1 files changed, 49 insertions, 0 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 4739cfbb41b7..5c23afb31ece 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/security.h>
 #include <linux/user_namespace.h>
 #include <asm/uaccess.h>
 #include "internal.h"
@@ -768,3 +769,51 @@ error:
         abort_creds(new);
         return ret;
 }
+
+/*
+ * Replace a process's session keyring when that process resumes userspace on
+ * behalf of one of its children
+ */
+void key_replace_session_keyring(void)
+{
+        const struct cred *old;
+        struct cred *new;
+
+        if (!current->replacement_session_keyring)
+                return;
+
+        write_lock_irq(&tasklist_lock);
+        new = current->replacement_session_keyring;
+        current->replacement_session_keyring = NULL;
+        write_unlock_irq(&tasklist_lock);
+
+        if (!new)
+                return;
+
+        old = current_cred();
+        new->  uid      = old->  uid;
+        new-> euid      = old-> euid;
+        new-> suid      = old-> suid;
+        new->fsuid      = old->fsuid;
+        new->  gid      = old->  gid;
+        new-> egid      = old-> egid;
+        new-> sgid      = old-> sgid;
+        new->fsgid      = old->fsgid;
+        new->user       = get_uid(old->user);
+        new->group_info = get_group_info(old->group_info);
+
+        new->securebits = old->securebits;
+        new->cap_inheritable    = old->cap_inheritable;
+        new->cap_permitted      = old->cap_permitted;
+        new->cap_effective      = old->cap_effective;
+        new->cap_bset           = old->cap_bset;
+
+        new->jit_keyring        = old->jit_keyring;
+        new->thread_keyring     = key_get(old->thread_keyring);
+        new->tgcred->tgid       = old->tgcred->tgid;
+        new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
+
+        security_transfer_creds(new, old);
+
+        commit_creds(new);
+}