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Groups > linux.kernel > #1456196 > unrolled thread

[RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI

Started bySargun Dhillon <sargun@sargun.me>
First post2016-08-04 09:20 +0200
Last post2016-08-04 13:00 +0200
Articles 3 — 2 participants

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  [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI Sargun Dhillon <sargun@sargun.me> - 2016-08-04 09:20 +0200
    Re: [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel  ABI Daniel Borkmann <daniel@iogearbox.net> - 2016-08-04 13:00 +0200
      Re: [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel  ABI Daniel Borkmann <daniel@iogearbox.net> - 2016-08-04 13:00 +0200

#1456196 — [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI

FromSargun Dhillon <sargun@sargun.me>
Date2016-08-04 09:20 +0200
Subject[RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI
Message-ID<s2l6F-5K2-15@gated-at.bofh.it>
I think it makes sense to restrict Checmate to loading programs that have been 
compiled with the current kernel ABI. We can further stabilize the ABI, and 
perhaps lift this restriction later.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
---
 kernel/bpf/syscall.c         | 2 +-
 samples/bpf/checmate1_kern.c | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 228f962..2a37b4d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -741,7 +741,7 @@ static int bpf_prog_load(union bpf_attr *attr)
 	if (attr->insn_cnt >= BPF_MAXINSNS)
 		return -EINVAL;
 
-	if (type == BPF_PROG_TYPE_KPROBE &&
+	if ((type & (BPF_PROG_TYPE_KPROBE | BPF_PROG_TYPE_CHECMATE)) &&
 	    attr->kern_version != LINUX_VERSION_CODE)
 		return -EINVAL;
 
diff --git a/samples/bpf/checmate1_kern.c b/samples/bpf/checmate1_kern.c
index f78b66b..d4ec1fa 100644
--- a/samples/bpf/checmate1_kern.c
+++ b/samples/bpf/checmate1_kern.c
@@ -3,6 +3,7 @@
 #include <linux/in.h>
 #include <linux/checmate.h>
 #include "bpf_helpers.h"
+#include <linux/version.h>
 
 SEC("checmate")
 int prog(struct checmate_ctx *ctx)
@@ -24,4 +25,4 @@ int prog(struct checmate_ctx *ctx)
 }
 
 char _license[] SEC("license") = "GPL";
-
+u32 _version SEC("version") = LINUX_VERSION_CODE;
-- 
2.7.4

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#1456333 — Re: [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI

FromDaniel Borkmann <daniel@iogearbox.net>
Date2016-08-04 13:00 +0200
SubjectRe: [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI
Message-ID<s2oxA-7OH-5@gated-at.bofh.it>
In reply to#1456196
On 08/04/2016 09:12 AM, Sargun Dhillon wrote:
> I think it makes sense to restrict Checmate to loading programs that have been
> compiled with the current kernel ABI. We can further stabilize the ABI, and
> perhaps lift this restriction later.
>
> Signed-off-by: Sargun Dhillon <sargun@sargun.me>
> ---
>   kernel/bpf/syscall.c         | 2 +-
>   samples/bpf/checmate1_kern.c | 3 ++-
>   2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 228f962..2a37b4d 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -741,7 +741,7 @@ static int bpf_prog_load(union bpf_attr *attr)
>   	if (attr->insn_cnt >= BPF_MAXINSNS)
>   		return -EINVAL;
>
> -	if (type == BPF_PROG_TYPE_KPROBE &&
> +	if ((type & (BPF_PROG_TYPE_KPROBE | BPF_PROG_TYPE_CHECMATE)) &&
>   	    attr->kern_version != LINUX_VERSION_CODE)

Btw, this check is correct, program types are not masks.

BPF_PROG_TYPE_KPROBE (== 2) and BPF_PROG_TYPE_CHECMATE (== 7) will now
require every type to have a version code ...

>   		return -EINVAL;
>
> diff --git a/samples/bpf/checmate1_kern.c b/samples/bpf/checmate1_kern.c
> index f78b66b..d4ec1fa 100644
> --- a/samples/bpf/checmate1_kern.c
> +++ b/samples/bpf/checmate1_kern.c
> @@ -3,6 +3,7 @@
>   #include <linux/in.h>
>   #include <linux/checmate.h>
>   #include "bpf_helpers.h"
> +#include <linux/version.h>
>
>   SEC("checmate")
>   int prog(struct checmate_ctx *ctx)
> @@ -24,4 +25,4 @@ int prog(struct checmate_ctx *ctx)
>   }
>
>   char _license[] SEC("license") = "GPL";
> -
> +u32 _version SEC("version") = LINUX_VERSION_CODE;
>

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#1456335 — Re: [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI

FromDaniel Borkmann <daniel@iogearbox.net>
Date2016-08-04 13:00 +0200
SubjectRe: [RFC 4/4] bpf: Restrict Checmate bpf programs to current kernel ABI
Message-ID<s2oxA-7OH-25@gated-at.bofh.it>
In reply to#1456333
On 08/04/2016 11:52 AM, Daniel Borkmann wrote:
> On 08/04/2016 09:12 AM, Sargun Dhillon wrote:
>> I think it makes sense to restrict Checmate to loading programs that have been
>> compiled with the current kernel ABI. We can further stabilize the ABI, and
>> perhaps lift this restriction later.
>>
>> Signed-off-by: Sargun Dhillon <sargun@sargun.me>
>> ---
>>   kernel/bpf/syscall.c         | 2 +-
>>   samples/bpf/checmate1_kern.c | 3 ++-
>>   2 files changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
>> index 228f962..2a37b4d 100644
>> --- a/kernel/bpf/syscall.c
>> +++ b/kernel/bpf/syscall.c
>> @@ -741,7 +741,7 @@ static int bpf_prog_load(union bpf_attr *attr)
>>       if (attr->insn_cnt >= BPF_MAXINSNS)
>>           return -EINVAL;
>>
>> -    if (type == BPF_PROG_TYPE_KPROBE &&
>> +    if ((type & (BPF_PROG_TYPE_KPROBE | BPF_PROG_TYPE_CHECMATE)) &&
>>           attr->kern_version != LINUX_VERSION_CODE)
>
> Btw, this check is correct, program types are not masks.

Sorry, I meant to write *not* correct, which was hopefully inferable from
the rest.

> BPF_PROG_TYPE_KPROBE (== 2) and BPF_PROG_TYPE_CHECMATE (== 7) will now
> require every type to have a version code ...
>
>>           return -EINVAL;
>>

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