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)
-                goto bad;
-        rc = next_entry(key, fp, len);
+        rc = str_read(&key, GFP_ATOMIC, fp, len);
         if (rc)
                 goto bad;
-        key[len] = '\0';
 
         rc = hashtab_insert(h, key, catdatum);
         if (rc)
@@ -1968,18 +1939,12 @@ static int filename_trans_read(struct policydb *p, void *fp)
                         goto out;
                 len = le32_to_cpu(buf[0]);
 
-                rc = -ENOMEM;
-                name = kmalloc(len + 1, GFP_KERNEL);
-                if (!name)
-                        goto out;
-
-                ft->name = name;
-
                 /* path component string */
-                rc = next_entry(name, fp, len);
+                rc = str_read(&name, GFP_KERNEL, fp, len);
                 if (rc)
                         goto out;
-                name[len] = 0;
+
+                ft->name = name;
 
                 rc = next_entry(buf, fp, sizeof(u32) * 4);
                 if (rc)
@@ -2045,17 +2010,10 @@ static int genfs_read(struct policydb *p, void *fp)
                 if (!newgenfs)
                         goto out;
 
-                rc = -ENOMEM;
-                newgenfs->fstype = kmalloc(len + 1, GFP_KERNEL);
-                if (!newgenfs->fstype)
-                        goto out;
-
-                rc = next_entry(newgenfs->fstype, fp, len);
+                rc = str_read(&newgenfs->fstype, GFP_KERNEL, fp, len);
                 if (rc)
                         goto out;
 
-                newgenfs->fstype[len] = 0;
-
                 for (genfs_p = NULL, genfs = p->genfs; genfs;
                      genfs_p = genfs, genfs = genfs->next) {
                         rc = -EINVAL;
@@ -2091,15 +2049,9 @@ static int genfs_read(struct policydb *p, void *fp)
                         if (!newc)
                                 goto out;
 
-                        rc = -ENOMEM;
-                        newc->u.name = kmalloc(len + 1, GFP_KERNEL);
-                        if (!newc->u.name)
-                                goto out;
-
-                        rc = next_entry(newc->u.name, fp, len);
+                        rc = str_read(&newc->u.name, GFP_KERNEL, fp, len);
                         if (rc)
                                 goto out;
-                        newc->u.name[len] = 0;
 
                         rc = next_entry(buf, fp, sizeof(u32));
                         if (rc)
@@ -2189,16 +2141,10 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
                                         goto out;
                                 len = le32_to_cpu(buf[0]);
 
-                                rc = -ENOMEM;
-                                c->u.name = kmalloc(len + 1, GFP_KERNEL);
-                                if (!c->u.name)
-                                        goto out;
-
-                                rc = next_entry(c->u.name, fp, len);
+                                rc = str_read(&c->u.name, GFP_KERNEL, fp, len);
                                 if (rc)
                                         goto out;
 
-                                c->u.name[len] = 0;
                                 rc = context_read_and_validate(&c->context[0], p, fp);
                                 if (rc)
                                         goto out;
@@ -2240,16 +2186,11 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
                                 if (c->v.behavior > SECURITY_FS_USE_MAX)
                                         goto out;
 
-                                rc = -ENOMEM;
                                 len = le32_to_cpu(buf[1]);
-                                c->u.name = kmalloc(len + 1, GFP_KERNEL);
-                                if (!c->u.name)
-                                        goto out;
-
-                                rc = next_entry(c->u.name, fp, len);
+                                rc = str_read(&c->u.name, GFP_KERNEL, fp, len);
                                 if (rc)
                                         goto out;
-                                c->u.name[len] = 0;
+
                                 rc = context_read_and_validate(&c->context[0], p, fp);
                                 if (rc)
                                         goto out;