Messages in this thread | | | Date | Fri, 1 Jun 2018 14:12:12 +0300 | From | "Dmitry V. Levin" <> | Subject | Re: [PATCH bpf 1/2] bpf: fix alignment of netns_dev/netns_ino fields in bpf_{map,prog}_info |
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On Fri, Jun 01, 2018 at 04:41:16AM -0400, Alexei Starovoitov wrote: > On Fri, Jun 01, 2018 at 06:12:10AM +0300, Dmitry V. Levin wrote: > > Hi, > > > > Looks like the ABI bug in bpf_map_info and bpf_prog info introduced > > in 4.16 is going to slip into 4.17, causing extra pain to 32-bit > > userspace. I'm adding Linus to this thread in hope it might help > > to get a fix applied before 4.17 is released. > > The issue identified in patch 1 is valid. > These two fields won't be properly accessible by 32-bit user space > on 64-bit kernel.
Yes, and currently there is no way to build a 32-bit userspace that would work properly both with 32-bit and 64-bit kernels.
> But the fix in patch 1 is wrong.
Please elaborate.
> The patch 2 is completely unnecessary.
The patch 2 doesn't have to be backported to 4.16, but if it was implemented in 4.16, there would be no bug to discuss. That is, the patch 2 is a good policy that would help to avoid this class of bugs in the future.
Alexei, looks like your Acked-by on the buggy commit 52775b33bb5072fbc07b02c0cf4fe8da1f7ee7cd affects your judgement. If this is the case, please refer patch 2 to other people who are less biased.
> Everyone can also see that the patches are still marked as 'new' in patchworks > meaning that we didn't process them. > At the moment many networking folks are traveling to netconf > and we only had a chance to discuss this set last night. > We'll try to send a fix in coming days. > But regardless whether 4.17 is realesed this sunday or not > we're not going to rush wrong patch in without proper code review > and discussion. > That future patch either will land in 4.17 (if it's dealyed into next sunday) > or it will be sent to stable.
Note that the fix was submitted to netdev on 2018-05-27. One week is surely enough to make this bug fixed, isn't it?
> To speed up the situation next time please report the issue that you find > to public netdev mailing list instead of using proprietary distro emails.
Please explain to me and to the public what do you mean by making this statement.
I do believe strace developers are free to discuss among themselves using whatever means of communication they find appropriate.
I do believe the issue was properly reported to netdev, see https://lkml.kernel.org/r/20180527112835.GA9118@asgard.redhat.com https://lkml.kernel.org/r/20180527112842.GA18204@asgard.redhat.com
I'd like to use this opportunity to thank Eugene for submitting the fix the same day the issue was identified as a kernel bug.
Alexei, please do not exclude my email address from this discussion. Thanks.
> > On Wed, May 30, 2018 at 09:18:58PM +0300, Dmitry V. Levin wrote: > > > On Sun, May 27, 2018 at 01:28:42PM +0200, Eugene Syromiatnikov wrote: > > > > Recent introduction of netns_dev/netns_ino to bpf_map_info/bpf_prog info > > > > has broken compat, as offsets of these fields are different in 32-bit > > > > and 64-bit ABIs. One fix (other than implementing compat support in > > > > syscall in order to handle this discrepancy) is to use __aligned_u64 > > > > instead of __u64 for these fields. > > > > > > > > Reported-by: Dmitry V. Levin <ldv@altlinux.org> > > > > Fixes: 52775b33bb507 ("bpf: offload: report device information about > > > > offloaded maps") > > > > Fixes: 675fc275a3a2d ("bpf: offload: report device information for > > > > offloaded programs") > > > > > > > > Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com> > > > > > > Reviewed-by: "Dmitry V. Levin" <ldv@altlinux.org> > > > Cc: <stable@vger.kernel.org> # v4.16+ > > > > > > Thanks, > > > > > > > --- > > > > include/uapi/linux/bpf.h | 8 ++++---- > > > > tools/include/uapi/linux/bpf.h | 8 ++++---- > > > > 2 files changed, 8 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > > > index c5ec897..903010a 100644 > > > > --- a/include/uapi/linux/bpf.h > > > > +++ b/include/uapi/linux/bpf.h > > > > @@ -1017,8 +1017,8 @@ struct bpf_prog_info { > > > > __aligned_u64 map_ids; > > > > char name[BPF_OBJ_NAME_LEN]; > > > > __u32 ifindex; > > > > - __u64 netns_dev; > > > > - __u64 netns_ino; > > > > + __aligned_u64 netns_dev; > > > > + __aligned_u64 netns_ino; > > > > } __attribute__((aligned(8))); > > > > > > > > struct bpf_map_info { > > > > @@ -1030,8 +1030,8 @@ struct bpf_map_info { > > > > __u32 map_flags; > > > > char name[BPF_OBJ_NAME_LEN]; > > > > __u32 ifindex; > > > > - __u64 netns_dev; > > > > - __u64 netns_ino; > > > > + __aligned_u64 netns_dev; > > > > + __aligned_u64 netns_ino; > > > > } __attribute__((aligned(8))); > > > > > > > > /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed > > > > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h > > > > index c5ec897..903010a 100644 > > > > --- a/tools/include/uapi/linux/bpf.h > > > > +++ b/tools/include/uapi/linux/bpf.h > > > > @@ -1017,8 +1017,8 @@ struct bpf_prog_info { > > > > __aligned_u64 map_ids; > > > > char name[BPF_OBJ_NAME_LEN]; > > > > __u32 ifindex; > > > > - __u64 netns_dev; > > > > - __u64 netns_ino; > > > > + __aligned_u64 netns_dev; > > > > + __aligned_u64 netns_ino; > > > > } __attribute__((aligned(8))); > > > > > > > > struct bpf_map_info { > > > > @@ -1030,8 +1030,8 @@ struct bpf_map_info { > > > > __u32 map_flags; > > > > char name[BPF_OBJ_NAME_LEN]; > > > > __u32 ifindex; > > > > - __u64 netns_dev; > > > > - __u64 netns_ino; > > > > + __aligned_u64 netns_dev; > > > > + __aligned_u64 netns_ino; > > > > } __attribute__((aligned(8))); > > > > > > > > /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
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