On 05/06/2016 04:06 PM, Roberts, William C wrote:
-----Original Message-----
From: James Carter [mailto:jwcart2@xxxxxxxxxxxxx]
Sent: Friday, May 6, 2016 12:47 PM
To: Roberts, William C <william.c.roberts@xxxxxxxxx>; William Roberts
<bill.c.roberts@xxxxxxxxx>
Cc: selinux@xxxxxxxxxxxxx
Subject: Re: [PATCH] libsepol: Change which attributes CIL keeps in the binary
policy
On 05/06/2016 03:39 PM, Roberts, William C wrote:
-----Original Message-----
From: Selinux [mailto:selinux-bounces@xxxxxxxxxxxxx] On Behalf Of
Roberts, William C
Sent: Friday, May 6, 2016 12:25 PM
To: William Roberts <bill.c.roberts@xxxxxxxxx>; James Carter
<jwcart2@xxxxxxxxxxxxx>
Cc: selinux@xxxxxxxxxxxxx
Subject: RE: [PATCH] libsepol: Change which attributes CIL keeps in
the binary policy
From: Selinux [mailto:selinux-bounces@xxxxxxxxxxxxx] On Behalf Of
William Roberts
Sent: Friday, May 6, 2016 12:16 PM
To: James Carter <jwcart2@xxxxxxxxxxxxx>
Cc: selinux@xxxxxxxxxxxxx
Subject: Re: [PATCH] libsepol: Change which attributes CIL keeps in
the binary policy
On May 6, 2016 11:58 AM, "James Carter" <jwcart2@xxxxxxxxxxxxx> wrote:
The removal of attributes that are only used in neverallow rules is
hindering AOSP adoption of the CIL compiler. This is because AOSP
extracts neverallow rules from its policy.conf for use in the
Android compatibility test suite. These neverallow rules are applied
against the binary policy being tested to check for a violation. Any
neverallow rules with an attribute that has been removed cannot be
checked.
Now attributes are kept unless they are not used in any allow rule
and they are auto-generated or named "cil_gen_require" or do not
have any types associated with them.
I see now, you’re keeping them unless they are generated or marked.
I'm still not convinced this does what's on the tin. In the case of
AOSP, the Attributes are not used in any allow rules, they are not
auto-generated or named cil_gen_require And they will not have any types
associated with them. So I see them being discarded.
If they don't have types associated with them, then I misunderstood the problem
and we will have to keep the attributes without types around.
This is pretty much all my understanding on this issue is from this link:
Per sds:
https://android-review.googlesource.com/#/c/145034/
"CIL also deletes unused attributes from the kernel policy, which is a problem for the Android neverallow checking. It considers an attribute that is only referenced by a neverallow rule to be unused since neverallows are not included in the kernel policy, so this drops data_file_type from the kernel policy. But we then would lose checking of the various neverallows on data_file_type by CTS." - sds
Looking through the policy in file.te:
file.te:151:type app_data_file, file_type, data_file_type;
file.te:153:type system_app_data_file, file_type, data_file_type, mlstrustedobject;
file.te:169:type asec_apk_file, file_type, data_file_type, mlstrustedobject;
file.te:171:type asec_public_file, file_type, data_file_type;
file.te:173:type asec_image_file, file_type, data_file_type;
file.te:175:type backup_data_file, file_type, data_file_type, mlstrustedobject;
Data file type does have type associations, but it does NOT have allow rules.
So when this gets generated to cil, how is indicated in cil intermediary not
to discard that data_file_type attribute?
It is not named "gen_require_attr", not a generated type with "_typeattr_" in
the middle, and it does have types associated with it, so
cil_typeattribute_used() will return CIL_TRUE and it will be kept.
Jim
Jim
I would imagine that a match on cil_gen_require, would yield the same result as
cil_attr->used.
Perhaps that if cil_gen_require causes a discard, the name is bad?
Can you perhaps tell me I am idiot and maybe find a more clear way to describe
this.
Signed-off-by: James Carter <jwcart2@xxxxxxxxxxxxx>
---
libsepol/cil/src/cil_post.c | 27 +++++++++++++++++++++++++++
libsepol/src/module_to_cil.c | 8 +++++---
2 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/libsepol/cil/src/cil_post.c
b/libsepol/cil/src/cil_post.c index a694b33..f8447c9 100644
--- a/libsepol/cil/src/cil_post.c
+++ b/libsepol/cil/src/cil_post.c
@@ -47,6 +47,9 @@
#include "cil_verify.h"
#include "cil_symtab.h"
+#define GEN_REQUIRE_ATTR "cil_gen_require" /* Also in
+libsepol/src/module_to_cil.c */ #define TYPEATTR_INFIX "_typeattr_"
+/* Also in libsepol/src/module_to_cil.c */
+
static int __cil_expr_to_bitmap(struct cil_list *expr, ebitmap_t
*out, int max, struct cil_db *db); static int
__cil_expr_list_to_bitmap(struct cil_list *expr_list, ebitmap_t
*out, int max, struct cil_db *db);
@@ -1186,6 +1189,27 @@ exit:
return SEPOL_ERR;
}
+static int cil_typeattribute_used(struct cil_typeattribute
+*cil_attr) {
+ if (cil_attr->used) {
+ return CIL_TRUE;
+ }
+
+ if (strcmp(DATUM(cil_attr)->name, GEN_REQUIRE_ATTR) == 0) {
+ return CIL_FALSE;
Just by reading this patch with 0 knowledge of cil, I would imagine
this would be CIL_TRUE on a match with GEN_REQUIRED_ATTR. Especially
since cardinality 0 below returns false.
+ }
+
+ if (strstr(DATUM(cil_attr)->name,TYPEATTR_INFIX) != NULL) {
+ return CIL_FALSE;
+ }
+
+ if (ebitmap_cardinality(cil_attr->types) == 0) {
+ return CIL_FALSE;
+ }
+
+ return CIL_TRUE;
+}
+
static int __cil_post_db_attr_helper(struct cil_tree_node *node,
uint32_t *finished, void *extra_args) {
int rc = SEPOL_ERR;
@@ -1208,6 +1232,9 @@ static int __cil_post_db_attr_helper(struct
cil_tree_node *node, uint32_t *finis
if (attr->types == NULL) {
rc = __evaluate_type_expression(attr, db);
if (rc != SEPOL_OK) goto exit;
+ if (cil_typeattribute_used(attr)) {
+ attr->used = CIL_TRUE;
+ }
}
break;
}
diff --git a/libsepol/src/module_to_cil.c
b/libsepol/src/module_to_cil.c index b9a4af7..bcbb4de 100644
--- a/libsepol/src/module_to_cil.c
+++ b/libsepol/src/module_to_cil.c
@@ -58,7 +58,9 @@ FILE *out_file;
#define STACK_SIZE 16
#define DEFAULT_LEVEL "systemlow"
#define DEFAULT_OBJECT "object_r"
-#define GEN_REQUIRE_ATTR "cil_gen_require"
+#define GEN_REQUIRE_ATTR "cil_gen_require" /* Also in
+libsepol/cil/src/cil_post.c */ #define TYPEATTR_INFIX "_typeattr_"
+/* Also in libsepol/cil/src/cil_post.c */ #define ROLEATTR_INFIX
"_roleattr_"
__attribute__ ((format(printf, 1, 2))) static void log_err(const
char *fmt, ...) @@ -626,9 +628,9 @@ static int
set_to_cil_attr(struct policydb *pdb, int is_type, char ***names,
uin
num_attrs++;
if (is_type) {
- attr_infix = "_typeattr_";
+ attr_infix = TYPEATTR_INFIX;
} else {
- attr_infix = "_roleattr_";
+ attr_infix = ROLEATTR_INFIX;
}
len = strlen(pdb->name) + strlen(attr_infix) +
num_digits(num_attrs) + 1;
--
2.5.5
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--
James Carter <jwcart2@xxxxxxxxxxxxx>
National Security Agency
--
James Carter <jwcart2@xxxxxxxxxxxxx>
National Security Agency
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