From: Tejun Heo <tj@kernel.org>
To: torvalds@linuxfoundation.org, ebiederm@xmission.com,
mkoutny@suse.com, axboe@kernel.dk, keescook@chromium.org,
oleg@redhat.com, peterz@infradead.org, tglx@linutronix.de,
jnewsome@torproject.org, legion@kernel.org, luto@amacapital.net,
jannh@google.com
Cc: linux-kernel@vger.kernel.org, security@kernel.org,
kernel-team@fb.com, Tejun Heo <tj@kernel.org>
Subject: [PATCH 6/6] selftests: cgroup: Test open-time cgroup namespace usage for migration checks
Date: Mon, 13 Dec 2021 09:18:33 -1000 [thread overview]
Message-ID: <20211213191833.916632-7-tj@kernel.org> (raw)
In-Reply-To: <20211213191833.916632-1-tj@kernel.org>
When a task is writing to an fd opened by a different task, the perm check
should use the cgroup namespace of the latter task. Add a test for it.
Signed-off-by: Tejun Heo <tj@kernel.org>
---
tools/testing/selftests/cgroup/test_core.c | 97 ++++++++++++++++++++++
1 file changed, 97 insertions(+)
diff --git a/tools/testing/selftests/cgroup/test_core.c b/tools/testing/selftests/cgroup/test_core.c
index 01b766506973..600123503063 100644
--- a/tools/testing/selftests/cgroup/test_core.c
+++ b/tools/testing/selftests/cgroup/test_core.c
@@ -1,11 +1,14 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#define _GNU_SOURCE
#include <linux/limits.h>
+#include <linux/sched.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
+#include <sched.h>
#include <stdio.h>
#include <errno.h>
#include <signal.h>
@@ -741,6 +744,99 @@ static int test_cgcore_lesser_euid_open(const char *root)
return ret;
}
+struct lesser_ns_open_thread_arg {
+ const char *path;
+ int fd;
+ int err;
+};
+
+static int lesser_ns_open_thread_fn(void *arg)
+{
+ struct lesser_ns_open_thread_arg *targ = arg;
+
+ targ->fd = open(targ->path, O_RDWR);
+ targ->err = errno;
+ return 0;
+}
+
+/*
+ * cgroup migration permission check should be performed based on the cgroup
+ * namespace at the time of open instead of write.
+ */
+static int test_cgcore_lesser_ns_open(const char *root)
+{
+ static char stack[65536];
+ 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;
+ struct lesser_ns_open_thread_arg targ = { .fd = -1 };
+ pid_t pid;
+ int status;
+
+ 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_b))
+ goto cleanup;
+
+ if (chown(cg_test_a_procs, test_euid, -1) ||
+ chown(cg_test_b_procs, test_euid, -1))
+ goto cleanup;
+
+ targ.path = cg_test_b_procs;
+ pid = clone(lesser_ns_open_thread_fn, stack + sizeof(stack),
+ CLONE_NEWCGROUP | CLONE_FILES | CLONE_VM | SIGCHLD,
+ &targ);
+ if (pid < 0)
+ goto cleanup;
+
+ if (waitpid(pid, &status, 0) < 0)
+ goto cleanup;
+
+ if (!WIFEXITED(status))
+ goto cleanup;
+
+ cg_test_b_procs_fd = targ.fd;
+ if (cg_test_b_procs_fd < 0)
+ goto cleanup;
+
+ if (cg_enter_current(cg_test_a))
+ goto cleanup;
+
+ if ((status = write(cg_test_b_procs_fd, "0", 1)) >= 0 || errno != ENOENT)
+ 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);
@@ -757,6 +853,7 @@ struct corecg_test {
T(test_cgcore_thread_migration),
T(test_cgcore_destroy),
T(test_cgcore_lesser_euid_open),
+ T(test_cgcore_lesser_ns_open),
};
#undef T
--
2.34.1
next prev parent reply other threads:[~2021-12-13 19:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-13 19:18 [PATCHSET v2 cgroup/for-5.16-fixes] cgroup: Use open-time creds and namespace for migration perm checks Tejun Heo
2021-12-13 19:18 ` [PATCH 1/6] cgroup: Use open-time credentials for process migraton " Tejun Heo
2021-12-14 17:03 ` Michal Koutný
2021-12-13 19:18 ` [PATCH 2/6] cgroup: Allocate cgroup_file_ctx for kernfs_open_file->priv Tejun Heo
2021-12-13 19:29 ` Linus Torvalds
2021-12-13 19:56 ` Tejun Heo
2021-12-14 17:03 ` Michal Koutný
2021-12-14 19:44 ` [PATCH v3 " Tejun Heo
2021-12-15 7:37 ` Michal Koutný
2021-12-16 9:22 ` [cgroup] 27183b4e07: WARNING:at_mm/slab.c:#___cache_free kernel test robot
2021-12-16 9:43 ` Michal Koutný
2021-12-13 19:18 ` [PATCH 3/6] cgroup: Use open-time cgroup namespace for process migration perm checks Tejun Heo
2021-12-14 17:04 ` Michal Koutný
2021-12-13 19:18 ` [PATCH 4/6] selftests: cgroup: Make cg_create() use 0755 for permission instead of 0644 Tejun Heo
2021-12-14 17:04 ` Michal Koutný
2021-12-13 19:18 ` [PATCH 5/6] selftests: cgroup: Test open-time credential usage for migration checks Tejun Heo
2021-12-14 17:04 ` Michal Koutný
2021-12-13 19:18 ` Tejun Heo [this message]
2021-12-14 17:04 ` [PATCH 6/6] selftests: cgroup: Test open-time cgroup namespace " Michal Koutný
2022-01-06 21:05 ` [PATCHSET v2 cgroup/for-5.16-fixes] cgroup: Use open-time creds and namespace for migration perm checks Tejun Heo
-- strict thread matches above, loose matches on Subject: below --
2021-12-09 21:47 [PATCHSET " Tejun Heo
2021-12-09 21:47 ` [PATCH 6/6] selftests: cgroup: Test open-time cgroup namespace usage for migration checks Tejun Heo
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