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Message-Id: <20241226-riscv-new-regset-v3-2-f5b96465826b@coelacanthus.name>
Date: Thu, 26 Dec 2024 18:45:10 +0800
From: Celeste Liu <uwu@...lacanthus.name>
To: Oleg Nesterov <oleg@...hat.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Eric Biederman <ebiederm@...ssion.com>,
Kees Cook <kees@...nel.org>, Shuah Khan <shuah@...nel.org>,
Albert Ou <aou@...s.berkeley.edu>
Cc: Alexandre Ghiti <alex@...ti.fr>, "Dmitry V. Levin" <ldv@...ace.io>,
Andrea Bolognani <abologna@...hat.com>,
Björn Töpel <bjorn@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>, Ron Economos <re@...z.net>,
Charlie Jenkins <charlie@...osinc.com>,
Andrew Jones <ajones@...tanamicro.com>, Quan Zhou <zhouquan@...as.ac.cn>,
Felix Yan <felixonmars@...hlinux.org>, Ruizhe Pan <c141028@...il.com>,
Guo Ren <guoren@...nel.org>, Yao Zi <ziyao@...root.org>,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
Celeste Liu <uwu@...lacanthus.name>,
Björn Töpel <bjorn@...osinc.com>
Subject: [PATCH v3 2/2] riscv: selftests: Add a ptrace test to verify
syscall parameter modification
This test checks that orig_a0 allows a syscall argument to be modified,
and that changing a0 does not change the syscall argument.
Co-developed-by: Quan Zhou <zhouquan@...as.ac.cn>
Signed-off-by: Quan Zhou <zhouquan@...as.ac.cn>
Co-developed-by: Charlie Jenkins <charlie@...osinc.com>
Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
Reviewed-by: Björn Töpel <bjorn@...osinc.com>
Signed-off-by: Celeste Liu <uwu@...lacanthus.name>
---
tools/testing/selftests/riscv/abi/.gitignore | 1 +
tools/testing/selftests/riscv/abi/Makefile | 5 +-
tools/testing/selftests/riscv/abi/ptrace.c | 151 +++++++++++++++++++++++++++
3 files changed, 156 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/riscv/abi/.gitignore b/tools/testing/selftests/riscv/abi/.gitignore
index b38358f91c4d2240ae64892871d9ca98bda1ae58..378c605919a3b3d58eec2701eb7af430cfe315d6 100644
--- a/tools/testing/selftests/riscv/abi/.gitignore
+++ b/tools/testing/selftests/riscv/abi/.gitignore
@@ -1 +1,2 @@
pointer_masking
+ptrace
diff --git a/tools/testing/selftests/riscv/abi/Makefile b/tools/testing/selftests/riscv/abi/Makefile
index ed82ff9c664e7eb3f760cbab81fb957ff72579c5..3f74d059dfdcbce4d45d8ff618781ccea1419061 100644
--- a/tools/testing/selftests/riscv/abi/Makefile
+++ b/tools/testing/selftests/riscv/abi/Makefile
@@ -2,9 +2,12 @@
CFLAGS += -I$(top_srcdir)/tools/include
-TEST_GEN_PROGS := pointer_masking
+TEST_GEN_PROGS := pointer_masking ptrace
include ../../lib.mk
$(OUTPUT)/pointer_masking: pointer_masking.c
$(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
+
+$(OUTPUT)/ptrace: ptrace.c
+ $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^
diff --git a/tools/testing/selftests/riscv/abi/ptrace.c b/tools/testing/selftests/riscv/abi/ptrace.c
new file mode 100644
index 0000000000000000000000000000000000000000..c89343cb4abc7da57f83879ecce619f503c438bb
--- /dev/null
+++ b/tools/testing/selftests/riscv/abi/ptrace.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/stat.h>
+#include <sys/user.h>
+#include <sys/wait.h>
+#include <sys/uio.h>
+#include <linux/elf.h>
+#include <linux/unistd.h>
+#include <linux/ptrace.h>
+#include <asm/ptrace.h>
+
+#include "../../kselftest_harness.h"
+
+#define ORIG_A0_MODIFY 0x01
+#define A0_MODIFY 0x02
+#define A0_OLD 0x03
+#define A0_NEW 0x04
+
+struct a0_regs {
+ __s64 orig_a0;
+ __u64 a0;
+};
+
+#define perr_and_exit(fmt, ...) \
+ ({ \
+ char buf[256]; \
+ snprintf(buf, sizeof(buf), "%s:%d:" fmt ": %m\n", \
+ __func__, __LINE__, ##__VA_ARGS__); \
+ ksft_exit_fail_perror(buf); \
+ })
+
+static inline void resume_and_wait_tracee(pid_t pid, int flag)
+{
+ int status;
+
+ if (ptrace(flag, pid, 0, 0))
+ perr_and_exit("failed to resume the tracee %d\n", pid);
+
+ if (waitpid(pid, &status, 0) != pid)
+ perr_and_exit("failed to wait for the tracee %d\n", pid);
+}
+
+static void ptrace_test(int opt, struct a0_regs *result)
+{
+ int status;
+ pid_t pid;
+ struct user_regs_struct regs;
+ struct iovec iov = {
+ .iov_base = ®s,
+ .iov_len = sizeof(regs),
+ };
+
+ unsigned long orig_a0;
+ struct iovec a0_iov = {
+ .iov_base = &orig_a0,
+ .iov_len = sizeof(orig_a0),
+ };
+ struct ptrace_syscall_info syscall_info_entry, syscall_info_exit;
+
+ pid = fork();
+ if (pid == 0) {
+ /* Mark oneself being traced */
+ long val = ptrace(PTRACE_TRACEME, 0, 0, 0);
+
+ if (val)
+ perr_and_exit("failed to request for tracer to trace me: %ld\n", val);
+
+ kill(getpid(), SIGSTOP);
+
+ /* Perform exit syscall that will be intercepted */
+ exit(A0_OLD);
+ }
+
+ if (pid < 0)
+ ksft_exit_fail_perror("failed to fork");
+
+ if (waitpid(pid, &status, 0) != pid)
+ perr_and_exit("failed to wait for the tracee %d\n", pid);
+
+ /* Stop at the entry point of the syscall */
+ resume_and_wait_tracee(pid, PTRACE_SYSCALL);
+
+ /* Check tracee regs before the syscall */
+ if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov))
+ perr_and_exit("failed to get tracee registers\n");
+ if (ptrace(PTRACE_GETREGSET, pid, NT_RISCV_ORIG_A0, &a0_iov))
+ perr_and_exit("failed to get tracee registers\n");
+ if (orig_a0 != A0_OLD)
+ perr_and_exit("unexpected orig_a0: 0x%lx\n", orig_a0);
+
+ /* Modify a0/orig_a0 for the syscall */
+ switch (opt) {
+ case A0_MODIFY:
+ regs.a0 = A0_NEW;
+ break;
+ case ORIG_A0_MODIFY:
+ orig_a0 = A0_NEW;
+ break;
+ }
+
+ if (ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS, &a0_iov))
+ perr_and_exit("failed to set tracee registers\n");
+ if (ptrace(PTRACE_SETREGSET, pid, NT_RISCV_ORIG_A0, &a0_iov))
+ perr_and_exit("failed to set tracee registers\n");
+
+ if (ptrace(PTRACE_GET_SYSCALL_INFO, pid, PTRACE_SYSCALL_INFO_ENTRY, &syscall_info_entry))
+ perr_and_exit("failed to get syscall info of entry\n");
+ result->orig_a0 = syscall_info_entry->entry.args[0];
+ if (ptrace(PTRACE_GET_SYSCALL_INFO, pid, PTRACE_SYSCALL_INFO_EXIT, &syscall_info_exit))
+ perr_and_exit("failed to get syscall info of exit\n");
+ result->a0 = syscall_info_exit->exit.rval;
+
+ /* Resume the tracee */
+ ptrace(PTRACE_CONT, pid, 0, 0);
+ if (waitpid(pid, &status, 0) != pid)
+ perr_and_exit("failed to wait for the tracee\n");
+
+}
+
+TEST(ptrace_modify_a0)
+{
+ struct a0_regs result;
+
+ ptrace_test(A0_MODIFY, &result);
+
+ /* The modification of a0 cannot affect the first argument of the syscall */
+ EXPECT_EQ(A0_OLD, result.orig_a0);
+ EXPECT_EQ(A0_NEW, result.a0);
+}
+
+TEST(ptrace_modify_orig_a0)
+{
+ struct a0_regs result;
+
+ ptrace_test(ORIG_A0_MODIFY, &result);
+
+ /* Only modify orig_a0 to change the first argument of the syscall */
+ EXPECT_EQ(A0_NEW, result.orig_a0);
+ /* a0 will keep default value, orig_a0 or -ENOSYS, depends on internal. */
+ EXPECT_NE(A0_NEW, result.a0);
+}
+
+TEST_HARNESS_MAIN
--
2.47.1
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