Merge tag 'landlock-6.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock test fixes from Mickaël Salaün:
 "Fix build issues for tests, and improve test compatibility"

* tag 'landlock-6.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
  selftests/landlock: Fix capability for net_test
  selftests/landlock: Fix fs_test build with old libc
  selftests/landlock: Fix net_test build with old libc

Author: torvalds

tools/testing/selftests/landlock/common.h

@@ -9,6 +9,7 @@
 
 #include <errno.h>
 #include <linux/landlock.h>
+#include <linux/securebits.h>
 #include <sys/capability.h>
 #include <sys/socket.h>
 #include <sys/syscall.h>
@@ -115,11 +116,16 @@ static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
 		/* clang-format off */
 		CAP_DAC_OVERRIDE,
 		CAP_MKNOD,
+		CAP_NET_ADMIN,
+		CAP_NET_BIND_SERVICE,
 		CAP_SYS_ADMIN,
 		CAP_SYS_CHROOT,
-		CAP_NET_BIND_SERVICE,
 		/* clang-format on */
 	};
+	const unsigned int noroot = SECBIT_NOROOT | SECBIT_NOROOT_LOCKED;
+
+	if ((cap_get_secbits() & noroot) != noroot)
+		EXPECT_EQ(0, cap_set_secbits(noroot));
 
 	cap_p = cap_get_proc();
 	EXPECT_NE(NULL, cap_p)
@@ -137,6 +143,8 @@ static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
 			TH_LOG("Failed to cap_set_flag: %s", strerror(errno));
 		}
 	}
+
+	/* Automatically resets ambient capabilities. */
 	EXPECT_NE(-1, cap_set_proc(cap_p))
 	{
 		TH_LOG("Failed to cap_set_proc: %s", strerror(errno));
@@ -145,6 +153,9 @@ static void _init_caps(struct __test_metadata *const _metadata, bool drop_all)
 	{
 		TH_LOG("Failed to cap_free: %s", strerror(errno));
 	}
+
+	/* Quickly checks that ambient capabilities are cleared. */
+	EXPECT_NE(-1, cap_get_ambient(caps[0]));
 }
 
 /* We cannot put such helpers in a library because of kselftest_harness.h . */
@@ -158,8 +169,9 @@ static void __maybe_unused drop_caps(struct __test_metadata *const _metadata)
 	_init_caps(_metadata, true);
 }
 
-static void _effective_cap(struct __test_metadata *const _metadata,
-			   const cap_value_t caps, const cap_flag_value_t value)
+static void _change_cap(struct __test_metadata *const _metadata,
+			const cap_flag_t flag, const cap_value_t cap,
+			const cap_flag_value_t value)
 {
 	cap_t cap_p;
 
@@ -168,7 +180,7 @@ static void _effective_cap(struct __test_metadata *const _metadata,
 	{
 		TH_LOG("Failed to cap_get_proc: %s", strerror(errno));
 	}
-	EXPECT_NE(-1, cap_set_flag(cap_p, CAP_EFFECTIVE, 1, &caps, value))
+	EXPECT_NE(-1, cap_set_flag(cap_p, flag, 1, &cap, value))
 	{
 		TH_LOG("Failed to cap_set_flag: %s", strerror(errno));
 	}
@@ -183,15 +195,35 @@ static void _effective_cap(struct __test_metadata *const _metadata,
 }
 
 static void __maybe_unused set_cap(struct __test_metadata *const _metadata,
-				   const cap_value_t caps)
+				   const cap_value_t cap)
 {
-	_effective_cap(_metadata, caps, CAP_SET);
+	_change_cap(_metadata, CAP_EFFECTIVE, cap, CAP_SET);
 }
 
 static void __maybe_unused clear_cap(struct __test_metadata *const _metadata,
-				     const cap_value_t caps)
+				     const cap_value_t cap)
+{
+	_change_cap(_metadata, CAP_EFFECTIVE, cap, CAP_CLEAR);
+}
+
+static void __maybe_unused
+set_ambient_cap(struct __test_metadata *const _metadata, const cap_value_t cap)
+{
+	_change_cap(_metadata, CAP_INHERITABLE, cap, CAP_SET);
+
+	EXPECT_NE(-1, cap_set_ambient(cap, CAP_SET))
+	{
+		TH_LOG("Failed to set ambient capability %d: %s", cap,
+		       strerror(errno));
+	}
+}
+
+static void __maybe_unused clear_ambient_cap(
+	struct __test_metadata *const _metadata, const cap_value_t cap)
 {
-	_effective_cap(_metadata, caps, CAP_CLEAR);
+	EXPECT_EQ(1, cap_get_ambient(cap));
+	_change_cap(_metadata, CAP_INHERITABLE, cap, CAP_CLEAR);
+	EXPECT_EQ(0, cap_get_ambient(cap));
 }
 
 /* Receives an FD from a UNIX socket. Returns the received FD, or -errno. */

tools/testing/selftests/landlock/fs_test.c

@@ -241,9 +241,11 @@ struct mnt_opt {
 	const char *const data;
 };
 
-const struct mnt_opt mnt_tmp = {
+#define MNT_TMP_DATA "size=4m,mode=700"
+
+static const struct mnt_opt mnt_tmp = {
 	.type = "tmpfs",
-	.data = "size=4m,mode=700",
+	.data = MNT_TMP_DATA,
 };
 
 static int mount_opt(const struct mnt_opt *const mnt, const char *const target)
@@ -4632,7 +4634,10 @@ FIXTURE_VARIANT(layout3_fs)
 /* clang-format off */
 FIXTURE_VARIANT_ADD(layout3_fs, tmpfs) {
 	/* clang-format on */
-	.mnt = mnt_tmp,
+	.mnt = {
+		.type = "tmpfs",
+		.data = MNT_TMP_DATA,
+	},
 	.file_path = file1_s1d1,
 };
 

tools/testing/selftests/landlock/net_test.c

@@ -17,6 +17,7 @@
 #include <string.h>
 #include <sys/prctl.h>
 #include <sys/socket.h>
+#include <sys/syscall.h>
 #include <sys/un.h>
 
 #include "common.h"
@@ -54,6 +55,11 @@ struct service_fixture {
 	};
 };
 
+static pid_t sys_gettid(void)
+{
+	return syscall(__NR_gettid);
+}
+
 static int set_service(struct service_fixture *const srv,
 		       const struct protocol_variant prot,
 		       const unsigned short index)
@@ -88,7 +94,7 @@ static int set_service(struct service_fixture *const srv,
 	case AF_UNIX:
 		srv->unix_addr.sun_family = prot.domain;
 		sprintf(srv->unix_addr.sun_path,
-			"_selftests-landlock-net-tid%d-index%d", gettid(),
+			"_selftests-landlock-net-tid%d-index%d", sys_gettid(),
 			index);
 		srv->unix_addr_len = SUN_LEN(&srv->unix_addr);
 		srv->unix_addr.sun_path[0] = '\0';
@@ -101,8 +107,11 @@ static void setup_loopback(struct __test_metadata *const _metadata)
 {
 	set_cap(_metadata, CAP_SYS_ADMIN);
 	ASSERT_EQ(0, unshare(CLONE_NEWNET));
-	ASSERT_EQ(0, system("ip link set dev lo up"));
 	clear_cap(_metadata, CAP_SYS_ADMIN);
+
+	set_ambient_cap(_metadata, CAP_NET_ADMIN);
+	ASSERT_EQ(0, system("ip link set dev lo up"));
+	clear_ambient_cap(_metadata, CAP_NET_ADMIN);
 }
 
 static bool is_restricted(const struct protocol_variant *const prot,