Re: [PATCH bpf-next v8 04/12] bpf: Only reply field should be writeable

[Alexei Starovoitov]

On 1/24/18 11:58 AM, Yuchung Cheng wrote:

On Tue, Jan 23, 2018 at 11:57 PM, Lawrence Brakmo  wrote:

Currently, a sock_ops BPF program can write the op field and all the
reply fields (reply and replylong). This is a bug. The op field should
not have been writeable and there is currently no way to use replylong
field for indices >= 1. This patch enforces that only the reply field
(which equals replylong[0]) is writeable.

Would this patch be more suitable for -net ?


yes. we will send it to 4.15 and 4.14 as soon as it's released.
See discussion with Eric.



Fixes: 40304b2a1567 ("bpf: BPF support for sock_ops")
Signed-off-by: Lawrence Brakmo 

Acked-by: Yuchung Cheng 


---
 net/core/filter.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 0cf170f..c356ec0 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3845,8 +3845,7 @@ static bool sock_ops_is_valid_access(int off, int size,
 {
if (type == BPF_WRITE) {
switch (off) {
-   case offsetof(struct bpf_sock_ops, op) ...
-offsetof(struct bpf_sock_ops, replylong[3]):
+   case offsetof(struct bpf_sock_ops, reply):
break;
default:
return false;
--
2.9.5

Re: [PATCH bpf-next v8 04/12] bpf: Only reply field should be writeable

[Yuchung Cheng]

On Tue, Jan 23, 2018 at 11:57 PM, Lawrence Brakmo  wrote:
> Currently, a sock_ops BPF program can write the op field and all the
> reply fields (reply and replylong). This is a bug. The op field should
> not have been writeable and there is currently no way to use replylong
> field for indices >= 1. This patch enforces that only the reply field
> (which equals replylong[0]) is writeable.
Would this patch be more suitable for -net ?

>
> Fixes: 40304b2a1567 ("bpf: BPF support for sock_ops")
> Signed-off-by: Lawrence Brakmo 
Acked-by: Yuchung Cheng 

> ---
>  net/core/filter.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 0cf170f..c356ec0 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -3845,8 +3845,7 @@ static bool sock_ops_is_valid_access(int off, int size,
>  {
> if (type == BPF_WRITE) {
> switch (off) {
> -   case offsetof(struct bpf_sock_ops, op) ...
> -offsetof(struct bpf_sock_ops, replylong[3]):
> +   case offsetof(struct bpf_sock_ops, reply):
> break;
> default:
> return false;
> --
> 2.9.5
>

[PATCH bpf-next v8 04/12] bpf: Only reply field should be writeable

[Lawrence Brakmo]

Currently, a sock_ops BPF program can write the op field and all the
reply fields (reply and replylong). This is a bug. The op field should
not have been writeable and there is currently no way to use replylong
field for indices >= 1. This patch enforces that only the reply field
(which equals replylong[0]) is writeable.

Fixes: 40304b2a1567 ("bpf: BPF support for sock_ops")
Signed-off-by: Lawrence Brakmo 
---
 net/core/filter.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 0cf170f..c356ec0 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3845,8 +3845,7 @@ static bool sock_ops_is_valid_access(int off, int size,
 {
if (type == BPF_WRITE) {
switch (off) {
-   case offsetof(struct bpf_sock_ops, op) ...
-offsetof(struct bpf_sock_ops, replylong[3]):
+   case offsetof(struct bpf_sock_ops, reply):
break;
default:
return false;
-- 
2.9.5