syscalls/request_key04: new test for request_key() permission check bug

From: Eric Biggers <[email protected]>

Add a test for a bug that allowed the request_key() system call to be used to add a key to a keyring using only Search permission. This bug was assigned CVE-2017-17807.

---
 include/lapi/keyctl.h                              |  4 +
 runtest/cve                                        |  1 +
 runtest/syscalls                                   |  1 +
 .../kernel/syscalls/request_key/request_key04.c    | 87 ++++++++++++++++++++++
 4 files changed, 93 insertions(+)
 create mode 100644 testcases/kernel/syscalls/request_key/request_key04.c

index 4b8098a59..440f9c7c6 100644
@@ -99,6 +99,10 @@ static inline key_serial_t keyctl_join_session_keyring(const char *name) {
 # define KEY_REQKEY_DEFL_THREAD_KEYRING 1
 #endif
 
+#ifndef KEY_REQKEY_DEFL_SESSION_KEYRING
+# define KEY_REQKEY_DEFL_SESSION_KEYRING 3
+#endif
+
 #ifndef KEY_REQKEY_DEFL_DEFAULT
 # define KEY_REQKEY_DEFL_DEFAULT	0
 #endif

index 2873df906..dce8c4af4 100644
@@ -25,4 +25,5 @@ cve-2017-15274 add_key02
 cve-2017-15299 request_key03 -b cve-2017-15299
 cve-2017-15537 ptrace07
 cve-2017-15951 request_key03 -b cve-2017-15951
+cve-2017-17807 request_key04
 cve-2017-1000364 stack_clash

index 97fc64300..94efd2305 100644
@@ -935,6 +935,7 @@ request_key01 request_key01
 request_key02 request_key02
 request_key03 request_key03
 cve-2017-6951 cve-2017-6951
+request_key04 request_key04
 
 rmdir01 rmdir01
 rmdir02 rmdir02

2.16.0.rc0.223.g4a4ac83678-goog