selinux: introduce str_read() helper

There're some code duplication for reading a string value during
policydb_read().  Add str_read() helper to fix it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Paul Moore <pmoore@redhat.com>

1 files changed, 37 insertions, 96 deletions

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 56eb65f67cb1..bc2a586f095c 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -1080,6 +1080,26 @@ out:
  * binary representation file.
  */
 
+static int str_read(char **strp, gfp_t flags, void *fp, u32 len)
+{
+        int rc;
+        char *str;
+
+        str = kmalloc(len + 1, flags);
+        if (!str)
+                return -ENOMEM;
+
+        /* it's expected the caller should free the str */
+        *strp = str;
+
+        rc = next_entry(str, fp, len);
+        if (rc)
+                return rc;
+
+        str[len] = '\0';
+        return 0;
+}
+
 static int perm_read(struct policydb *p, struct hashtab *h, void *fp)
 {
         char *key = NULL;
@@ -1100,15 +1120,9 @@ static int perm_read(struct policydb *p, struct hashtab *h, void *fp)
         len = le32_to_cpu(buf[0]);
         perdatum->value = le32_to_cpu(buf[1]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_KERNEL);
-        if (!key)
-                goto bad;
-
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_KERNEL, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         rc = hashtab_insert(h, key, perdatum);
         if (rc)
@@ -1146,15 +1160,9 @@ static int common_read(struct policydb *p, struct hashtab *h, void *fp)
         comdatum->permissions.nprim = le32_to_cpu(buf[2]);
         nel = le32_to_cpu(buf[3]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_KERNEL);
-        if (!key)
-                goto bad;
-
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_KERNEL, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         for (i = 0; i < nel; i++) {
                 rc = perm_read(p, comdatum->permissions.table, fp);
@@ -1321,25 +1329,14 @@ static int class_read(struct policydb *p, struct hashtab *h, void *fp)
 
         ncons = le32_to_cpu(buf[5]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_KERNEL);
-        if (!key)
-                goto bad;
-
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_KERNEL, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         if (len2) {
-                rc = -ENOMEM;
-                cladatum->comkey = kmalloc(len2 + 1, GFP_KERNEL);
-                if (!cladatum->comkey)
-                        goto bad;
-                rc = next_entry(cladatum->comkey, fp, len2);
+                rc = str_read(&cladatum->comkey, GFP_KERNEL, fp, len2);
                 if (rc)
                         goto bad;
-                cladatum->comkey[len2] = '\0';
 
                 rc = -EINVAL;
                 cladatum->comdatum = hashtab_search(p->p_commons.table, cladatum->comkey);
@@ -1422,15 +1419,9 @@ static int role_read(struct policydb *p, struct hashtab *h, void *fp)
         if (p->policyvers >= POLICYDB_VERSION_BOUNDARY)
                 role->bounds = le32_to_cpu(buf[2]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_KERNEL);
-        if (!key)
-                goto bad;
-
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_KERNEL, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         rc = ebitmap_read(&role->dominates, fp);
         if (rc)
@@ -1495,14 +1486,9 @@ static int type_read(struct policydb *p, struct hashtab *h, void *fp)
                 typdatum->primary = le32_to_cpu(buf[2]);
         }
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_KERNEL);
-        if (!key)
-                goto bad;
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_KERNEL, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         rc = hashtab_insert(h, key, typdatum);
         if (rc)
@@ -1565,14 +1551,9 @@ static int user_read(struct policydb *p, struct hashtab *h, void *fp)
         if (p->policyvers >= POLICYDB_VERSION_BOUNDARY)
                 usrdatum->bounds = le32_to_cpu(buf[2]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_KERNEL);
-        if (!key)
-                goto bad;
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_KERNEL, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         rc = ebitmap_read(&usrdatum->roles, fp);
         if (rc)
@@ -1616,14 +1597,9 @@ static int sens_read(struct policydb *p, struct hashtab *h, void *fp)
         len = le32_to_cpu(buf[0]);
         levdatum->isalias = le32_to_cpu(buf[1]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_ATOMIC);
-        if (!key)
-                goto bad;
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_ATOMIC, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         rc = -ENOMEM;
         levdatum->level = kmalloc(sizeof(struct mls_level), GFP_ATOMIC);
@@ -1664,14 +1640,9 @@ static int cat_read(struct policydb *p, struct hashtab *h, void *fp)
         catdatum->value = le32_to_cpu(buf[1]);
         catdatum->isalias = le32_to_cpu(buf[2]);
 
-        rc = -ENOMEM;
-        key = kmalloc(len + 1, GFP_ATOMIC);
-        if (!key)
+        rc = str_read(&key, GFP_ATOMIC, fp, len);