[LTP] [PATCH] open|creat: skip S_ISGID check on files created by non-group members

[Jan Stancek]

0fa3ecd87848 ("Fix up non-directory creation in SGID directories")
fixes problem described in CVE-2018-13405. This commit is getting
backported to older streams as well.

This patch removes S_ISGID check for files created by non-group members
in LTP tests creat08 and open10.

Once 0fa3ecd87848 will be in non-rc kernel, we could add a new test
for this CVE that would be limited to 4.18+ kernels.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
 testcases/kernel/syscalls/creat/creat08.c | 13 ++++++-------
 testcases/kernel/syscalls/open/open10.c   | 12 +++++-------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/testcases/kernel/syscalls/creat/creat08.c b/testcases/kernel/syscalls/creat/creat08.c
index 50f2b39931b8..d22558ac3c53 100644
--- a/testcases/kernel/syscalls/creat/creat08.c
+++ b/testcases/kernel/syscalls/creat/creat08.c
@@ -361,13 +361,12 @@ int main(int ac, char **av)
 			local_flag = FAILED;
 		}
 
-		/* Verify modes */
-		if (!(buf.st_mode & S_ISGID)) {
-			tst_resm(TFAIL,
-				 "%s: Incorrect modes, setgid bit should be set",
-				 setgid_B);
-			local_flag = FAILED;
-		}
+		/*
+		 * Skip S_ISGID check
+		 * 0fa3ecd87848 ("Fix up non-directory creation in SGID directories")
+		 * clears S_ISGID for files created by non-group members
+		 */
+
 		close(fd);
 
 		if (local_flag == PASSED) {
diff --git a/testcases/kernel/syscalls/open/open10.c b/testcases/kernel/syscalls/open/open10.c
index 613f2288fbde..14feec9e127e 100644
--- a/testcases/kernel/syscalls/open/open10.c
+++ b/testcases/kernel/syscalls/open/open10.c
@@ -345,13 +345,11 @@ int main(int ac, char *av[])
 			local_flag = FAILED;
 		}
 
-		/* Verify modes */
-		if (!(buf.st_mode & S_ISGID)) {
-			tst_resm(TFAIL,
-				 "%s: Incorrect modes, setgid bit not set",
-				 setgid_B);
-			local_flag = FAILED;
-		}
+		/*
+		 * Skip S_ISGID check
+		 * 0fa3ecd87848 ("Fix up non-directory creation in SGID directories")
+		 * clears S_ISGID for files created by non-group members
+		 */
 
 		if (local_flag == PASSED) {
 			tst_resm(TPASS, "Test passed in block2.");
-- 
1.8.3.1