1 files changed, 18 insertions, 0 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index ec158dd02b3a..a721acfd4fdc 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1448,10 +1448,28 @@ static const struct file_operations proc_fd_operations = {
 };
 
 /*
+ * /proc/pid/fd needs a special permission handler so that a process can still
+ * access /proc/self/fd after it has executed a setuid().
+ */
+static int proc_fd_permission(struct inode *inode, int mask,
+                                struct nameidata *nd)
+{
+        int rv;
+
+        rv = generic_permission(inode, mask, NULL);
+        if (rv == 0)
+                return 0;
+        if (task_pid(current) == proc_pid(inode))
+                rv = 0;
+        return rv;
+}
+
+/*
  * proc directories can do almost nothing..
  */
 static const struct inode_operations proc_fd_inode_operations = {
         .lookup         = proc_lookupfd,
+        .permission     = proc_fd_permission,
         .setattr        = proc_setattr,
 };