.../clone3/clone3_cap_checkpoint_restore.c | 58 +++++++++---------- 1 file changed, 27 insertions(+), 31 deletions(-)
From: zhouyuhang <zhouyuhang@kylinos.cn>
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
# clone3_cap_checkpoint_restore.c:160:clone3_cap_checkpoint_restore:Expected set_capability() (-1) == 0 (0)
# 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.
Signed-off-by: zhouyuhang <zhouyuhang@kylinos.cn>
---
.../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,
+ };
+ __u32 cap0 = 1 << CAP_SETUID | 1 << CAP_SETGID;
+ __u32 cap1 = 1 << (CAP_CHECKPOINT_RESTORE - 32);
+ 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;
}
--
2.27.0On 10/29/24 20:50, zhouyuhang wrote:
> From: zhouyuhang <zhouyuhang@kylinos.cn>
>
> 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@kylinos.cn>> ---
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;
> }
>
在 2024/11/1 06:59, Shuah Khan 写道:
> On 10/29/24 20:50, zhouyuhang wrote:
>> From: zhouyuhang <zhouyuhang@kylinos.cn>
>>
>> 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().
Yes, cap_set_proc returns -EPERM here.
>
>> #
>> 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?
set_capability always returns -1 on failure, which is not related to EPERM.
Here I'll take your advice and use strerror and let set_capability
return the actual error code.
>
>> #
>> 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.
>
I think it's a match. The main code has not changed from v1 to v3.
The comment at the beginning of this file says "capabilities related code
based on selftests/bpf/test_verifier.c" and we only need capget and capset,
this is the same as the bpf commit.
The output is as follows:
# RUN global.clone3_cap_checkpoint_restore ...
# clone3() syscall supported
#
clone3_cap_checkpoint_restore.c:147:clone3_cap_checkpoint_restore:Child
has PID 18631
#
clone3_cap_checkpoint_restore.c:91:clone3_cap_checkpoint_restore:[18630]
Trying clone3() with CLONE_SET_TID to 18631
#
clone3_cap_checkpoint_restore.c:58:clone3_cap_checkpoint_restore:Operation
not permitted - Failed to create new process
#
clone3_cap_checkpoint_restore.c:93:clone3_cap_checkpoint_restore:[18630]
clone3() with CLONE_SET_TID 18631 says:-1
#
clone3_cap_checkpoint_restore.c:91:clone3_cap_checkpoint_restore:[18630]
Trying clone3() with CLONE_SET_TID to 18631
# clone3_cap_checkpoint_restore.c:73:clone3_cap_checkpoint_restore:I
am the parent (18630). My child's pid is 18631
# clone3_cap_checkpoint_restore.c:66:clone3_cap_checkpoint_restore:I
am the child, my PID is 18631 (expected 18631)
#
clone3_cap_checkpoint_restore.c:93:clone3_cap_checkpoint_restore:[18630]
clone3() with CLONE_SET_TID 18631 says:0
# OK global.clone3_cap_checkpoint_restore
ok 1 global.clone3_cap_checkpoint_restore
# PASSED: 1 / 1 tests passed.
>>
>> Signed-off-by: zhouyuhang <zhouyuhang@kylinos.cn>> ---
>
> 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.
>
Sorry, I'm not very familiar with this.
The changes from v1 to v3 mainly removed the locally declared
capget and capset system calls. Perhaps you still have an impression of
this.
---
v3:
* Remove locally declared system calls and retained the - lcap in
the Makefile.
v2:
* Move locally declared system calls to header file.
v1:
* Directly using capget and capset and declare them locally.
---
>> .../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.
CAP_CHECKPOINT_RESTORE is greater than 32, using _LINUX_CAPABILITY_VERSION_1
here causes the kernel to copy only data[0] and ignore data[1], which
invalidates the
CAP_CHECKPOINT_RESTORE setting.
_LINUX_CAPABILITY_VERSION_2 has already been deprecated.
>
>> + };
>> + __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.
>
CAP_CHECKPOINT_RESTORE is greater than 32, so we need two u32.
They will be combined into a u64 in mk_kernel_cap.
I'll add a few comments above and here.
Thank you very much for the above advice.
I'll make changes in v4.
>> + 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;
>> }
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