[PATCH v3 2/4] selftests/seccomp: Remove the need for HAVE_ARCH_TRACEHOOK

[Mickaël Salaün]

Some architectures do not implement PTRACE_GETREGSET nor
PTRACE_SETREGSET (required by HAVE_ARCH_TRACEHOOK) but only implement
PTRACE_GETREGS and PTRACE_SETREGS (e.g. User-mode Linux).

This improve seccomp selftest portability for architectures without
HAVE_ARCH_TRACEHOOK support by defining a new trigger HAVE_GETREGS. For
now, this is only enabled for i386 and x86_64 architectures. This is
required to be able to run this tests on User-mode Linux.

Signed-off-by: Mickaël Salaün <m...@digikod.net>
Cc: Jeff Dike <jd...@addtoit.com>
Cc: Richard Weinberger <rich...@nod.at>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Will Drewry <w...@chromium.org>
Cc: Shuah Khan <shua...@osg.samsung.com>
Cc: Meredydd Luff <mered...@senatehouse.org>
Cc: David Drysdale <drysd...@google.com>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c 
b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 882fe83a3554..b9453b838162 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -1246,11 +1246,24 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # error "Do not know how to find your architecture's registers and syscalls"
 #endif
 
+/* Use PTRACE_GETREGS and PTRACE_SETREGS when available. This is useful for
+ * architectures without HAVE_ARCH_TRACEHOOK (e.g. User-mode Linux).
+ */
+#if defined(__x86_64__) || defined(__i386__)
+#define HAVE_GETREGS
+#endif
+
 /* Architecture-specific syscall fetching routine. */
 int get_syscall(struct __test_metadata *_metadata, pid_t tracee)
 {
-       struct iovec iov;
        ARCH_REGS regs;
+#ifdef HAVE_GETREGS
+       EXPECT_EQ(0, ptrace(PTRACE_GETREGS, tracee, 0, &regs)) {
+               TH_LOG("PTRACE_GETREGS failed");
+               return -1;
+       }
+#else
+       struct iovec iov;
 
        iov.iov_base = &regs;
        iov.iov_len = sizeof(regs);
@@ -1258,6 +1271,7 @@ int get_syscall(struct __test_metadata *_metadata, pid_t 
tracee)
                TH_LOG("PTRACE_GETREGSET failed");
                return -1;
        }
+#endif
 
        return regs.SYSCALL_NUM;
 }
@@ -1266,13 +1280,16 @@ int get_syscall(struct __test_metadata *_metadata, 
pid_t tracee)
 void change_syscall(struct __test_metadata *_metadata,
                    pid_t tracee, int syscall)
 {
-       struct iovec iov;
        int ret;
        ARCH_REGS regs;
-
+#ifdef HAVE_GETREGS
+       ret = ptrace(PTRACE_GETREGS, tracee, 0, &regs);
+#else
+       struct iovec iov;
        iov.iov_base = &regs;
        iov.iov_len = sizeof(regs);
        ret = ptrace(PTRACE_GETREGSET, tracee, NT_PRSTATUS, &iov);
+#endif
        EXPECT_EQ(0, ret);
 
 #if defined(__x86_64__) || defined(__i386__) || defined(__powerpc__) || \
@@ -1312,9 +1329,13 @@ void change_syscall(struct __test_metadata *_metadata,
        if (syscall == -1)
                regs.SYSCALL_RET = 1;
 
+#ifdef HAVE_GETREGS
+       ret = ptrace(PTRACE_SETREGS, tracee, 0, &regs);
+#else
        iov.iov_base = &regs;
        iov.iov_len = sizeof(regs);
        ret = ptrace(PTRACE_SETREGSET, tracee, NT_PRSTATUS, &iov);
+#endif
        EXPECT_EQ(0, ret);
 }
 
-- 
2.6.4

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