL_TYPEATTRIBUTE:
+		/* type and typeattribute statements insert empty datums, ret true */
+		rc = CIL_TRUE;
+		break;
+	default:
+		break;
+	}
+	return rc;
+}
+
  int cil_gen_node(__attribute__((unused)) struct cil_db *db, struct cil_tree_node *ast_node, struct cil_symtab_datum *datum, hashtab_key_t key, enum cil_sym_index sflavor, enum cil_flavor nflavor)
  {
  	int rc = SEPOL_ERR;
  	symtab_t *symtab = NULL;
+	struct cil_symtab_datum *prev;
rc = __cil_verify_name((const char*)key);
  	if (rc != SEPOL_OK) {
@@ -103,15 +126,24 @@ int cil_gen_node(__attribute__((unused)) struct cil_db *db, struct cil_tree_node
  	if (symtab != NULL) {
  		rc = cil_symtab_insert(symtab, (hashtab_key_t)key, datum, ast_node);
  		if (rc == SEPOL_EEXIST) {
-			cil_log(CIL_ERR, "Re-declaration of %s %s\n",
-				cil_node_to_string(ast_node), key);
-			if (cil_symtab_get_datum(symtab, key, &datum) == SEPOL_OK) {
-				if (sflavor == CIL_SYM_BLOCKS) {
-					struct cil_tree_node *node = datum->nodes->head->data;
-					cil_tree_log(node, CIL_ERR, "Previous declaration");
+			if (!db->multiple_decls ||
+			    cil_symtab_get_datum(symtab, (hashtab_key_t)key, &prev) != SEPOL_OK ||
+			    !cil_is_datum_multiple_decl(datum, prev, nflavor)) {
+
+				/* multiple_decls not ok, ret error */
+				cil_log(CIL_ERR, "Re-declaration of %s %s\n",
+					cil_node_to_string(ast_node), key);
+				if (cil_symtab_get_datum(symtab, key, &datum) == SEPOL_OK) {
+					if (sflavor == CIL_SYM_BLOCKS) {
+						struct cil_tree_node *node = datum->nodes->head->data;
+						cil_tree_log(node, CIL_ERR, "Previous declaration");
+					}
  				}
+				goto exit;
  			}
-			goto exit;
+			/* multiple_decls is enabled and works for this datum type, add node */
+			cil_list_append(prev->nodes, CIL_NODE, ast_node);
+			ast_node->data = prev;

You also need:
cil_symtab_datum_destroy(datum);
free(datum);

  		}
  	}
diff --git a/libsepol/cil/src/cil_internal.h b/libsepol/cil/src/cil_internal.h
index aee3f00c..abfacd8d 100644
--- a/libsepol/cil/src/cil_internal.h
+++ b/libsepol/cil/src/cil_internal.h
@@ -312,6 +312,7 @@ struct cil_db {
  	int preserve_tunables;
  	int handle_unknown;
  	int mls;
+	int multiple_decls;
  	int target_platform;
  	int policy_version;
  };

You also need to add cil_set_multiple_decls to libsepol/src/libsepol.map.in


diff --git a/secilc/secilc.c b/secilc/secilc.c
index f2232e72..0be6975b 100644
--- a/secilc/secilc.c
+++ b/secilc/secilc.c
@@ -63,6 +63,7 @@ static __attribute__((__noreturn__)) void usage(const char *prog)
  	printf("                                 statement if present in the policy\n");
  	printf("  -D, --disable-dontaudit        do not add dontaudit rules to the binary policy\n");
  	printf("  -P, --preserve-tunables        treat tunables as booleans\n");
+	printf("  -m, --multiple-decls           allow some statements to be re-declared\n");
  	printf("  -N, --disable-neverallow       do not check neverallow rules\n");
  	printf("  -G, --expand-generated         Expand and remove auto-generated attributes\n");
  	printf("  -X, --expand-size <SIZE>       Expand type attributes with fewer than <SIZE>\n");
@@ -89,6 +90,7 @@ int main(int argc, char *argv[])
  	int target = SEPOL_TARGET_SELINUX;
  	int mls = -1;
  	int disable_dontaudit = 0;
+	int multiple_decls = 0;
  	int disable_neverallow = 0;
  	int preserve_tunables = 0;
  	int handle_unknown = -1;
@@ -108,6 +110,7 @@ int main(int argc, char *argv[])
  		{"policyversion", required_argument, 0, 'c'},
  		{"handle-unknown", required_argument, 0, 'U'},
  		{"disable-dontaudit", no_argument, 0, 'D'},
+		{"multiple-decls", no_argument, 0, 'm'},
  		{"disable-neverallow", no_argument, 0, 'N'},
  		{"preserve-tunables", no_argument, 0, 'P'},
  		{"output", required_argument, 0, 'o'},
@@ -119,7 +122,7 @@ int main(int argc, char *argv[])
  	int i;
while (1) {
-		opt_char = getopt_long(argc, argv, "o:f:U:hvt:M:PDNc:GX:", long_opts, &opt_index);
+		opt_char = getopt_long(argc, argv, "o:f:U:hvt:M:PDmNc:GX:", long_opts, &opt_index);
  		if (opt_char == -1) {
  			break;
  		}
@@ -175,6 +178,9 @@ int main(int argc, char *argv[])
  			case 'D':
  				disable_dontaudit = 1;
  				break;
+			case 'm':
+				multiple_decls = 1;
+				break;
  			case 'N':
  				disable_neverallow = 1;
  				break;
@@ -223,6 +229,7 @@ int main(int argc, char *argv[])
cil_db_init(&db);
  	cil_set_disable_dontaudit(db, disable_dontaudit);
+	cil_set_multiple_decls(db, multiple_decls);
  	cil_set_disable_neverallow(db, disable_neverallow);
  	cil_set_preserve_tunables(db, preserve_tunables);
  	if (handle_unknown != -1) {


Overall, the patch seems to work. I am a little worried that I might be missing a particular corner case where it won't.

Jim


--
James Carter <jwcart2@xxxxxxxxxxxxx>
National Security Agency



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