On 10/29/24 20:50, zhouyuhang wrote:
From: zhouyuhang <zhouyuhang@xxxxxxxxxx>
The libcap commit aca076443591 ("Make cap_t operations thread safe.")
added a __u8 mutex at the beginning of the struct _cap_struct, it changes
the offset of the members in the structure that breaks the assumption
made in the "struct libcap" definition in clone3_cap_checkpoint_restore.c.
This will cause the test case to fail with the following output:
# RUN global.clone3_cap_checkpoint_restore ...
# clone3() syscall supported
# clone3_cap_checkpoint_restore.c:151:clone3_cap_checkpoint_restore:Child has PID 130508
cap_set_proc: Operation not permitted
Sounds like EPERM is returned here. What's the error number from
cap_set_proc().
# clone3_cap_checkpoint_restore.c:160:clone3_cap_checkpoint_restore:Expected set_capability() (-1) == 0 (0)
What's the error number here? Looks like this test simply
uses perror - it is better to use strerror() which includes
the error number.
Is this related EPERM?
# clone3_cap_checkpoint_restore.c:161:clone3_cap_checkpoint_restore:Could not set CAP_CHECKPOINT_RESTORE
# clone3_cap_checkpoint_restore: Test terminated by assertion
# FAIL global.clone3_cap_checkpoint_restore
Changing to using capget and capset syscall directly here can fix this error,
just like what the commit 663af70aabb7 ("bpf: selftests: Add helpers to directly
use the capget and capset syscall") does.
Is this still accurate for v3 - Does this patch match the
bpf commit?
What is the output with this patch? Include it in the change log.
Signed-off-by: zhouyuhang <zhouyuhang@xxxxxxxxxx>> ---
Please mention the changes from v2 to v3 here so it makes it
easier for reviewers associating the changes to the reviewer.
I had to go look up v1 and v2.
.../clone3/clone3_cap_checkpoint_restore.c | 58 +++++++++----------
1 file changed, 27 insertions(+), 31 deletions(-)
diff --git a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
index 3c196fa86c99..8b61702bf721 100644
--- a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
+++ b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
@@ -27,6 +27,13 @@
#include "../kselftest_harness.h"
#include "clone3_selftests.h"
+/*
+ * Prevent not being defined in the header file
+ */
+#ifndef CAP_CHECKPOINT_RESTORE
+#define CAP_CHECKPOINT_RESTORE 40
+#endif
+
static void child_exit(int ret)
{
fflush(stdout);
@@ -87,47 +94,36 @@ static int test_clone3_set_tid(struct __test_metadata *_metadata,
return ret;
}
-struct libcap {
- struct __user_cap_header_struct hdr;
- struct __user_cap_data_struct data[2];
-};
-
static int set_capability(void)
{
- cap_value_t cap_values[] = { CAP_SETUID, CAP_SETGID };
- struct libcap *cap;
- int ret = -1;
- cap_t caps;
-
- caps = cap_get_proc();
- if (!caps) {
- perror("cap_get_proc");
+ struct __user_cap_data_struct data[2];
+ struct __user_cap_header_struct hdr = {
+ .version = _LINUX_CAPABILITY_VERSION_3,
cap_validate_magic() handles _LINUX_CAPABILITY_VERSION_1,
_LINUX_CAPABILITY_VERSION_2, and _LINUX_CAPABILITY_VERSION_3
It would help to add a comment on why it is necessary to
set the version here.
+ };
+ __u32 cap0 = 1 << CAP_SETUID | 1 << CAP_SETGID;
+ __u32 cap1 = 1 << (CAP_CHECKPOINT_RESTORE - 32);
Explain why this is necessary - a comment will help future
maintenance of this code.
+ int ret;
+
+ ret = capget(&hdr, data);
+ if (ret) {
+ perror("capget");
return -1;
}
/* Drop all capabilities */
- if (cap_clear(caps)) {
- perror("cap_clear");
- goto out;
- }
-
- cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET);
- cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET);
+ memset(&data, 0, sizeof(data));
- cap = (struct libcap *) caps;
+ data[0].effective |= cap0;
+ data[0].permitted |= cap0;
- /* 40 -> CAP_CHECKPOINT_RESTORE */
- cap->data[1].effective |= 1 << (40 - 32);
- cap->data[1].permitted |= 1 << (40 - 32);
+ data[1].effective |= cap1;
+ data[1].permitted |= cap1;
- if (cap_set_proc(caps)) {
- perror("cap_set_proc");
- goto out;
+ ret = capset(&hdr, data);
+ if (ret) {
+ perror("capset");
+ return -1;
}
- ret = 0;
-out:
- if (cap_free(caps))
- perror("cap_free");
return ret;
}
