[tip:x86/entry] selftests/x86: Add a test for process_vm_readv() on the vsyscall page

From: tip-bot for Andy Lutomirski
Date: Thu Jun 27 2019 - 18:18:53 EST


Commit-ID: 7f0a5e0755832301e7b010eab46fb715c483ba60
Gitweb: https://git.kernel.org/tip/7f0a5e0755832301e7b010eab46fb715c483ba60
Author: Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Wed, 26 Jun 2019 21:45:09 -0700
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 28 Jun 2019 00:04:40 +0200

selftests/x86: Add a test for process_vm_readv() on the vsyscall page

get_gate_page() is a piece of somewhat alarming code to make
get_user_pages() work on the vsyscall page. Test it via
process_vm_readv().

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Florian Weimer <fweimer@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Kernel Hardening <kernel-hardening@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/0fe34229a9330e8f9de9765967939cc4f1cf26b1.1561610354.git.luto@xxxxxxxxxx

---
tools/testing/selftests/x86/test_vsyscall.c | 35 +++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)

diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c
index 34a1d35995ef..4602326b8f5b 100644
--- a/tools/testing/selftests/x86/test_vsyscall.c
+++ b/tools/testing/selftests/x86/test_vsyscall.c
@@ -18,6 +18,7 @@
#include <sched.h>
#include <stdbool.h>
#include <setjmp.h>
+#include <sys/uio.h>

#ifdef __x86_64__
# define VSYS(x) (x)
@@ -459,6 +460,38 @@ static int test_vsys_x(void)
return 0;
}

+static int test_process_vm_readv(void)
+{
+#ifdef __x86_64__
+ char buf[4096];
+ struct iovec local, remote;
+ int ret;
+
+ printf("[RUN]\tprocess_vm_readv() from vsyscall page\n");
+
+ local.iov_base = buf;
+ local.iov_len = 4096;
+ remote.iov_base = (void *)0xffffffffff600000;
+ remote.iov_len = 4096;
+ ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0);
+ if (ret != 4096) {
+ printf("[OK]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno);
+ return 0;
+ }
+
+ if (vsyscall_map_r) {
+ if (!memcmp(buf, (const void *)0xffffffffff600000, 4096)) {
+ printf("[OK]\tIt worked and read correct data\n");
+ } else {
+ printf("[FAIL]\tIt worked but returned incorrect data\n");
+ return 1;
+ }
+ }
+#endif
+
+ return 0;
+}
+
#ifdef __x86_64__
#define X86_EFLAGS_TF (1UL << 8)
static volatile sig_atomic_t num_vsyscall_traps;
@@ -533,6 +566,8 @@ int main(int argc, char **argv)
nerrs += test_vsys_r();
nerrs += test_vsys_x();

+ nerrs += test_process_vm_readv();
+
#ifdef __x86_64__
nerrs += test_emulation();
#endif