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authorTejun Heo <tj@kernel.org>2022-01-07 00:02:29 +0300
committerTejun Heo <tj@kernel.org>2022-01-07 00:02:29 +0300
commit613e040e4dc285367bff0f8f75ea59839bc10947 (patch)
tree5556aa81ceeed1f035d60bb5f72fe15edf1157cf /tools/testing/selftests/cgroup
parentb09c2baa56347ae65795350dfcc633dedb1c2970 (diff)
downloadlinux-613e040e4dc285367bff0f8f75ea59839bc10947.tar.xz
selftests: cgroup: Test open-time credential usage for migration checks
When a task is writing to an fd opened by a different task, the perm check should use the credentials of the latter task. Add a test for it. Tested-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'tools/testing/selftests/cgroup')
-rw-r--r--tools/testing/selftests/cgroup/test_core.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/tools/testing/selftests/cgroup/test_core.c b/tools/testing/selftests/cgroup/test_core.c
index 3df648c37876..01b766506973 100644
--- a/tools/testing/selftests/cgroup/test_core.c
+++ b/tools/testing/selftests/cgroup/test_core.c
@@ -674,6 +674,73 @@ cleanup:
return ret;
}
+/*
+ * cgroup migration permission check should be performed based on the
+ * credentials at the time of open instead of write.
+ */
+static int test_cgcore_lesser_euid_open(const char *root)
+{
+ const uid_t test_euid = 65534; /* usually nobody, any !root is fine */
+ int ret = KSFT_FAIL;
+ char *cg_test_a = NULL, *cg_test_b = NULL;
+ char *cg_test_a_procs = NULL, *cg_test_b_procs = NULL;
+ int cg_test_b_procs_fd = -1;
+ uid_t saved_uid;
+
+ cg_test_a = cg_name(root, "cg_test_a");
+ cg_test_b = cg_name(root, "cg_test_b");
+
+ if (!cg_test_a || !cg_test_b)
+ goto cleanup;
+
+ cg_test_a_procs = cg_name(cg_test_a, "cgroup.procs");
+ cg_test_b_procs = cg_name(cg_test_b, "cgroup.procs");
+
+ if (!cg_test_a_procs || !cg_test_b_procs)
+ goto cleanup;
+
+ if (cg_create(cg_test_a) || cg_create(cg_test_b))
+ goto cleanup;
+
+ if (cg_enter_current(cg_test_a))
+ goto cleanup;
+
+ if (chown(cg_test_a_procs, test_euid, -1) ||
+ chown(cg_test_b_procs, test_euid, -1))
+ goto cleanup;
+
+ saved_uid = geteuid();
+ if (seteuid(test_euid))
+ goto cleanup;
+
+ cg_test_b_procs_fd = open(cg_test_b_procs, O_RDWR);
+
+ if (seteuid(saved_uid))
+ goto cleanup;
+
+ if (cg_test_b_procs_fd < 0)
+ goto cleanup;
+
+ if (write(cg_test_b_procs_fd, "0", 1) >= 0 || errno != EACCES)
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ cg_enter_current(root);
+ if (cg_test_b_procs_fd >= 0)
+ close(cg_test_b_procs_fd);
+ if (cg_test_b)
+ cg_destroy(cg_test_b);
+ if (cg_test_a)
+ cg_destroy(cg_test_a);
+ free(cg_test_b_procs);
+ free(cg_test_a_procs);
+ free(cg_test_b);
+ free(cg_test_a);
+ return ret;
+}
+
#define T(x) { x, #x }
struct corecg_test {
int (*fn)(const char *root);
@@ -689,6 +756,7 @@ struct corecg_test {
T(test_cgcore_proc_migration),
T(test_cgcore_thread_migration),
T(test_cgcore_destroy),
+ T(test_cgcore_lesser_euid_open),
};
#undef T