[tip: x86/iopl] selftests/x86/ioperm: Extend testing so the shared bitmap is exercised

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the x86/iopl branch of tip:

Commit-ID:     b7091d239d19ef5cf69b139902fda665f74fd7c1
Gitweb:        https://git.kernel.org/tip/b7091d239d19ef5cf69b139902fda665f74fd7c1
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Wed, 13 Nov 2019 21:42:55 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 14 Nov 2019 20:15:06 +01:00

selftests/x86/ioperm: Extend testing so the shared bitmap is exercised

Add code to the fork path which forces the shared bitmap to be duplicated
and the reference count to be dropped. Verify that the child modifications
did not affect the parent.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20191113210105.169922940@xxxxxxxxxxxxx


---
 tools/testing/selftests/x86/ioperm.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/x86/ioperm.c b/tools/testing/selftests/x86/ioperm.c
index 01de41c..57ec5e9 100644
--- a/tools/testing/selftests/x86/ioperm.c
+++ b/tools/testing/selftests/x86/ioperm.c
@@ -131,6 +131,17 @@ int main(void)
 		printf("[RUN]\tchild: check that we inherited permissions\n");
 		expect_ok(0x80);
 		expect_gp(0xed);
+		printf("[RUN]\tchild: Extend permissions to 0x81\n");
+		if (ioperm(0x81, 1, 1) != 0) {
+			printf("[FAIL]\tioperm(0x81, 1, 1) failed (%d)", errno);
+			return 1;
+		}
+		printf("[RUN]\tchild: Drop permissions to 0x80\n");
+		if (ioperm(0x80, 1, 0) != 0) {
+			printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+			return 1;
+		}
+		expect_gp(0x80);
 		return 0;
 	} else {
 		int status;
@@ -146,8 +157,11 @@ int main(void)
 		}
 	}
 
-	/* Test the capability checks. */
+	/* Verify that the child dropping 0x80 did not affect the parent */
+	printf("\tVerify that unsharing the bitmap worked\n");
+	expect_ok(0x80);
 
+	/* Test the capability checks. */
 	printf("\tDrop privileges\n");
 	if (setresuid(1, 1, 1) != 0) {
 		printf("[WARN]\tDropping privileges failed\n");