@@ -1 +1,2 @@
pointer_masking
+ptrace
@@ -1,10 +1,14 @@
# SPDX-License-Identifier: GPL-2.0
CFLAGS += -I$(top_srcdir)/tools/include
+CFLAGS += $(KHDR_INCLUDES)
-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) $^
new file mode 100644
@@ -0,0 +1,201 @@
+// 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"
+
+#ifndef sizeof_field
+#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+#endif
+#ifndef offsetofend
+#define offsetofend(TYPE, MEMBER) \
+ (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER))
+#endif
+
+
+#define ORIG_A0_MODIFY 0x01
+#define A0_MODIFY 0x02
+#define A0_OLD 0xbadbeefbeeff
+#define A0_NEW 0xffeebfeebdab
+
+
+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 void ptrace_test(int opt, struct a0_regs result[])
+{
+ int status;
+ long rc;
+ 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 = {
+ .op = 0xff,
+ };
+ const unsigned int expected_sci_entry_size =
+ offsetofend(struct ptrace_syscall_info, entry.args);
+ const unsigned int expected_sci_exit_size =
+ offsetofend(struct ptrace_syscall_info, exit.is_error);
+
+ pid = fork();
+ if (pid == 0) {
+ /* Mark oneself being traced */
+ long val = ptrace(PTRACE_TRACEME, 0, 0, 0);
+
+ if (val < 0)
+ perr_and_exit("failed to request for tracer to trace me: %ld", val);
+
+ kill(getpid(), SIGSTOP);
+
+ /* Perform chdir syscall that will be intercepted */
+ syscall(__NR_chdir, A0_OLD);
+
+ exit(0);
+ }
+
+ if (pid < 0)
+ ksft_exit_fail_perror("failed to fork");
+
+ for (int i = 0; i < 3; i++) {
+ if (waitpid(pid, &status, 0) != pid)
+ perr_and_exit("failed to wait for the tracee %d", pid);
+ if (WIFSTOPPED(status)) {
+ switch (WSTOPSIG(status)) {
+ case SIGSTOP:
+ if (ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACESYSGOOD) < 0)
+ perr_and_exit("failed to set PTRACE_O_TRACESYSGOOD");
+ break;
+ case SIGTRAP|0x80:
+ /* Modify twice so GET_SYSCALL_INFO get modified a0 and orig_a0 */
+ if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov))
+ perr_and_exit("failed to get tracee registers");
+ if (ptrace(PTRACE_GETREGSET, pid, NT_RISCV_ORIG_A0, &a0_iov))
+ perr_and_exit("failed to get tracee registers");
+
+ /* 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, &iov))
+ perr_and_exit("failed to set tracee registers");
+ if (ptrace(PTRACE_SETREGSET, pid, NT_RISCV_ORIG_A0, &a0_iov))
+ perr_and_exit("failed to set tracee registers");
+ switch (i) {
+ case 1:
+ /* Stop at the beginning of syscall */
+ rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid,
+ sizeof(syscall_info), &syscall_info);
+ if (rc < 0)
+ perr_and_exit("failed to get syscall info of entry");
+ if (rc < expected_sci_entry_size
+ || syscall_info.op != PTRACE_SYSCALL_INFO_ENTRY)
+ perr_and_exit("stop position of entry mismatched");
+ result[0].orig_a0 = syscall_info.entry.args[0];
+ break;
+
+ case 2:
+ /* Stop at the end of syscall */
+ rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid,
+ sizeof(syscall_info), &syscall_info);
+ if (rc < 0)
+ perr_and_exit("failed to get syscall info of entry");
+ if (rc < expected_sci_exit_size
+ || syscall_info.op != PTRACE_SYSCALL_INFO_EXIT)
+ perr_and_exit("stop position of exit mismatched");
+ result[0].a0 = syscall_info.exit.rval;
+
+ if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov))
+ perr_and_exit("failed to get tracee registers");
+ result[1].a0 = regs.a0;
+ if (ptrace(PTRACE_GETREGSET, pid, NT_RISCV_ORIG_A0,
+ &a0_iov))
+ perr_and_exit("failed to get tracee registers");
+ result[1].orig_a0 = orig_a0;
+ }
+ }
+ if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
+ perr_and_exit("failed to resume tracee");
+ }
+ }
+
+ /* Resume the tracee */
+ ptrace(PTRACE_CONT, pid, 0, 0);
+ if (waitpid(pid, &status, 0) != pid)
+ perr_and_exit("failed to wait for the tracee");
+
+}
+
+TEST(ptrace_access_a0)
+{
+ struct a0_regs result[2];
+
+ ptrace_test(A0_MODIFY, result);
+
+ /* Verify PTRACE_SETREGSET */
+ /* The modification of a0 cannot affect the first argument of the syscall */
+ EXPECT_EQ(A0_OLD, result[0].orig_a0);
+ EXPECT_EQ(A0_NEW, result[0].a0);
+
+ /* Verify PTRACE_GETREGSET */
+ EXPECT_EQ(result[1].orig_a0, result[0].orig_a0);
+ EXPECT_EQ(result[1].a0, result[0].a0);
+}
+
+TEST(ptrace_access_orig_a0)
+{
+ struct a0_regs result[2];
+
+ ptrace_test(ORIG_A0_MODIFY, result);
+
+ /* Verify PTRACE_SETREGSET */
+ /* Only modify orig_a0 to change the first argument of the syscall */
+ EXPECT_EQ(A0_NEW, result[0].orig_a0);
+ /* a0 will keep default value, orig_a0 or -ENOSYS, depends on internal. */
+ EXPECT_NE(A0_NEW, result[0].a0);
+
+ /* Verify PTRACE_GETREGSET */
+ EXPECT_EQ(result[1].orig_a0, result[0].orig_a0);
+ EXPECT_EQ(result[1].a0, result[0].a0);
+}
+
+TEST_HARNESS_MAIN