Re: [PATCH v1 bpf-next 06/11] bpf: Introduce two attach types for BPF_PROG_TYPE_SK_REUSEPORT.
I'm sending this mail just for logging because I failed to send mails only
to LKML, netdev, and bpf yesterday.
From: Martin KaFai Lau
Date: Thu, 3 Dec 2020 21:56:53 -0800
> On Thu, Dec 03, 2020 at 11:16:08PM +0900, Kuniyuki Iwashima wrote:
> > From: Martin KaFai Lau
> > Date: Wed, 2 Dec 2020 20:24:02 -0800
> > > On Wed, Dec 02, 2020 at 11:19:02AM -0800, Martin KaFai Lau wrote:
> > > > On Tue, Dec 01, 2020 at 06:04:50PM -0800, Andrii Nakryiko wrote:
> > > > > On Tue, Dec 1, 2020 at 6:49 AM Kuniyuki Iwashima
> > > > > wrote:
> > > > > >
> > > > > > This commit adds new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT
> > > > > > to
> > > > > > check if the attached eBPF program is capable of migrating sockets.
> > > > > >
> > > > > > When the eBPF program is attached, the kernel runs it for socket
> > > > > > migration
> > > > > > only if the expected_attach_type is
> > > > > > BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.
> > > > > > The kernel will change the behaviour depending on the returned
> > > > > > value:
> > > > > >
> > > > > > - SK_PASS with selected_sk, select it as a new listener
> > > > > > - SK_PASS with selected_sk NULL, fall back to the random selection
> > > > > > - SK_DROP, cancel the migration
> > > > > >
> > > > > > Link:
> > > > > > https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6t...@kafai-mbp.dhcp.thefacebook.com/
> > > > > > Suggested-by: Martin KaFai Lau
> > > > > > Signed-off-by: Kuniyuki Iwashima
> > > > > > ---
> > > > > > include/uapi/linux/bpf.h | 2 ++
> > > > > > kernel/bpf/syscall.c | 8
> > > > > > tools/include/uapi/linux/bpf.h | 2 ++
> > > > > > 3 files changed, 12 insertions(+)
> > > > > >
> > > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > > > > index 85278deff439..cfc207ae7782 100644
> > > > > > --- a/include/uapi/linux/bpf.h
> > > > > > +++ b/include/uapi/linux/bpf.h
> > > > > > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > > > > > BPF_XDP_CPUMAP,
> > > > > > BPF_SK_LOOKUP,
> > > > > > BPF_XDP,
> > > > > > + BPF_SK_REUSEPORT_SELECT,
> > > > > > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > > > > > __MAX_BPF_ATTACH_TYPE
> > > > > > };
> > > > > >
> > > > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > > > > index f3fe9f53f93c..a0796a8de5ea 100644
> > > > > > --- a/kernel/bpf/syscall.c
> > > > > > +++ b/kernel/bpf/syscall.c
> > > > > > @@ -2036,6 +2036,14 @@ bpf_prog_load_check_attach(enum
> > > > > > bpf_prog_type prog_type,
> > > > > > if (expected_attach_type == BPF_SK_LOOKUP)
> > > > > > return 0;
> > > > > > return -EINVAL;
> > > > > > + case BPF_PROG_TYPE_SK_REUSEPORT:
> > > > > > + switch (expected_attach_type) {
> > > > > > + case BPF_SK_REUSEPORT_SELECT:
> > > > > > + case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:
> > > > > > + return 0;
> > > > > > + default:
> > > > > > + return -EINVAL;
> > > > > > + }
> > > > >
> > > > > this is a kernel regression, previously expected_attach_type wasn't
> > > > > enforced, so user-space could have provided any number without an
> > > > > error.
> > > > I also think this change alone will break things like when the usual
> > > > attr->expected_attach_type == 0 case. At least changes is needed in
> > > > bpf_prog_load_fixup_attach_type() which is also handling a
> > > > similar situation for BPF_PROG_TYPE_CGROUP_SOCK.
> > > >
> > > > I now think there is no need to expose new bpf_attach_type to the UAPI.
> > > > Since the prog->expected_attach_type is not used, it can be cleared at
> > > > load time
> > > > and then only set to BPF_SK_REUSEPORT_SELECT_OR_MIGRATE (probably
> > > > defined
> > > > internally at filter.[c|h]) in the is_valid_access() when "migration"
> > > > is accessed. When "migration" is accessed, the bpf prog can handle
> > > > migration (and the original not-migration) case.
> > > Scrap this internal only BPF_SK_REUSEPORT_SELECT_OR_MIGRATE idea.
> > > I think there will be cases that bpf prog wants to do both
> > > without accessing any field from sk_reuseport_md.
> > >
> > > Lets go back to the discussion on using a similar
> > > idea as BPF_PROG_TYPE_CGROUP_SOCK in bpf_prog_load_fixup_attach_type().
> > > I am not aware there is loader setting a random number
> > > in expected_attach_type, so the chance of breaking
> > > is very low. There was a similar discussion earlier [0].
> > >
> > > [0]:
> > > https://lore.kernel.org/netdev/20200126045443.f47dzxdglazzchfm@ast-mbp/
> >
> > Thank you for the idea and reference.
> >
> > I will remove the change in bpf_prog_load_check_attach() and set the
> > default value (BPF_SK_REUSEPORT_SELECT) in bpf_prog_load_fixup_attach_type()
> > for backward compatibility if expected_attach_type is 0.
> check_attach_type() can be kept. You can refer to
Re: [PATCH v1 bpf-next 06/11] bpf: Introduce two attach types for BPF_PROG_TYPE_SK_REUSEPORT.
On Thu, Dec 03, 2020 at 11:16:08PM +0900, Kuniyuki Iwashima wrote:
> From: Martin KaFai Lau
> Date: Wed, 2 Dec 2020 20:24:02 -0800
> > On Wed, Dec 02, 2020 at 11:19:02AM -0800, Martin KaFai Lau wrote:
> > > On Tue, Dec 01, 2020 at 06:04:50PM -0800, Andrii Nakryiko wrote:
> > > > On Tue, Dec 1, 2020 at 6:49 AM Kuniyuki Iwashima
> > > > wrote:
> > > > >
> > > > > This commit adds new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT to
> > > > > check if the attached eBPF program is capable of migrating sockets.
> > > > >
> > > > > When the eBPF program is attached, the kernel runs it for socket
> > > > > migration
> > > > > only if the expected_attach_type is
> > > > > BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.
> > > > > The kernel will change the behaviour depending on the returned value:
> > > > >
> > > > > - SK_PASS with selected_sk, select it as a new listener
> > > > > - SK_PASS with selected_sk NULL, fall back to the random selection
> > > > > - SK_DROP, cancel the migration
> > > > >
> > > > > Link:
> > > > > https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6t...@kafai-mbp.dhcp.thefacebook.com/
> > > > > Suggested-by: Martin KaFai Lau
> > > > > Signed-off-by: Kuniyuki Iwashima
> > > > > ---
> > > > > include/uapi/linux/bpf.h | 2 ++
> > > > > kernel/bpf/syscall.c | 8
> > > > > tools/include/uapi/linux/bpf.h | 2 ++
> > > > > 3 files changed, 12 insertions(+)
> > > > >
> > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > > > index 85278deff439..cfc207ae7782 100644
> > > > > --- a/include/uapi/linux/bpf.h
> > > > > +++ b/include/uapi/linux/bpf.h
> > > > > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > > > > BPF_XDP_CPUMAP,
> > > > > BPF_SK_LOOKUP,
> > > > > BPF_XDP,
> > > > > + BPF_SK_REUSEPORT_SELECT,
> > > > > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > > > > __MAX_BPF_ATTACH_TYPE
> > > > > };
> > > > >
> > > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > > > index f3fe9f53f93c..a0796a8de5ea 100644
> > > > > --- a/kernel/bpf/syscall.c
> > > > > +++ b/kernel/bpf/syscall.c
> > > > > @@ -2036,6 +2036,14 @@ bpf_prog_load_check_attach(enum bpf_prog_type
> > > > > prog_type,
> > > > > if (expected_attach_type == BPF_SK_LOOKUP)
> > > > > return 0;
> > > > > return -EINVAL;
> > > > > + case BPF_PROG_TYPE_SK_REUSEPORT:
> > > > > + switch (expected_attach_type) {
> > > > > + case BPF_SK_REUSEPORT_SELECT:
> > > > > + case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:
> > > > > + return 0;
> > > > > + default:
> > > > > + return -EINVAL;
> > > > > + }
> > > >
> > > > this is a kernel regression, previously expected_attach_type wasn't
> > > > enforced, so user-space could have provided any number without an
> > > > error.
> > > I also think this change alone will break things like when the usual
> > > attr->expected_attach_type == 0 case. At least changes is needed in
> > > bpf_prog_load_fixup_attach_type() which is also handling a
> > > similar situation for BPF_PROG_TYPE_CGROUP_SOCK.
> > >
> > > I now think there is no need to expose new bpf_attach_type to the UAPI.
> > > Since the prog->expected_attach_type is not used, it can be cleared at
> > > load time
> > > and then only set to BPF_SK_REUSEPORT_SELECT_OR_MIGRATE (probably defined
> > > internally at filter.[c|h]) in the is_valid_access() when "migration"
> > > is accessed. When "migration" is accessed, the bpf prog can handle
> > > migration (and the original not-migration) case.
> > Scrap this internal only BPF_SK_REUSEPORT_SELECT_OR_MIGRATE idea.
> > I think there will be cases that bpf prog wants to do both
> > without accessing any field from sk_reuseport_md.
> >
> > Lets go back to the discussion on using a similar
> > idea as BPF_PROG_TYPE_CGROUP_SOCK in bpf_prog_load_fixup_attach_type().
> > I am not aware there is loader setting a random number
> > in expected_attach_type, so the chance of breaking
> > is very low. There was a similar discussion earlier [0].
> >
> > [0]: https://lore.kernel.org/netdev/20200126045443.f47dzxdglazzchfm@ast-mbp/
>
> Thank you for the idea and reference.
>
> I will remove the change in bpf_prog_load_check_attach() and set the
> default value (BPF_SK_REUSEPORT_SELECT) in bpf_prog_load_fixup_attach_type()
> for backward compatibility if expected_attach_type is 0.
check_attach_type() can be kept. You can refer to
commit aac3fc320d94 for a similar situation.
Re: [PATCH v1 bpf-next 06/11] bpf: Introduce two attach types for BPF_PROG_TYPE_SK_REUSEPORT.
From: Martin KaFai Lau
Date: Wed, 2 Dec 2020 20:24:02 -0800
> On Wed, Dec 02, 2020 at 11:19:02AM -0800, Martin KaFai Lau wrote:
> > On Tue, Dec 01, 2020 at 06:04:50PM -0800, Andrii Nakryiko wrote:
> > > On Tue, Dec 1, 2020 at 6:49 AM Kuniyuki Iwashima
> > > wrote:
> > > >
> > > > This commit adds new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT to
> > > > check if the attached eBPF program is capable of migrating sockets.
> > > >
> > > > When the eBPF program is attached, the kernel runs it for socket
> > > > migration
> > > > only if the expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.
> > > > The kernel will change the behaviour depending on the returned value:
> > > >
> > > > - SK_PASS with selected_sk, select it as a new listener
> > > > - SK_PASS with selected_sk NULL, fall back to the random selection
> > > > - SK_DROP, cancel the migration
> > > >
> > > > Link:
> > > > https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6t...@kafai-mbp.dhcp.thefacebook.com/
> > > > Suggested-by: Martin KaFai Lau
> > > > Signed-off-by: Kuniyuki Iwashima
> > > > ---
> > > > include/uapi/linux/bpf.h | 2 ++
> > > > kernel/bpf/syscall.c | 8
> > > > tools/include/uapi/linux/bpf.h | 2 ++
> > > > 3 files changed, 12 insertions(+)
> > > >
> > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > > index 85278deff439..cfc207ae7782 100644
> > > > --- a/include/uapi/linux/bpf.h
> > > > +++ b/include/uapi/linux/bpf.h
> > > > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > > > BPF_XDP_CPUMAP,
> > > > BPF_SK_LOOKUP,
> > > > BPF_XDP,
> > > > + BPF_SK_REUSEPORT_SELECT,
> > > > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > > > __MAX_BPF_ATTACH_TYPE
> > > > };
> > > >
> > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > > index f3fe9f53f93c..a0796a8de5ea 100644
> > > > --- a/kernel/bpf/syscall.c
> > > > +++ b/kernel/bpf/syscall.c
> > > > @@ -2036,6 +2036,14 @@ bpf_prog_load_check_attach(enum bpf_prog_type
> > > > prog_type,
> > > > if (expected_attach_type == BPF_SK_LOOKUP)
> > > > return 0;
> > > > return -EINVAL;
> > > > + case BPF_PROG_TYPE_SK_REUSEPORT:
> > > > + switch (expected_attach_type) {
> > > > + case BPF_SK_REUSEPORT_SELECT:
> > > > + case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:
> > > > + return 0;
> > > > + default:
> > > > + return -EINVAL;
> > > > + }
> > >
> > > this is a kernel regression, previously expected_attach_type wasn't
> > > enforced, so user-space could have provided any number without an
> > > error.
> > I also think this change alone will break things like when the usual
> > attr->expected_attach_type == 0 case. At least changes is needed in
> > bpf_prog_load_fixup_attach_type() which is also handling a
> > similar situation for BPF_PROG_TYPE_CGROUP_SOCK.
> >
> > I now think there is no need to expose new bpf_attach_type to the UAPI.
> > Since the prog->expected_attach_type is not used, it can be cleared at load
> > time
> > and then only set to BPF_SK_REUSEPORT_SELECT_OR_MIGRATE (probably defined
> > internally at filter.[c|h]) in the is_valid_access() when "migration"
> > is accessed. When "migration" is accessed, the bpf prog can handle
> > migration (and the original not-migration) case.
> Scrap this internal only BPF_SK_REUSEPORT_SELECT_OR_MIGRATE idea.
> I think there will be cases that bpf prog wants to do both
> without accessing any field from sk_reuseport_md.
>
> Lets go back to the discussion on using a similar
> idea as BPF_PROG_TYPE_CGROUP_SOCK in bpf_prog_load_fixup_attach_type().
> I am not aware there is loader setting a random number
> in expected_attach_type, so the chance of breaking
> is very low. There was a similar discussion earlier [0].
>
> [0]: https://lore.kernel.org/netdev/20200126045443.f47dzxdglazzchfm@ast-mbp/
Thank you for the idea and reference.
I will remove the change in bpf_prog_load_check_attach() and set the
default value (BPF_SK_REUSEPORT_SELECT) in bpf_prog_load_fixup_attach_type()
for backward compatibility if expected_attach_type is 0.
> > > > case BPF_PROG_TYPE_EXT:
> > > > if (expected_attach_type)
> > > > return -EINVAL;
> > > > diff --git a/tools/include/uapi/linux/bpf.h
> > > > b/tools/include/uapi/linux/bpf.h
> > > > index 85278deff439..cfc207ae7782 100644
> > > > --- a/tools/include/uapi/linux/bpf.h
> > > > +++ b/tools/include/uapi/linux/bpf.h
> > > > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > > > BPF_XDP_CPUMAP,
> > > > BPF_SK_LOOKUP,
> > > > BPF_XDP,
> > > > + BPF_SK_REUSEPORT_SELECT,
> > > > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > > > __MAX_BPF_ATTACH_TYPE
> > > > };
> > > >
> > > > --
> > > > 2.17.2 (Apple Git-113)
Re: [PATCH v1 bpf-next 06/11] bpf: Introduce two attach types for BPF_PROG_TYPE_SK_REUSEPORT.
On Wed, Dec 02, 2020 at 11:19:02AM -0800, Martin KaFai Lau wrote:
> On Tue, Dec 01, 2020 at 06:04:50PM -0800, Andrii Nakryiko wrote:
> > On Tue, Dec 1, 2020 at 6:49 AM Kuniyuki Iwashima
> > wrote:
> > >
> > > This commit adds new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT to
> > > check if the attached eBPF program is capable of migrating sockets.
> > >
> > > When the eBPF program is attached, the kernel runs it for socket migration
> > > only if the expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.
> > > The kernel will change the behaviour depending on the returned value:
> > >
> > > - SK_PASS with selected_sk, select it as a new listener
> > > - SK_PASS with selected_sk NULL, fall back to the random selection
> > > - SK_DROP, cancel the migration
> > >
> > > Link:
> > > https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6t...@kafai-mbp.dhcp.thefacebook.com/
> > > Suggested-by: Martin KaFai Lau
> > > Signed-off-by: Kuniyuki Iwashima
> > > ---
> > > include/uapi/linux/bpf.h | 2 ++
> > > kernel/bpf/syscall.c | 8
> > > tools/include/uapi/linux/bpf.h | 2 ++
> > > 3 files changed, 12 insertions(+)
> > >
> > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > index 85278deff439..cfc207ae7782 100644
> > > --- a/include/uapi/linux/bpf.h
> > > +++ b/include/uapi/linux/bpf.h
> > > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > > BPF_XDP_CPUMAP,
> > > BPF_SK_LOOKUP,
> > > BPF_XDP,
> > > + BPF_SK_REUSEPORT_SELECT,
> > > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > > __MAX_BPF_ATTACH_TYPE
> > > };
> > >
> > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > index f3fe9f53f93c..a0796a8de5ea 100644
> > > --- a/kernel/bpf/syscall.c
> > > +++ b/kernel/bpf/syscall.c
> > > @@ -2036,6 +2036,14 @@ bpf_prog_load_check_attach(enum bpf_prog_type
> > > prog_type,
> > > if (expected_attach_type == BPF_SK_LOOKUP)
> > > return 0;
> > > return -EINVAL;
> > > + case BPF_PROG_TYPE_SK_REUSEPORT:
> > > + switch (expected_attach_type) {
> > > + case BPF_SK_REUSEPORT_SELECT:
> > > + case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:
> > > + return 0;
> > > + default:
> > > + return -EINVAL;
> > > + }
> >
> > this is a kernel regression, previously expected_attach_type wasn't
> > enforced, so user-space could have provided any number without an
> > error.
> I also think this change alone will break things like when the usual
> attr->expected_attach_type == 0 case. At least changes is needed in
> bpf_prog_load_fixup_attach_type() which is also handling a
> similar situation for BPF_PROG_TYPE_CGROUP_SOCK.
>
> I now think there is no need to expose new bpf_attach_type to the UAPI.
> Since the prog->expected_attach_type is not used, it can be cleared at load
> time
> and then only set to BPF_SK_REUSEPORT_SELECT_OR_MIGRATE (probably defined
> internally at filter.[c|h]) in the is_valid_access() when "migration"
> is accessed. When "migration" is accessed, the bpf prog can handle
> migration (and the original not-migration) case.
Scrap this internal only BPF_SK_REUSEPORT_SELECT_OR_MIGRATE idea.
I think there will be cases that bpf prog wants to do both
without accessing any field from sk_reuseport_md.
Lets go back to the discussion on using a similar
idea as BPF_PROG_TYPE_CGROUP_SOCK in bpf_prog_load_fixup_attach_type().
I am not aware there is loader setting a random number
in expected_attach_type, so the chance of breaking
is very low. There was a similar discussion earlier [0].
[0]: https://lore.kernel.org/netdev/20200126045443.f47dzxdglazzchfm@ast-mbp/
>
> >
> > > case BPF_PROG_TYPE_EXT:
> > > if (expected_attach_type)
> > > return -EINVAL;
> > > diff --git a/tools/include/uapi/linux/bpf.h
> > > b/tools/include/uapi/linux/bpf.h
> > > index 85278deff439..cfc207ae7782 100644
> > > --- a/tools/include/uapi/linux/bpf.h
> > > +++ b/tools/include/uapi/linux/bpf.h
> > > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > > BPF_XDP_CPUMAP,
> > > BPF_SK_LOOKUP,
> > > BPF_XDP,
> > > + BPF_SK_REUSEPORT_SELECT,
> > > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > > __MAX_BPF_ATTACH_TYPE
> > > };
> > >
> > > --
> > > 2.17.2 (Apple Git-113)
> > >
Re: [PATCH v1 bpf-next 06/11] bpf: Introduce two attach types for BPF_PROG_TYPE_SK_REUSEPORT.
On Tue, Dec 01, 2020 at 06:04:50PM -0800, Andrii Nakryiko wrote:
> On Tue, Dec 1, 2020 at 6:49 AM Kuniyuki Iwashima wrote:
> >
> > This commit adds new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT to
> > check if the attached eBPF program is capable of migrating sockets.
> >
> > When the eBPF program is attached, the kernel runs it for socket migration
> > only if the expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.
> > The kernel will change the behaviour depending on the returned value:
> >
> > - SK_PASS with selected_sk, select it as a new listener
> > - SK_PASS with selected_sk NULL, fall back to the random selection
> > - SK_DROP, cancel the migration
> >
> > Link:
> > https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6t...@kafai-mbp.dhcp.thefacebook.com/
> > Suggested-by: Martin KaFai Lau
> > Signed-off-by: Kuniyuki Iwashima
> > ---
> > include/uapi/linux/bpf.h | 2 ++
> > kernel/bpf/syscall.c | 8
> > tools/include/uapi/linux/bpf.h | 2 ++
> > 3 files changed, 12 insertions(+)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 85278deff439..cfc207ae7782 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > BPF_XDP_CPUMAP,
> > BPF_SK_LOOKUP,
> > BPF_XDP,
> > + BPF_SK_REUSEPORT_SELECT,
> > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > __MAX_BPF_ATTACH_TYPE
> > };
> >
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index f3fe9f53f93c..a0796a8de5ea 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> > @@ -2036,6 +2036,14 @@ bpf_prog_load_check_attach(enum bpf_prog_type
> > prog_type,
> > if (expected_attach_type == BPF_SK_LOOKUP)
> > return 0;
> > return -EINVAL;
> > + case BPF_PROG_TYPE_SK_REUSEPORT:
> > + switch (expected_attach_type) {
> > + case BPF_SK_REUSEPORT_SELECT:
> > + case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:
> > + return 0;
> > + default:
> > + return -EINVAL;
> > + }
>
> this is a kernel regression, previously expected_attach_type wasn't
> enforced, so user-space could have provided any number without an
> error.
I also think this change alone will break things like when the usual
attr->expected_attach_type == 0 case. At least changes is needed in
bpf_prog_load_fixup_attach_type() which is also handling a
similar situation for BPF_PROG_TYPE_CGROUP_SOCK.
I now think there is no need to expose new bpf_attach_type to the UAPI.
Since the prog->expected_attach_type is not used, it can be cleared at load time
and then only set to BPF_SK_REUSEPORT_SELECT_OR_MIGRATE (probably defined
internally at filter.[c|h]) in the is_valid_access() when "migration"
is accessed. When "migration" is accessed, the bpf prog can handle
migration (and the original not-migration) case.
>
> > case BPF_PROG_TYPE_EXT:
> > if (expected_attach_type)
> > return -EINVAL;
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index 85278deff439..cfc207ae7782 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -241,6 +241,8 @@ enum bpf_attach_type {
> > BPF_XDP_CPUMAP,
> > BPF_SK_LOOKUP,
> > BPF_XDP,
> > + BPF_SK_REUSEPORT_SELECT,
> > + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> > __MAX_BPF_ATTACH_TYPE
> > };
> >
> > --
> > 2.17.2 (Apple Git-113)
> >
Re: [PATCH v1 bpf-next 06/11] bpf: Introduce two attach types for BPF_PROG_TYPE_SK_REUSEPORT.
On Tue, Dec 1, 2020 at 6:49 AM Kuniyuki Iwashima wrote:
>
> This commit adds new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT to
> check if the attached eBPF program is capable of migrating sockets.
>
> When the eBPF program is attached, the kernel runs it for socket migration
> only if the expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.
> The kernel will change the behaviour depending on the returned value:
>
> - SK_PASS with selected_sk, select it as a new listener
> - SK_PASS with selected_sk NULL, fall back to the random selection
> - SK_DROP, cancel the migration
>
> Link:
> https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6t...@kafai-mbp.dhcp.thefacebook.com/
> Suggested-by: Martin KaFai Lau
> Signed-off-by: Kuniyuki Iwashima
> ---
> include/uapi/linux/bpf.h | 2 ++
> kernel/bpf/syscall.c | 8
> tools/include/uapi/linux/bpf.h | 2 ++
> 3 files changed, 12 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 85278deff439..cfc207ae7782 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -241,6 +241,8 @@ enum bpf_attach_type {
> BPF_XDP_CPUMAP,
> BPF_SK_LOOKUP,
> BPF_XDP,
> + BPF_SK_REUSEPORT_SELECT,
> + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> __MAX_BPF_ATTACH_TYPE
> };
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index f3fe9f53f93c..a0796a8de5ea 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2036,6 +2036,14 @@ bpf_prog_load_check_attach(enum bpf_prog_type
> prog_type,
> if (expected_attach_type == BPF_SK_LOOKUP)
> return 0;
> return -EINVAL;
> + case BPF_PROG_TYPE_SK_REUSEPORT:
> + switch (expected_attach_type) {
> + case BPF_SK_REUSEPORT_SELECT:
> + case BPF_SK_REUSEPORT_SELECT_OR_MIGRATE:
> + return 0;
> + default:
> + return -EINVAL;
> + }
this is a kernel regression, previously expected_attach_type wasn't
enforced, so user-space could have provided any number without an
error.
> case BPF_PROG_TYPE_EXT:
> if (expected_attach_type)
> return -EINVAL;
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 85278deff439..cfc207ae7782 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -241,6 +241,8 @@ enum bpf_attach_type {
> BPF_XDP_CPUMAP,
> BPF_SK_LOOKUP,
> BPF_XDP,
> + BPF_SK_REUSEPORT_SELECT,
> + BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
> __MAX_BPF_ATTACH_TYPE
> };
>
> --
> 2.17.2 (Apple Git-113)
>
