prctl: implement PR_[GS]ET_MDWE decodingesyr/prctl-mdwe

Introduced by Linux commit v6.3-rc1~113^2~215.

* src/xlat/pr_mdwe_flags.in: New file.
* src/prctl.c: Include "xlat/pr_mdwe_flags.h".
(SYS_FUNC(prctl)) <case PR_SET_MDWE, case PR_GET_MDWE>: Implement
command decoders.
* tests/.gitignore: Add prctl-mdwe.
* tests/Makefile.am (check_PROGRAMS): Add prctl-mdwe.
* tests/gen_tests.in (prctl-mdwe): New test.
* tests/prctl-mdwe.c: New file.
* NEWS: Mention it.

7 files changed, 176 insertions, 4 deletions

diff --git a/NEWS b/NEWS
index c614cd0ab..964b868e6 100644
--- a/NEWS
+++ b/NEWS
@@ -6,11 +6,13 @@ Noteworthy changes in release ?.? (????-??-??)
     that operate on the specified set of file descriptors.
   * Implemented -l/--syscall-limit option to automatically detach tracees
     after capturing the specified number of syscalls.
+  * Implemented decoding of PR_GET_MDWE and PR_SET_MDWE operations of prctl
+    syscall.
   * Implemented decoding of IFLA_BRPORT_MCAST_N_GROUPS,
     IFLA_BRPORT_MCAST_MAX_GROUPS, IFLA_GSO_IPV4_MAX_SIZE,
     IFLA_GRO_IPV4_MAX_SIZE, and TCA_EXT_WARN_MSG netlink attributes.
-  * Updated lists of F_SEAL_*, IFLA_*, IORING_*, IP_*, MFD_*, NFT_*, PR_*,
-    TCA_*, and V4L2_PIX_FMT_* constants.
+  * Updated lists of F_SEAL_*, IFLA_*, IORING_*, IP_*, MFD_*, NFT_*, TCA_*,
+    and V4L2_PIX_FMT_* constants.
   * Updated lists of ioctl commands from Linux 6.3.
 
 Noteworthy changes in release 6.2 (2023-02-26)
diff --git a/src/prctl.c b/src/prctl.c
index 6c1776522..2396c6bc6 100644
--- a/src/prctl.c
+++ b/src/prctl.c
@@ -20,6 +20,7 @@
 #include "xlat/pr_fp_mode.h"
 #include "xlat/pr_mce_kill.h"
 #include "xlat/pr_mce_kill_policy.h"
+#include "xlat/pr_mdwe_flags.h"
 #include "xlat/pr_pac_enabled_keys.h"
 #include "xlat/pr_pac_keys.h"
 #include "xlat/pr_sched_core_cmds.h"
@@ -360,6 +361,18 @@ SYS_FUNC(prctl)
 
 		return RVAL_HEX | RVAL_STR;
 
+	case PR_GET_MDWE:
+		if (entering(tcp)) {
+			print_prctl_args(tcp, 1);
+			break;
+		}
+		if (syserror(tcp))
+			return 0;
+		tcp->auxstr = sprintflags_ex("", pr_mdwe_flags,
+				(kernel_ulong_t) tcp->u_rval, '\0',
+				XLAT_STYLE_DEFAULT | SPFF_AUXSTR_MODE);
+		return RVAL_HEX | RVAL_STR;
+
 	/* PR_TASK_PERF_EVENTS_* take no arguments. */
 	case PR_TASK_PERF_EVENTS_DISABLE:
 	case PR_TASK_PERF_EVENTS_ENABLE:
@@ -497,10 +510,15 @@ SYS_FUNC(prctl)
 		printflags(pr_unalign_flags, arg2, "PR_UNALIGN_???");
 		return RVAL_DECODED;
 
+	case PR_SET_MDWE:
+		tprint_arg_next();
+		printflags(pr_mdwe_flags, arg2, "PR_MDWE_???");
+		print_prctl_args(tcp, 2);
+		return RVAL_DECODED;
+
 	case PR_SET_NO_NEW_PRIVS:
 	case PR_SET_THP_DISABLE:
 	case PR_SET_IO_FLUSHER:
-	case PR_SET_MDWE:
 		tprint_arg_next();
 		PRINT_VAL_U(arg2);
 		print_prctl_args(tcp, 2);
@@ -629,7 +647,6 @@ SYS_FUNC(prctl)
 	case PR_MPX_DISABLE_MANAGEMENT:
 	case PR_MPX_ENABLE_MANAGEMENT:
 	case PR_GET_IO_FLUSHER:
-	case PR_GET_MDWE:
 	default:
 		print_prctl_args(tcp, 1);
 		return RVAL_DECODED;
diff --git a/src/xlat/pr_mdwe_flags.in b/src/xlat/pr_mdwe_flags.in
new file mode 100644
index 000000000..581da1fd2
--- /dev/null
+++ b/src/xlat/pr_mdwe_flags.in
@@ -0,0 +1 @@
+PR_MDWE_REFUSE_EXEC_GAIN	1
diff --git a/tests/.gitignore b/tests/.gitignore
index 62f1fd0f4..a39408627 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -718,6 +718,7 @@ prctl-capbset
 prctl-dumpable
 prctl-fp-mode
 prctl-mce-kill
+prctl-mdwe
 prctl-name
 prctl-no-args
 prctl-pac-enabled-keys
diff --git a/tests/Makefile.am b/tests/Makefile.am
index b2734b77b..170876eed 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -286,6 +286,7 @@ check_PROGRAMS = $(PURE_EXECUTABLES) \
 	ppoll-e-trace-fds-not-9-42-P \
 	ppoll-v \
 	prctl-fp-mode \
+	prctl-mdwe \
 	prctl-pac-enabled-keys-success \
 	prctl-pac-enabled-keys-success-Xabbrev \
 	prctl-pac-enabled-keys-success-Xraw \
diff --git a/tests/gen_tests.in b/tests/gen_tests.in
index e4686ea40..db70ee1b4 100644
--- a/tests/gen_tests.in
+++ b/tests/gen_tests.in
@@ -718,6 +718,7 @@ prctl-capbset		+prctl.sh -a21
 prctl-dumpable		+prctl.sh -a23
 prctl-fp-mode		+prctl-success.sh PRCTL_INJECT_RETVALS="error=ENOTTY 0 1 2 3 32 35" -a21
 prctl-mce-kill		+prctl.sh -a21
+prctl-mdwe		+prctl-success.sh PRCTL_INJECT_RETVALS="error=ENOTTY 0 1 2 3 2124532478" -a31
 prctl-name		+prctl.sh -a23
 prctl-no-args		+prctl.sh -a21
 prctl-pac-enabled-keys		+prctl.sh -a43
diff --git a/tests/prctl-mdwe.c b/tests/prctl-mdwe.c
new file mode 100644
index 000000000..00c30e9a3
--- /dev/null
+++ b/tests/prctl-mdwe.c
@@ -0,0 +1,149 @@
+/*
+ * Check decoding of prctl PR_GET_MDWE/PR_SET_MDWE operations.
+ *
+ * Copyright (c) 2021-2023 The strace developers.
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "tests.h"
+#include "scno.h"
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/prctl.h>
+
+static long injected_val;
+
+static long
+do_prctl(kernel_ulong_t cmd, kernel_ulong_t arg2, kernel_ulong_t arg3,
+	 kernel_ulong_t arg4, kernel_ulong_t arg5)
+{
+	long rc = syscall(__NR_prctl, cmd, arg2, arg3, arg4, arg5);
+
+	if (rc != injected_val) {
+		error_msg_and_fail("Return value (%ld) differs from expected "
+						   "injected value (%ld)",
+						   rc, injected_val);
+	}
+
+	return rc;
+}
+
+int
+main(int argc, char **argv)
+{
+	static const kernel_ulong_t bogus_arg2 =
+			(kernel_ulong_t) 0xdecafeedbeefda7eULL;
+	static const kernel_ulong_t bogus_arg3 =
+			(kernel_ulong_t) 0xbadc0dedfacef00dULL;
+	static const kernel_ulong_t bogus_arg4 =
+			(kernel_ulong_t) 0xcafeda7efeedbeefULL;
+	static const kernel_ulong_t bogus_arg5 =
+			(kernel_ulong_t) 0xfa57beeffacefeedULL;
+
+	static const struct {
+		long arg;
+		const char *str;
+	} get_strs[] = {
+			{-1,         ""},
+			{0,          ""},
+			{1,          " (PR_MDWE_REFUSE_EXEC_GAIN)"},
+			{2,          ""},
+			{3,          " (PR_MDWE_REFUSE_EXEC_GAIN|0x2)"},
+			{0x7ea1cafe, ""},
+	};
+	static const struct {
+		kernel_ulong_t arg;
+		const char *str;
+	} set_strs[] = {
+			{0,          "0"},
+			{1,          "PR_MDWE_REFUSE_EXEC_GAIN"},
+			{2,          "0x2 /* PR_MDWE_??? */"},
+			{3,          "PR_MDWE_REFUSE_EXEC_GAIN|0x2"},
+			{0x7ea1cafe, "0x7ea1cafe /* PR_MDWE_??? */"}
+	};
+
+	long rc;
+	unsigned long num_skip;
+	const char *str = NULL;
+	bool locked = false;
+
+	if (argc < 3)
+		error_msg_and_fail("Usage: %s NUM_SKIP INJECT_RETVAL", argv[0]);
+
+	num_skip = strtoul(argv[1], NULL, 0);
+	injected_val = strtol(argv[2], NULL, 0);
+
+	for (size_t i = 0; i < num_skip; i++) {
+		if ((prctl_marker() != injected_val) ||
+		    ((injected_val == -1) && (errno != ENOTTY)))
+			continue;
+
+		locked = true;
+		break;
+	}
+
+	if (!locked)
+		error_msg_and_fail("Have not locked on prctl(-1, -2, -3, -4"
+				   ", -5) returning %ld", injected_val);
+
+	/* PR_GET_MDWE */
+	for (unsigned int j = 0; j < 2; j++) {
+		if (j) {
+			rc = do_prctl(PR_GET_MDWE, bogus_arg2, bogus_arg3,
+						   bogus_arg4, bogus_arg5);
+		} else {
+			rc = do_prctl(PR_GET_MDWE, 0, 0, 0, 0);
+		}
+
+		const char *errstr = sprintrc(rc);
+
+		for (size_t i = 0; i < ARRAY_SIZE(get_strs); i++) {
+			if (get_strs[i].arg == rc) {
+				str = get_strs[i].str;
+				break;
+			}
+		}
+		if (!str)
+			error_msg_and_fail("Unknown return value: %ld", rc);
+
+		printf("prctl(PR_GET_MDWE, %s) = ", j ?
+#if SIZEOF_KERNEL_LONG_T > 4
+		       "0xdecafeedbeefda7e, 0xbadc0dedfacef00d"
+		       ", 0xcafeda7efeedbeef, 0xfa57beeffacefeed"
+#else
+		       "0xbeefda7e, 0xfacef00d, 0xfeedbeef, 0xfacefeed"
+#endif
+		       : "0, 0, 0, 0");
+		if (rc < 0)
+			printf("%s", errstr);
+		else
+			printf("%#lx", rc);
+		printf("%s (INJECTED)\n", str);
+	}
+
+	/* PR_SET_FP_MODE */
+	for (size_t i = 0; i < ARRAY_SIZE(set_strs); i++) {
+		rc = do_prctl(PR_SET_MDWE, set_strs[i].arg, 0, 0, 0);
+		printf("prctl(PR_SET_MDWE, %s, 0, 0, 0) = %s (INJECTED)\n",
+		       set_strs[i].str, sprintrc(rc));
+
+		rc = do_prctl(PR_SET_MDWE, set_strs[i].arg,
+			      bogus_arg3, bogus_arg4, bogus_arg5);
+		printf("prctl(PR_SET_MDWE, %s, %s) = %s (INJECTED)\n",
+		       set_strs[i].str,
+#if SIZEOF_KERNEL_LONG_T > 4
+		       "0xbadc0dedfacef00d, 0xcafeda7efeedbeef"
+		       ", 0xfa57beeffacefeed"
+#else
+		       "0xfacef00d, 0xfeedbeef, 0xfacefeed"
+#endif
+		       , sprintrc(rc));
+	}
+
+	puts("+++ exited with 0 +++");
+	return 0;
+}