IMA: update ima_counts_put

- As ima_counts_put() may be called after the inode has been freed,
verify that the inode is not NULL, before dereferencing it.

- Maintain the IMA file counters in may_open() properly, decrementing
any counter increments on subsequent errors.

Reported-by: Ciprian Docan <docan@eden.rutgers.edu>
Reported-by: J.R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/fs/namei.c b/fs/namei.c
index f3c5b27..1f13751 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1542,28 +1542,31 @@ int may_open(struct path *path, int acc_mode, int flag)
         * An append-only file must be opened in append mode for writing.
         */
        if (IS_APPEND(inode)) {
+               error = -EPERM;
                if  ((flag & FMODE_WRITE) && !(flag & O_APPEND))
-                       return -EPERM;
+                       goto err_out;
                if (flag & O_TRUNC)
-                       return -EPERM;
+                       goto err_out;
        }
 
        /* O_NOATIME can only be set by the owner or superuser */
        if (flag & O_NOATIME)
-               if (!is_owner_or_cap(inode))
-                       return -EPERM;
+               if (!is_owner_or_cap(inode)) {
+                       error = -EPERM;
+                       goto err_out;
+               }
 
        /*
         * Ensure there are no outstanding leases on the file.
         */
        error = break_lease(inode, flag);
        if (error)
-               return error;
+               goto err_out;
 
        if (flag & O_TRUNC) {
                error = get_write_access(inode);
                if (error)
-                       return error;
+                       goto err_out;
 
                /*
                 * Refuse to truncate files with mandatory locks held on them.
@@ -1581,12 +1584,17 @@ int may_open(struct path *path, int acc_mode, int flag)
                }
                put_write_access(inode);
                if (error)
-                       return error;
+                       goto err_out;
        } else
                if (flag & FMODE_WRITE)
                        vfs_dq_init(inode);
 
        return 0;
+err_out:
+       ima_counts_put(path, acc_mode ?
+                      acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC) :
+                      ACC_MODE(flag) & (MAY_READ | MAY_WRITE));
+       return error;
 }
 
 /*

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 4732f5e..b85e61b 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -249,7 +249,11 @@ void ima_counts_put(struct path *path, int mask)
        struct inode *inode = path->dentry->d_inode;
        struct ima_iint_cache *iint;
 
-       if (!ima_initialized || !S_ISREG(inode->i_mode))
+       /* The inode may already have been freed, freeing the iint
+        * with it. Verify the inode is not NULL before dereferencing
+        * it.
+        */
+       if (!ima_initialized || !inode || !S_ISREG(inode->i_mode))
                return;
        iint = ima_iint_find_insert_get(inode);
        if (!iint)