SELinux: put name based create rules in a hashtable

To shorten the list we need to run if filename trans rules exist for the type
of the given parent directory I put them in a hashtable.  Given the policy we
are expecting to use in Fedora this takes the worst case list run from about
5,000 entries to 17.

Signed-off-by: Eric Paris <eparis@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>

3 files changed, 135 insertions, 61 deletions

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index ca7a7231b5a2..549120c56edd 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -184,6 +184,43 @@ out:
         return rc;
 }
 
+static u32 filenametr_hash(struct hashtab *h, const void *k)
+{
+        const struct filename_trans *ft = k;
+        unsigned long hash;
+        unsigned int byte_num;
+        unsigned char focus;
+
+        hash = ft->stype ^ ft->ttype ^ ft->tclass;
+
+        byte_num = 0;
+        while ((focus = ft->name[byte_num++]))
+                hash = partial_name_hash(focus, hash);
+        return hash & (h->size - 1);
+}
+
+static int filenametr_cmp(struct hashtab *h, const void *k1, const void *k2)
+{
+        const struct filename_trans *ft1 = k1;
+        const struct filename_trans *ft2 = k2;
+        int v;
+
+        v = ft1->stype - ft2->stype;
+        if (v)
+                return v;
+
+        v = ft1->ttype - ft2->ttype;
+        if (v)
+                return v;
+
+        v = ft1->tclass - ft2->tclass;
+        if (v)
+                return v;
+
+        return strcmp(ft1->name, ft2->name);
+
+}
+
 static u32 rangetr_hash(struct hashtab *h, const void *k)
 {
         const struct range_trans *key = k;
@@ -236,6 +273,10 @@ static int policydb_init(struct policydb *p)
         if (rc)
                 goto out;
 
+        p->filename_trans = hashtab_create(filenametr_hash, filenametr_cmp, (1 << 10));
+        if (!p->filename_trans)
+                goto out;
+
         p->range_tr = hashtab_create(rangetr_hash, rangetr_cmp, 256);
         if (!p->range_tr)
                 goto out;
@@ -246,6 +287,8 @@ static int policydb_init(struct policydb *p)
 
         return 0;
 out:
+        hashtab_destroy(p->filename_trans);
+        hashtab_destroy(p->range_tr);
         for (i = 0; i < SYM_NUM; i++)
                 hashtab_destroy(p->symtab[i].table);
         return rc;
@@ -675,6 +718,16 @@ static int (*destroy_f[SYM_NUM]) (void *key, void *datum, void *datap) =
         cat_destroy,
 };
 
+static int filenametr_destroy(void *key, void *datum, void *p)
+{
+        struct filename_trans *ft = key;
+        kfree(ft->name);
+        kfree(key);
+        kfree(datum);
+        cond_resched();
+        return 0;
+}
+
 static int range_tr_destroy(void *key, void *datum, void *p)
 {
         struct mls_range *rt = datum;
@@ -709,7 +762,6 @@ void policydb_destroy(struct policydb *p)
         int i;
         struct role_allow *ra, *lra = NULL;
         struct role_trans *tr, *ltr = NULL;
-        struct filename_trans *ft, *nft;
 
         for (i = 0; i < SYM_NUM; i++) {
                 cond_resched();
@@ -773,6 +825,9 @@ void policydb_destroy(struct policydb *p)
         }
         kfree(lra);
 
+        hashtab_map(p->filename_trans, filenametr_destroy, NULL);
+        hashtab_destroy(p->filename_trans);
+
         hashtab_map(p->range_tr, range_tr_destroy, NULL);
         hashtab_destroy(p->range_tr);
 
@@ -788,14 +843,6 @@ void policydb_destroy(struct policydb *p)
                 flex_array_free(p->type_attr_map_array);
         }
 
-        ft = p->filename_trans;
-        while (ft) {
-                nft = ft->next;
-                kfree(ft->name);
-                kfree(ft);
-                ft = nft;
-        }
-
         ebitmap_destroy(&p->filename_trans_ttypes);
         ebitmap_destroy(&p->policycaps);
         ebitmap_destroy(&p->permissive_map);
@@ -1806,9 +1853,10 @@ out:
 
 static int filename_trans_read(struct policydb *p, void *fp)
 {
-        struct filename_trans *ft, *last;
-        u32 nel, len;
+        struct filename_trans *ft;
+        struct filename_trans_datum *otype;
         char *name;
+        u32 nel, len;
         __le32 buf[4];
         int rc, i;
 
@@ -1817,25 +1865,23 @@ static int filename_trans_read(struct policydb *p, void *fp)
 
         rc = next_entry(buf, fp, sizeof(u32));
         if (rc)
-                goto out;
+                return rc;
         nel = le32_to_cpu(buf[0]);
 
-        last = p->filename_trans;
-        while (last && last->next)
-                last = last->next;
-
         for (i = 0; i < nel; i++) {
+                ft = NULL;
+                otype = NULL;
+                name = NULL;
+
                 rc = -ENOMEM;
                 ft = kzalloc(sizeof(*ft), GFP_KERNEL);
                 if (!ft)
                         goto out;
 
-                /* add it to the tail of the list */
-                if (!last)
-                        p->filename_trans = ft;
-                else
-                        last->next = ft;
-                last = ft;
+                rc = -ENOMEM;
+                otype = kmalloc(sizeof(*otype), GFP_KERNEL);
+                if (!otype)
+                        goto out;
 
                 /* length of the path component string */
                 rc = next_entry(buf, fp, sizeof(u32));
@@ -1863,14 +1909,22 @@ static int filename_trans_read(struct policydb *p, void *fp)
                 ft->stype = le32_to_cpu(buf[0]);
                 ft->ttype = le32_to_cpu(buf[1]);
                 ft->tclass = le32_to_cpu(buf[2]);
-                ft->otype = le32_to_cpu(buf[3]);
+
+                otype->otype = le32_to_cpu(buf[3]);
 
                 rc = ebitmap_set_bit(&p->filename_trans_ttypes, ft->ttype, 1);
                 if (rc)
                         goto out;
+
+                hashtab_insert(p->filename_trans, ft, otype);
         }
-        rc = 0;
+        hash_eval(p->filename_trans, "filenametr");
+        return 0;
 out:
+        kfree(ft);
+        kfree(name);
+        kfree(otype);
+
         return rc;
 }
 
@@ -3131,43 +3185,60 @@ static int range_write(struct policydb *p, void *fp)
         return 0;
 }
 
-static int filename_trans_write(struct policydb *p, void *fp)
+static int filename_write_helper(void *key, void *data, void *ptr)
 {
-        struct filename_trans *ft;
-        u32 len, nel = 0;
         __le32 buf[4];
+        struct filename_trans *ft = key;
+        struct filename_trans_datum *otype = data;
+        void *fp = ptr;
         int rc;
+        u32 len;
 
-        for (ft = p->filename_trans; ft; ft = ft->next)
-                nel++;
-
-        buf[0] = cpu_to_le32(nel);
+        len = strlen(ft->name);
+        buf[0] = cpu_to_le32(len);
         rc = put_entry(buf, sizeof(u32), 1, fp);
         if (rc)
                 return rc;
 
-        for (ft = p->filename_trans; ft; ft = ft->next) {
-                len = strlen(ft->name);
-                buf[0] = cpu_to_le32(len);
-                rc = put_entry(buf, sizeof(u32), 1, fp);
-                if (rc)
-                        return rc;
+        rc = put_entry(ft->name, sizeof(char), len, fp);
+        if (rc)
+                return rc;
 
-                rc = put_entry(ft->name, sizeof(char), len, fp);
-                if (rc)
-                        return rc;
+        buf[0] = ft->stype;
+        buf[1] = ft->ttype;
+        buf[2] = ft->tclass;
+        buf[3] = otype->otype;
 
-                buf[0] = ft->stype;
-                buf[1] = ft->ttype;
-                buf[2] = ft->tclass;
-                buf[3] = ft->otype;
+        rc = put_entry(buf, sizeof(u32), 4, fp);
+        if (rc)
+                return rc;
 
-                rc = put_entry(buf, sizeof(u32), 4, fp);
-                if (rc)
-                        return rc;
-        }
         return 0;
 }
+
+static int filename_trans_write(struct policydb *p, void *fp)
+{
+        u32 nel;
+        __le32 buf[1];
+        int rc;
+
+        nel = 0;
+        rc = hashtab_map(p->filename_trans, hashtab_cnt, &nel);
+        if (rc)
+                return rc;
+
+        buf[0] = cpu_to_le32(nel);
+        rc = put_entry(buf, sizeof(u32), 1, fp);
+        if (rc)
+                return rc;
+
+        rc = hashtab_map(p->filename_trans, filename_write_helper, fp);
+        if (rc)
+                return rc;
+
+        return 0;
+}
+
 /*
  * Write the configuration data in a policy database
  * structure to a policy database binary representation
diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index f054a9d4d114..b846c0387180 100644
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -79,11 +79,13 @@ struct role_trans {
 };
 
 struct filename_trans {
-        struct filename_trans *next;
         u32 stype;              /* current process */
         u32 ttype;              /* parent dir context */
         u16 tclass;             /* class of new object */
         const char *name;       /* last path component */
+};
+
+struct filename_trans_datum {
         u32 otype;              /* expected of new object */
 };
 
@@ -227,10 +229,11 @@ struct policydb {
         /* role transitions */
         struct role_trans *role_tr;
 
+        /* file transitions with the last path component */
         /* quickly exclude lookups when parent ttype has no rules */
         struct ebitmap filename_trans_ttypes;
-        /* file transitions with the last path component */
-        struct filename_trans *filename_trans;
+        /* actual set of filename_trans rules */
+        struct hashtab *filename_trans;
 
         /* bools indexed by (value - 1) */
         struct cond_bool_datum **bool_val_to_struct;
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 6a22eaebf3b7..e11b4b038f4a 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -1362,7 +1362,8 @@ static void filename_compute_type(struct policydb *p, struct context *newcontext
                                   u32 stype, u32 ttype, u16 tclass,
                                   const char *objname)
 {
-        struct filename_trans *ft;
+        struct filename_trans ft;
+        struct filename_trans_datum *otype;
 
         /*
          * Most filename trans rules are going to live in specific directories
@@ -1372,15 +1373,14 @@ static void filename_compute_type(struct policydb *p, struct context *newcontext
         if (!ebitmap_get_bit(&p->filename_trans_ttypes, ttype))
                 return;
 
-        for (ft = p->filename_trans; ft; ft = ft->next) {
-                if (ft->stype == stype &&
-                    ft->ttype == ttype &&
-                    ft->tclass == tclass &&
-                    !strcmp(ft->name, objname)) {
-                        newcontext->type = ft->otype;
-                        return;
-                }
-        }
+        ft.stype = stype;
+        ft.ttype = ttype;
+        ft.tclass = tclass;
+        ft.name = objname;
+
+        otype = hashtab_search(p->filename_trans, &ft);
+        if (otype)
+                newcontext->type = otype->otype;
 }
 
 static int security_compute_sid(u32 ssid,