[PATCH] Keys: Pass session keyring to call_usermodehelper()

The attached patch makes it possible to pass a session keyring through to the
process spawned by call_usermodehelper().  This allows patch 3/3 to pass an
authorisation key through to /sbin/request-key, thus permitting better access
controls when doing just-in-time key creation.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 21 insertions, 2 deletions

diff --git a/include/linux/key.h b/include/linux/key.h
index 2c24ffaca86f..2bfbf88d2740 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -273,14 +273,22 @@ extern void key_fsuid_changed(struct task_struct *tsk);
 extern void key_fsgid_changed(struct task_struct *tsk);
 extern void key_init(void);
 
+#define __install_session_keyring(tsk, keyring)                 \
+({                                                              \
+        struct key *old_session = tsk->signal->session_keyring; \
+        tsk->signal->session_keyring = keyring;                 \
+        old_session;                                            \
+})
+
 #else /* CONFIG_KEYS */
 
 #define key_validate(k)                 0
 #define key_serial(k)                   0
-#define key_get(k)                      NULL
+#define key_get(k)                      ({ NULL; })
 #define key_put(k)                      do { } while(0)
 #define alloc_uid_keyring(u)            0
 #define switch_uid_keyring(u)           do { } while(0)
+#define __install_session_keyring(t, k) ({ NULL; })
 #define copy_keys(f,t)                  0
 #define copy_thread_group_keys(t)       0
 #define exit_keys(t)                    do { } while(0)
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 95d0e4b0814d..e4a231549407 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -19,6 +19,7 @@
  *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#include <linux/stddef.h>
 #include <linux/config.h>
 #include <linux/errno.h>
 #include <linux/compiler.h>
@@ -34,7 +35,17 @@ static inline int request_module(const char * name, ...) { return -ENOSYS; }
 #endif
 
 #define try_then_request_module(x, mod...) ((x) ?: (request_module(mod), (x)))
-extern int call_usermodehelper(char *path, char *argv[], char *envp[], int wait);
+
+struct key;
+extern int call_usermodehelper_keys(char *path, char *argv[], char *envp[],
+                                    struct key *session_keyring, int wait);
+
+static inline int
+call_usermodehelper(char *path, char **argv, char **envp, int wait)
+{
+        return call_usermodehelper_keys(path, argv, envp, NULL, wait);
+}
+
 extern void usermodehelper_init(void);
 
 #endif /* __LINUX_KMOD_H__ */