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Add support for duplicate allow rule detection (-D / --dups).

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Usage:
sepolicy-analyze -D -P out/target/product/<board>/root/sepolicy

Displays duplicate allow rules, i.e. pairs of allow rules that grant
the same permissions where one allow rule is written directly in terms
of individual types and the other is written in terms of attributes
associated with those same types.  The rule with individual types is
a candidate for removal.  The rule with individual types may be directly
represented in the source policy or may be a result of expansion of
a type negation (e.g. domain -foo -bar is expanded to individual allow
rules by the policy compiler).  Domains with unconfineddomain will
typically have such duplicate rules as a natural side effect and can
be ignored.

Also add a tools/README with a description of all of the tools.

Change-Id: I07838dbd22c5cc8a4a65b57003ccae38129050f5
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
This commit is contained in:
Stephen Smalley 2013-11-17 18:17:29 -05:00
parent ae49e7a369
commit bec54f42ed
2 changed files with 162 additions and 18 deletions
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83
tools/README Normal file
View file

@ -0,0 +1,83 @@
This directory contains a number of tools related to policy, some of
which are used in building and validating the policy and others are
available for help in auditing and analyzing policy. The tools are
described further below.
checkfc
A utility for checking the validity of a file_contexts or a
property_contexts configuration file. Used as part of the policy
build to validate both files. Requires the sepolicy file as an
argument in order to check the validity of the security contexts
in the file_contexts or property_contexts file.
Usage:
checkfc sepolicy file_contexts
checkfc -p sepolicy property_contexts
checkseapp
A utility for merging together the main seapp_contexts
configuration and the device-specific one, and simultaneously
checking the validity of the configurations. Used as part of the
policy build process to merge and validate the configuration.
Usage:
checkseapp -p sepolicy input_seapp_contexts0 [input_seapp_contexts1...] -o seapp_contexts
insertkeys.py
A helper script for mapping tags in the signature stanzas of
mac_permissions.xml to public keys found in pem files. This
script is described further in the top-level sepolicy/README.
sepolicy-check
A tool for auditing a sepolicy file for any allow rule that grants
a given permission.
Usage:
sepolicy-check -s <domain> -t <type> -c <class> -p <permission> -P out/target/product/<board>/root/sepolicy
sepolicy-analyze
A tool for performing various kinds of analysis on a sepolicy
file. The current kinds of analysis that are currently supported
include:
TYPE EQUIVALENCE
sepolicy-analyze -e -P out/target/product/<board>/root/sepolicy
Display all type pairs that are "equivalent", i.e. they are
identical with respect to allow rules, including indirect allow
rules via attributes and default-enabled conditional rules
(i.e. default boolean values yield a true conditional expression).
Equivalent types are candidates for being coalesced into a single
type. However, there may be legitimate reasons for them to remain
separate, for example: - the types may differ in a respect not
included in the current analysis, such as default-disabled
conditional rules, audit-related rules (auditallow or dontaudit),
default type transitions, or constraints (e.g. mls), or - the
current policy may be overly permissive with respect to one or the
other of the types and thus the correct action may be to tighten
access to one or the other rather than coalescing them together,
or - the domains that would in fact have different accesses to the
types may not yet be defined or may be unconfined in the policy
you are analyzing.
TYPE DIFFERENCE
sepolicy-analyze -d -P out/target/product/<board>/root/sepolicy
Display type pairs that differ and the first difference found
between the two types. This may be used in looking for similar
types that are not equivalent but may be candidates for coalescing.
DUPLICATE ALLOW RULES
sepolicy-analyze -D -P out/target/product/<board>/root/sepolicy
Displays duplicate allow rules, i.e. pairs of allow rules that
grant the same permissions where one allow rule is written
directly in terms of individual types and the other is written in
terms of attributes associated with those same types. The rule
with individual types is a candidate for removal. The rule with
individual types may be directly represented in the source policy
or may be a result of expansion of a type negation (e.g. domain
-foo -bar is expanded to individual allow rules by the policy
compiler). Domains with unconfineddomain will typically have such
duplicate rules as a natural side effect and can be ignored.

93
tools/sepolicy-analyze.c
View file

@ -14,7 +14,7 @@
void usage(char *arg0)
{
fprintf(stderr, "%s [-e|--equiv] [-d|--diff] -P <policy file>\n", arg0);
fprintf(stderr, "%s [-e|--equiv] [-d|--diff] [-D|--dups] -P <policy file>\n", arg0);
exit(1);
}
@ -173,18 +173,18 @@ static void free_type_rules(struct avtab_node *l)
}
}
static void display_allow(policydb_t *policydb, struct avtab_node *n, int idx,
static void display_allow(policydb_t *policydb, avtab_key_t *key, int idx,
uint32_t perms)
{
printf(" allow %s %s:%s { %s };\n",
policydb->p_type_val_to_name[n->key.source_type
? n->key.source_type - 1 : idx],
n->key.target_type == n->key.source_type ? "self" :
policydb->p_type_val_to_name[n->key.target_type
? n->key.target_type - 1 : idx],
policydb->p_class_val_to_name[n->key.target_class - 1],
policydb->p_type_val_to_name[key->source_type
? key->source_type - 1 : idx],
key->target_type == key->source_type ? "self" :
policydb->p_type_val_to_name[key->target_type
? key->target_type - 1 : idx],
policydb->p_class_val_to_name[key->target_class - 1],
sepol_av_to_string
(policydb, n->key.target_class, perms));
(policydb, key->target_class, perms));
}
static int find_match(policydb_t *policydb, struct avtab_node *l1,
@ -213,9 +213,9 @@ static int find_match(policydb_t *policydb, struct avtab_node *l1,
perms2 = c->datum.data & ~l1->datum.data;
if (perms1 || perms2) {
if (perms1)
display_allow(policydb, l1, idx1, perms1);
display_allow(policydb, &l1->key, idx1, perms1);
if (perms2)
display_allow(policydb, c, idx2, perms2);
display_allow(policydb, &c->key, idx2, perms2);
printf("\n");
return 1;
}
@ -311,9 +311,9 @@ static int analyze_types(policydb_t * policydb, char equiv, char diff)
continue;
}
if (l1)
display_allow(policydb, l1, i, l1->datum.data);
display_allow(policydb, &l1->key, i, l1->datum.data);
if (l2)
display_allow(policydb, l2, j, l2->datum.data);
display_allow(policydb, &l2->key, j, l2->datum.data);
printf("\n");
}
continue;
@ -334,22 +334,76 @@ static int analyze_types(policydb_t * policydb, char equiv, char diff)
return 0;
}
static int find_dups_helper(avtab_key_t * k, avtab_datum_t * d,
void *args)
{
policydb_t *policydb = args;
ebitmap_t *sattr, *tattr;
ebitmap_node_t *snode, *tnode;
unsigned int i, j;
avtab_key_t avkey;
avtab_ptr_t node;
if (!(k->specified & AVTAB_ALLOWED))
return 0;
avkey.target_class = k->target_class;
avkey.specified = k->specified;
sattr = &policydb->type_attr_map[k->source_type - 1];
tattr = &policydb->type_attr_map[k->target_type - 1];
ebitmap_for_each_bit(sattr, snode, i) {
if (!ebitmap_node_get_bit(snode, i))
continue;
ebitmap_for_each_bit(tattr, tnode, j) {
if (!ebitmap_node_get_bit(tnode, j))
continue;
avkey.source_type = i + 1;
avkey.target_type = j + 1;
if (avkey.source_type == k->source_type &&
avkey.target_type == k->target_type)
continue;
for (node = avtab_search_node(&policydb->te_avtab, &avkey);
node != NULL;
node = avtab_search_node_next(node, avkey.specified)) {
if (node->datum.data & d->data) {
uint32_t perms = node->datum.data & d->data;
printf("Duplicate allow rule found:\n");
display_allow(policydb, k, i, perms);
display_allow(policydb, &node->key, i, perms);
printf("\n");
}
}
}
}
return 0;
}
static int find_dups(policydb_t * policydb)
{
if (avtab_map(&policydb->te_avtab, find_dups_helper, policydb))
return -1;
return 0;
}
int main(int argc, char **argv)
{
char *policy = NULL;
struct policy_file pf;
policydb_t policydb;
char ch;
char equiv = 0, diff = 0;
char equiv = 0, diff = 0, dups = 0;
struct option long_options[] = {
{"equiv", no_argument, NULL, 'e'},
{"diff", no_argument, NULL, 'd'},
{"dups", no_argument, NULL, 'D'},
{"policy", required_argument, NULL, 'P'},
{NULL, 0, NULL, 0}
};
while ((ch = getopt_long(argc, argv, "edP:", long_options, NULL)) != -1) {
while ((ch = getopt_long(argc, argv, "edDP:", long_options, NULL)) != -1) {
switch (ch) {
case 'e':
equiv = 1;
@ -357,6 +411,9 @@ int main(int argc, char **argv)
case 'd':
diff = 1;
break;
case 'D':
dups = 1;
break;
case 'P':
policy = optarg;
break;
@ -365,14 +422,18 @@ int main(int argc, char **argv)
}
}
if (!policy || (!equiv && !diff))
if (!policy || (!equiv && !diff && !dups))
usage(argv[0]);
if (load_policy(policy, &policydb, &pf))
exit(1);
if (equiv || diff)
analyze_types(&policydb, equiv, diff);
if (dups)
find_dups(&policydb);
policydb_destroy(&policydb);
return 0;