apparmor: group dfa policydb unpacking

There are currently three policydb rule groupings (xmatch, file,
policydb) that each do their own slightly different thing. Group them
into a single routine and unify.

This extends/unifies dfa features by
- all dfas are allowed having an optional start field
- all dfas are allowed having a string/transition table

Signed-off-by: John Johansen <john.johansen@canonical.com>

diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index 052e3b9..a1fe0a5 100644 (file)
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -648,6 +648,54 @@ fail:
        return false;
 }
 
+static int unpack_pdb(struct aa_ext *e, struct aa_policydb *policy,
+                     bool required_dfa, bool required_trans,
+                     const char **info)
+{
+       int i;
+
+       policy->dfa = unpack_dfa(e);
+       if (IS_ERR(policy->dfa)) {
+               int error = PTR_ERR(policy->dfa);
+
+               policy->dfa = NULL;
+               *info = "failed to unpack - dfa";
+               return error;
+       } else if (!policy->dfa) {
+               if (required_dfa) {
+                       *info = "missing required dfa";
+                       return -EPROTO;
+               }
+               goto out;
+       }
+
+       /*
+        * only unpack the following if a dfa is present
+        *
+        * sadly start was given different names for file and policydb
+        * but since it is optional we can try both
+        */
+       if (!unpack_u32(e, &policy->start[0], "start"))
+               /* default start state */
+               policy->start[0] = DFA_START;
+       if (!unpack_u32(e, &policy->start[AA_CLASS_FILE], "dfa_start")) {
+               /* default start state for xmatch and file dfa */
+               policy->start[AA_CLASS_FILE] = DFA_START;
+       }       /* setup class index */
+       for (i = AA_CLASS_FILE + 1; i <= AA_CLASS_LAST; i++) {
+               policy->start[i] = aa_dfa_next(policy->dfa, policy->start[0],
+                                              i);
+       }
+       if (!unpack_trans_table(e, &policy->trans) && required_trans) {
+               *info = "failed to unpack profile transition table";
+               return -EPROTO;
+       }
+       /* TODO: move compat mapping here, requires dfa merging first */
+
+out:
+       return 0;
+}
+
 static u32 strhash(const void *data, u32 len, u32 seed)
 {
        const char * const *key = data;
@@ -679,7 +727,7 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
        struct rhashtable_params params = { 0 };
        char *key = NULL;
        struct aa_data *data;
-       int i, error = -EPROTO;
+       int error = -EPROTO;
        kernel_cap_t tmpcap;
        u32 tmp;
 
@@ -714,13 +762,10 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
        (void) unpack_str(e, &profile->attach, "attach");
 
        /* xmatch is optional and may be NULL */
-       profile->xmatch.dfa = unpack_dfa(e);
-       if (IS_ERR(profile->xmatch.dfa)) {
-               error = PTR_ERR(profile->xmatch.dfa);
-               profile->xmatch.dfa = NULL;
-               info = "bad xmatch";
+       error = unpack_pdb(e, &profile->xmatch, false, false, &info);
+       if (error)
                goto fail;
-       }
+
        /* neither xmatch_len not xmatch_perms are optional if xmatch is set */
        if (profile->xmatch.dfa) {
                if (!unpack_u32(e, &tmp, NULL)) {
@@ -838,25 +883,16 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
        if (unpack_nameX(e, AA_STRUCT, "policydb")) {
                /* generic policy dfa - optional and may be NULL */
                info = "failed to unpack policydb";
-               profile->policy.dfa = unpack_dfa(e);
-               if (IS_ERR(profile->policy.dfa)) {
-                       error = PTR_ERR(profile->policy.dfa);
-                       profile->policy.dfa = NULL;
-                       goto fail;
-               } else if (!profile->policy.dfa) {
-                       error = -EPROTO;
+               error = unpack_pdb(e, &profile->policy, true, false, &info);
+               if (error)
                        goto fail;
-               }
-               if (!unpack_u32(e, &profile->policy.start[0], "start"))
-                       /* default start state */
-                       profile->policy.start[0] = DFA_START;
-               /* setup class index */
-               for (i = AA_CLASS_FILE; i <= AA_CLASS_LAST; i++) {
-                       profile->policy.start[i] =
-                               aa_dfa_next(profile->policy.dfa,
-                                           profile->policy.start[0],
-                                           i);
-               }
+               /* Fixup: drop when we get rid of start array */
+               if (aa_dfa_next(profile->policy.dfa, profile->policy.start[0],
+                               AA_CLASS_FILE))
+                       profile->policy.start[AA_CLASS_FILE] =
+                         aa_dfa_next(profile->policy.dfa,
+                                     profile->policy.start[0],
+                                     AA_CLASS_FILE);
                if (!unpack_nameX(e, AA_STRUCTEND, NULL))
                        goto fail;
                if (aa_compat_map_policy(&profile->policy, e->version)) {
@@ -867,25 +903,14 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
                profile->policy.dfa = aa_get_dfa(nulldfa);
 
        /* get file rules */
-       profile->file.dfa = unpack_dfa(e);
-       if (IS_ERR(profile->file.dfa)) {
-               error = PTR_ERR(profile->file.dfa);
-               profile->file.dfa = NULL;
-               info = "failed to unpack profile file rules";
+       error = unpack_pdb(e, &profile->file, false, true, &info);
+       if (error) {
                goto fail;
        } else if (profile->file.dfa) {
-               if (!unpack_u32(e, &profile->file.start[AA_CLASS_FILE],
-                               "dfa_start"))
-                       /* default start state */
-                       profile->file.start[AA_CLASS_FILE] = DFA_START;
                if (aa_compat_map_file(&profile->file)) {
                        info = "failed to remap file permission table";
                        goto fail;
                }
-               if (!unpack_trans_table(e, &profile->file.trans)) {
-                       info = "failed to unpack profile transition table";
-                       goto fail;
-               }
        } else if (profile->policy.dfa &&
                   profile->policy.start[AA_CLASS_FILE]) {
                profile->file.dfa = aa_get_dfa(profile->policy.dfa);