From: David van Moolenbroek <david@minix3.org>
Date: Sun, 27 Dec 2015 22:44:34 +0000 (+0000)
Subject: VFS: disallow opening files of unsupported types
X-Git-Url: http://zhaoyanbai.com/repos/man.nsec3hash.html?a=commitdiff_plain;h=0eb6caa076338b568e6cdf671b5c1605c4f9075e;p=minix.git

VFS: disallow opening files of unsupported types

Any attempt to use open(2) to open a socket file now fails with
EOPNOTSUPP, as is common and in the process of being standardized.
The behavior and error code is now tested in test56.

Any attempt to open a file of which the type is not known to VFS
(e.g., as a result of bogus file system contents) now fails with EIO.
For now, this is a safety feature, to prevent VFS tripping over such
types in unchecked cases.  In the future, a proper VFS code audit
should determine whether we can lift this restriction again, although
it does not seem particularly useful to be able to open files of
unknown types anyway.  Another error code may be assigned to this case
later, too.

Change-Id: Ib4cb4341eec954f0448fe469ecf28bd78edebde2
---

diff --git a/minix/servers/vfs/open.c b/minix/servers/vfs/open.c
index 5fd23b0d9..7dc9e7222 100644
--- a/minix/servers/vfs/open.c
+++ b/minix/servers/vfs/open.c
@@ -263,6 +263,14 @@ int common_open(char path[PATH_MAX], int oflags, mode_t omode, int for_exec)
 				}
 			}
 			break;
+		   case S_IFSOCK:
+			r = EOPNOTSUPP;
+			break;
+		   default:
+			printf("VFS: attempt to open file <%llu,%llu> of "
+			    "type 0%o\n", vp->v_dev, vp->v_inode_nr,
+			    vp->v_mode & S_IFMT);
+			r = EIO;
 		}
 	}
   }
diff --git a/minix/tests/test56.c b/minix/tests/test56.c
index efe24b0e6..9a408911b 100644
--- a/minix/tests/test56.c
+++ b/minix/tests/test56.c
@@ -1379,6 +1379,51 @@ static void test_fchmod(void)
 	close(socks[1]);
 }
 
+/*
+ * Test various aspects related to the socket files on the file system.
+ * This subtest is woefully incomplete and currently only attempts to test
+ * aspects that have recently been affected by code changes.  In the future,
+ * there should be tests for path canonicalization and the entire range of file
+ * system path and access related error codes (TODO).
+ */
+static void
+test_file(void)
+{
+	struct sockaddr_un addr;
+	int sd;
+
+	UNLINK(TEST_SUN_PATH);
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sun_family = AF_UNIX;
+	strlcpy(addr.sun_path, TEST_SUN_PATH, sizeof(addr.sun_path));
+
+	/*
+	 * Only socket(2), socketpair(2), and accept(2) may be used to obtain
+	 * new file descriptors to sockets (or "sockets"); open(2) on a socket
+	 * file is expected to fail with EOPNOTSUPP (Austin Group Issue #943),
+	 * regardless of whether the socket is in use.
+	 */
+	if ((sd = socket(PF_UNIX, SOCK_DGRAM, 0)) == -1)
+		test_fail("Can't open socket");
+	if (bind(sd, (struct sockaddr *)&addr, sizeof(addr)) != 0)
+		test_fail("Can't bind socket");
+
+	if (open(TEST_SUN_PATH, O_RDWR) != -1)
+		test_fail("Unexpectedly opened socket file");
+	if (errno != EOPNOTSUPP)
+		test_fail("Open failed with wrong error");
+
+	CLOSE(sd);
+
+	if (open(TEST_SUN_PATH, O_RDONLY) != -1)
+		test_fail("Unexpectedly opened socket file");
+	if (errno != EOPNOTSUPP)
+		test_fail("Open failed with wrong error");
+
+	UNLINK(TEST_SUN_PATH);
+}
+
 int main(int argc, char *argv[])
 {
 	int i;
@@ -1463,6 +1508,7 @@ int main(int argc, char *argv[])
 	test_connect_close(&info);
 	test_listen_close(&info);
 	test_listen_close_nb(&info);
+	test_file();
 
 	quit();