2 files changed, 32 insertions, 4 deletions

diff --git a/security/safesetid/lsm.h b/security/safesetid/lsm.h
index 4a34f558d964..db6d16e6bbc3 100644
--- a/security/safesetid/lsm.h
+++ b/security/safesetid/lsm.h
@@ -41,6 +41,7 @@ struct setuid_rule {
 
 struct setuid_ruleset {
         DECLARE_HASHTABLE(rules, SETID_HASH_BITS);
+        char *policy_str;
         struct rcu_head rcu;
 };
 
diff --git a/security/safesetid/securityfs.c b/security/safesetid/securityfs.c
index 250d59e046c1..997b403c6255 100644
--- a/security/safesetid/securityfs.c
+++ b/security/safesetid/securityfs.c
@@ -19,7 +19,7 @@
 
 #include "lsm.h"
 
-static DEFINE_SPINLOCK(policy_update_lock);
+static DEFINE_MUTEX(policy_update_lock);
 
 /*
  * In the case the input buffer contains one or more invalid UIDs, the kuid_t
@@ -67,6 +67,7 @@ static void __release_ruleset(struct rcu_head *rcu)
 
         hash_for_each_safe(pol->rules, bucket, tmp, rule, next)
                 kfree(rule);
+        kfree(pol->policy_str);
         kfree(pol);
 }
 
@@ -85,6 +86,7 @@ static ssize_t handle_policy_update(struct file *file,
         pol = kmalloc(sizeof(struct setuid_ruleset), GFP_KERNEL);
         if (!pol)
                 return -ENOMEM;
+        pol->policy_str = NULL;
         hash_init(pol->rules);
 
         p = buf = memdup_user_nul(ubuf, len);
@@ -92,6 +94,11 @@ static ssize_t handle_policy_update(struct file *file,
                 err = PTR_ERR(buf);
                 goto out_free_pol;
         }
+        pol->policy_str = kstrdup(buf, GFP_KERNEL);
+        if (pol->policy_str == NULL) {
+                err = -ENOMEM;
+                goto out_free_buf;
+        }
 
         /* policy lines, including the last one, end with \n */
         while (*p != '\0') {
@@ -135,10 +142,10 @@ out_free_rule:
          * What we really want here is an xchg() wrapper for RCU, but since that
          * doesn't currently exist, just use a spinlock for now.
          */
-        spin_lock(&policy_update_lock);
+        mutex_lock(&policy_update_lock);
         rcu_swap_protected(safesetid_setuid_rules, pol,
                            lockdep_is_held(&policy_update_lock));
-        spin_unlock(&policy_update_lock);
+        mutex_unlock(&policy_update_lock);
         err = len;
 
 out_free_buf:
@@ -162,7 +169,27 @@ static ssize_t safesetid_file_write(struct file *file,
         return handle_policy_update(file, buf, len);
 }
 
+static ssize_t safesetid_file_read(struct file *file, char __user *buf,
+                                   size_t len, loff_t *ppos)
+{
+        ssize_t res = 0;
+        struct setuid_ruleset *pol;
+        const char *kbuf;
+
+        mutex_lock(&policy_update_lock);
+        pol = rcu_dereference_protected(safesetid_setuid_rules,
+                                        lockdep_is_held(&policy_update_lock));
+        if (pol) {
+                kbuf = pol->policy_str;
+                res = simple_read_from_buffer(buf, len, ppos,
+                                              kbuf, strlen(kbuf));
+        }
+        mutex_unlock(&policy_update_lock);
+        return res;
+}
+
 static const struct file_operations safesetid_file_fops = {
+        .read = safesetid_file_read,
         .write = safesetid_file_write,
 };
 
@@ -181,7 +208,7 @@ static int __init safesetid_init_securityfs(void)
                 goto error;
         }
 
-        policy_file = securityfs_create_file("whitelist_policy", 0200,
+        policy_file = securityfs_create_file("whitelist_policy", 0600,
                         policy_dir, NULL, &safesetid_file_fops);
         if (IS_ERR(policy_file)) {
                 ret = PTR_ERR(policy_file);