On Tue, Apr 09, 2019 at 10:27:37AM -0700, Stanislav Fomichev wrote:
> Add new set of arguments to bpf_attr for BPF_PROG_TEST_RUN:
> * ctx_in/ctx_size_in - input context
> * ctx_out/ctx_size_out - output context
>
> The intended use case is to pass some meta data to the test runs that
> operate on skb (this has being brought up on recent LPC).
>
> For programs that use bpf_prog_test_run_skb, support __sk_buff input and
> output. Initially, from input __sk_buff, copy _only_ cb and priority into
> skb, all other non-zero fields are prohibited (with EINVAL).
> If the user has set ctx_out/ctx_size_out, copy the potentially modified
> __sk_buff back to the userspace.
>
> We require all fields of input __sk_buff except the ones we explicitly
> support to be set to zero. The expectation is that in the future we might
> add support for more fields and we want to fail explicitly if the user
> runs the program on the kernel where we don't yet support them.
>
> The API is intentionally vague (i.e. we don't explicitly add __sk_buff
> to bpf_attr, but ctx_in) to potentially let other test_run types use
> this interface in the future (this can be xdp_md for xdp types for
> example).
>
> v3:
> * handle case where ctx_in is NULL, but ctx_out is not [Martin]
> * convert size==0 checks to ptr==NULL checks and add some extra ptr
> checks [Martin]
>
> v2:
> * Addressed comments from Martin Lau
>
> Cc: Martin Lau <kafai@xxxxxx>
> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 7 ++
> kernel/bpf/syscall.c | 10 ++-
> net/bpf/test_run.c | 142 ++++++++++++++++++++++++++++++++++++---
> 3 files changed, 150 insertions(+), 9 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 837024512baf..8e96f99cebf8 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -396,6 +396,13 @@ union bpf_attr {
> __aligned_u64 data_out;
> __u32 repeat;
> __u32 duration;
> + __u32 ctx_size_in; /* input: len of ctx_in */
> + __u32 ctx_size_out; /* input/output: len of ctx_out
> + * returns ENOSPC if ctx_out
> + * is too small.
> + */
> + __aligned_u64 ctx_in;
> + __aligned_u64 ctx_out;
> } test;
>
> struct { /* anonymous struct used by BPF_*_GET_*_ID */
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 1d65e56594db..5bb963e8f9b0 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1949,7 +1949,7 @@ static int bpf_prog_query(const union bpf_attr *attr,
> return cgroup_bpf_prog_query(attr, uattr);
> }
>
> -#define BPF_PROG_TEST_RUN_LAST_FIELD test.duration
> +#define BPF_PROG_TEST_RUN_LAST_FIELD test.ctx_out
>
> static int bpf_prog_test_run(const union bpf_attr *attr,
> union bpf_attr __user *uattr)
> @@ -1962,6 +1962,14 @@ static int bpf_prog_test_run(const union bpf_attr *attr,
> if (CHECK_ATTR(BPF_PROG_TEST_RUN))
> return -EINVAL;
>
> + if ((attr->test.ctx_size_in && !attr->test.ctx_in) ||
> + (!attr->test.ctx_size_in && attr->test.ctx_in))
> + return -EINVAL;
> +
> + if ((attr->test.ctx_size_out && !attr->test.ctx_out) ||
> + (!attr->test.ctx_size_out && attr->test.ctx_out))
> + return -EINVAL;
> +
> prog = bpf_prog_get(attr->test.prog_fd);
> if (IS_ERR(prog))
> return PTR_ERR(prog);
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index fab142b796ef..2023d8841c6d 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -123,12 +123,125 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 size,
> return data;
> }
>
> +static void *bpf_ctx_init(const union bpf_attr *kattr, u32 max_size)
> +{
> + void __user *data_in = u64_to_user_ptr(kattr->test.ctx_in);
> + void __user *data_out = u64_to_user_ptr(kattr->test.ctx_out);
> + u32 size = kattr->test.ctx_size_in;
> + void *data;
> + int err;
> +
> + if (!data_in && !data_out)
> + return NULL;
> +
> + data = kzalloc(max_size, GFP_USER);
> + if (!data)
> + return ERR_PTR(-ENOMEM);
> +
> + if (data_in) {
> + err = bpf_check_uarg_tail_zero(data_in, max_size, size);
> + if (err) {
> + kfree(data);
> + return ERR_PTR(err);
> + }
> +
> + if (copy_from_user(data, data_in, size)) {
A min_t is needed:
size = min_t(u32, max_size, size);
if (copy_from_user(data, data_in, size)) {
Others lgtm,
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
> + kfree(data);
> + return ERR_PTR(-EFAULT);
> + }
> + }
> + return data;
> +}
