main/linux-grsec: security fixes (CVE-2015-7872, CVE-2015-7885)

1 files changed, 117 insertions, 0 deletions

diff --git a/main/linux-grsec/keys-fixes.patch b/main/linux-grsec/keys-fixes.patch
new file mode 100644
index 0000000000..8ef8a0c359
--- /dev/null
+++ b/main/linux-grsec/keys-fixes.patch
@@ -0,0 +1,117 @@
+From f05819df10d7b09f6d1eb6f8534a8f68e5a4fe61 Mon Sep 17 00:00:00 2001
+From: David Howells <dhowells@redhat.com>
+Date: Thu, 15 Oct 2015 17:21:37 +0100
+Subject: KEYS: Fix crash when attempt to garbage collect an uninstantiated
+ keyring
+
+The following sequence of commands:
+
+    i=`keyctl add user a a @s`
+    keyctl request2 keyring foo bar @t
+    keyctl unlink $i @s
+
+tries to invoke an upcall to instantiate a keyring if one doesn't already
+exist by that name within the user's keyring set.  However, if the upcall
+fails, the code sets keyring->type_data.reject_error to -ENOKEY or some
+other error code.  When the key is garbage collected, the key destroy
+function is called unconditionally and keyring_destroy() uses list_empty()
+on keyring->type_data.link - which is in a union with reject_error.
+Subsequently, the kernel tries to unlink the keyring from the keyring names
+list - which oopses like this:
+
+	BUG: unable to handle kernel paging request at 00000000ffffff8a
+	IP: [<ffffffff8126e051>] keyring_destroy+0x3d/0x88
+	...
+	Workqueue: events key_garbage_collector
+	...
+	RIP: 0010:[<ffffffff8126e051>] keyring_destroy+0x3d/0x88
+	RSP: 0018:ffff88003e2f3d30  EFLAGS: 00010203
+	RAX: 00000000ffffff82 RBX: ffff88003bf1a900 RCX: 0000000000000000
+	RDX: 0000000000000000 RSI: 000000003bfc6901 RDI: ffffffff81a73a40
+	RBP: ffff88003e2f3d38 R08: 0000000000000152 R09: 0000000000000000
+	R10: ffff88003e2f3c18 R11: 000000000000865b R12: ffff88003bf1a900
+	R13: 0000000000000000 R14: ffff88003bf1a908 R15: ffff88003e2f4000
+	...
+	CR2: 00000000ffffff8a CR3: 000000003e3ec000 CR4: 00000000000006f0
+	...
+	Call Trace:
+	 [<ffffffff8126c756>] key_gc_unused_keys.constprop.1+0x5d/0x10f
+	 [<ffffffff8126ca71>] key_garbage_collector+0x1fa/0x351
+	 [<ffffffff8105ec9b>] process_one_work+0x28e/0x547
+	 [<ffffffff8105fd17>] worker_thread+0x26e/0x361
+	 [<ffffffff8105faa9>] ? rescuer_thread+0x2a8/0x2a8
+	 [<ffffffff810648ad>] kthread+0xf3/0xfb
+	 [<ffffffff810647ba>] ? kthread_create_on_node+0x1c2/0x1c2
+	 [<ffffffff815f2ccf>] ret_from_fork+0x3f/0x70
+	 [<ffffffff810647ba>] ? kthread_create_on_node+0x1c2/0x1c2
+
+Note the value in RAX.  This is a 32-bit representation of -ENOKEY.
+
+The solution is to only call ->destroy() if the key was successfully
+instantiated.
+
+Reported-by: Dmitry Vyukov <dvyukov@google.com>
+Signed-off-by: David Howells <dhowells@redhat.com>
+Tested-by: Dmitry Vyukov <dvyukov@google.com>
+---
+ security/keys/gc.c | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/security/keys/gc.c b/security/keys/gc.c
+index 39eac1f..addf060 100644
+--- a/security/keys/gc.c
++++ b/security/keys/gc.c
+@@ -134,8 +134,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
+ 		kdebug("- %u", key->serial);
+ 		key_check(key);
+ 
+-		/* Throw away the key data */
+-		if (key->type->destroy)
++		/* Throw away the key data if the key is instantiated */
++		if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
++		    !test_bit(KEY_FLAG_NEGATIVE, &key->flags) &&
++		    key->type->destroy)
+ 			key->type->destroy(key);
+ 
+ 		security_key_free(key);
+-- 
+cgit v0.11.2
+
+
+From 911b79cde95c7da0ec02f48105358a36636b7a71 Mon Sep 17 00:00:00 2001
+From: David Howells <dhowells@redhat.com>
+Date: Mon, 19 Oct 2015 11:20:28 +0100
+Subject: KEYS: Don't permit request_key() to construct a new keyring
+
+If request_key() is used to find a keyring, only do the search part - don't
+do the construction part if the keyring was not found by the search.  We
+don't really want keyrings in the negative instantiated state since the
+rejected/negative instantiation error value in the payload is unioned with
+keyring metadata.
+
+Now the kernel gives an error:
+
+	request_key("keyring", "#selinux,bdekeyring", "keyring", KEY_SPEC_USER_SESSION_KEYRING) = -1 EPERM (Operation not permitted)
+
+Signed-off-by: David Howells <dhowells@redhat.com>
+---
+ security/keys/request_key.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/security/keys/request_key.c b/security/keys/request_key.c
+index 486ef6f..0d62531 100644
+--- a/security/keys/request_key.c
++++ b/security/keys/request_key.c
+@@ -440,6 +440,9 @@ static struct key *construct_key_and_link(struct keyring_search_context *ctx,
+ 
+ 	kenter("");
+ 
++	if (ctx->index_key.type == &key_type_keyring)
++		return ERR_PTR(-EPERM);
++	
+ 	user = key_user_lookup(current_fsuid());
+ 	if (!user)
+ 		return ERR_PTR(-ENOMEM);
+-- 
+cgit v0.11.2
+