* Re: [PATCH net-next v2 1/1] net/tls: Combined memory allocation for decryption request
From: David Miller @ 2018-08-09 21:23 UTC (permalink / raw)
To: vakul.garg; +Cc: netdev, borisp, aviadye, davejwatson
In-Reply-To: <20180808232623.18075-2-vakul.garg@nxp.com>
From: Vakul Garg <vakul.garg@nxp.com>
Date: Thu, 9 Aug 2018 04:56:23 +0530
> For preparing decryption request, several memory chunks are required
> (aead_req, sgin, sgout, iv, aad). For submitting the decrypt request to
> an accelerator, it is required that the buffers which are read by the
> accelerator must be dma-able and not come from stack. The buffers for
> aad and iv can be separately kmalloced each, but it is inefficient.
> This patch does a combined allocation for preparing decryption request
> and then segments into aead_req || sgin || sgout || iv || aad.
>
> Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
> ---
> This patch needs to be applied over Doron Roberts-Kedes's patch.
> net/tls: Calculate nsg for zerocopy path without skb_cow_data.
That's going to have many changes, I gave feedback on it yesterday.
Please do not post patches which have pre-requisites which are in
the process of changing or similar as that makes a lot more work
for me and you are also asking people to review changes on top
of code which is going to change.
Thanks.
^ permalink raw reply
* Re: [PATCH net-next v2] net: allow to call netif_reset_xps_queues() under cpus_read_lock
From: David Miller @ 2018-08-09 21:26 UTC (permalink / raw)
To: avagin; +Cc: netdev, avagin, amritha.nambiar, mst, jasowang
In-Reply-To: <20180809030735.16173-1-avagin@openvz.org>
From: Andrei Vagin <avagin@openvz.org>
Date: Wed, 8 Aug 2018 20:07:35 -0700
> From: Andrei Vagin <avagin@gmail.com>
>
> The definition of static_key_slow_inc() has cpus_read_lock in place. In the
> virtio_net driver, XPS queues are initialized after setting the queue:cpu
> affinity in virtnet_set_affinity() which is already protected within
> cpus_read_lock. Lockdep prints a warning when we are trying to acquire
> cpus_read_lock when it is already held.
>
> This patch adds an ability to call __netif_set_xps_queue under
> cpus_read_lock().
...
Applied, thank you.
^ permalink raw reply
* Re: [PATCH net-next] cxgb4: update 1.20.8.0 as the latest firmware supported
From: David Miller @ 2018-08-09 21:27 UTC (permalink / raw)
To: ganeshgr; +Cc: netdev, nirranjan, indranil, dt
In-Reply-To: <1533798123-21071-1-git-send-email-ganeshgr@chelsio.com>
From: Ganesh Goudar <ganeshgr@chelsio.com>
Date: Thu, 9 Aug 2018 12:32:03 +0530
> Change t4fw_version.h to update latest firmware version
> number to 1.20.8.0.
>
> Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Applied, thank you.
^ permalink raw reply
* Re: [PATCH bpf-next] bpf: enable btf for use in all maps
From: Daniel Borkmann @ 2018-08-09 21:30 UTC (permalink / raw)
To: Alexei Starovoitov; +Cc: ast, netdev, yhs
In-Reply-To: <20180809211416.oznmx5jlnbagkk3w@ast-mbp>
On 08/09/2018 11:14 PM, Alexei Starovoitov wrote:
> On Thu, Aug 09, 2018 at 09:42:20PM +0200, Daniel Borkmann wrote:
>> Commit a26ca7c982cb ("bpf: btf: Add pretty print support to
>> the basic arraymap") enabled support for BTF and dumping via
>> BPF fs for arraymap. However, both can be decoupled from each
>> other such that all BPF maps can be supported for attaching
>> BTF key/value information, while not all maps necessarily
>> need to dump via map_seq_show_elem() callback.
>>
>> The check in array_map_check_btf() can be generalized as
>> ultimatively the key and value size is the only contraint
>> that needs to match for the map. The fact that the key needs
>> to be of type int is optional; it could be any data type as
>> long as it matches the 4 byte key size, just like hash table
>> key or others could be of any data type as well.
>>
>> Minimal example of a hash table dump which then works out
>> of the box for bpftool:
>>
>> # bpftool map dump id 19
>> [{
>> "key": {
>> "": {
>> "vip": 0,
>> "vipv6": []
>> },
>> "port": 0,
>> "family": 0,
>> "proto": 0
>> },
>> "value": {
>> "flags": 0,
>> "vip_num": 0
>> }
>> }
>> ]
>>
>> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
>> Cc: Yonghong Song <yhs@fb.com>
>> ---
>> include/linux/bpf.h | 4 +---
>> kernel/bpf/arraymap.c | 27 ---------------------------
>> kernel/bpf/inode.c | 3 ++-
>> kernel/bpf/syscall.c | 24 ++++++++++++++++++++----
>> 4 files changed, 23 insertions(+), 35 deletions(-)
>>
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index cd8790d..eb76e8e 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -48,8 +48,6 @@ struct bpf_map_ops {
>> u32 (*map_fd_sys_lookup_elem)(void *ptr);
>> void (*map_seq_show_elem)(struct bpf_map *map, void *key,
>> struct seq_file *m);
>> - int (*map_check_btf)(const struct bpf_map *map, const struct btf *btf,
>> - u32 key_type_id, u32 value_type_id);
>> };
>>
>> struct bpf_map {
>> @@ -118,7 +116,7 @@ static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
>>
>> static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
>> {
>> - return map->ops->map_seq_show_elem && map->ops->map_check_btf;
>> + return map->btf && map->ops->map_seq_show_elem;
>> }
>>
>> extern const struct bpf_map_ops bpf_map_offload_ops;
>> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
>> index 2aa55d030..67f0bdf 100644
>> --- a/kernel/bpf/arraymap.c
>> +++ b/kernel/bpf/arraymap.c
>> @@ -358,32 +358,6 @@ static void array_map_seq_show_elem(struct bpf_map *map, void *key,
>> rcu_read_unlock();
>> }
>>
>> -static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
>> - u32 btf_key_id, u32 btf_value_id)
>> -{
>> - const struct btf_type *key_type, *value_type;
>> - u32 key_size, value_size;
>> - u32 int_data;
>> -
>> - key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
>> - if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
>> - return -EINVAL;
>> -
>> - int_data = *(u32 *)(key_type + 1);
>> - /* bpf array can only take a u32 key. This check makes
>> - * sure that the btf matches the attr used during map_create.
>> - */
>> - if (BTF_INT_BITS(int_data) != 32 || key_size != 4 ||
>> - BTF_INT_OFFSET(int_data))
>> - return -EINVAL;
>
> I think most of these checks are still necessary for array type.
> Relaxing BTF array key from BTF_KIND_INT to, for example, BTF_KIND_ENUM
> is probably ok, but key being BTF_KIND_PTR or BTF_KIND_ARRAY doesn't makes sense.
Hmm, so on 64 bit archs BTF_KIND_PTR would get rejected for array,
on 32 bit it may be allowed due to sizeof(void *) == 4. BTF_KIND_ARRAY
could be array of u8 foo[4], for example, or u16 foo[2]. But how would
it ultimately be different from e.g. having 'struct a' versus 'struct b'
where both are of same size and while actual key has 'struct a', the one
who writes the prog resp. loads the BTF into the kernel would lie about
it stating it's of type 'struct b' instead? It's basically trusting the
app that it advertised sane key types which kernel is propagating back.
Thanks,
Daniel
^ permalink raw reply
* Re: [Patch net-next] net_sched: fix a potential out-of-bound access
From: Cong Wang @ 2018-08-09 21:43 UTC (permalink / raw)
To: Vlad Buslov; +Cc: Linux Kernel Network Developers, Jiri Pirko
In-Reply-To: <vbflg9g2dx5.fsf@reg-r-vrt-018-180.mtr.labs.mlnx>
On Thu, Aug 9, 2018 at 12:32 AM Vlad Buslov <vladbu@mellanox.com> wrote:
>
> Before version V5 of my action API patchset this functionality was
> implemented in exactly the same way as in your patch. Unfortunately, it
> has a double-free bug. The problem is that if you have multiple
> actions(N) being deleted, and deleted succeeded for first K actions,
> this implementation will try to delete all N actions second time
> (including first K actions that were already deleted). That is why I
> added 'acts_deleted' variable that tracks actual amount of actions that
> were deleted successfully, and only delete last N-K actions in case of
> error.
Interesting, I didn't notice you call it for tcf_del_notify()'s failure too.
But this is easy to resolve, we can just set succeeded ones to NULL
and teach tcf_action_put_many() to scan the whole array but
skip NULL's.
>
> In order to fix that issue I did following code changes in V5:
> - Added 'acts_deleted' variable to delete only actions [K, N) in case of
> error.
> - Extended 'actions' array size by one to ensure that it always ends
> with NULL pointer.
Oh, I see, this is not how we use C, you can at least rollback
by passing acts_deleted as a parameter as the start of the array.
You picked the most confusing way to handle it.
I will send an updated patch.
^ permalink raw reply
* Re: [PATCH bpf-next] bpf: enable btf for use in all maps
From: Alexei Starovoitov @ 2018-08-09 21:44 UTC (permalink / raw)
To: Daniel Borkmann; +Cc: ast, netdev, yhs
In-Reply-To: <d851548d-e027-57ee-55c9-a61c48ffcf15@iogearbox.net>
On Thu, Aug 09, 2018 at 11:30:52PM +0200, Daniel Borkmann wrote:
> On 08/09/2018 11:14 PM, Alexei Starovoitov wrote:
> > On Thu, Aug 09, 2018 at 09:42:20PM +0200, Daniel Borkmann wrote:
> >> Commit a26ca7c982cb ("bpf: btf: Add pretty print support to
> >> the basic arraymap") enabled support for BTF and dumping via
> >> BPF fs for arraymap. However, both can be decoupled from each
> >> other such that all BPF maps can be supported for attaching
> >> BTF key/value information, while not all maps necessarily
> >> need to dump via map_seq_show_elem() callback.
> >>
> >> The check in array_map_check_btf() can be generalized as
> >> ultimatively the key and value size is the only contraint
> >> that needs to match for the map. The fact that the key needs
> >> to be of type int is optional; it could be any data type as
> >> long as it matches the 4 byte key size, just like hash table
> >> key or others could be of any data type as well.
> >>
> >> Minimal example of a hash table dump which then works out
> >> of the box for bpftool:
> >>
> >> # bpftool map dump id 19
> >> [{
> >> "key": {
> >> "": {
> >> "vip": 0,
> >> "vipv6": []
> >> },
> >> "port": 0,
> >> "family": 0,
> >> "proto": 0
> >> },
> >> "value": {
> >> "flags": 0,
> >> "vip_num": 0
> >> }
> >> }
> >> ]
> >>
> >> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> >> Cc: Yonghong Song <yhs@fb.com>
> >> ---
> >> include/linux/bpf.h | 4 +---
> >> kernel/bpf/arraymap.c | 27 ---------------------------
> >> kernel/bpf/inode.c | 3 ++-
> >> kernel/bpf/syscall.c | 24 ++++++++++++++++++++----
> >> 4 files changed, 23 insertions(+), 35 deletions(-)
> >>
> >> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> >> index cd8790d..eb76e8e 100644
> >> --- a/include/linux/bpf.h
> >> +++ b/include/linux/bpf.h
> >> @@ -48,8 +48,6 @@ struct bpf_map_ops {
> >> u32 (*map_fd_sys_lookup_elem)(void *ptr);
> >> void (*map_seq_show_elem)(struct bpf_map *map, void *key,
> >> struct seq_file *m);
> >> - int (*map_check_btf)(const struct bpf_map *map, const struct btf *btf,
> >> - u32 key_type_id, u32 value_type_id);
> >> };
> >>
> >> struct bpf_map {
> >> @@ -118,7 +116,7 @@ static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
> >>
> >> static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
> >> {
> >> - return map->ops->map_seq_show_elem && map->ops->map_check_btf;
> >> + return map->btf && map->ops->map_seq_show_elem;
> >> }
> >>
> >> extern const struct bpf_map_ops bpf_map_offload_ops;
> >> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
> >> index 2aa55d030..67f0bdf 100644
> >> --- a/kernel/bpf/arraymap.c
> >> +++ b/kernel/bpf/arraymap.c
> >> @@ -358,32 +358,6 @@ static void array_map_seq_show_elem(struct bpf_map *map, void *key,
> >> rcu_read_unlock();
> >> }
> >>
> >> -static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
> >> - u32 btf_key_id, u32 btf_value_id)
> >> -{
> >> - const struct btf_type *key_type, *value_type;
> >> - u32 key_size, value_size;
> >> - u32 int_data;
> >> -
> >> - key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
> >> - if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
> >> - return -EINVAL;
> >> -
> >> - int_data = *(u32 *)(key_type + 1);
> >> - /* bpf array can only take a u32 key. This check makes
> >> - * sure that the btf matches the attr used during map_create.
> >> - */
> >> - if (BTF_INT_BITS(int_data) != 32 || key_size != 4 ||
> >> - BTF_INT_OFFSET(int_data))
> >> - return -EINVAL;
> >
> > I think most of these checks are still necessary for array type.
> > Relaxing BTF array key from BTF_KIND_INT to, for example, BTF_KIND_ENUM
> > is probably ok, but key being BTF_KIND_PTR or BTF_KIND_ARRAY doesn't makes sense.
>
> Hmm, so on 64 bit archs BTF_KIND_PTR would get rejected for array,
> on 32 bit it may be allowed due to sizeof(void *) == 4. BTF_KIND_ARRAY
> could be array of u8 foo[4], for example, or u16 foo[2]. But how would
> it ultimately be different from e.g. having 'struct a' versus 'struct b'
> where both are of same size and while actual key has 'struct a', the one
> who writes the prog resp. loads the BTF into the kernel would lie about
> it stating it's of type 'struct b' instead? It's basically trusting the
> app that it advertised sane key types which kernel is propagating back.
for hash map - yes. the kernel cannot yet catch the lie that
key == 'struct a' that user said in BTF is not what program used
(which used 'struct b' of the same size).
Eventually we will annotate all load/store in the program and will
make sure that memory access match what BTF said.
For array we can catch the lie today that key is not 4 byte int,
since it matters from pretty printing point of view.
If it's PTR or ARRAY or STRUCT, the printer will go nuts.
When userspace can trust kernel that array key is u32 it can print
int arr[10];
just like gdb does:
(gdb) p arr
$1 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
(gdb) ptype arr
type = int [10]
What user printer suppose to do if kernel says that key=PTR or, worse, key=STRUCT ?
I cannot think of sane way of printing such array.
Even key=ENUM is not trivial to print, but I think it can be useful and
practical to use ENUM as a key, but for now I'd stick to INT only
like the check does today.
^ permalink raw reply
* Re: [PATCH lora-next v2 7/8] net: lora: sx1301: add initial registration for regmap
From: Andreas Färber @ 2018-08-09 21:58 UTC (permalink / raw)
To: Ben Whitten
Cc: starnight, hasnain.virk, netdev, liuxuenetmail, shess,
Ben Whitten
In-Reply-To: <1533818018-29005-7-git-send-email-ben.whitten@lairdtech.com>
Am 09.08.2018 um 14:33 schrieb Ben Whitten:
> The register and bit-field definitions are taken from the SX1301
> datasheet version 2.01 dated June 2014 with the revision information
> 'First released version'.
>
> The reset state and RW capability of each field is not reflected in this
> patch however from the datasheet:
> "Bits and registers that are not documented are reserved. They may
> include calibration values. It is important not to modify these bits and
> registers. If specific bits must be changed in a register with reserved
> bits, the register must be read first, specific bits modified while
> masking reserved bits and then the register can be written."
>
> Then goes on to state:
> "Reserved bits should be written with their reset state, they may be
> read different states."
>
> Caching is currently disabled.
>
> The version is read back using regmap_read to verify regmap operation,
> in doing so needs to be moved after priv and regmap allocation.
>
> Further registers or fields are added as they are required in conversion.
>
> Signed-off-by: Ben Whitten <ben.whitten@lairdtech.com>
> ---
> drivers/net/lora/Kconfig | 1 +
> drivers/net/lora/sx1301.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
> drivers/net/lora/sx1301.h | 10 ++++++++++
> 3 files changed, 53 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/lora/Kconfig b/drivers/net/lora/Kconfig
> index bb57a01..79d23f2 100644
> --- a/drivers/net/lora/Kconfig
> +++ b/drivers/net/lora/Kconfig
> @@ -49,6 +49,7 @@ config LORA_SX1301
> tristate "Semtech SX1301 SPI driver"
> default y
> depends on SPI
> + select REGMAP_SPI
> help
> Semtech SX1301
>
> diff --git a/drivers/net/lora/sx1301.c b/drivers/net/lora/sx1301.c
> index 8e81179..766df06 100644
> --- a/drivers/net/lora/sx1301.c
> +++ b/drivers/net/lora/sx1301.c
> @@ -20,11 +20,11 @@
> #include <linux/of_gpio.h>
> #include <linux/lora/dev.h>
> #include <linux/spi/spi.h>
> +#include <linux/regmap.h>
Misordered.
>
> #include "sx1301.h"
>
> #define REG_PAGE_RESET 0
> -#define REG_VERSION 1
> #define REG_MCU_PROM_ADDR 9
> #define REG_MCU_PROM_DATA 10
> #define REG_GPIO_SELECT_INPUT 27
> @@ -68,6 +68,35 @@
>
> #define REG_EMERGENCY_FORCE_HOST_CTRL BIT(0)
>
> +static const struct regmap_range_cfg sx1301_ranges[] = {
Let's rename to _regmap_ranges for consistency.
> @@ -81,6 +110,7 @@ struct sx1301_priv {
> struct gpio_desc *rst_gpio;
> u8 cur_page;
> struct spi_controller *radio_a_ctrl, *radio_b_ctrl;
> + struct regmap *regmap;
Note: We need a consistent style. Either whitespace or tabs, not both
depending on author. Same in an earlier patch. Problem with tabs is that
at some point it's always one tab too little, but we can try it.
Applied.
Thanks,
Andreas
--
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
^ permalink raw reply
* Re: KCM - recvmsg() mangles packets?
From: Dominique Martinet @ 2018-08-09 22:06 UTC (permalink / raw)
To: Tom Herbert; +Cc: Linux Kernel Network Developers
In-Reply-To: <CAPDqMeptLoLZ2RU+T-d7YwkO2AeKV+nfow4C-LqqeZd9mo-vMg@mail.gmail.com>
Tom Herbert wrote on Thu, Aug 09, 2018:
> > diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
> > index 625acb27efcc..348ff5945591 100644
> > --- a/net/strparser/strparser.c
> > +++ b/net/strparser/strparser.c
> > @@ -222,6 +222,16 @@ static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
> > if (!stm->strp.full_len) {
> > ssize_t len;
> >
> > + /* Can only parse if there is no offset */
> > + if (unlikely(stm->strp.offset)) {
> > + if (!pskb_pull(skb, stm->strp.offset)) {
> > + STRP_STATS_INCR(strp->stats.mem_fail);
> > + strp_parser_err(strp, -ENOMEM, desc);
> > + break;
> > + }
> > + stm->strp.offset = 0;
> > + }
> > +
>
> Seems okay to me for a fix.
Hmm, if you say so, I'll send this as a patch for broader comments right
away.
> Looks like strp.offset is only set in one place and read in one
> place. With this pull maybe that just can go away?
Good point, when strp.offset is set the full_len is also being init'd so
we will necessarily do the pull next...
But the way tls uses strparser is also kind of weird, since they modify
the strp_msg's offset and full_len, I wouldn't want to assume we can't
have full_len == 0 *again* later with a non zero offset...
On the other hand they do handle non-zero offset in their parse function
so they'd be ok with that... Ultimately it's probably closer to a design
choice than anything else.
I'll still send a v0 of the patch as is, because I feel it's easier to
understand that we pull because the existing parse_msg functions do not
handle it properly, and will write a note that I intend to move it up a
few lines as a comment.
Thanks,
--
Dominique Martinet
^ permalink raw reply
* Re: [PATCH net-next v2] net: allow to call netif_reset_xps_queues() under cpus_read_lock
From: Michael S. Tsirkin @ 2018-08-09 22:13 UTC (permalink / raw)
To: Andrei Vagin
Cc: David S. Miller, netdev, Andrei Vagin, Nambiar, Amritha,
Jason Wang
In-Reply-To: <20180809030735.16173-1-avagin@openvz.org>
On Wed, Aug 08, 2018 at 08:07:35PM -0700, Andrei Vagin wrote:
> From: Andrei Vagin <avagin@gmail.com>
>
> The definition of static_key_slow_inc() has cpus_read_lock in place. In the
> virtio_net driver, XPS queues are initialized after setting the queue:cpu
> affinity in virtnet_set_affinity() which is already protected within
> cpus_read_lock. Lockdep prints a warning when we are trying to acquire
> cpus_read_lock when it is already held.
>
> This patch adds an ability to call __netif_set_xps_queue under
> cpus_read_lock().
>
> ============================================
> WARNING: possible recursive locking detected
> 4.18.0-rc3-next-20180703+ #1 Not tainted
> --------------------------------------------
> swapper/0/1 is trying to acquire lock:
> 00000000cf973d46 (cpu_hotplug_lock.rw_sem){++++}, at: static_key_slow_inc+0xe/0x20
>
> but task is already holding lock:
> 00000000cf973d46 (cpu_hotplug_lock.rw_sem){++++}, at: init_vqs+0x513/0x5a0
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(cpu_hotplug_lock.rw_sem);
> lock(cpu_hotplug_lock.rw_sem);
>
> *** DEADLOCK ***
>
> May be due to missing lock nesting notation
>
> 3 locks held by swapper/0/1:
> #0: 00000000244bc7da (&dev->mutex){....}, at: __driver_attach+0x5a/0x110
> #1: 00000000cf973d46 (cpu_hotplug_lock.rw_sem){++++}, at: init_vqs+0x513/0x5a0
> #2: 000000005cd8463f (xps_map_mutex){+.+.}, at: __netif_set_xps_queue+0x8d/0xc60
>
> v2: move cpus_read_lock() out of __netif_set_xps_queue()
FYI you change log should go after -- below, not before it.
> Cc: "Nambiar, Amritha" <amritha.nambiar@intel.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue")
>
> Signed-off-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> drivers/net/virtio_net.c | 4 +++-
> net/core/dev.c | 20 +++++++++++++++-----
> net/core/net-sysfs.c | 4 ++++
> 3 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 62311dde6e71..39a7f4452587 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1903,9 +1903,11 @@ static void virtnet_set_affinity(struct virtnet_info *vi)
>
> i = 0;
> for_each_online_cpu(cpu) {
> + const unsigned long *mask = cpumask_bits(cpumask_of(cpu));
> +
> virtqueue_set_affinity(vi->rq[i].vq, cpu);
> virtqueue_set_affinity(vi->sq[i].vq, cpu);
> - netif_set_xps_queue(vi->dev, cpumask_of(cpu), i);
> + __netif_set_xps_queue(vi->dev, mask, i, false);
> i++;
> }
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index f68122f0ab02..325fc5088370 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2176,6 +2176,7 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
> if (!static_key_false(&xps_needed))
> return;
>
> + cpus_read_lock();
> mutex_lock(&xps_map_mutex);
>
> if (static_key_false(&xps_rxqs_needed)) {
> @@ -2199,10 +2200,11 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
>
> out_no_maps:
> if (static_key_enabled(&xps_rxqs_needed))
> - static_key_slow_dec(&xps_rxqs_needed);
> + static_key_slow_dec_cpuslocked(&xps_rxqs_needed);
>
> - static_key_slow_dec(&xps_needed);
> + static_key_slow_dec_cpuslocked(&xps_needed);
> mutex_unlock(&xps_map_mutex);
> + cpus_read_unlock();
> }
>
> static void netif_reset_xps_queues_gt(struct net_device *dev, u16 index)
> @@ -2250,6 +2252,7 @@ static struct xps_map *expand_xps_map(struct xps_map *map, int attr_index,
> return new_map;
> }
>
> +/* Must be called under cpus_read_lock */
> int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
> u16 index, bool is_rxqs_map)
> {
> @@ -2317,9 +2320,9 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
> if (!new_dev_maps)
> goto out_no_new_maps;
>
> - static_key_slow_inc(&xps_needed);
> + static_key_slow_inc_cpuslocked(&xps_needed);
> if (is_rxqs_map)
> - static_key_slow_inc(&xps_rxqs_needed);
> + static_key_slow_inc_cpuslocked(&xps_rxqs_needed);
>
> for (j = -1; j = netif_attrmask_next(j, possible_mask, nr_ids),
> j < nr_ids;) {
> @@ -2448,11 +2451,18 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask,
> kfree(new_dev_maps);
> return -ENOMEM;
> }
> +EXPORT_SYMBOL_GPL(__netif_set_xps_queue);
>
> int netif_set_xps_queue(struct net_device *dev, const struct cpumask *mask,
> u16 index)
> {
> - return __netif_set_xps_queue(dev, cpumask_bits(mask), index, false);
> + int ret;
> +
> + cpus_read_lock();
> + ret = __netif_set_xps_queue(dev, cpumask_bits(mask), index, false);
> + cpus_read_unlock();
> +
> + return ret;
> }
> EXPORT_SYMBOL(netif_set_xps_queue);
>
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 0a95bcf64cdc..bd67c4d0fcfd 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -26,6 +26,7 @@
> #include <linux/pm_runtime.h>
> #include <linux/of.h>
> #include <linux/of_net.h>
> +#include <linux/cpu.h>
>
> #include "net-sysfs.h"
>
> @@ -1400,7 +1401,10 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,
> return err;
> }
>
> + cpus_read_lock();
> err = __netif_set_xps_queue(dev, mask, index, true);
> + cpus_read_unlock();
> +
> kfree(mask);
> return err ? : len;
> }
> --
> 2.17.1
^ permalink raw reply
* Re: [PATCH lora-next v2 8/8] net: lora: sx1301: convert driver over to regmap reads and writes
From: Andreas Färber @ 2018-08-09 22:34 UTC (permalink / raw)
To: Ben Whitten
Cc: starnight, hasnain.virk, netdev, liuxuenetmail, shess,
Ben Whitten, Yannick Lanz
In-Reply-To: <1533818018-29005-8-git-send-email-ben.whitten@lairdtech.com>
Am 09.08.2018 um 14:33 schrieb Ben Whitten:
> The reads and writes are replaced with regmap versions and unneeded
> functions, variable, and defines removed.
>
> Signed-off-by: Ben Whitten <ben.whitten@lairdtech.com>
> ---
> drivers/net/lora/sx1301.c | 204 +++++++++++++++-------------------------------
> drivers/net/lora/sx1301.h | 30 +++++++
> 2 files changed, 95 insertions(+), 139 deletions(-)
>
> diff --git a/drivers/net/lora/sx1301.c b/drivers/net/lora/sx1301.c
> index 766df06..4db5a43 100644
> --- a/drivers/net/lora/sx1301.c
> +++ b/drivers/net/lora/sx1301.c
[...]
> @@ -140,50 +115,9 @@ static int sx1301_write(struct sx1301_priv *priv, u8 reg, u8 val)
> return sx1301_write_burst(priv, reg, &val, 1);
> }
_write and _read are now unused, causing warnings. Dropping.
The _burst versions are still in use for firmware load, and I saw a
discussion indicating that regmap is lacking the capability to not
increment the reg for bulk reads at the moment. So we still can't
cleanly switch to regmap entirely and thereby remain bound to SPI.
[...]
> @@ -235,8 +169,8 @@ static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
> {
> struct spi_sx1301 *ssx = spi_controller_get_devdata(ctrl);
> struct sx1301_priv *priv = spi_get_drvdata(ssx->parent);
> - const u8 *tx_buf = xfr->tx_buf;
> - u8 *rx_buf = xfr->rx_buf;
> + const unsigned int *tx_buf = xfr->tx_buf;
> + unsigned int *rx_buf = xfr->rx_buf;
These are wrong both for Little Endian and even worse for Big Endian.
> int ret;
>
> if (xfr->len == 0 || xfr->len > 3)
> @@ -245,13 +179,13 @@ static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
> dev_dbg(&spi->dev, "transferring one (%u)\n", xfr->len);
>
> if (tx_buf) {
> - ret = sx1301_page_write(priv, ssx->page, ssx->regs + REG_RADIO_X_ADDR, tx_buf ? tx_buf[0] : 0);
> + ret = regmap_write(priv->regmap, ssx->regs + REG_RADIO_X_ADDR, tx_buf ? tx_buf[0] : 0);
> if (ret) {
> dev_err(&spi->dev, "SPI radio address write failed\n");
> return ret;
> }
>
> - ret = sx1301_page_write(priv, ssx->page, ssx->regs + REG_RADIO_X_DATA, (tx_buf && xfr->len >= 2) ? tx_buf[1] : 0);
> + ret = regmap_write(priv->regmap, ssx->regs + REG_RADIO_X_DATA, (tx_buf && xfr->len >= 2) ? tx_buf[1] : 0);
> if (ret) {
> dev_err(&spi->dev, "SPI radio data write failed\n");
> return ret;
> @@ -271,7 +205,7 @@ static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
> }
>
> if (rx_buf) {
> - ret = sx1301_page_read(priv, ssx->page, ssx->regs + REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
> + ret = regmap_read(priv->regmap, ssx->regs + REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
> if (ret) {
> dev_err(&spi->dev, "SPI radio data read failed\n");
> return ret;
Fixing by adding a local variable instead:
@@ -239,6 +163,7 @@ static int sx1301_radio_spi_transfer_one(struct
spi_controll
er *ctrl,
struct sx1301_priv *priv = netdev_priv(netdev);
const u8 *tx_buf = xfr->tx_buf;
u8 *rx_buf = xfr->rx_buf;
+ unsigned int val;
int ret;
if (xfr->len == 0 || xfr->len > 3)
[...]
@@ -273,27 +198,28 @@ static int sx1301_radio_spi_transfer_one(struct
spi_controller *ctrl,
}
if (rx_buf) {
- ret = sx1301_page_read(priv, ssx->page, ssx->regs +
REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
+ ret = regmap_read(priv->regmap, ssx->regs +
REG_RADIO_X_DATA_READBACK, &val);
if (ret) {
dev_err(&spi->dev, "SPI radio data read failed\n");
return ret;
}
+ rx_buf[xfr->len - 1] = val & 0xff;
}
return 0;
[...]
> diff --git a/drivers/net/lora/sx1301.h b/drivers/net/lora/sx1301.h
> index 2fc283f..b21e5c6 100644
> --- a/drivers/net/lora/sx1301.h
> +++ b/drivers/net/lora/sx1301.h
> @@ -18,11 +18,41 @@
> /* Page independent */
> #define SX1301_PAGE 0x00
> #define SX1301_VER 0x01
> +#define SX1301_MPA 0x09
Those are the official register names? I find these much harder to read
than my guessed names. Could we keep the long names as aliases?
> +#define SX1301_MPD 0x0A
> +#define SX1301_GEN 0x10
> +#define SX1301_CKEN 0x11
> +#define SX1301_GPSO 0x1C
> +#define SX1301_GPMODE 0x1D
> +#define SX1301_AGCSTS 0x20
>
> #define SX1301_VIRT_BASE 0x100
> #define SX1301_PAGE_LEN 0x80
> #define SX1301_PAGE_BASE(n) (SX1301_VIRT_BASE + (SX1301_PAGE_LEN * n))
>
> +/* Page 0 */
> +#define SX1301_CHRS (SX1301_PAGE_BASE(0) + 0x23)
> +#define SX1301_FORCE_CTRL (SX1301_PAGE_BASE(0) + 0x69)
> +#define SX1301_MCU_CTRL (SX1301_PAGE_BASE(0) + 0x6A)
> +
> +/* Page 2 */
> +#define SX1301_RADIO_A_SPI_DATA (SX1301_PAGE_BASE(2) + 0x21)
> +#define SX1301_RADIO_A_SPI_DATA_RB (SX1301_PAGE_BASE(2) + 0x22)
> +#define SX1301_RADIO_A_SPI_ADDR (SX1301_PAGE_BASE(2) + 0x23)
> +#define SX1301_RADIO_A_SPI_CS (SX1301_PAGE_BASE(2) + 0x25)
> +#define SX1301_RADIO_B_SPI_DATA (SX1301_PAGE_BASE(2) + 0x26)
> +#define SX1301_RADIO_B_SPI_DATA_RB (SX1301_PAGE_BASE(2) + 0x27)
> +#define SX1301_RADIO_B_SPI_ADDR (SX1301_PAGE_BASE(2) + 0x28)
> +#define SX1301_RADIO_B_SPI_CS (SX1301_PAGE_BASE(2) + 0x2A)
> +#define SX1301_RADIO_CFG (SX1301_PAGE_BASE(2) + 0x2B)
> +#define SX1301_DBG_ARB_MCU_RAM_DATA (SX1301_PAGE_BASE(2) + 0x40)
> +#define SX1301_DBG_AGC_MCU_RAM_DATA (SX1301_PAGE_BASE(2) + 0x41)
> +#define SX1301_DBG_ARB_MCU_RAM_ADDR (SX1301_PAGE_BASE(2) + 0x50)
> +#define SX1301_DBG_AGC_MCU_RAM_ADDR (SX1301_PAGE_BASE(2) + 0x51)
> +
> +/* Page 3 */
> +#define SX1301_EMERGENCY_FORCE_HOST_CTRL (SX1301_PAGE_BASE(3) + 0x7F)
> +
> #define SX1301_MAX_REGISTER (SX1301_PAGE_BASE(3) + 0x7F)
>
> #endif
Applying so that we can continue based on regmap.
Regards,
Andreas
--
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
^ permalink raw reply
* [PATCH v0] strparser: remove any offset before parsing messages
From: Dominique Martinet @ 2018-08-09 22:40 UTC (permalink / raw)
To: Doron Roberts-Kedes, Tom Herbert, Dave Watson
Cc: Dominique Martinet, David S. Miller, netdev, linux-kernel
Offset is not well handled by strparser users right now.
Out of the current strparser users, we have:
- tls, that handles offset properly in parse and rcv callbacks
- kcm, that handles offset in rcv but not in parse
- bpf sockmap, that does not seem to handle offset anywhere
Calling pskb_pull() on the skb before parsing ensures that the offset
will be 0 everywhere in practice unless the user modifies it themselves
like tls, as a workaround for the other two protocols.
This fixes a bug whilch can be exhibited by implementing a simpe kcm
parser that looks for the packet size in the first word of the packet,
and sending two such packets in a single write() call on the other side:
the second message will be cut at the length of the first message.
Since this is a stream protocol, all the following messages will also
be corrupt since it will start looking for the next offset at a wrong
position.
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
---
Discussions on the bug along with a (bad) reproducer can be found here:
http://lkml.kernel.org/m/20180803182830.GB29193@nautica
(now the problem is better understood though it's much simpler to send
two messages at once than to spam and wait for tcp aggregation to do it)
Two notes:
- I've marked this patch v0 as we could move the pskb_pull() up to
where strp.offset is set, and just always leave it at 0 in the strparser
code.
This will let applications that are fine dealing with a non-zero offset
deal with it as they seem fit (tls writes into the offset and full_len
fields behind the back of the stream parser), while still being safe for
kcm/sockmap
- Even with that modification I'm not totally happy with
single-handedly eating the offset for strparser users which could handle
it, but I'm not really familiar with the cost this really has in
practice...
A better fix would be to handle the offset properly in the callbacks,
but frankly at least for kcm I don't see how (maybe because I'm not
familiar with how bpf programs work)
Another idea I had would be to write flags when registering the protocol
e.g. strp->cb.flags & STRP_CAN_PARSE_WITH_OFFSET or something like that,
but without an idea of the cost of that pull I don't know if it's worth
doing.
Anyway, comments welcome.
net/strparser/strparser.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
index 625acb27efcc..d7a3b81c3481 100644
--- a/net/strparser/strparser.c
+++ b/net/strparser/strparser.c
@@ -222,6 +222,16 @@ static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
if (!stm->strp.full_len) {
ssize_t len;
+ /* Can only parse if there is no offset */
+ if (unlikely(stm->strp.offset)) {
+ if (!pskb_pull(skb, stm->strp.offset)) {
+ STRP_STATS_INCR(strp->stats.mem_fail);
+ strp_parser_err(strp, -ENOMEM, desc);
+ break;
+ }
+ stm->strp.offset = 0;
+ }
+
len = (*strp->cb.parse_msg)(strp, head);
if (!len) {
@@ -249,8 +259,7 @@ static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
STRP_STATS_INCR(strp->stats.msg_too_big);
strp_parser_err(strp, -EMSGSIZE, desc);
break;
- } else if (len <= (ssize_t)head->len -
- skb->len - stm->strp.offset) {
+ } else if (len <= (ssize_t)head->len - skb->len) {
/* Length must be into new skb (and also
* greater than zero)
*/
--
2.17.1
^ permalink raw reply related
* Re: [PATCH bpf-next] bpf: enable btf for use in all maps
From: Daniel Borkmann @ 2018-08-09 22:43 UTC (permalink / raw)
To: Alexei Starovoitov; +Cc: ast, netdev, yhs
In-Reply-To: <20180809214430.gd4zwsnmbwmq7b26@ast-mbp>
On 08/09/2018 11:44 PM, Alexei Starovoitov wrote:
> On Thu, Aug 09, 2018 at 11:30:52PM +0200, Daniel Borkmann wrote:
>> On 08/09/2018 11:14 PM, Alexei Starovoitov wrote:
>>> On Thu, Aug 09, 2018 at 09:42:20PM +0200, Daniel Borkmann wrote:
>>>> Commit a26ca7c982cb ("bpf: btf: Add pretty print support to
>>>> the basic arraymap") enabled support for BTF and dumping via
>>>> BPF fs for arraymap. However, both can be decoupled from each
>>>> other such that all BPF maps can be supported for attaching
>>>> BTF key/value information, while not all maps necessarily
>>>> need to dump via map_seq_show_elem() callback.
>>>>
>>>> The check in array_map_check_btf() can be generalized as
>>>> ultimatively the key and value size is the only contraint
>>>> that needs to match for the map. The fact that the key needs
>>>> to be of type int is optional; it could be any data type as
>>>> long as it matches the 4 byte key size, just like hash table
>>>> key or others could be of any data type as well.
>>>>
>>>> Minimal example of a hash table dump which then works out
>>>> of the box for bpftool:
>>>>
>>>> # bpftool map dump id 19
>>>> [{
>>>> "key": {
>>>> "": {
>>>> "vip": 0,
>>>> "vipv6": []
>>>> },
>>>> "port": 0,
>>>> "family": 0,
>>>> "proto": 0
>>>> },
>>>> "value": {
>>>> "flags": 0,
>>>> "vip_num": 0
>>>> }
>>>> }
>>>> ]
>>>>
>>>> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
>>>> Cc: Yonghong Song <yhs@fb.com>
>>>> ---
>>>> include/linux/bpf.h | 4 +---
>>>> kernel/bpf/arraymap.c | 27 ---------------------------
>>>> kernel/bpf/inode.c | 3 ++-
>>>> kernel/bpf/syscall.c | 24 ++++++++++++++++++++----
>>>> 4 files changed, 23 insertions(+), 35 deletions(-)
>>>>
>>>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>>>> index cd8790d..eb76e8e 100644
>>>> --- a/include/linux/bpf.h
>>>> +++ b/include/linux/bpf.h
>>>> @@ -48,8 +48,6 @@ struct bpf_map_ops {
>>>> u32 (*map_fd_sys_lookup_elem)(void *ptr);
>>>> void (*map_seq_show_elem)(struct bpf_map *map, void *key,
>>>> struct seq_file *m);
>>>> - int (*map_check_btf)(const struct bpf_map *map, const struct btf *btf,
>>>> - u32 key_type_id, u32 value_type_id);
>>>> };
>>>>
>>>> struct bpf_map {
>>>> @@ -118,7 +116,7 @@ static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
>>>>
>>>> static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
>>>> {
>>>> - return map->ops->map_seq_show_elem && map->ops->map_check_btf;
>>>> + return map->btf && map->ops->map_seq_show_elem;
>>>> }
>>>>
>>>> extern const struct bpf_map_ops bpf_map_offload_ops;
>>>> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
>>>> index 2aa55d030..67f0bdf 100644
>>>> --- a/kernel/bpf/arraymap.c
>>>> +++ b/kernel/bpf/arraymap.c
>>>> @@ -358,32 +358,6 @@ static void array_map_seq_show_elem(struct bpf_map *map, void *key,
>>>> rcu_read_unlock();
>>>> }
>>>>
>>>> -static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
>>>> - u32 btf_key_id, u32 btf_value_id)
>>>> -{
>>>> - const struct btf_type *key_type, *value_type;
>>>> - u32 key_size, value_size;
>>>> - u32 int_data;
>>>> -
>>>> - key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
>>>> - if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
>>>> - return -EINVAL;
>>>> -
>>>> - int_data = *(u32 *)(key_type + 1);
>>>> - /* bpf array can only take a u32 key. This check makes
>>>> - * sure that the btf matches the attr used during map_create.
>>>> - */
>>>> - if (BTF_INT_BITS(int_data) != 32 || key_size != 4 ||
>>>> - BTF_INT_OFFSET(int_data))
>>>> - return -EINVAL;
>>>
>>> I think most of these checks are still necessary for array type.
>>> Relaxing BTF array key from BTF_KIND_INT to, for example, BTF_KIND_ENUM
>>> is probably ok, but key being BTF_KIND_PTR or BTF_KIND_ARRAY doesn't makes sense.
>>
>> Hmm, so on 64 bit archs BTF_KIND_PTR would get rejected for array,
>> on 32 bit it may be allowed due to sizeof(void *) == 4. BTF_KIND_ARRAY
>> could be array of u8 foo[4], for example, or u16 foo[2]. But how would
>> it ultimately be different from e.g. having 'struct a' versus 'struct b'
>> where both are of same size and while actual key has 'struct a', the one
>> who writes the prog resp. loads the BTF into the kernel would lie about
>> it stating it's of type 'struct b' instead? It's basically trusting the
>> app that it advertised sane key types which kernel is propagating back.
>
> for hash map - yes. the kernel cannot yet catch the lie that
> key == 'struct a' that user said in BTF is not what program used
> (which used 'struct b' of the same size).
> Eventually we will annotate all load/store in the program and will
> make sure that memory access match what BTF said.
But in that case, would you reject the program? E.g. from prog point of
view, it's just a buffer of x bytes, so key could be casted to different
struct/types potentially and used for lookup; similar with value if you
would go the route to annotate all access into it. I don't think this
serves as a security feature (since you might as well just load the prog
without BTF just fine), but it can be used to help verifier to perform
rewrites like in tracing for implicit bpf_probe_read() based on member
access. But also in that case, if you might have e.g. stale or wrong BTF
data e.g. of the whole kernel or some application it would follow/walk
that one instead. But such user error would be "acceptable" since it serves
as a hint, roughly similar to (explicitly) walking the data structures
based on the headers today, you do have better control in terms of header
mismatches in that you can ship the BTF directly from the build, but there's
still no guarantee in that sense that you "verified" that these bytes
originally were mapped to struct foo somewhere in a C program.
> For array we can catch the lie today that key is not 4 byte int,
> since it matters from pretty printing point of view.
> If it's PTR or ARRAY or STRUCT, the printer will go nuts.
In that case, would you enforce a hash map key size of 4 also to INT-only
instead of e.g. allowing STRUCT and various others? I don't think it's
that much different from pretty printer PoV (e.g. see bpftool transparently
handling them via btf_dumper_type()), it's some key with 4 bytes of memory
and a type matching these 4 bytes in size for pretty printer.
Thanks,
Daniel
^ permalink raw reply
* Re: [PATCH net-next,v4] net/tls: Calculate nsg for zerocopy path without skb_cow_data.
From: Doron Roberts-Kedes @ 2018-08-09 22:43 UTC (permalink / raw)
To: David Miller; +Cc: davejwatson, vakul.garg, borisp, aviadye, netdev
In-Reply-To: <20180808.121430.2168057232319674612.davem@davemloft.net>
On Wed, Aug 08, 2018 at 12:14:30PM -0700, David Miller wrote:
> From: Doron Roberts-Kedes <doronrk@fb.com>
> Date: Tue, 7 Aug 2018 11:09:39 -0700
>
> > +static int __skb_nsg(struct sk_buff *skb, int offset, int len,
> > + unsigned int recursion_level)
> > +{
> > + int start = skb_headlen(skb);
> > + int i, copy = start - offset;
> > + struct sk_buff *frag_iter;
> > + int elt = 0;
> > +
> > + if (unlikely(recursion_level >= 24))
> > + return -EMSGSIZE;
>
> This recursion is kinda crazy.
>
> Even skb_cow_data() doesn't recurse like this (of course because it copies
> into linear buffers).
>
> There has to be a way to simplify this. Fragment lists are such a rarely
> used SKB geometry, and few if any devices support it for transmission
> (so the fraglist will get undone at transmit time anyways).
>
Interesting. Just wanted to clarify whether the issue is the use of
recursion or the fact that the function is handling the frag_list at
all. This is the rx path, so my understanding was that we need to handle
the frag_list. Please let me know if I'm misunderstanding your point
about the rare use of fragment lists.
If the issue is the recursion, I can rewrite the function to not use
recursion, but skb_to_sgvec uses a similar pattern and is invoked
immediately afterwards.
Taking a step back, is there an existing solution for what this function
is trying to do? I was surprised to find that there did not seem to
exist a function for determining the number of scatterlist elements
required to map an skb without COW.
^ permalink raw reply
* Re: [PATCH lora-next v2 8/8] net: lora: sx1301: convert driver over to regmap reads and writes
From: Ben Whitten @ 2018-08-09 22:47 UTC (permalink / raw)
To: Andreas Färber
Cc: 潘建宏, hasnain.virk, netdev, Xue Liu, shess,
Ben Whitten, yannick.lanz
In-Reply-To: <e7b112d9-d8ac-1654-fc97-9289180d6a02@suse.de>
On Thu, 9 Aug 2018 at 23:34, Andreas Färber <afaerber@suse.de> wrote:
>
> Am 09.08.2018 um 14:33 schrieb Ben Whitten:
> > The reads and writes are replaced with regmap versions and unneeded
> > functions, variable, and defines removed.
> >
> > Signed-off-by: Ben Whitten <ben.whitten@lairdtech.com>
> > ---
> > drivers/net/lora/sx1301.c | 204 +++++++++++++++-------------------------------
> > drivers/net/lora/sx1301.h | 30 +++++++
> > 2 files changed, 95 insertions(+), 139 deletions(-)
> >
> > diff --git a/drivers/net/lora/sx1301.c b/drivers/net/lora/sx1301.c
> > index 766df06..4db5a43 100644
> > --- a/drivers/net/lora/sx1301.c
> > +++ b/drivers/net/lora/sx1301.c
> [...]
> > @@ -140,50 +115,9 @@ static int sx1301_write(struct sx1301_priv *priv, u8 reg, u8 val)
> > return sx1301_write_burst(priv, reg, &val, 1);
> > }
>
> _write and _read are now unused, causing warnings. Dropping.
>
> The _burst versions are still in use for firmware load, and I saw a
> discussion indicating that regmap is lacking the capability to not
> increment the reg for bulk reads at the moment. So we still can't
> cleanly switch to regmap entirely and thereby remain bound to SPI.
>
> [...]
> > @@ -235,8 +169,8 @@ static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
> > {
> > struct spi_sx1301 *ssx = spi_controller_get_devdata(ctrl);
> > struct sx1301_priv *priv = spi_get_drvdata(ssx->parent);
> > - const u8 *tx_buf = xfr->tx_buf;
> > - u8 *rx_buf = xfr->rx_buf;
> > + const unsigned int *tx_buf = xfr->tx_buf;
> > + unsigned int *rx_buf = xfr->rx_buf;
>
> These are wrong both for Little Endian and even worse for Big Endian.
>
> > int ret;
> >
> > if (xfr->len == 0 || xfr->len > 3)
> > @@ -245,13 +179,13 @@ static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
> > dev_dbg(&spi->dev, "transferring one (%u)\n", xfr->len);
> >
> > if (tx_buf) {
> > - ret = sx1301_page_write(priv, ssx->page, ssx->regs + REG_RADIO_X_ADDR, tx_buf ? tx_buf[0] : 0);
> > + ret = regmap_write(priv->regmap, ssx->regs + REG_RADIO_X_ADDR, tx_buf ? tx_buf[0] : 0);
> > if (ret) {
> > dev_err(&spi->dev, "SPI radio address write failed\n");
> > return ret;
> > }
> >
> > - ret = sx1301_page_write(priv, ssx->page, ssx->regs + REG_RADIO_X_DATA, (tx_buf && xfr->len >= 2) ? tx_buf[1] : 0);
> > + ret = regmap_write(priv->regmap, ssx->regs + REG_RADIO_X_DATA, (tx_buf && xfr->len >= 2) ? tx_buf[1] : 0);
> > if (ret) {
> > dev_err(&spi->dev, "SPI radio data write failed\n");
> > return ret;
> > @@ -271,7 +205,7 @@ static int sx1301_radio_spi_transfer_one(struct spi_controller *ctrl,
> > }
> >
> > if (rx_buf) {
> > - ret = sx1301_page_read(priv, ssx->page, ssx->regs + REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
> > + ret = regmap_read(priv->regmap, ssx->regs + REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
> > if (ret) {
> > dev_err(&spi->dev, "SPI radio data read failed\n");
> > return ret;
>
> Fixing by adding a local variable instead:
>
> @@ -239,6 +163,7 @@ static int sx1301_radio_spi_transfer_one(struct
> spi_controll
> er *ctrl,
> struct sx1301_priv *priv = netdev_priv(netdev);
> const u8 *tx_buf = xfr->tx_buf;
> u8 *rx_buf = xfr->rx_buf;
> + unsigned int val;
> int ret;
>
> if (xfr->len == 0 || xfr->len > 3)
> [...]
> @@ -273,27 +198,28 @@ static int sx1301_radio_spi_transfer_one(struct
> spi_controller *ctrl,
> }
>
> if (rx_buf) {
> - ret = sx1301_page_read(priv, ssx->page, ssx->regs +
> REG_RADIO_X_DATA_READBACK, &rx_buf[xfr->len - 1]);
> + ret = regmap_read(priv->regmap, ssx->regs +
> REG_RADIO_X_DATA_READBACK, &val);
> if (ret) {
> dev_err(&spi->dev, "SPI radio data read failed\n");
> return ret;
> }
> + rx_buf[xfr->len - 1] = val & 0xff;
> }
>
> return 0;
>
> [...]
> > diff --git a/drivers/net/lora/sx1301.h b/drivers/net/lora/sx1301.h
> > index 2fc283f..b21e5c6 100644
> > --- a/drivers/net/lora/sx1301.h
> > +++ b/drivers/net/lora/sx1301.h
> > @@ -18,11 +18,41 @@
> > /* Page independent */
> > #define SX1301_PAGE 0x00
> > #define SX1301_VER 0x01
> > +#define SX1301_MPA 0x09
>
> Those are the official register names? I find these much harder to read
> than my guessed names. Could we keep the long names as aliases?
Yes these are the official register names, aliases to improve readability
sound like a good plan as all the official names are terse.
> > +#define SX1301_MPD 0x0A
> > +#define SX1301_GEN 0x10
> > +#define SX1301_CKEN 0x11
> > +#define SX1301_GPSO 0x1C
> > +#define SX1301_GPMODE 0x1D
> > +#define SX1301_AGCSTS 0x20
> >
> > #define SX1301_VIRT_BASE 0x100
> > #define SX1301_PAGE_LEN 0x80
> > #define SX1301_PAGE_BASE(n) (SX1301_VIRT_BASE + (SX1301_PAGE_LEN * n))
> >
> > +/* Page 0 */
> > +#define SX1301_CHRS (SX1301_PAGE_BASE(0) + 0x23)
> > +#define SX1301_FORCE_CTRL (SX1301_PAGE_BASE(0) + 0x69)
> > +#define SX1301_MCU_CTRL (SX1301_PAGE_BASE(0) + 0x6A)
> > +
> > +/* Page 2 */
> > +#define SX1301_RADIO_A_SPI_DATA (SX1301_PAGE_BASE(2) + 0x21)
> > +#define SX1301_RADIO_A_SPI_DATA_RB (SX1301_PAGE_BASE(2) + 0x22)
> > +#define SX1301_RADIO_A_SPI_ADDR (SX1301_PAGE_BASE(2) + 0x23)
> > +#define SX1301_RADIO_A_SPI_CS (SX1301_PAGE_BASE(2) + 0x25)
> > +#define SX1301_RADIO_B_SPI_DATA (SX1301_PAGE_BASE(2) + 0x26)
> > +#define SX1301_RADIO_B_SPI_DATA_RB (SX1301_PAGE_BASE(2) + 0x27)
> > +#define SX1301_RADIO_B_SPI_ADDR (SX1301_PAGE_BASE(2) + 0x28)
> > +#define SX1301_RADIO_B_SPI_CS (SX1301_PAGE_BASE(2) + 0x2A)
> > +#define SX1301_RADIO_CFG (SX1301_PAGE_BASE(2) + 0x2B)
> > +#define SX1301_DBG_ARB_MCU_RAM_DATA (SX1301_PAGE_BASE(2) + 0x40)
> > +#define SX1301_DBG_AGC_MCU_RAM_DATA (SX1301_PAGE_BASE(2) + 0x41)
> > +#define SX1301_DBG_ARB_MCU_RAM_ADDR (SX1301_PAGE_BASE(2) + 0x50)
> > +#define SX1301_DBG_AGC_MCU_RAM_ADDR (SX1301_PAGE_BASE(2) + 0x51)
> > +
> > +/* Page 3 */
> > +#define SX1301_EMERGENCY_FORCE_HOST_CTRL (SX1301_PAGE_BASE(3) + 0x7F)
> > +
> > #define SX1301_MAX_REGISTER (SX1301_PAGE_BASE(3) + 0x7F)
> >
> > #endif
>
> Applying so that we can continue based on regmap.
Thanks!
Ben Whitten
^ permalink raw reply
* Re: [PATCH] net: ethernet: cpsw-phy-sel: prefer phandle for phy sel and update binding
From: Grygorii Strashko @ 2018-08-09 22:47 UTC (permalink / raw)
To: Tony Lindgren, Andrew Lunn
Cc: David Miller, netdev, linux-omap, devicetree, Ivan Khoronzhuk,
Mark Rutland, Murali Karicheri, Rob Herring
In-Reply-To: <20180809104653.GV99251@atomide.com>
On 08/09/2018 05:46 AM, Tony Lindgren wrote:
> * Tony Lindgren <tony@atomide.com> [180808 13:52]:
>> * Andrew Lunn <andrew@lunn.ch> [180808 12:02]:
>>>
>>> Do you need to handle EPROBE_DEFER here? The phandle points to a
>>> device which has not yet been loaded? I'm not sure exactly where it
>>> will be returned, maybe it is bus_find_device(), but i expect to see
>>> some handling of it somewhere in this function.
>
> If no device is found the driver just produces a warning currently.
> And in that case cpsw attempts to continue with bootloader settings.
>
> And looking at the caller function cpsw_slave_open() it also just
> produces warnings for phy_connect() too..
>
> I agree that in general this this whole pile of cpsw related drivers sure
> could use some better error handling. Starting with making cpsw_slave_open()
> and cpsw_phy_sel() return errors instead of just ignoring them might be a
> good start.
>
> Grygorii, care to add that note of things to do into your cpsw maintainer
> hat?
Right. EPROBE_DEFER not supported for this module as of now.
>
>> With the proper interconnect hierarchy in the device tree there should be
>> no EPROBE_DEFER happening here as the interconnects are probed in the
>> right order with the always on interrupt with system control module first :)
>>
>> But then again, adding support for EPROBE_DEFER here won't hurt either,
>> will take a look.
>
> I'll just add some notes about that to the patch description considering
> the above.
thanks Tony.
--
regards,
-grygorii
^ permalink raw reply
* [net-next:master 1939/1953] drivers/net/ethernet/qlogic/qede/qede_main.c:539:5: sparse: symbol 'qede_setup_tc' was not declared. Should it be static?
From: kbuild test robot @ 2018-08-10 1:29 UTC (permalink / raw)
To: Manish Chopra
Cc: kbuild-all, netdev, Ariel Elior, everest-linux-l2, linux-kernel
tree: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
head: 36d2f761b5aa688567b6aebdc6d68e73682275d4
commit: 5e7baf0fcb2a3aef7329f3c7543d4695a46bd321 [1939/1953] qed/qede: Multi CoS support.
reproduce:
# apt-get install sparse
git checkout 5e7baf0fcb2a3aef7329f3c7543d4695a46bd321
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__
sparse warnings: (new ones prefixed by >>)
>> drivers/net/ethernet/qlogic/qede/qede_main.c:539:5: sparse: symbol 'qede_setup_tc' was not declared. Should it be static?
include/linux/slab.h:631:13: sparse: undefined identifier '__builtin_mul_overflow'
include/linux/slab.h:631:13: sparse: not a function <noident>
drivers/net/ethernet/qlogic/qede/qede_main.c:1175:19: sparse: expression using sizeof(void)
drivers/net/ethernet/qlogic/qede/qede_main.c:1175:19: sparse: expression using sizeof(void)
include/linux/slab.h:631:13: sparse: call with no type!
Please review and possibly fold the followup patch.
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
^ permalink raw reply
* Re: [PATCH bpf-next 0/4] Convert filter.txt to RST
From: Tobin C. Harding @ 2018-08-10 1:46 UTC (permalink / raw)
To: Daniel Borkmann
Cc: Alexei Starovoitov, Alexei Starovoitov, Jonathan Corbet,
David S. Miller, Kees Cook, Andy Lutomirski, Will Drewry,
linux-doc, netdev, linux-kernel
In-Reply-To: <80bdc251-9f57-602f-6536-b34651684bb7@iogearbox.net>
On Thu, Aug 09, 2018 at 10:24:54AM +0200, Daniel Borkmann wrote:
> On 08/09/2018 09:27 AM, Tobin C. Harding wrote:
> > On Wed, Aug 08, 2018 at 11:07:35PM -0700, Alexei Starovoitov wrote:
> >> On Thu, Aug 09, 2018 at 03:23:24PM +1000, Tobin C. Harding wrote:
> >>>
> >>> Daniel and Alexei, can I please have permission to add GPLv2+ to the BPF
> >>> docs?
> >>
> >> kernel licensing is GPLv2 without +
> >
> > According to process/license-rules.rst
> >
> > GPL-2.0+ : GNU General Public License v2.0 or later
>
> Not really, please see the first three paragraphs of process/license-rules.rst.
> The COPYING file of the kernel says that it's 'v2' and not 'v2 or later',
> unless otherwise _explicitly_ noted. Given that and given there is no other
> specific note in filter.txt, it would mean it's v2-only due to that rule.
Thanks for clarifying. My understanding is now; this is a case where
checkpatch is too verbose and we do not actually need to add a specific
license identifier to the documentation files (new or otherwise). They
get an implicit GPLv2.
I'll remove the licences identifiers and re-spin.
thanks,
Tobin.
^ permalink raw reply
* pull-request: bpf 2018-08-10
From: Daniel Borkmann @ 2018-08-09 23:21 UTC (permalink / raw)
To: davem; +Cc: daniel, ast, netdev
Hi David,
The following pull-request contains BPF updates for your *net* tree.
The main changes are:
1) Fix cpumap and devmap on teardown as they're under RCU context
and won't have same assumption as running under NAPI protection,
from Jesper.
2) Fix various sockmap bugs in bpf_tcp_sendmsg() code, e.g. we had
a bug where socket error was not propagated correctly, from Daniel.
3) Fix incompatible libbpf header license for BTF code and match it
before it gets officially released with the rest of libbpf which
is LGPL-2.1, from Martin.
Please consider pulling these changes from:
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
Thanks a lot!
----------------------------------------------------------------
The following changes since commit 82a40777de12728dedf4075453b694f0d1baee80:
ip6_tunnel: use the right value for ipv4 min mtu check in ip6_tnl_xmit (2018-08-05 17:35:02 -0700)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
for you to fetch changes up to 9c95420117393ed5f76de373e3c6479c21e3e380:
Merge branch 'bpf-fix-cpu-and-devmap-teardown' (2018-08-09 21:50:45 +0200)
----------------------------------------------------------------
Alexei Starovoitov (1):
Merge branch 'sockmap-fixes'
Daniel Borkmann (4):
bpf, sockmap: fix bpf_tcp_sendmsg sock error handling
bpf, sockmap: fix leak in bpf_tcp_sendmsg wait for mem path
bpf, sockmap: fix cork timeout for select due to epipe
Merge branch 'bpf-fix-cpu-and-devmap-teardown'
Jesper Dangaard Brouer (3):
xdp: fix bug in cpumap teardown code path
samples/bpf: xdp_redirect_cpu adjustment to reproduce teardown race easier
xdp: fix bug in devmap teardown code path
Martin KaFai Lau (1):
bpf: btf: Change tools/lib/bpf/btf to LGPL
kernel/bpf/cpumap.c | 15 +++++++++------
kernel/bpf/devmap.c | 14 +++++++++-----
kernel/bpf/sockmap.c | 9 ++++++---
samples/bpf/xdp_redirect_cpu_kern.c | 2 +-
samples/bpf/xdp_redirect_cpu_user.c | 4 ++--
tools/lib/bpf/btf.c | 2 +-
tools/lib/bpf/btf.h | 2 +-
tools/testing/selftests/bpf/test_sockmap.c | 2 +-
8 files changed, 30 insertions(+), 20 deletions(-)
^ permalink raw reply
* [net-next:master 518/519] drivers/net/virtio_net.c:1910:3: error: implicit declaration of function '__netif_set_xps_queue'; did you mean 'netif_set_xps_queue'?
From: kbuild test robot @ 2018-08-09 23:34 UTC (permalink / raw)
To: Andrei Vagin; +Cc: kbuild-all, netdev
[-- Attachment #1: Type: text/plain, Size: 2204 bytes --]
tree: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
head: 36d2f761b5aa688567b6aebdc6d68e73682275d4
commit: 4d99f6602cb552fb58db0c3b1d935bb6fa017f24 [518/519] net: allow to call netif_reset_xps_queues() under cpus_read_lock
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
git checkout 4d99f6602cb552fb58db0c3b1d935bb6fa017f24
# save the attached .config to linux build tree
GCC_VERSION=7.2.0 make.cross ARCH=sh
All errors (new ones prefixed by >>):
drivers/net/virtio_net.c: In function 'virtnet_set_affinity':
>> drivers/net/virtio_net.c:1910:3: error: implicit declaration of function '__netif_set_xps_queue'; did you mean 'netif_set_xps_queue'? [-Werror=implicit-function-declaration]
__netif_set_xps_queue(vi->dev, mask, i, false);
^~~~~~~~~~~~~~~~~~~~~
netif_set_xps_queue
cc1: some warnings being treated as errors
vim +1910 drivers/net/virtio_net.c
1888
1889 static void virtnet_set_affinity(struct virtnet_info *vi)
1890 {
1891 int i;
1892 int cpu;
1893
1894 /* In multiqueue mode, when the number of cpu is equal to the number of
1895 * queue pairs, we let the queue pairs to be private to one cpu by
1896 * setting the affinity hint to eliminate the contention.
1897 */
1898 if (vi->curr_queue_pairs == 1 ||
1899 vi->max_queue_pairs != num_online_cpus()) {
1900 virtnet_clean_affinity(vi, -1);
1901 return;
1902 }
1903
1904 i = 0;
1905 for_each_online_cpu(cpu) {
1906 const unsigned long *mask = cpumask_bits(cpumask_of(cpu));
1907
1908 virtqueue_set_affinity(vi->rq[i].vq, cpu);
1909 virtqueue_set_affinity(vi->sq[i].vq, cpu);
> 1910 __netif_set_xps_queue(vi->dev, mask, i, false);
1911 i++;
1912 }
1913
1914 vi->affinity_hint_set = true;
1915 }
1916
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 48753 bytes --]
^ permalink raw reply
* [BUG] net: xfrm: Two possible sleep-in-atomic-context bugs
From: bai @ 2018-08-10 2:02 UTC (permalink / raw)
To: steffen.klassert, herbert, davem; +Cc: netdev, linux-kernel
The code may sleep in interrupt handler.
xfrm_trans_reinject() is an interrupt handler set in tasklet_init().
The function call paths (from bottom to top) in Linux-4.16 are:
[FUNC] schedule_timeout
net/core/sock.c, 2044: schedule_timeout in sock_wait_for_wmem
net/core/sock.c, 2083: sock_wait_for_wmem in sock_alloc_send_pskb
net/core/sock.c, 2102: sock_alloc_send_pskb in sock_alloc_send_skb
net/ipv6/mcast.c, 1989: sock_alloc_send_skb in igmp6_send
net/ipv6/mcast.c, 2391: igmp6_send in igmp6_join_group
net/ipv6/mcast.c, 670: igmp6_join_group in igmp6_group_added
net/ipv6/mcast.c, 914: igmp6_group_added in ipv6_dev_mc_inc
net/ipv6/ndisc.c, 379: ipv6_dev_mc_inc in pndisc_constructor
net/core/neighbour.c, 640: [FUNC_PTR]pndisc_constructor in pneigh_lookup
net/ipv6/ip6_output.c, 483: pneigh_lookup in ip6_forward
./include/net/dst.h, 449: [FUNC_PTR]ip6_forward in dst_input
net/ipv6/ip6_input.c, 71: dst_input in ip6_rcv_finish
net/xfrm/xfrm_input.c, 511: [FUNC_PTR]ip6_rcv_finish in xfrm_trans_reinject
[FUNC] kmalloc(GFP_KERNEL)
net/core/neighbour.c, 630: kmalloc in pneigh_lookup
net/ipv6/ip6_output.c, 483: pneigh_lookup in ip6_forward
./include/net/dst.h, 449: [FUNC_PTR]ip6_forward in dst_input
net/ipv6/ip6_input.c, 71: dst_input in ip6_rcv_finish
net/xfrm/xfrm_input.c, 511: [FUNC_PTR]ip6_rcv_finish in xfrm_trans_reinject
Note that [FUNC_PTR] means a function pointer call is used.
I do not find a good way to fix them, so I only report.
These possible bugs are found by my static analysis tool (DSAC) and
checked by my code review.
Best wishes,
Jia-Ju Bai
^ permalink raw reply
* Re: [PATCH bpf-next 1/3] bpf: add bpf queue map
From: Mauricio Vasquez @ 2018-08-09 23:41 UTC (permalink / raw)
To: Alexei Starovoitov; +Cc: Daniel Borkmann, Alexei Starovoitov, netdev
In-Reply-To: <20180809162328.rnyxihpiim2wz5dk@ast-mbp>
On 08/09/2018 11:23 AM, Alexei Starovoitov wrote:
> On Thu, Aug 09, 2018 at 09:51:49AM -0500, Mauricio Vasquez wrote:
>>> Agree that existing ops are not the right alias, but deferring to user
>>> space as inline function also doesn't really seem like a good fit, imho,
>>> so I'd prefer rather to have something native. (Aside from that, the
>>> above inline bpf_pop() would also race between CPUs.)
>> I think we should have push/pop/peek syscalls as well, having a bpf_pop()
>> that is race prone would create problems. Users expected maps operations to
>> be safe, so having one that is not will confuse them.
> agree the races are not acceptable.
> How about a mixed solution:
> - introduce bpf_push/pop/peak helpers that programs will use, so
> they don't need to pass useless key=NULL
> - introduce map->ops->lookup_and_delete and map->ops->lookup_or_init
> that prog-side helpers can use and syscall has 1-1 mapping for
I think if is a fair solution.
> Native lookup_or_init() helper for programs and syscall is badly missing.
> Most of the bcc scripts use it and bcc has a racy workaround.
> Similarly lookup_and_delete() syscall is 1-1 to pop() for stack/queue
> and useful for regular hash maps.
>
> At the end for stack/queue map the programs will use:
> int bpf_push(map, value);
Also flags should be passed here.
> value_or_null = bpf_pop(map); // guaranteed non-racy for multi-cpu
> value_or_null = bpf_peak(map); // racy if 2+ cpus doing it
Is there any reason for it to be racy?
>
> from syscall:
> bpf_map_lookup_elem(map, NULL, &value); // returns top of stack
> bpf_map_lookup_and_delete_elem(map, NULL, &value); // returns top and deletes top atomically
> bpf_map_update_elem(map, NULL, &value); // pushes new value into stack atomically
>
> Eventually hash and other maps will implement bpf_map_lookup_and_delete()
> for both bpf progs and syscall.
>
> The main point that prog-side api doesn't have to match 1-1 to syscall-side,
> since they're different enough already.
> Like lookup_or_init() is badly needed for programs, but unnecessary for syscall.
>
> Thoughts?
>
I agree with the idea, if there are not more thoughts on this I'd
proceed to the implementation.
^ permalink raw reply
* Re: [PATCH net-next v6 10/11] net: sched: atomically check-allocate action
From: Cong Wang @ 2018-08-09 23:43 UTC (permalink / raw)
To: Vlad Buslov
Cc: Linux Kernel Network Developers, David Miller, Jamal Hadi Salim,
Jiri Pirko, Alexei Starovoitov, Daniel Borkmann,
Yevgeny Kliteynik, Jiri Pirko
In-Reply-To: <vbfpnyt2hbw.fsf@reg-r-vrt-018-180.mtr.labs.mlnx>
On Wed, Aug 8, 2018 at 5:06 AM Vlad Buslov <vladbu@mellanox.com> wrote:
>
>
> On Wed 08 Aug 2018 at 01:20, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> > On Thu, Jul 5, 2018 at 7:24 AM Vlad Buslov <vladbu@mellanox.com> wrote:
> >>
> >> Implement function that atomically checks if action exists and either takes
> >> reference to it, or allocates idr slot for action index to prevent
> >> concurrent allocations of actions with same index. Use EBUSY error pointer
> >> to indicate that idr slot is reserved.
> >
> > A dumb question:
> >
> > How could "concurrent allocations of actions with same index" happen
> > as you already take idrinfo->lock for the whole
> > tcf_idr_check_alloc()??
>
> I guess my changelog is not precise enough in this description.
> Let look into sequence of events of initialization of new action:
> 1) tcf_idr_check_alloc() is called by action init.
> 2) idrinfo->lock is taken.
> 3) Lookup in idr is performed to determine if action with specified
> index already exists.
> 4) EBUSY pointer is inserted to indicate that id is taken.
> 5) idrinfo->lock is released.
> 6) tcf_idr_check_alloc() returns to action init code.
> 7) New action is allocated and initialized.
> 8) tcf_idr_insert() is called.
> 9) idrinfo->lock is taken.
> 10) EBUSY pointer is substituted with pointer to new action.
> 11) idrinfo->lock is released.
> 12) tcf_idr_insert() returns.
>
> So in this case "concurrent allocations of actions with same index"
> means not the allocation with same index during tcf_idr_check_alloc(),
> but during the period when idrinfo->lock was released(6-8).
Yes but it is unnecessary:
a) When adding a new action, you can actually allocate and init it before
touching idrinfo, therefore the check and insert can be done in one step
instead of breaking down it into multiple steps, which means you can
acquire idrinfo->lock once.
b) When updating an existing action, it is slightly complicated.
However, you can still allocate a new one first, then find the old one
and copy it into the new one and finally replace it.
In summary, we can do the following:
1. always allocate a new action
2. acquire idrinfo->lock
3a. if it is an add operation: allocate a new ID and insert the new action
3b. if it is a replace operation: find the old one with ID, copy it into the
new one and replace it
4. release idrinfo->lock
5. If 3a or 3b fails, free the allocation. Otherwise succeed.
I know, the locking scope is now per netns rather than per action,
but this can be optimized for replacing, you can hold the old action
and then release the idrinfo->lock, as idr_replace() later doesn't
require idrinfo->lock AFAIK.
Is there anything I miss here?
>
> >
> > For me, it should be only one allocation could succeed, all others
> > should fail.
>
> Correct! And this change is made specifically to enforce that rule.
>
> Otherwise, multiple processes could try to create new action with same
> id at the same time, and all processes that executed 3, before any
> process reached 10, will "succeed" by overwriting each others action in
> idr. (and leak memory while doing so)
I know but again it doesn't look necessary to achieve a same goal.
>
> >
> > Maybe you are trying to prevent others treat it like existing one,
> > but in that case you can just hold the idinfo->lock for all idr operations.
> >
> > And more importantly, upper layer is able to tell it is a creation or
> > just replace, you don't have to check this in this complicated way.
> >
> > IOW, all of these complicated code should not exist.
>
> Original code was simpler and didn't involve temporary EBUSY pointer.
> This change was made according to Jiri's request. He wanted to have
> unified API to be used by all actions and suggested this approach
> specifically.
I will work on this, as this is aligned to my work to make
it RCU-complete.
^ permalink raw reply
* [PATCH bpf-next v2 0/4] Convert filter.txt to RST
From: Tobin C. Harding @ 2018-08-10 2:24 UTC (permalink / raw)
To: Daniel Borkmann, Alexei Starovoitov
Cc: Tobin C. Harding, Jonathan Corbet, David S. Miller, Kees Cook,
Andy Lutomirski, Will Drewry, linux-doc, netdev, linux-kernel
seccomp_filter.rst change removed from set, leaving CC list same as v1
for continuity.
Hi,
This is my latest attempt at converting Documentation/filter.txt to RST
format. This version removes the SPDX licence identifiers added in the
previous version.
This work has gotten a bit mixed up; for reference this set is a
progression of the follow sets (newest set last)
1. [PATCH bpf-next 00/13] docs: Convert BPF filter.txt to RST
2. [RFC bpf-next 0/3] docs: Convert filter.txt to RST
3. [RFC bpf-next v2 0/3] docs: Convert filter.txt to RST
4. [PATCH bpf-next 0/4] Convert filter.txt to RST
As discussed on LKML this set does all the conversion in a single
patch.
Please note this set adds three files to the MAINTAINERS file for the
BPF maintainers.
thanks,
Tobin.
v2:
- Remove SPDX licence identifiers
- Update old intree references to filter.txt
Tobin C. Harding (4):
docs: net: Fix various minor typos
docs: Separate and convert filter.txt to RST
docs: Judiciously use double ticks
docs: Remove filter.txt from the tree
Documentation/bpf/index.rst | 15 +-
Documentation/networking/00-INDEX | 2 -
Documentation/networking/filter.txt | 1476 -----------------
Documentation/networking/packet_mmap.txt | 2 +-
Documentation/userspace-api/cBPF.rst | 430 +++++
Documentation/userspace-api/eBPF.rst | 1004 +++++++++++
Documentation/userspace-api/index.rst | 3 +
.../userspace-api/seccomp_filter.rst | 9 +
Documentation/userspace-api/socket_filter.rst | 181 ++
MAINTAINERS | 4 +-
tools/bpf/bpf_asm.c | 6 +-
tools/bpf/bpf_dbg.c | 9 +-
12 files changed, 1653 insertions(+), 1488 deletions(-)
delete mode 100644 Documentation/networking/filter.txt
create mode 100644 Documentation/userspace-api/cBPF.rst
create mode 100644 Documentation/userspace-api/eBPF.rst
create mode 100644 Documentation/userspace-api/socket_filter.rst
--
2.17.1
^ permalink raw reply
* [PATCH bpf-next v2 1/4] docs: net: Fix various minor typos
From: Tobin C. Harding @ 2018-08-10 2:24 UTC (permalink / raw)
To: Daniel Borkmann, Alexei Starovoitov
Cc: Tobin C. Harding, Jonathan Corbet, David S. Miller, Kees Cook,
Andy Lutomirski, Will Drewry, linux-doc, netdev, linux-kernel
In-Reply-To: <20180810022450.1237-1-me@tobin.cc>
Document contains a few minor typos and grammatical issues. We should
however try to keep the current flavour of the document.
Fix typos and grammar if fix is _really_ an improvement.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
---
Documentation/networking/filter.txt | 66 +++++++++++++++--------------
1 file changed, 35 insertions(+), 31 deletions(-)
diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
index e6b4ebb2b243..1fe4adf9c4c6 100644
--- a/Documentation/networking/filter.txt
+++ b/Documentation/networking/filter.txt
@@ -29,8 +29,8 @@ removing the old one and placing your new one in its place, assuming your
filter has passed the checks, otherwise if it fails the old filter will
remain on that socket.
-SO_LOCK_FILTER option allows to lock the filter attached to a socket. Once
-set, a filter cannot be removed or changed. This allows one process to
+SO_LOCK_FILTER option allows locking of the filter attached to a socket.
+Once set, a filter cannot be removed or changed. This allows one process to
setup a socket, attach a filter, lock it then drop privileges and be
assured that the filter will be kept until the socket is closed.
@@ -463,7 +463,7 @@ JIT compiler
------------
The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC, PowerPC,
-ARM, ARM64, MIPS and s390 and can be enabled through CONFIG_BPF_JIT. The JIT
+ARM, ARM64, MIPS and s390 which can be enabled through CONFIG_BPF_JIT. The JIT
compiler is transparently invoked for each attached filter from user space
or for internal kernel users if it has been previously enabled by root:
@@ -572,7 +572,7 @@ Internally, for the kernel interpreter, a different instruction set
format with similar underlying principles from BPF described in previous
paragraphs is being used. However, the instruction set format is modelled
closer to the underlying architecture to mimic native instruction sets, so
-that a better performance can be achieved (more details later). This new
+that better performance can be achieved (more details later). This new
ISA is called 'eBPF' or 'internal BPF' interchangeably. (Note: eBPF which
originates from [e]xtended BPF is not the same as BPF extensions! While
eBPF is an ISA, BPF extensions date back to classic BPF's 'overloading'
@@ -647,12 +647,12 @@ Some core changes of the new internal format:
32-bit architectures run 64-bit internal BPF programs via interpreter.
Their JITs may convert BPF programs that only use 32-bit subregisters into
- native instruction set and let the rest being interpreted.
+ native instruction set and let the rest be interpreted.
- Operation is 64-bit, because on 64-bit architectures, pointers are also
- 64-bit wide, and we want to pass 64-bit values in/out of kernel functions,
- so 32-bit eBPF registers would otherwise require to define register-pair
- ABI, thus, there won't be able to use a direct eBPF register to HW register
+ Operation is 64-bit since on 64-bit architectures pointers are also
+ 64-bit wide and we want to pass 64-bit values in/out of kernel functions.
+ 32-bit eBPF registers would otherwise require us to define a register-pair
+ ABI, thus we would not be able to use a direct eBPF register to HW register
mapping and JIT would need to do combine/split/move operations for every
register in and out of the function, which is complex, bug prone and slow.
Another reason is the use of atomic 64-bit counters.
@@ -677,7 +677,7 @@ Some core changes of the new internal format:
situations without performance penalty.
After an in-kernel function call, R1 - R5 are reset to unreadable and R0 has
- a return value of the function. Since R6 - R9 are callee saved, their state
+ the return value of the function. Since R6 - R9 are callee saved, their state
is preserved across the call.
For example, consider three C functions:
@@ -715,7 +715,7 @@ Some core changes of the new internal format:
are currently not supported, but these restrictions can be lifted if necessary
in the future.
- On 64-bit architectures all register map to HW registers one to one. For
+ On 64-bit architectures all registers map to HW registers one to one. For
example, x86_64 JIT compiler can map them as ...
R0 - rax
@@ -814,9 +814,10 @@ A program, that is translated internally consists of the following elements:
op:16, jt:8, jf:8, k:32 ==> op:8, dst_reg:4, src_reg:4, off:16, imm:32
-So far 87 internal BPF instructions were implemented. 8-bit 'op' opcode field
-has room for new instructions. Some of them may use 16/24/32 byte encoding. New
-instructions must be multiple of 8 bytes to preserve backward compatibility.
+So far 87 internal BPF instructions have been implemented. 8-bit 'op' opcode
+field has room for new instructions. Some of them may use 16/24/32 byte
+encoding. New instructions must be a multiple of 8 bytes to preserve backward
+compatibility.
Internal BPF is a general purpose RISC instruction set. Not every register and
every instruction are used during translation from original BPF to new format.
@@ -827,11 +828,11 @@ out of registers and would have to resort to spill/fill to stack.
Internal BPF can used as generic assembler for last step performance
optimizations, socket filters and seccomp are using it as assembler. Tracing
-filters may use it as assembler to generate code from kernel. In kernel usage
+filters may use it as assembler to generate code from kernel. In-kernel usage
may not be bounded by security considerations, since generated internal BPF code
-may be optimizing internal code path and not being exposed to the user space.
-Safety of internal BPF can come from a verifier (TBD). In such use cases as
-described, it may be used as safe instruction set.
+may use an optimised internal code path and may not be being exposed to user
+space. Safety of internal BPF can come from a verifier (TBD). In such use cases
+as described, it may be used as safe as the instruction set.
Just like the original BPF, the new format runs within a controlled environment,
is deterministic and the kernel can easily prove that. The safety of the program
@@ -927,7 +928,7 @@ Classic BPF is using BPF_MISC class to represent A = X and X = A moves.
eBPF is using BPF_MOV | BPF_X | BPF_ALU code instead. Since there are no
BPF_MISC operations in eBPF, the class 7 is used as BPF_ALU64 to mean
exactly the same operations as BPF_ALU, but with 64-bit wide operands
-instead. So BPF_ADD | BPF_X | BPF_ALU64 means 64-bit addition, i.e.:
+instead. So BPF_ADD | BPF_X | BPF_ALU64 means 64-bit addition i.e.
dst_reg = dst_reg + src_reg
Classic BPF wastes the whole BPF_RET class to represent a single 'ret'
@@ -1005,9 +1006,10 @@ BPF_XADD | BPF_DW | BPF_STX: lock xadd *(u64 *)(dst_reg + off16) += src_reg
Where size is one of: BPF_B or BPF_H or BPF_W or BPF_DW. Note that 1 and
2 byte atomic increments are not supported.
-eBPF has one 16-byte instruction: BPF_LD | BPF_DW | BPF_IMM which consists
-of two consecutive 'struct bpf_insn' 8-byte blocks and interpreted as single
+eBPF has one 16-byte instruction: BPF_LD | BPF_DW | BPF_IMM which consists of
+two consecutive 'struct bpf_insn' 8-byte blocks and is interpreted as single
instruction that loads 64-bit immediate value into a dst_reg.
+
Classic BPF has similar instruction: BPF_LD | BPF_W | BPF_IMM which loads
32-bit immediate value into a register.
@@ -1016,8 +1018,8 @@ eBPF verifier
The safety of the eBPF program is determined in two steps.
First step does DAG check to disallow loops and other CFG validation.
-In particular it will detect programs that have unreachable instructions.
-(though classic BPF checker allows them)
+In particular it will detect programs that have unreachable instructions
+(though classic BPF checker allows them).
Second step starts from the first insn and descends all possible paths.
It simulates execution of every insn and observes the state change of
@@ -1078,7 +1080,9 @@ Classic BPF verifier does similar check with M[0-15] memory slots.
For example:
bpf_ld R0 = *(u32 *)(R10 - 4)
bpf_exit
-is invalid program.
+
+is an invalid program.
+
Though R10 is correct read-only register and has type PTR_TO_STACK
and R10 - 4 is within stack bounds, there were no stores into that location.
@@ -1089,13 +1093,13 @@ Allowed function calls are customized with bpf_verifier_ops->get_func_proto()
The eBPF verifier will check that registers match argument constraints.
After the call register R0 will be set to return type of the function.
-Function calls is a main mechanism to extend functionality of eBPF programs.
-Socket filters may let programs to call one set of functions, whereas tracing
-filters may allow completely different set.
+Function calls is an important mechanism to extend functionality of eBPF
+programs. Socket filters may let programs call one set of functions,
+whereas tracing filters may allow a completely different set.
-If a function made accessible to eBPF program, it needs to be thought through
-from safety point of view. The verifier will guarantee that the function is
-called with valid arguments.
+If a function is made accessible to eBPF program, it needs to be thought
+through from a safety point of view. The verifier will guarantee that the
+function is called with valid arguments.
seccomp vs socket filters have different security restrictions for classic BPF.
Seccomp solves this by two stage verifier: classic BPF verifier is followed
@@ -1167,7 +1171,7 @@ checked and found to be non-NULL, all copies can become PTR_TO_MAP_VALUEs.
As well as range-checking, the tracked information is also used for enforcing
alignment of pointer accesses. For instance, on most systems the packet pointer
is 2 bytes after a 4-byte alignment. If a program adds 14 bytes to that to jump
-over the Ethernet header, then reads IHL and addes (IHL * 4), the resulting
+over the Ethernet header, then reads IHL and adds (IHL * 4), the resulting
pointer will have a variable offset known to be 4n+2 for some n, so adding the 2
bytes (NET_IP_ALIGN) gives a 4-byte alignment and so word-sized accesses through
that pointer are safe.
--
2.17.1
^ permalink raw reply related
* [PATCH bpf-next v2 2/4] docs: Separate and convert filter.txt to RST
From: Tobin C. Harding @ 2018-08-10 2:24 UTC (permalink / raw)
To: Daniel Borkmann, Alexei Starovoitov
Cc: Tobin C. Harding, Jonathan Corbet, David S. Miller, Kees Cook,
Andy Lutomirski, Will Drewry, linux-doc, netdev, linux-kernel
In-Reply-To: <20180810022450.1237-1-me@tobin.cc>
RST is the preferred format for kernel documentation now. Convert
networking/filter.txt to RST format. Currently filer.txt contains
documentation on various things related to BPF. To improve the quality
of the kernel documentation we can split this file up. Also, BPF is
useful to userspace for applications outside of just networking.
Split filter.txt up into three RST files, all now located under
Documentation/userspace-api/. After the split there should be no Sphinx
warnings.
Create three new files from the content of filter.txt
- socket-filter.rst on how to write socket filters
- cBPF.rst describing classic BPF and its tools
- eBPF.rst describing extended BPF
Add files to MAINTAINERS.
Do conversion
- Fix line length (72 character maximum).
- Use double spaces after a period (full stop).
- Use RST format directives for code snippets (::).
- Fix indentation of code snippets.
- Use correct heading adornments.
Admittedly double spaces is a style issue and should really not be done
however doing the line length change requires double spacing because of
the tool I have available (emacs). Line length limint seems more
important so lets do both changes.
Because these three files are related (also seccomp_filter.rst) there
are a number of references to each. Add an RST reference label to the
top of each file and use it with the relative path (starting at
Documentation) as is typical in kernel docs. Use a list so as to make
the text file readable as well as the rendered HTML.
Add RST reference label to seccomp_filter.rst
Signed-off-by: Tobin C. Harding <me@tobin.cc>
---
Documentation/userspace-api/cBPF.rst | 430 +++++++
Documentation/userspace-api/eBPF.rst | 1005 +++++++++++++++++
Documentation/userspace-api/index.rst | 3 +
.../userspace-api/seccomp_filter.rst | 9 +
Documentation/userspace-api/socket_filter.rst | 181 +++
MAINTAINERS | 4 +-
6 files changed, 1631 insertions(+), 1 deletion(-)
create mode 100644 Documentation/userspace-api/cBPF.rst
create mode 100644 Documentation/userspace-api/eBPF.rst
create mode 100644 Documentation/userspace-api/socket_filter.rst
diff --git a/Documentation/userspace-api/cBPF.rst b/Documentation/userspace-api/cBPF.rst
new file mode 100644
index 000000000000..5e820c5fe46c
--- /dev/null
+++ b/Documentation/userspace-api/cBPF.rst
@@ -0,0 +1,430 @@
+.. _cbpf:
+
+====================================
+Classic Berkley Packet Filter (cBPF)
+====================================
+
+For an introduction to BPF and Linux Socket Filtering please see
+:ref:`Documentation/userspace-api/socket-filter.rst <socket-filter>`
+
+Under tools/bpf/ there's a small helper tool called bpf_asm which can be
+used to write low-level filters for example scenarios mentioned in the
+above linked document. Asm-like syntax mentioned here has been
+implemented in bpf_asm and will be used for further explanations
+(instead of dealing with less readable opcodes directly, principles are
+the same). The syntax is closely modelled after Steven McCanne's and
+Van Jacobson's BPF paper [1].
+
+The BPF architecture consists of the following basic elements:
+
+.. flat-table:: BPF Elements
+
+ * - Element
+ - Description
+
+ * - A
+ - 32 bit wide accumulator
+
+ * - X
+ - 32 bit wide X register
+
+ * - M[]
+ - 16 x 32 bit wide misc registers aka "scratch memory store",
+ addressable from 0 to 15
+
+A program, that is translated by bpf_asm into "opcodes" is an array that
+consists of the following elements (as already mentioned)::
+
+ op:16, jt:8, jf:8, k:32
+
+The element op is a 16 bit wide opcode that has a particular instruction
+encoded. jt and jf are two 8 bit wide jump targets, one for condition
+"jump if true", the other one "jump if false". Eventually, element k
+contains a miscellaneous argument that can be interpreted in different
+ways depending on the given instruction in op.
+
+The instruction set consists of load, store, branch, alu, miscellaneous
+and return instructions that are also represented in bpf_asm syntax.
+This table lists all bpf_asm instructions available resp. what their
+underlying opcodes as defined in linux/filter.h stand for:
+::
+
+ Instruction Addressing mode Description
+
+ ld 1, 2, 3, 4, 10 Load word into A
+ ldi 4 Load word into A
+ ldh 1, 2 Load half-word into A
+ ldb 1, 2 Load byte into A
+ ldx 3, 4, 5, 10 Load word into X
+ ldxi 4 Load word into X
+ ldxb 5 Load byte into X
+
+ st 3 Store A into M[]
+ stx 3 Store X into M[]
+
+ jmp 6 Jump to label
+ ja 6 Jump to label
+ jeq 7, 8 Jump on A == k
+ jneq 8 Jump on A != k
+ jne 8 Jump on A != k
+ jlt 8 Jump on A < k
+ jle 8 Jump on A <= k
+ jgt 7, 8 Jump on A > k
+ jge 7, 8 Jump on A >= k
+ jset 7, 8 Jump on A & k
+
+ add 0, 4 A + <x>
+ sub 0, 4 A - <x>
+ mul 0, 4 A * <x>
+ div 0, 4 A / <x>
+ mod 0, 4 A % <x>
+ neg !A
+ and 0, 4 A & <x>
+ or 0, 4 A | <x>
+ xor 0, 4 A ^ <x>
+ lsh 0, 4 A << <x>
+ rsh 0, 4 A >> <x>
+
+ tax Copy A into X
+ txa Copy X into A
+
+ ret 4, 9 Return
+
+The next table shows addressing formats from the 2nd column::
+
+ Addressing mode Syntax Description
+
+ 0 x/%x Register X
+ 1 [k] BHW at byte offset k in the packet
+ 2 [x + k] BHW at the offset X + k in the packet
+ 3 M[k] Word at offset k in M[]
+ 4 #k Literal value stored in k
+ 5 4*([k]&0xf) Lower nibble * 4 at byte offset k in the packet
+ 6 L Jump label L
+ 7 #k,Lt,Lf Jump to Lt if true, otherwise jump to Lf
+ 8 #k,Lt Jump to Lt if predicate is true
+ 9 a/%a Accumulator A
+ 10 extension BPF extension
+
+The Linux kernel also has a couple of BPF extensions that are used along
+with the class of load instructions by "overloading" the k argument with
+a negative offset + a particular extension offset. The result of such
+BPF extensions are loaded into A.
+
+Possible BPF extensions are shown in the following table::
+
+ Extension Description
+
+ len skb->len
+ proto skb->protocol
+ type skb->pkt_type
+ poff Payload start offset
+ ifidx skb->dev->ifindex
+ nla Netlink attribute of type X with offset A
+ nlan Nested Netlink attribute of type X with offset A
+ mark skb->mark
+ queue skb->queue_mapping
+ hatype skb->dev->type
+ rxhash skb->hash
+ cpu raw_smp_processor_id()
+ vlan_tci skb_vlan_tag_get(skb)
+ vlan_avail skb_vlan_tag_present(skb)
+ vlan_tpid skb->vlan_proto
+ rand prandom_u32()
+
+These extensions can also be prefixed with '#'.
+Examples for low-level BPF:
+
+ARP packets::
+
+ ldh [12]
+ jne #0x806, drop
+ ret #-1
+ drop: ret #0
+
+IPv4 TCP packets::
+
+ ldh [12]
+ jne #0x800, drop
+ ldb [23]
+ jneq #6, drop
+ ret #-1
+ drop: ret #0
+
+(Accelerated) VLAN w/ id 10::
+
+ ld vlan_tci
+ jneq #10, drop
+ ret #-1
+ drop: ret #0
+
+icmp random packet sampling, 1 in 4::
+
+ ldh [12]
+ jne #0x800, drop
+ ldb [23]
+ jneq #1, drop
+ # get a random uint32 number
+ ld rand
+ mod #4
+ jneq #1, drop
+ ret #-1
+ drop: ret #0
+
+SECCOMP filter example::
+
+ ld [4] /* offsetof(struct seccomp_data, arch) */
+ jne #0xc000003e, bad /* AUDIT_ARCH_X86_64 */
+ ld [0] /* offsetof(struct seccomp_data, nr) */
+ jeq #15, good /* __NR_rt_sigreturn */
+ jeq #231, good /* __NR_exit_group */
+ jeq #60, good /* __NR_exit */
+ jeq #0, good /* __NR_read */
+ jeq #1, good /* __NR_write */
+ jeq #5, good /* __NR_fstat */
+ jeq #9, good /* __NR_mmap */
+ jeq #14, good /* __NR_rt_sigprocmask */
+ jeq #13, good /* __NR_rt_sigaction */
+ jeq #35, good /* __NR_nanosleep */
+ bad: ret #0 /* SECCOMP_RET_KILL_THREAD */
+ good: ret #0x7fff0000 /* SECCOMP_RET_ALLOW */
+
+The above example code can be placed into a file (here called "foo"),
+and then be passed to the bpf_asm tool for generating opcodes, output
+that xt_bpf and cls_bpf understands and can directly be loaded with.
+Example with above ARP code::
+
+ $ ./bpf_asm foo
+ 4,40 0 0 12,21 0 1 2054,6 0 0 4294967295,6 0 0 0,
+
+In copy and paste C-like output::
+
+ $ ./bpf_asm -c foo
+ { 0x28, 0, 0, 0x0000000c },
+ { 0x15, 0, 1, 0x00000806 },
+ { 0x06, 0, 0, 0xffffffff },
+ { 0x06, 0, 0, 0000000000 },
+
+In particular, as usage with xt_bpf or cls_bpf can result in more
+complex BPF filters that might not be obvious at first, it's good to
+test filters before attaching to a live system. For that purpose,
+there's a small tool called bpf_dbg under tools/bpf/ in the kernel
+source directory. This debugger allows for testing BPF filters against
+given pcap files, single stepping through the BPF code on the pcap's
+packets and to do BPF machine register dumps.
+
+Starting bpf_dbg is trivial and just requires issuing::
+
+ # ./bpf_dbg
+
+In case input and output do not equal stdin/stdout, bpf_dbg takes an
+alternative stdin source as a first argument, and an alternative stdout
+sink as a second one, e.g. `./bpf_dbg test_in.txt test_out.txt`.
+
+Other than that, a particular libreadline configuration can be set via
+file "~/.bpf_dbg_init" and the command history is stored in the file
+"~/.bpf_dbg_history".
+
+Interaction in bpf_dbg happens through a shell that also has
+auto-completion support (follow-up example commands starting with '>'
+denote bpf_dbg shell). The usual workflow would be to ... ::
+
+ > load bpf 6,40 0 0 12,21 0 3 2048,48 0 0 23,21 0 1 1,6 0 0 65535,6 0 0 0
+ Loads a BPF filter from standard output of bpf_asm, or transformed via
+ e.g. `tcpdump -iem1 -ddd port 22 | tr '\n' ','`. Note that for JIT
+ debugging (next section), this command creates a temporary socket and
+ loads the BPF code into the kernel. Thus, this will also be useful for
+ JIT developers.
+
+ > load pcap foo.pcap
+ Loads standard tcpdump pcap file.
+
+ > run [<n>]
+ bpf passes:1 fails:9
+ Runs through all packets from a pcap to account how many passes and fails
+ the filter will generate. A limit of packets to traverse can be given.
+
+ > disassemble
+ l0: ldh [12]
+ l1: jeq #0x800, l2, l5
+ l2: ldb [23]
+ l3: jeq #0x1, l4, l5
+ l4: ret #0xffff
+ l5: ret #0
+ Prints out BPF code disassembly.
+
+ > dump
+ /* { op, jt, jf, k }, */
+ { 0x28, 0, 0, 0x0000000c },
+ { 0x15, 0, 3, 0x00000800 },
+ { 0x30, 0, 0, 0x00000017 },
+ { 0x15, 0, 1, 0x00000001 },
+ { 0x06, 0, 0, 0x0000ffff },
+ { 0x06, 0, 0, 0000000000 },
+ Prints out C-style BPF code dump.
+
+ > breakpoint 0
+ breakpoint at: l0: ldh [12]
+ > breakpoint 1
+ breakpoint at: l1: jeq #0x800, l2, l5
+ ...
+ Sets breakpoints at particular BPF instructions. Issuing a `run` command
+ will walk through the pcap file continuing from the current packet and
+ break when a breakpoint is being hit (another `run` will continue from
+ the currently active breakpoint executing next instructions):
+
+ > run
+ -- register dump --
+ pc: [0] <-- program counter
+ code: [40] jt[0] jf[0] k[12] <-- plain BPF code of current instruction
+ curr: l0: ldh [12] <-- disassembly of current instruction
+ A: [00000000][0] <-- content of A (hex, decimal)
+ X: [00000000][0] <-- content of X (hex, decimal)
+ M[0,15]: [00000000][0] <-- folded content of M (hex, decimal)
+ -- packet dump -- <-- Current packet from pcap (hex)
+ len: 42
+ 0: 00 19 cb 55 55 a4 00 14 a4 43 78 69 08 06 00 01
+ 16: 08 00 06 04 00 01 00 14 a4 43 78 69 0a 3b 01 26
+ 32: 00 00 00 00 00 00 0a 3b 01 01
+ (breakpoint)
+ >
+
+ > breakpoint
+ breakpoints: 0 1
+ Prints currently set breakpoints.
+
+ > step [-<n>, +<n>]
+ Performs single stepping through the BPF program from the current pc
+ offset. Thus, on each step invocation, above register dump is issued.
+ This can go forwards and backwards in time, a plain `step` will break
+ on the next BPF instruction, thus +1. (No `run` needs to be issued here.)
+
+ > select <n>
+ Selects a given packet from the pcap file to continue from. Thus, on
+ the next `run` or `step`, the BPF program is being evaluated against
+ the user pre-selected packet. Numbering starts just as in Wireshark
+ with index 1.
+
+ > quit
+ #
+ Exits bpf_dbg.
+
+JIT compiler
+============
+
+The Linux kernel has a built-in BPF JIT compiler for x86_64, SPARC,
+PowerPC, ARM, ARM64, MIPS and s390 which can be enabled through
+CONFIG_BPF_JIT. The JIT compiler is transparently invoked for each
+attached filter from user space or for internal kernel users if it has
+been previously enabled by root::
+
+ echo 1 > /proc/sys/net/core/bpf_jit_enable
+
+For JIT developers, doing audits etc, each compile run can output the
+generated opcode image into the kernel log via::
+
+ echo 2 > /proc/sys/net/core/bpf_jit_enable
+
+Example output from dmesg::
+
+ [ 3389.935842] flen=6 proglen=70 pass=3 image=ffffffffa0069c8f
+ [ 3389.935847] JIT code: 00000000: 55 48 89 e5 48 83 ec 60 48 89 5d f8 44 8b 4f 68
+ [ 3389.935849] JIT code: 00000010: 44 2b 4f 6c 4c 8b 87 d8 00 00 00 be 0c 00 00 00
+ [ 3389.935850] JIT code: 00000020: e8 1d 94 ff e0 3d 00 08 00 00 75 16 be 17 00 00
+ [ 3389.935851] JIT code: 00000030: 00 e8 28 94 ff e0 83 f8 01 75 07 b8 ff ff 00 00
+ [ 3389.935852] JIT code: 00000040: eb 02 31 c0 c9 c3
+
+When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently
+set to 1 and setting any other value than that will return in failure.
+This is even the case for setting bpf_jit_enable to 2, since dumping the
+final JIT image into the kernel log is discouraged and introspection
+through bpftool (under tools/bpf/bpftool/) is the generally recommended
+approach instead.
+
+In the kernel source tree under tools/bpf/, there's bpf_jit_disasm for
+generating disassembly out of the kernel log's hexdump::
+
+ # ./bpf_jit_disasm
+ 70 bytes emitted from JIT compiler (pass:3, flen:6)
+ ffffffffa0069c8f + <x>:
+ 0: push %rbp
+ 1: mov %rsp,%rbp
+ 4: sub $0x60,%rsp
+ 8: mov %rbx,-0x8(%rbp)
+ c: mov 0x68(%rdi),%r9d
+ 10: sub 0x6c(%rdi),%r9d
+ 14: mov 0xd8(%rdi),%r8
+ 1b: mov $0xc,%esi
+ 20: callq 0xffffffffe0ff9442
+ 25: cmp $0x800,%eax
+ 2a: jne 0x0000000000000042
+ 2c: mov $0x17,%esi
+ 31: callq 0xffffffffe0ff945e
+ 36: cmp $0x1,%eax
+ 39: jne 0x0000000000000042
+ 3b: mov $0xffff,%eax
+ 40: jmp 0x0000000000000044
+ 42: xor %eax,%eax
+ 44: leaveq
+ 45: retq
+
+Issuing option `-o` will "annotate" opcodes to resulting assembler
+instructions, which can be very useful for JIT developers::
+
+ # ./bpf_jit_disasm -o
+ 70 bytes emitted from JIT compiler (pass:3, flen:6)
+ ffffffffa0069c8f + <x>:
+ 0: push %rbp
+ 55
+ 1: mov %rsp,%rbp
+ 48 89 e5
+ 4: sub $0x60,%rsp
+ 48 83 ec 60
+ 8: mov %rbx,-0x8(%rbp)
+ 48 89 5d f8
+ c: mov 0x68(%rdi),%r9d
+ 44 8b 4f 68
+ 10: sub 0x6c(%rdi),%r9d
+ 44 2b 4f 6c
+ 14: mov 0xd8(%rdi),%r8
+ 4c 8b 87 d8 00 00 00
+ 1b: mov $0xc,%esi
+ be 0c 00 00 00
+ 20: callq 0xffffffffe0ff9442
+ e8 1d 94 ff e0
+ 25: cmp $0x800,%eax
+ 3d 00 08 00 00
+ 2a: jne 0x0000000000000042
+ 75 16
+ 2c: mov $0x17,%esi
+ be 17 00 00 00
+ 31: callq 0xffffffffe0ff945e
+ e8 28 94 ff e0
+ 36: cmp $0x1,%eax
+ 83 f8 01
+ 39: jne 0x0000000000000042
+ 75 07
+ 3b: mov $0xffff,%eax
+ b8 ff ff 00 00
+ 40: jmp 0x0000000000000044
+ eb 02
+ 42: xor %eax,%eax
+ 31 c0
+ 44: leaveq
+ c9
+ 45: retq
+ c3
+
+For BPF JIT developers, bpf_jit_disasm, bpf_asm and bpf_dbg provides a
+useful toolchain for developing and testing the kernel's JIT compiler.
+
+Reference
+=========
+
+The original BPF paper:
+
+[1] Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new
+architecture for user-level packet capture. In Proceedings of the
+USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993
+Conference Proceedings (USENIX'93). USENIX Association, Berkeley, CA,
+USA, 2-2. [http://www.tcpdump.org/papers/bpf-usenix93.pdf]
diff --git a/Documentation/userspace-api/eBPF.rst b/Documentation/userspace-api/eBPF.rst
new file mode 100644
index 000000000000..6fe1d966aee9
--- /dev/null
+++ b/Documentation/userspace-api/eBPF.rst
@@ -0,0 +1,1005 @@
+.. _ebpf:
+
+=====================================
+Internal Berkley Packet Filter (eBPF)
+=====================================
+
+For an introduction to BPF and Linux Socket Filtering please see
+:ref:`Documentation/userspace-api/socket-filter.rst <socket-filter>`
+
+Internally, for the kernel interpreter, a different instruction set format
+with similar underlying principles from BPF described in the document
+linked to above is being used. However, the instruction set format is
+modelled closer to the underlying architecture to mimic native instruction
+sets, so that better performance can be achieved (more details later).
+This new ISA is called 'eBPF' or 'internal BPF' interchangeably. (Note:
+eBPF which originates from [e]xtended BPF is not the same as BPF
+extensions! While eBPF is an ISA, BPF extensions date back to classic BPF's
+'overloading' of BPF_LD | BPF_{B,H,W} | BPF_ABS instruction.)
+
+It is designed to be JITed with one to one mapping, which can also open up
+the possibility for GCC/LLVM compilers to generate optimized eBPF code
+through an eBPF backend that performs almost as fast as natively compiled
+code.
+
+The new instruction set was originally designed with the possible goal in
+mind to write programs in "restricted C" and compile into eBPF with a
+optional GCC/LLVM backend, so that it can just-in-time map to modern 64-bit
+CPUs with minimal performance overhead over two steps, that is, C -> eBPF
+-> native code.
+
+Currently, the new format is being used for running user BPF programs,
+which includes seccomp BPF, classic socket filters, cls_bpf traffic
+classifier, team driver's classifier for its load-balancing mode,
+netfilter's xt_bpf extension, PTP dissector/classifier, and much more.
+
+For more information please see:
+
+- :ref:`Documentation/userspace-api/seccomp_filter.rst <seccomp-filter>`
+- :ref:`Documentation/userspace-api/socket_filter.rst <socket-filter>`
+- :ref:`Documentation/userspace-api/cBPF.rst <ebpf>`
+
+They are all internally converted by the kernel into the new instruction
+set representation and run in the eBPF interpreter. For in-kernel
+handlers, this all works transparently by using bpf_prog_create() for
+setting up the filter, resp. bpf_prog_destroy() for destroying it. The
+macro BPF_PROG_RUN(filter, ctx) transparently invokes eBPF interpreter or
+JITed code to run the filter. 'filter' is a pointer to struct bpf_prog
+that we got from bpf_prog_create(), and 'ctx' the given context (e.g. skb
+pointer). All constraints and restrictions from bpf_check_classic() apply
+before a conversion to the new layout is being done behind the scenes!
+
+Currently, the classic BPF format is being used for JITing on most 32-bit
+architectures, whereas x86-64, aarch64, s390x, powerpc64, sparc64, arm32
+perform JIT compilation from eBPF instruction set. (see cBPF document
+linked above.)
+
+Some core changes of the new internal format
+--------------------------------------------
+
+Number of registers increase from 2 to 10
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The old format had two registers A and X, and a hidden frame pointer.
+The new layout extends this to be 10 internal registers and a read-only
+frame pointer. Since 64-bit CPUs are passing arguments to functions via
+registers the number of args from eBPF program to in-kernel function is
+restricted to 5 and one register is used to accept return value from an
+in-kernel function. Natively, x86_64 passes first 6 arguments in
+registers, aarch64/ sparcv9/mips64 have 7 - 8 registers for arguments;
+x86_64 has 6 callee saved registers, and aarch64/sparcv9/mips64 have 11
+or more callee saved registers.
+
+.. flat-table:: eBPF Calling Convention
+ :widths: 1 2
+
+ * - Register
+ - Convention
+
+ * - R0
+ - return value from in-kernel function, and exit value for eBPF
+ program
+
+ * - R1 - R5
+ - arguments from eBPF program to in-kernel function
+
+ * - R6 - R9
+ - callee saved registers that in-kernel function will preserve
+
+ * - R10
+ - read-only frame pointer to access stack
+
+Thus, all eBPF registers map one to one to HW registers on x86_64,
+aarch64, etc, and eBPF calling convention maps directly to ABIs used by
+the kernel on 64-bit architectures.
+
+On 32-bit architectures JIT may map programs that use only 32-bit
+arithmetic and may let more complex programs to be interpreted.
+
+R0 - R5 are scratch registers and eBPF program needs spill/fill them if
+necessary across calls. Note that there is only one eBPF program (==
+one eBPF main routine) and it cannot call other eBPF functions, it can
+only call predefined in-kernel functions, though.
+
+Register width increases from 32-bit to 64-bit
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Still, the semantics of the original 32-bit ALU operations are preserved
+via 32-bit subregisters. All eBPF registers are 64-bit with 32-bit
+lower subregisters that zero-extend into 64-bit if they are being
+written to. That behavior maps directly to x86_64 and arm64 subregister
+definition, but makes other JITs more difficult.
+
+32-bit architectures run 64-bit internal BPF programs via interpreter.
+Their JITs may convert BPF programs that only use 32-bit subregisters
+into native instruction set and let the rest be interpreted.
+
+Operation is 64-bit since on 64-bit architectures pointers are also
+64-bit wide and we want to pass 64-bit values in/out of kernel
+functions. 32-bit eBPF registers would otherwise require us to define a
+register-pair ABI, thus we would not be able to use a direct eBPF
+register to HW register mapping and JIT would need to do
+combine/split/move operations for every register in and out of the
+function, which is complex, bug prone and slow. Another reason is the
+use of atomic 64-bit counters.
+
+Conditional jt/jf targets replaced with jt/fall-through
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+While the original design has constructs such as::
+
+ if (cond)
+ jump_true;
+ else
+ jump_false;
+
+they are being replaced into alternative constructs like::
+
+ if (cond)
+ jump_true;
+
+ /* else fall-through */".
+
+Zero overhead calls from/to other kernel functions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Introduces bpf_call insn and register passing convention for zero
+overhead calls from/to other kernel functions.
+
+Before an in-kernel function call, the internal BPF program needs to
+place function arguments into R1 to R5 registers to satisfy calling
+convention, then the interpreter will take them from registers and pass
+to in-kernel function. If R1 - R5 registers are mapped to CPU registers
+that are used for argument passing on given architecture, the JIT
+compiler doesn't need to emit extra moves. Function arguments will be
+in the correct registers and BPF_CALL instruction will be JITed as
+single 'call' HW instruction. This calling convention was picked to
+cover common call situations without performance penalty.
+
+After an in-kernel function call, R1 - R5 are reset to unreadable and R0
+has the return value of the function. Since R6 - R9 are callee saved,
+their state is preserved across the call.
+
+For example, consider three C functions::
+
+ u64 f1() { return (*_f2)(1); }
+ u64 f2(u64 a) { return f3(a + 1, a); }
+ u64 f3(u64 a, u64 b) { return a - b; }
+
+GCC can compile f1, f3 into x86_64::
+
+ f1:
+ movl $1, %edi
+ movq _f2(%rip), %rax
+ jmp *%rax
+ f3:
+ movq %rdi, %rax
+ subq %rsi, %rax
+ ret
+
+Function f2 in eBPF may look like::
+
+ f2:
+ bpf_mov R2, R1
+ bpf_add R1, 1
+ bpf_call f3
+ bpf_exit
+
+If f2 is JITed and the pointer stored to '_f2'. The calls f1 -> f2 ->
+f3 and returns will be seamless. Without JIT, __bpf_prog_run()
+interpreter needs to be used to call into f2.
+
+For practical reasons all eBPF programs have only one argument 'ctx'
+which is already placed into R1 (e.g. on __bpf_prog_run() startup) and
+the programs can call kernel functions with up to 5 arguments. Calls
+with 6 or more arguments are currently not supported, but these
+restrictions can be lifted if necessary in the future.
+
+On 64-bit architectures all registers map to HW registers one to one.
+For example, x86_64 JIT compiler can map them as ::
+
+ R0 - rax
+ R1 - rdi
+ R2 - rsi
+ R3 - rdx
+ R4 - rcx
+ R5 - r8
+ R6 - rbx
+ R7 - r13
+ R8 - r14
+ R9 - r15
+ R10 - rbp
+
+since x86_64 ABI mandates rdi, rsi, rdx, rcx, r8, r9 for argument
+passing and rbx, r12 - r15 are callee saved.
+
+Then the following internal BPF pseudo-program::
+
+ bpf_mov R6, R1 /* save ctx */
+ bpf_mov R2, 2
+ bpf_mov R3, 3
+ bpf_mov R4, 4
+ bpf_mov R5, 5
+ bpf_call foo
+ bpf_mov R7, R0 /* save foo() return value */
+ bpf_mov R1, R6 /* restore ctx for next call */
+ bpf_mov R2, 6
+ bpf_mov R3, 7
+ bpf_mov R4, 8
+ bpf_mov R5, 9
+ bpf_call bar
+ bpf_add R0, R7
+ bpf_exit
+
+After JIT to x86_64 may look like::
+
+ push %rbp
+ mov %rsp,%rbp
+ sub $0x228,%rsp
+ mov %rbx,-0x228(%rbp)
+ mov %r13,-0x220(%rbp)
+ mov %rdi,%rbx
+ mov $0x2,%esi
+ mov $0x3,%edx
+ mov $0x4,%ecx
+ mov $0x5,%r8d
+ callq foo
+ mov %rax,%r13
+ mov %rbx,%rdi
+ mov $0x2,%esi
+ mov $0x3,%edx
+ mov $0x4,%ecx
+ mov $0x5,%r8d
+ callq bar
+ add %r13,%rax
+ mov -0x228(%rbp),%rbx
+ mov -0x220(%rbp),%r13
+ leaveq
+ retq
+
+Which is in this example equivalent in C to::
+
+ u64 bpf_filter(u64 ctx)
+ {
+ return foo(ctx, 2, 3, 4, 5) + bar(ctx, 6, 7, 8, 9);
+ }
+
+In-kernel functions foo() and bar() with prototype: u64 (*)(u64 arg1,
+u64 arg2, u64 arg3, u64 arg4, u64 arg5); will receive arguments in
+proper registers and place their return value into '%rax' which is R0 in
+eBPF. Prologue and epilogue are emitted by JIT and are implicit in the
+interpreter. R0-R5 are scratch registers, so eBPF program needs to
+preserve them across the calls as defined by calling convention.
+
+For example the following program is invalid::
+
+ bpf_mov R1, 1
+ bpf_call foo
+ bpf_mov R0, R1
+ bpf_exit
+
+After the call the registers R1-R5 contain junk values and cannot be
+read. An in-kernel eBPF verifier is used to validate internal BPF
+programs.
+
+Additional miscellaneous changes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Also in the new design, eBPF is limited to 4096 insns, which means that
+any program will terminate quickly and will only call a fixed number of
+kernel functions. Original BPF and the new format are two operand
+instructions, which helps to do one-to-one mapping between eBPF insn and
+x86 insn during JIT.
+
+The input context pointer for invoking the interpreter function is
+generic, its content is defined by a specific use case. For seccomp
+register R1 points to seccomp_data, for converted BPF filters R1 points
+to a skb.
+
+A program, that is translated internally consists of the following
+elements::
+
+ op:16, jt:8, jf:8, k:32 ==> op:8, dst_reg:4, src_reg:4, off:16, imm:32
+
+So far 87 internal BPF instructions have been implemented. 8-bit 'op'
+opcode field has room for new instructions. Some of them may use
+16/24/32 byte encoding. New instructions must be a multiple of 8 bytes
+to preserve backward compatibility.
+
+Internal BPF is a general purpose RISC instruction set. Not every
+register and every instruction are used during translation from original
+BPF to new format. For example, socket filters are not using 'exclusive
+add' instruction, but tracing filters may do to maintain counters of
+events, for example. Register R9 is not used by socket filters either,
+but more complex filters may be running out of registers and would have
+to resort to spill/fill to stack.
+
+Internal BPF can used as generic assembler for last step performance
+optimizations, socket filters and seccomp are using it as assembler.
+Tracing filters may use it as assembler to generate code from kernel.
+In-kernel usage may not be bounded by security considerations, since
+generated internal BPF code may use an optimised internal code path and
+may not be being exposed to user space. Safety of internal BPF can come
+from a verifier (TBD). In such use cases as described, it may be used
+as safe as the instruction set.
+
+Just like the original BPF, the new format runs within a controlled
+environment, is deterministic and the kernel can easily prove that. The
+safety of the program can be determined in two steps: first step does
+depth-first-search to disallow loops and other CFG validation; second
+step starts from the first insn and descends all possible paths. It
+simulates execution of every insn and observes the state change of
+registers and stack.
+
+eBPF opcode encoding
+====================
+
+eBPF is reusing most of the opcode encoding from classic to simplify
+conversion of classic BPF to eBPF. For arithmetic and jump instructions
+the 8-bit 'code' field is divided into three parts::
+
+ +----------------+--------+--------------------+
+ | 4 bits | 1 bit | 3 bits |
+ | operation code | source | instruction class |
+ +----------------+--------+--------------------+
+ (MSB) (LSB)
+
+Three LSB bits store instruction class which is one of::
+
+ Classic BPF classes: eBPF classes:
+
+ BPF_LD 0x00 BPF_LD 0x00
+ BPF_LDX 0x01 BPF_LDX 0x01
+ BPF_ST 0x02 BPF_ST 0x02
+ BPF_STX 0x03 BPF_STX 0x03
+ BPF_ALU 0x04 BPF_ALU 0x04
+ BPF_JMP 0x05 BPF_JMP 0x05
+ BPF_RET 0x06 [ class 6 unused, for future if needed ]
+ BPF_MISC 0x07 BPF_ALU64 0x07
+
+When BPF_CLASS(code) == BPF_ALU or BPF_JMP, 4th bit encodes source
+operand ... ::
+
+ BPF_K 0x00
+ BPF_X 0x08
+
+in classic BPF, this means::
+
+ BPF_SRC(code) == BPF_X - use register X as source operand
+ BPF_SRC(code) == BPF_K - use 32-bit immediate as source operand
+
+in eBPF, this means::
+
+ BPF_SRC(code) == BPF_X - use 'src_reg' register as source operand
+ BPF_SRC(code) == BPF_K - use 32-bit immediate as source operand
+
+... and four MSB bits store operation code.
+
+If BPF_CLASS(code) == BPF_ALU or BPF_ALU64 [ in eBPF ], BPF_OP(code) is
+one of::
+
+ BPF_ADD 0x00
+ BPF_SUB 0x10
+ BPF_MUL 0x20
+ BPF_DIV 0x30
+ BPF_OR 0x40
+ BPF_AND 0x50
+ BPF_LSH 0x60
+ BPF_RSH 0x70
+ BPF_NEG 0x80
+ BPF_MOD 0x90
+ BPF_XOR 0xa0
+ BPF_MOV 0xb0 /* eBPF only: mov reg to reg */
+ BPF_ARSH 0xc0 /* eBPF only: sign extending shift right */
+ BPF_END 0xd0 /* eBPF only: endianness conversion */
+
+If BPF_CLASS(code) == BPF_JMP, BPF_OP(code) is one of::
+
+ BPF_JA 0x00
+ BPF_JEQ 0x10
+ BPF_JGT 0x20
+ BPF_JGE 0x30
+ BPF_JSET 0x40
+ BPF_JNE 0x50 /* eBPF only: jump != */
+ BPF_JSGT 0x60 /* eBPF only: signed '>' */
+ BPF_JSGE 0x70 /* eBPF only: signed '>=' */
+ BPF_CALL 0x80 /* eBPF only: function call */
+ BPF_EXIT 0x90 /* eBPF only: function return */
+ BPF_JLT 0xa0 /* eBPF only: unsigned '<' */
+ BPF_JLE 0xb0 /* eBPF only: unsigned '<=' */
+ BPF_JSLT 0xc0 /* eBPF only: signed '<' */
+ BPF_JSLE 0xd0 /* eBPF only: signed '<=' */
+
+So BPF_ADD | BPF_X | BPF_ALU means 32-bit addition in both classic BPF
+and eBPF. There are only two registers in classic BPF, so it means A
++= X. In eBPF it means dst_reg = (u32) dst_reg + (u32) src_reg;
+similarly, BPF_XOR | BPF_K | BPF_ALU means A ^= imm32 in classic BPF and
+analogous src_reg = (u32) src_reg ^ (u32) imm32 in eBPF.
+
+Classic BPF is using BPF_MISC class to represent A = X and X = A moves.
+eBPF is using BPF_MOV | BPF_X | BPF_ALU code instead. Since there are
+no BPF_MISC operations in eBPF, the class 7 is used as BPF_ALU64 to mean
+exactly the same operations as BPF_ALU, but with 64-bit wide operands
+instead. So BPF_ADD | BPF_X | BPF_ALU64 means 64-bit addition i.e.
+dst_reg = dst_reg + src_reg
+
+Classic BPF wastes the whole BPF_RET class to represent a single 'ret'
+operation. Classic BPF_RET | BPF_K means copy imm32 into return
+register and perform function exit. eBPF is modeled to match CPU, so
+BPF_JMP | BPF_EXIT in eBPF means function exit only. The eBPF program
+needs to store return value into register R0 before doing a BPF_EXIT.
+Class 6 in eBPF is currently unused and reserved for future use.
+
+For load and store instructions the 8-bit 'code' field is divided as::
+
+ +--------+--------+-------------------+
+ | 3 bits | 2 bits | 3 bits |
+ | mode | size | instruction class |
+ +--------+--------+-------------------+
+ (MSB) (LSB)
+
+Size modifier is one of ... ::
+
+ BPF_W 0x00 /* word */
+ BPF_H 0x08 /* half word */
+ BPF_B 0x10 /* byte */
+ BPF_DW 0x18 /* eBPF only, double word */
+
+... which encodes size of load/store operation::
+
+ B - 1 byte
+ H - 2 byte
+ W - 4 byte
+ DW - 8 byte (eBPF only)
+
+Mode modifier is one of::
+
+ BPF_IMM 0x00 /* used for 32-bit mov in classic BPF and 64-bit in eBPF */
+ BPF_ABS 0x20
+ BPF_IND 0x40
+ BPF_MEM 0x60
+ BPF_LEN 0x80 /* classic BPF only, reserved in eBPF */
+ BPF_MSH 0xa0 /* classic BPF only, reserved in eBPF */
+ BPF_XADD 0xc0 /* eBPF only, exclusive add */
+
+eBPF has two non-generic instructions: (BPF_ABS | <size> | BPF_LD) and
+(BPF_IND | <size> | BPF_LD) which are used to access packet data.
+
+They had to be carried over from classic to have strong performance of
+socket filters running in eBPF interpreter. These instructions can only
+be used when interpreter context is a pointer to 'struct sk_buff' and
+have seven implicit operands. Register R6 is an implicit input that
+must contain pointer to sk_buff. Register R0 is an implicit output
+which contains the data fetched from the packet. Registers R1-R5 are
+scratch registers and must not be used to store the data across BPF_ABS
+| BPF_LD or BPF_IND | BPF_LD instructions.
+
+These instructions have implicit program exit condition as well. When
+eBPF program is trying to access the data beyond the packet boundary,
+the interpreter will abort the execution of the program. JIT compilers
+therefore must preserve this property. src_reg and imm32 fields are
+explicit inputs to these instructions.
+
+For example::
+
+ BPF_IND | BPF_W | BPF_LD means:
+
+ R0 = ntohl(*(u32 *) (((struct sk_buff *) R6)->data + src_reg + imm32))
+ and R1 - R5 were scratched.
+
+Unlike classic BPF instruction set, eBPF has generic load/store
+operations::
+
+ BPF_MEM | <size> | BPF_STX: *(size *) (dst_reg + off) = src_reg
+ BPF_MEM | <size> | BPF_ST: *(size *) (dst_reg + off) = imm32
+ BPF_MEM | <size> | BPF_LDX: dst_reg = *(size *) (src_reg + off)
+ BPF_XADD | BPF_W | BPF_STX: lock xadd *(u32 *)(dst_reg + off16) += src_reg
+ BPF_XADD | BPF_DW | BPF_STX: lock xadd *(u64 *)(dst_reg + off16) += src_reg
+
+Where size is one of: BPF_B or BPF_H or BPF_W or BPF_DW. Note that 1
+and 2 byte atomic increments are not supported.
+
+eBPF has one 16-byte instruction: BPF_LD | BPF_DW | BPF_IMM which
+consists of two consecutive 'struct bpf_insn' 8-byte blocks and is
+interpreted as single instruction that loads 64-bit immediate value into
+a dst_reg.
+
+Classic BPF has similar instruction: BPF_LD | BPF_W | BPF_IMM which
+loads 32-bit immediate value into a register.
+
+eBPF verifier
+=============
+
+The safety of the eBPF program is determined in two steps.
+
+First step does DAG check to disallow loops and other CFG validation.
+In particular it will detect programs that have unreachable instructions
+(though classic BPF checker allows them).
+
+Second step starts from the first insn and descends all possible paths.
+It simulates execution of every insn and observes the state change of
+registers and stack.
+
+At the start of the program the register R1 contains a pointer to context
+and has type PTR_TO_CTX.
+
+If verifier sees an insn that does R2=R1, then R2 has now type
+PTR_TO_CTX as well and can be used on the right hand side of expression.
+
+If R1=PTR_TO_CTX and insn is R2=R1+R1, then R2=SCALAR_VALUE, since
+addition of two valid pointers makes invalid pointer. (In 'secure' mode
+verifier will reject any type of pointer arithmetic to make sure that
+kernel addresses don't leak to unprivileged users)
+
+If register was never written to, it's not readable::
+
+ bpf_mov R0 = R2
+ bpf_exit
+
+will be rejected, since R2 is unreadable at the start of the program.
+
+After kernel function call, R1-R5 are reset to unreadable and R0 has a
+return type of the function.
+
+Since R6-R9 are callee saved, their state is preserved across the call.::
+
+ bpf_mov R6 = 1
+ bpf_call foo
+ bpf_mov R0 = R6
+ bpf_exit
+
+is a correct program. If there was R1 instead of R6, it would have been
+rejected.
+
+load/store instructions are allowed only with registers of valid types,
+which are PTR_TO_CTX, PTR_TO_MAP, PTR_TO_STACK. They are bounds and
+alignment checked. For example::
+
+ bpf_mov R1 = 1
+ bpf_mov R2 = 2
+ bpf_xadd *(u32 *)(R1 + 3) += R2
+ bpf_exit
+
+will be rejected, since R1 doesn't have a valid pointer type at the time
+of execution of instruction bpf_xadd.
+
+At the start R1 type is PTR_TO_CTX (a pointer to generic 'struct
+bpf_context'). A callback is used to customize verifier to restrict
+eBPF program access to only certain fields within ctx structure with
+specified size and alignment.
+
+For example, the following insn::
+
+ bpf_ld R0 = *(u32 *)(R6 + 8)
+
+intends to load a word from address R6 + 8 and store it into R0
+
+If R6=PTR_TO_CTX, via is_valid_access() callback the verifier will know
+that offset 8 of size 4 bytes can be accessed for reading, otherwise the
+verifier will reject the program.
+
+If R6=PTR_TO_STACK, then access should be aligned and be within stack
+bounds, which are [-MAX_BPF_STACK, 0). In this example offset is 8, so
+it will fail verification, since it's out of bounds.
+
+The verifier will allow eBPF program to read data from stack only after
+it wrote into it.
+
+Classic BPF verifier does similar check with M[0-15] memory slots, for
+example::
+
+ bpf_ld R0 = *(u32 *)(R10 - 4)
+ bpf_exit
+
+is an invalid program.
+
+Though R10 is correct read-only register and has type PTR_TO_STACK and
+R10 - 4 is within stack bounds, there were no stores into that location.
+
+Pointer register spill/fill is tracked as well, since four (R6-R9)
+callee saved registers may not be enough for some programs.
+
+Allowed function calls are customized with::
+
+ bpf_verifier_ops->get_func_proto()
+
+The eBPF verifier will check that registers match argument constraints.
+After the call register R0 will be set to return type of the function.
+
+Function calls is an important mechanism to extend functionality of eBPF
+programs. Socket filters may let programs call one set of functions,
+whereas tracing filters may allow a completely different set.
+
+If a function is made accessible to eBPF program, it needs to be thought
+through from a safety point of view. The verifier will guarantee that
+the function is called with valid arguments.
+
+seccomp vs socket filters have different security restrictions for
+classic BPF. Seccomp solves this by two stage verifier: classic BPF
+verifier is followed by seccomp verifier. In case of eBPF one
+configurable verifier is shared for all use cases.
+
+See details of eBPF verifier in kernel/bpf/verifier.c
+
+Register value tracking
+=======================
+
+In order to determine the safety of an eBPF program, the verifier must
+track the range of possible values in each register and also in each
+stack slot. This is done with 'struct bpf_reg_state', defined in
+include/linux/bpf_verifier.h, which unifies tracking of scalar and
+pointer values. Each register state has a type, which is either
+NOT_INIT (the register has not been written to), SCALAR_VALUE (some
+value which is not usable as a pointer), or a pointer type. The types
+of pointers describe their base, as follows::
+
+ PTR_TO_CTX Pointer to bpf_context.
+ CONST_PTR_TO_MAP Pointer to struct bpf_map. "Const" because arithmetic
+ on these pointers is forbidden.
+ PTR_TO_MAP_VALUE Pointer to the value stored in a map element.
+ PTR_TO_MAP_VALUE_OR_NULL
+ Either a pointer to a map value, or NULL; map accesses
+ (see section 'eBPF maps', below) return this type,
+ which becomes a PTR_TO_MAP_VALUE when checked != NULL.
+ Arithmetic on these pointers is forbidden.
+ PTR_TO_STACK Frame pointer.
+ PTR_TO_PACKET skb->data.
+ PTR_TO_PACKET_END skb->data + headlen; arithmetic forbidden.
+
+However, a pointer may be offset from this base (as a result of pointer
+arithmetic), and this is tracked in two parts: the 'fixed offset' and
+'variable offset'. The former is used when an exactly-known value
+(e.g. an immediate operand) is added to a pointer, while the latter is
+used for values which are not exactly known. The variable offset is
+also used in SCALAR_VALUEs, to track the range of possible values in the
+register.
+
+The verifier's knowledge about the variable offset consists of three
+things 1) minimum and maximum values as unsigned. 2) minimum and maximum
+values as signed. 3) knowledge of the values of individual bits, in the
+form of a 'tnum': a u64 'mask' and a u64 'value'. 1s in the mask
+represent bits whose value is unknown; 1s in the value represent bits
+known to be 1. Bits known to be 0 have 0 in both mask and value; no bit
+should ever be 1 in both. For example, if a byte is read into a
+register from memory, the register's top 56 bits are known zero, while
+the low 8 are unknown - which is represented as the tnum (0x0; 0xff).
+If we then OR this with 0x40, we get (0x40; 0xbf), then if we add 1 we
+get (0x0; 0x1ff), because of potential carries.
+
+Besides arithmetic, the register state can also be updated by
+conditional branches. For instance, if a SCALAR_VALUE is compared > 8,
+in the 'true' branch it will have a umin_value (unsigned minimum value)
+of 9, whereas in the 'false' branch it will have a umax_value of 8. A
+signed compare (with BPF_JSGT or BPF_JSGE) would instead update the
+signed minimum/maximum values. Information from the signed and unsigned
+bounds can be combined; for instance if a value is first tested < 8 and
+then tested s> 4, the verifier will conclude that the value is also > 4
+and s< 8, since the bounds prevent crossing the sign boundary.
+
+PTR_TO_PACKETs with a variable offset part have an 'id', which is common
+to all pointers sharing that same variable offset. This is important
+for packet range checks: after adding a variable to a packet pointer
+register A, if you then copy it to another register B and then add a
+constant 4 to A, both registers will share the same 'id' but the A will
+have a fixed offset of +4. Then if A is bounds-checked and found to be
+less than a PTR_TO_PACKET_END, the register B is now known to have a
+safe range of at least 4 bytes. See 'Direct packet access', below, for
+more on PTR_TO_PACKET ranges.
+
+The 'id' field is also used on PTR_TO_MAP_VALUE_OR_NULL, common to all
+copies of the pointer returned from a map lookup. This means that when
+one copy is checked and found to be non-NULL, all copies can become
+PTR_TO_MAP_VALUEs. As well as range-checking, the tracked information
+is also used for enforcing alignment of pointer accesses. For instance,
+on most systems the packet pointer is 2 bytes after a 4-byte alignment.
+If a program adds 14 bytes to that to jump over the Ethernet header,
+then reads IHL and adds (IHL * 4), the resulting pointer will have a
+variable offset known to be 4n+2 for some n, so adding the 2 bytes
+(NET_IP_ALIGN) gives a 4-byte alignment and so word-sized accesses
+through that pointer are safe.
+
+Direct packet access
+====================
+
+In cls_bpf and act_bpf programs the verifier allows direct access to the packet
+data via skb->data and skb->data_end pointers, e.g.::
+
+ 1: r4 = *(u32 *)(r1 +80) /* load skb->data_end */
+ 2: r3 = *(u32 *)(r1 +76) /* load skb->data */
+ 3: r5 = r3
+ 4: r5 += 14
+ 5: if r5 > r4 goto pc+16
+ R1=ctx R3=pkt(id=0,off=0,r=14) R4=pkt_end R5=pkt(id=0,off=14,r=14) R10=fp
+ 6: r0 = *(u16 *)(r3 +12) /* access 12 and 13 bytes of the packet */
+
+this 2byte load from the packet is safe to do, since the program author
+did check 'if (skb->data + 14 > skb->data_end) goto err' at insn #5
+which means that in the fall-through case the register R3 (which points
+to skb->data) has at least 14 directly accessible bytes. The verifier
+marks it as R3=pkt(id=0,off=0,r=14). id=0 means that no additional
+variables were added to the register. off=0 means that no additional
+constants were added. r=14 is the range of safe access which means that
+bytes [R3, R3 + 14) are ok. Note that R5 is marked as
+R5=pkt(id=0,off=14,r=14). It also points to the packet data, but
+constant 14 was added to the register, so it now points to 'skb->data +
+14' and accessible range is [R5, R5 + 14 - 14) which is zero bytes.
+
+More complex packet access may look like::
+
+ R0=inv1 R1=ctx R3=pkt(id=0,off=0,r=14) R4=pkt_end R5=pkt(id=0,off=14,r=14) R10=fp
+ 6: r0 = *(u8 *)(r3 +7) /* load 7th byte from the packet */
+ 7: r4 = *(u8 *)(r3 +12)
+ 8: r4 *= 14
+ 9: r3 = *(u32 *)(r1 +76) /* load skb->data */
+ 10: r3 += r4
+ 11: r2 = r1
+ 12: r2 <<= 48
+ 13: r2 >>= 48
+ 14: r3 += r2
+ 15: r2 = r3
+ 16: r2 += 8
+ 17: r1 = *(u32 *)(r1 +80) /* load skb->data_end */
+ 18: if r2 > r1 goto pc+2
+ R0=inv(id=0,umax_value=255,var_off=(0x0; 0xff)) R1=pkt_end R2=pkt(id=2,off=8,r=8) R3=pkt(id=2,off=0,r=8) R4=inv(id=0,umax_value=3570,var_off=(0x0; 0xfffe)) R5=pkt(id=0,off=14,r=14) R10=fp
+ 19: r1 = *(u8 *)(r3 +4)
+
+The state of the register R3 is R3=pkt(id=2,off=0,r=8) id=2 means that
+two 'r3 += rX' instructions were seen, so r3 points to some offset
+within a packet and since the program author did 'if (r3 + 8 > r1) goto
+err' at insn #18, the safe range is [R3, R3 + 8). The verifier only
+allows 'add'/'sub' operations on packet registers. Any other operation
+will set the register state to 'SCALAR_VALUE' and it won't be available
+for direct packet access. Operation 'r3 += rX' may overflow and become
+less than original skb->data, therefore the verifier has to prevent
+that. So when it sees 'r3 += rX' instruction and rX is more than 16-bit
+value, any subsequent bounds-check of r3 against skb->data_end will not
+give us 'range' information, so attempts to read through the pointer
+will give "invalid access to packet" error. Ex. after insn 'r4 = *(u8
+*)(r3 +12)' (insn #7 above) the state of r4 is
+R4=inv(id=0,umax_value=255,var_off=(0x0; 0xff)) which means that upper
+56 bits of the register are guaranteed to be zero, and nothing is known
+about the lower 8 bits. After insn 'r4 *= 14' the state becomes
+R4=inv(id=0,umax_value=3570,var_off=(0x0; 0xfffe)), since multiplying an
+8-bit value by constant 14 will keep upper 52 bits as zero, also the
+least significant bit will be zero as 14 is even. Similarly 'r2 >>= 48'
+will make R2=inv(id=0,umax_value=65535,var_off=(0x0; 0xffff)), since the
+shift is not sign extending. This logic is implemented in
+adjust_reg_min_max_vals() function, which calls
+adjust_ptr_min_max_vals() for adding pointer to scalar (or vice versa)
+and adjust_scalar_min_max_vals() for operations on two scalars.
+
+The end result is that bpf program author can access packet directly
+using normal C code as::
+
+ void *data = (void *)(long)skb->data;
+ void *data_end = (void *)(long)skb->data_end;
+ struct eth_hdr *eth = data;
+ struct iphdr *iph = data + sizeof(*eth);
+ struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);
+
+ if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)
+ return 0;
+ if (eth->h_proto != htons(ETH_P_IP))
+ return 0;
+ if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)
+ return 0;
+ if (udp->dest == 53 || udp->source == 9)
+ ...;
+
+which makes such programs easier to write comparing to LD_ABS insn
+and significantly faster.
+
+eBPF maps
+=========
+
+'maps' is a generic storage of different types for sharing data between
+kernel and userspace.
+
+The maps are accessed from user space via BPF syscall, which has commands:
+
+- create a map with given type and attributes::
+
+ map_fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size)
+ using attr->map_type, attr->key_size, attr->value_size, attr->max_entries
+ returns process-local file descriptor or negative error
+
+- lookup key in a given map::
+
+ err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size)
+ using attr->map_fd, attr->key, attr->value
+ returns zero and stores found elem into value or negative error
+
+- create or update key/value pair in a given map::
+
+ err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)
+ using attr->map_fd, attr->key, attr->value
+ returns zero or negative error
+
+- find and delete element by key in a given map::
+
+ err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size)
+ using attr->map_fd, attr->key
+
+- to delete map::
+
+ close(fd)
+ Exiting process will delete maps automatically
+
+userspace programs use this syscall to create/access maps that eBPF
+programs are concurrently updating.
+
+maps can have different types: hash, array, bloom filter, radix-tree,
+etc.
+
+The map is defined by:
+
+- type
+- max number of elements
+- key size in bytes
+- value size in bytes
+
+Pruning
+=======
+
+The verifier does not actually walk all possible paths through the
+program. For each new branch to analyse, the verifier looks at all the
+states it's previously been in when at this instruction. If any of them
+contain the current state as a subset, the branch is 'pruned' - that is,
+the fact that the previous state was accepted implies the current state
+would be as well. For instance, if in the previous state, r1 held a
+packet-pointer, and in the current state, r1 holds a packet-pointer with
+a range as long or longer and at least as strict an alignment, then r1
+is safe. Similarly, if r2 was NOT_INIT before then it can't have been
+used by any path from that point, so any value in r2 (including another
+NOT_INIT) is safe. The implementation is in the function regsafe().
+Pruning considers not only the registers but also the stack (and any
+spilled registers it may hold). They must all be safe for the branch to
+be pruned. This is implemented in states_equal().
+
+Understanding eBPF verifier messages
+====================================
+
+The following are few examples of invalid eBPF programs and verifier error
+messages as seen in the log:
+
+Program with unreachable instructions::
+
+ static struct bpf_insn prog[] = {
+ BPF_EXIT_INSN(),
+ BPF_EXIT_INSN(),
+ };
+
+ Error:
+ unreachable insn 1
+
+Program that reads uninitialized register::
+
+ BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (bf) r0 = r2
+ R2 !read_ok
+
+Program that doesn't initialize R0 before exiting::
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_1),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (bf) r2 = r1
+ 1: (95) exit
+ R0 !read_ok
+
+Program that accesses stack out of bounds::
+
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, 8, 0),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (7a) *(u64 *)(r10 +8) = 0
+ invalid stack off=8 size=8
+
+Program that doesn't initialize stack before passing its address into function::
+
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (bf) r2 = r10
+ 1: (07) r2 += -8
+ 2: (b7) r1 = 0x0
+ 3: (85) call 1
+ invalid indirect read from stack off -8+0 size 8
+
+Program that uses invalid map_fd=0 while calling to map_lookup_elem() function::
+
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (7a) *(u64 *)(r10 -8) = 0
+ 1: (bf) r2 = r10
+ 2: (07) r2 += -8
+ 3: (b7) r1 = 0x0
+ 4: (85) call 1
+ fd 0 is not pointing to valid bpf_map
+
+Program that doesn't check return value of map_lookup_elem() before
+accessing map element::
+
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_ST_MEM(BPF_DW, BPF_REG_0, 0, 0),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (7a) *(u64 *)(r10 -8) = 0
+ 1: (bf) r2 = r10
+ 2: (07) r2 += -8
+ 3: (b7) r1 = 0x0
+ 4: (85) call 1
+ 5: (7a) *(u64 *)(r0 +0) = 0
+ R0 invalid mem access 'map_value_or_null'
+
+Program that correctly checks map_lookup_elem() returned value for NULL,
+but accesses the memory with incorrect alignment::
+
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+ BPF_ST_MEM(BPF_DW, BPF_REG_0, 4, 0),
+ BPF_EXIT_INSN(),
+
+ Error:
+ 0: (7a) *(u64 *)(r10 -8) = 0
+ 1: (bf) r2 = r10
+ 2: (07) r2 += -8
+ 3: (b7) r1 = 1
+ 4: (85) call 1
+ 5: (15) if r0 == 0x0 goto pc+1
+ R0=map_ptr R10=fp
+ 6: (7a) *(u64 *)(r0 +4) = 0
+ misaligned access off 4 size 8
+
+Program that correctly checks map_lookup_elem() returned value for NULL
+and accesses memory with correct alignment in one side of 'if' branch,
+but fails to do so in the other side of 'if' branch::
+
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_ST_MEM(BPF_DW, BPF_REG_0, 0, 0),
+ BPF_EXIT_INSN(),
+ BPF_ST_MEM(BPF_DW, BPF_REG_0, 0, 1),
+ BPF_EXIT_INSN(),
+ Error:
+ 0: (7a) *(u64 *)(r10 -8) = 0
+ 1: (bf) r2 = r10
+ 2: (07) r2 += -8
+ 3: (b7) r1 = 1
+ 4: (85) call 1
+ 5: (15) if r0 == 0x0 goto pc+2
+ R0=map_ptr R10=fp
+ 6: (7a) *(u64 *)(r0 +0) = 0
+ 7: (95) exit
+
+ from 5 to 8: R0=imm0 R10=fp
+ 8: (7a) *(u64 *)(r0 +0) = 1
+ R0 invalid mem access 'imm'
diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
index a3233da7fa88..5e389aaf177c 100644
--- a/Documentation/userspace-api/index.rst
+++ b/Documentation/userspace-api/index.rst
@@ -18,8 +18,11 @@ place where this information is gathered.
no_new_privs
seccomp_filter
+ socket_filter
unshare
spec_ctrl
+ cBPF
+ eBPF
.. only:: subproject and html
diff --git a/Documentation/userspace-api/seccomp_filter.rst b/Documentation/userspace-api/seccomp_filter.rst
index 82a468bc7560..04e734cb90be 100644
--- a/Documentation/userspace-api/seccomp_filter.rst
+++ b/Documentation/userspace-api/seccomp_filter.rst
@@ -1,3 +1,5 @@
+.. _seccomp-filter:
+
===========================================
Seccomp BPF (SECure COMPuting with filters)
===========================================
@@ -40,6 +42,13 @@ path (avoiding pathological sizes or selecting which of the multiplexed
system calls in socketcall() is allowed, for instance) which could be
construed, incorrectly, as a more complete sandboxing solution.
+For more information on BPF please see:
+
+- Linux Socket Filters -
+ :ref:`Documentation/userspace-api/socket_filter.rst <socket-filter>`
+- Classic BPF (cBPF) - :ref:`Documentation/userspace-api/cBPF.rst <cbpf>`
+- Internal BPF (eBPF) - :ref:`Documentation/userspace-api/eBPF.rst <ebpf>`
+
Usage
=====
diff --git a/Documentation/userspace-api/socket_filter.rst b/Documentation/userspace-api/socket_filter.rst
new file mode 100644
index 000000000000..87363e8177f9
--- /dev/null
+++ b/Documentation/userspace-api/socket_filter.rst
@@ -0,0 +1,181 @@
+.. _socket-filter:
+
+======================
+Linux Socket Filtering
+======================
+
+Linux Socket Filtering (LSF) is derived from the Berkeley Packet
+Filter.
+
+Introduction
+============
+
+Though there are some distinct differences between the BSD and Linux
+kernel socket filtering, but when we speak of BPF or LSF in Linux
+context, we mean the very same mechanism of filtering in the Linux
+kernel.
+
+BPF allows a user-space program to attach a filter onto any socket and
+allow or disallow certain types of data to come through the socket. LSF
+follows exactly the same filter code structure as BSD's BPF, so
+referring to the BSD bpf.4 manpage is very helpful in creating filters.
+
+On Linux, BPF is much simpler than on BSD. One does not have to worry
+about devices or anything like that. You simply create your filter
+code, send it to the kernel via the SO_ATTACH_FILTER option and if your
+filter code passes the kernel check on it, you then immediately begin
+filtering data on that socket.
+
+You can also detach filters from your socket via the SO_DETACH_FILTER
+option. This will probably not be used much since when you close a
+socket that has a filter on it the filter is automagically removed. The
+other less common case may be adding a different filter on the same
+socket where you had another filter that is still running: the kernel
+takes care of removing the old one and placing your new one in its
+place, assuming your filter has passed the checks, otherwise if it fails
+the old filter will remain on that socket.
+
+SO_LOCK_FILTER option allows locking of the filter attached to a socket.
+Once set, a filter cannot be removed or changed. This allows one
+process to setup a socket, attach a filter, lock it then drop privileges
+and be assured that the filter will be kept until the socket is closed.
+
+The biggest user of this construct might be libpcap. Issuing a
+high-level filter command like `tcpdump -i em1 port 22` passes through
+the libpcap internal compiler that generates a structure that can
+eventually be loaded via SO_ATTACH_FILTER to the kernel. `tcpdump -i
+em1 port 22 -ddd` displays what is being placed into this structure.
+
+Although we were only speaking about sockets here, BPF in Linux is used
+in many more places. There's xt_bpf for netfilter, cls_bpf in the
+kernel qdisc layer, SECCOMP-BPF (SECure COMPuting), and lots of
+other places such as team driver, PTP code, etc. where BPF is being used.
+
+For more information please see the following documents:
+
+- Classic BPF (cBPF) - :ref:`Documentation/userspace-api/cBPF.rst <cbpf>`
+- Internal BPF (eBPF) - :ref:`Documentation/userspace-api/eBPF.rst <ebpf>`
+- SECCOMP BPF -
+ :ref:`Documentation/userspace-api/seccomp_filter.rst <seccomp-filter>`
+
+And the original BPF paper:
+
+Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new
+architecture for user-level packet capture. In Proceedings of the
+USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993
+Conference Proceedings (USENIX'93). USENIX Association, Berkeley,
+CA, USA, 2-2. [http://www.tcpdump.org/papers/bpf-usenix93.pdf]
+
+Structure
+=========
+
+User space applications include <linux/filter.h> which contains the
+following relevant structures::
+
+ struct sock_filter { /* Filter block */
+ __u16 code; /* Actual filter code */
+ __u8 jt; /* Jump true */
+ __u8 jf; /* Jump false */
+ __u32 k; /* Generic multiuse field */
+ };
+
+Such a structure is assembled as an array of 4-tuples, that contains
+a code, jt, jf and k value. jt and jf are jump offsets and k a generic
+value to be used for a provided code. ::
+
+ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */
+ unsigned short len; /* Number of filter blocks. */
+ struct sock_filter __user *filter;
+ };
+
+For socket filtering, a pointer to this structure (as shown in the
+follow-up example) is being passed to the kernel through setsockopt(2).
+
+Example
+=======
+::
+
+ #include <sys/socket.h>
+ #include <sys/types.h>
+ #include <arpa/inet.h>
+ #include <linux/if_ether.h>
+ /* ... */
+
+ /* From the example above: tcpdump -i em1 port 22 -dd */
+ struct sock_filter code[] = {
+ { 0x28, 0, 0, 0x0000000c },
+ { 0x15, 0, 8, 0x000086dd },
+ { 0x30, 0, 0, 0x00000014 },
+ { 0x15, 2, 0, 0x00000084 },
+ { 0x15, 1, 0, 0x00000006 },
+ { 0x15, 0, 17, 0x00000011 },
+ { 0x28, 0, 0, 0x00000036 },
+ { 0x15, 14, 0, 0x00000016 },
+ { 0x28, 0, 0, 0x00000038 },
+ { 0x15, 12, 13, 0x00000016 },
+ { 0x15, 0, 12, 0x00000800 },
+ { 0x30, 0, 0, 0x00000017 },
+ { 0x15, 2, 0, 0x00000084 },
+ { 0x15, 1, 0, 0x00000006 },
+ { 0x15, 0, 8, 0x00000011 },
+ { 0x28, 0, 0, 0x00000014 },
+ { 0x45, 6, 0, 0x00001fff },
+ { 0xb1, 0, 0, 0x0000000e },
+ { 0x48, 0, 0, 0x0000000e },
+ { 0x15, 2, 0, 0x00000016 },
+ { 0x48, 0, 0, 0x00000010 },
+ { 0x15, 0, 1, 0x00000016 },
+ { 0x06, 0, 0, 0x0000ffff },
+ { 0x06, 0, 0, 0x00000000 },
+ };
+
+ struct sock_fprog bpf = {
+ .len = ARRAY_SIZE(code),
+ .filter = code,
+ };
+
+ sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
+ if (sock < 0)
+ /* ... bail out ... */
+
+ ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf));
+ if (ret < 0)
+ /* ... bail out ... */
+
+ /* ... */
+ close(sock);
+
+The above example code attaches a socket filter for a PF_PACKET socket
+in order to let all IPv4/IPv6 packets with port 22 pass. The rest will
+be dropped for this socket.
+
+The setsockopt(2) call to SO_DETACH_FILTER doesn't need any arguments
+and SO_LOCK_FILTER for preventing the filter to be detached, takes an
+integer value with 0 or 1.
+
+Note that socket filters are not restricted to PF_PACKET sockets only,
+but can also be used on other socket families.
+
+Summary of system calls::
+
+ setsockopt(sockfd, SOL_SOCKET, SO_ATTACH_FILTER, &val, sizeof(val));
+ setsockopt(sockfd, SOL_SOCKET, SO_DETACH_FILTER, &val, sizeof(val));
+ setsockopt(sockfd, SOL_SOCKET, SO_LOCK_FILTER, &val, sizeof(val));
+
+Normally, most use cases for socket filtering on packet sockets will be
+covered by libpcap in high-level syntax, so as an application developer
+you should stick to that. libpcap wraps its own layer around all that.
+
+Unless i) using/linking to libpcap is not an option, ii) the required
+BPF filters use Linux extensions that are not supported by libpcap's
+compiler, iii) a filter might be more complex and not cleanly
+implementable with libpcap's compiler, or iv) particular filter codes
+should be optimized differently than libpcap's internal compiler does;
+then in such cases writing such a filter "by hand" can be of an
+alternative. For example, xt_bpf and cls_bpf users might have
+requirements that could result in more complex filter code, or one that
+cannot be expressed with libpcap (e.g. different return codes for
+various code paths). Moreover, BPF JIT implementors may wish to
+manually write test cases and thus need low-level access to BPF code as
+well.
+
diff --git a/MAINTAINERS b/MAINTAINERS
index 82f277462349..1611f9f6607f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2746,8 +2746,10 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
Q: https://patchwork.ozlabs.org/project/netdev/list/?delegate=77147
S: Supported
F: arch/x86/net/bpf_jit*
-F: Documentation/networking/filter.txt
F: Documentation/bpf/
+F: Documentation/userspace-api/socket_filter.rst
+F: Documentation/userspace-api/eBPF.rst
+F: Documentation/userspace-api/cBPF.rst
F: include/linux/bpf*
F: include/linux/filter.h
F: include/trace/events/xdp.h
--
2.17.1
^ permalink raw reply related
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox