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Date: Wed, 5 Jun 2019 14:16:30 -0700
From: Stanislav Fomichev <sdf@...ichev.me>
To: Martin Lau <kafai@...com>
Cc: Stanislav Fomichev <sdf@...gle.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"bpf@...r.kernel.org" <bpf@...r.kernel.org>,
"davem@...emloft.net" <davem@...emloft.net>,
"ast@...nel.org" <ast@...nel.org>,
"daniel@...earbox.net" <daniel@...earbox.net>
Subject: Re: [PATCH bpf-next 1/7] bpf: implement getsockopt and setsockopt
hooks
On 06/05, Martin Lau wrote:
> On Wed, Jun 05, 2019 at 12:17:24PM -0700, Stanislav Fomichev wrote:
> > On 06/05, Martin Lau wrote:
> > > On Tue, Jun 04, 2019 at 02:35:18PM -0700, Stanislav Fomichev wrote:
> > > > Implement new BPF_PROG_TYPE_CGROUP_SOCKOPT program type and
> > > > BPF_CGROUP_{G,S}ETSOCKOPT cgroup hooks.
> > > >
> > > > BPF_CGROUP_SETSOCKOPT get a read-only view of the setsockopt arguments.
> > > > BPF_CGROUP_GETSOCKOPT can modify the supplied buffer.
> > > > Both of them reuse existing PTR_TO_PACKET{,_END} infrastructure.
> > > >
> > > > The buffer memory is pre-allocated (because I don't think there is
> > > > a precedent for working with __user memory from bpf). This might be
> > > > slow to do for each {s,g}etsockopt call, that's why I've added
> > > > __cgroup_bpf_has_prog_array that exits early if there is nothing
> > > > attached to a cgroup. Note, however, that there is a race between
> > > > __cgroup_bpf_has_prog_array and BPF_PROG_RUN_ARRAY where cgroup
> > > > program layout might have changed; this should not be a problem
> > > > because in general there is a race between multiple calls to
> > > > {s,g}etsocktop and user adding/removing bpf progs from a cgroup.
> > > >
> > > > By default, kernel code path is executed after the hook (to let
> > > > BPF handle only a subset of the options). There is new
> > > > bpf_sockopt_handled handler that returns control to the userspace
> > > > instead (bypassing the kernel handling).
> > > >
> > > > The return code is either 1 (success) or 0 (EPERM).
> > > >
> > > > Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
> > > > ---
> > > > include/linux/bpf-cgroup.h | 29 ++++
> > > > include/linux/bpf.h | 2 +
> > > > include/linux/bpf_types.h | 1 +
> > > > include/linux/filter.h | 19 +++
> > > > include/uapi/linux/bpf.h | 17 ++-
> > > > kernel/bpf/cgroup.c | 288 +++++++++++++++++++++++++++++++++++++
> > > > kernel/bpf/syscall.c | 19 +++
> > > > kernel/bpf/verifier.c | 12 ++
> > > > net/core/filter.c | 4 +-
> > > > net/socket.c | 18 +++
> > > > 10 files changed, 406 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
> > > > index b631ee75762d..406f1ba82531 100644
> > > > --- a/include/linux/bpf-cgroup.h
> > > > +++ b/include/linux/bpf-cgroup.h
> > > > @@ -124,6 +124,13 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
> > > > loff_t *ppos, void **new_buf,
> > > > enum bpf_attach_type type);
> > > >
> > > > +int __cgroup_bpf_run_filter_setsockopt(struct sock *sock, int level,
> > > > + int optname, char __user *optval,
> > > > + unsigned int optlen);
> > > > +int __cgroup_bpf_run_filter_getsockopt(struct sock *sock, int level,
> > > > + int optname, char __user *optval,
> > > > + int __user *optlen);
> > > > +
> > > > static inline enum bpf_cgroup_storage_type cgroup_storage_type(
> > > > struct bpf_map *map)
> > > > {
> > > > @@ -280,6 +287,26 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
> > > > __ret; \
> > > > })
> > > >
> > > > +#define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen) \
> > > > +({ \
> > > > + int __ret = 0; \
> > > > + if (cgroup_bpf_enabled) \
> > > > + __ret = __cgroup_bpf_run_filter_setsockopt(sock, level, \
> > > > + optname, optval, \
> > > > + optlen); \
> > > > + __ret; \
> > > > +})
> > > > +
> > > > +#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, optlen) \
> > > > +({ \
> > > > + int __ret = 0; \
> > > > + if (cgroup_bpf_enabled) \
> > > > + __ret = __cgroup_bpf_run_filter_getsockopt(sock, level, \
> > > > + optname, optval, \
> > > > + optlen); \
> > > > + __ret; \
> > > > +})
> > > > +
> > > > int cgroup_bpf_prog_attach(const union bpf_attr *attr,
> > > > enum bpf_prog_type ptype, struct bpf_prog *prog);
> > > > int cgroup_bpf_prog_detach(const union bpf_attr *attr,
> > > > @@ -349,6 +376,8 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
> > > > #define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
> > > > #define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
> > > > #define BPF_CGROUP_RUN_PROG_SYSCTL(head,table,write,buf,count,pos,nbuf) ({ 0; })
> > > > +#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, optlen) ({ 0; })
> > > > +#define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen) ({ 0; })
> > > >
> > > > #define for_each_cgroup_storage_type(stype) for (; false; )
> > > >
> > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > > > index e5a309e6a400..fb4e6ef5a971 100644
> > > > --- a/include/linux/bpf.h
> > > > +++ b/include/linux/bpf.h
> > > > @@ -1054,6 +1054,8 @@ extern const struct bpf_func_proto bpf_spin_unlock_proto;
> > > > extern const struct bpf_func_proto bpf_get_local_storage_proto;
> > > > extern const struct bpf_func_proto bpf_strtol_proto;
> > > > extern const struct bpf_func_proto bpf_strtoul_proto;
> > > > +extern const struct bpf_func_proto bpf_sk_fullsock_proto;
> > > > +extern const struct bpf_func_proto bpf_tcp_sock_proto;
> > > >
> > > > /* Shared helpers among cBPF and eBPF. */
> > > > void bpf_user_rnd_init_once(void);
> > > > diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
> > > > index 5a9975678d6f..eec5aeeeaf92 100644
> > > > --- a/include/linux/bpf_types.h
> > > > +++ b/include/linux/bpf_types.h
> > > > @@ -30,6 +30,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, raw_tracepoint_writable)
> > > > #ifdef CONFIG_CGROUP_BPF
> > > > BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
> > > > BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SYSCTL, cg_sysctl)
> > > > +BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCKOPT, cg_sockopt)
> > > > #endif
> > > > #ifdef CONFIG_BPF_LIRC_MODE2
> > > > BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
> > > > diff --git a/include/linux/filter.h b/include/linux/filter.h
> > > > index 43b45d6db36d..7a07fd2e14d3 100644
> > > > --- a/include/linux/filter.h
> > > > +++ b/include/linux/filter.h
> > > > @@ -1199,4 +1199,23 @@ struct bpf_sysctl_kern {
> > > > u64 tmp_reg;
> > > > };
> > > >
> > > > +struct bpf_sockopt_kern {
> > > > + struct sock *sk;
> > > > + s32 level;
> > > > + s32 optname;
> > > > + u32 optlen;
> > > It seems there is hole.
> > Ack, will move the pointers up.
> >
> > > > + u8 *optval;
> > > > + u8 *optval_end;
> > > > +
> > > > + /* If true, BPF program had consumed the sockopt request.
> > > > + * Control is returned to the userspace (i.e. kernel doesn't
> > > > + * handle this option).
> > > > + */
> > > > + bool handled;
> > > > +
> > > > + /* Small on-stack optval buffer to avoid small allocations.
> > > > + */
> > > > + u8 buf[64];
> > > Is it better to align to 8 bytes?
> > Do you mean manually set size to be 64 + x where x is a remainder
> > to align to 8 bytes? Is there some macro to help with that maybe?
> I think __attribute__((aligned(8))) should do.
Ah, you meant to align the buffer itself to avoid unaligned
access from the bpf progs. Got it, will do.
> >
> > > > +};
> > > > +
> > > > #endif /* __LINUX_FILTER_H__ */
> > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > > index 7c6aef253173..b6c3891241ef 100644
> > > > --- a/include/uapi/linux/bpf.h
> > > > +++ b/include/uapi/linux/bpf.h
> > > > @@ -170,6 +170,7 @@ enum bpf_prog_type {
> > > > BPF_PROG_TYPE_FLOW_DISSECTOR,
> > > > BPF_PROG_TYPE_CGROUP_SYSCTL,
> > > > BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
> > > > + BPF_PROG_TYPE_CGROUP_SOCKOPT,
> > > > };
> > > >
> > > > enum bpf_attach_type {
> > > > @@ -192,6 +193,8 @@ enum bpf_attach_type {
> > > > BPF_LIRC_MODE2,
> > > > BPF_FLOW_DISSECTOR,
> > > > BPF_CGROUP_SYSCTL,
> > > > + BPF_CGROUP_GETSOCKOPT,
> > > > + BPF_CGROUP_SETSOCKOPT,
> > > > __MAX_BPF_ATTACH_TYPE
> > > > };
> > > >
> > > > @@ -2815,7 +2818,8 @@ union bpf_attr {
> > > > FN(strtoul), \
> > > > FN(sk_storage_get), \
> > > > FN(sk_storage_delete), \
> > > > - FN(send_signal),
> > > > + FN(send_signal), \
> > > > + FN(sockopt_handled),
> > > Document.
> > Ah, totally forgot about that, sure, will do!
> >
> > > >
> > > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> > > > * function eBPF program intends to call
> > > > @@ -3533,4 +3537,15 @@ struct bpf_sysctl {
> > > > */
> > > > };
> > > >
> > > > +struct bpf_sockopt {
> > > > + __bpf_md_ptr(struct bpf_sock *, sk);
> > > > +
> > > > + __s32 level;
> > > > + __s32 optname;
> > > > +
> > > > + __u32 optlen;
> > > > + __u32 optval;
> > > > + __u32 optval_end;
> > > > +};
> > > > +
> > > > #endif /* _UAPI__LINUX_BPF_H__ */
> > > > diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> > > > index 1b65ab0df457..4ec99ea97023 100644
> > > > --- a/kernel/bpf/cgroup.c
> > > > +++ b/kernel/bpf/cgroup.c
> > > > @@ -18,6 +18,7 @@
> > > > #include <linux/bpf.h>
> > > > #include <linux/bpf-cgroup.h>
> > > > #include <net/sock.h>
> > > > +#include <net/bpf_sk_storage.h>
> > > >
> > > > DEFINE_STATIC_KEY_FALSE(cgroup_bpf_enabled_key);
> > > > EXPORT_SYMBOL(cgroup_bpf_enabled_key);
> > > > @@ -924,6 +925,142 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
> > > > }
> > > > EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
> > > >
> > > > +static bool __cgroup_bpf_has_prog_array(struct cgroup *cgrp,
> > > > + enum bpf_attach_type attach_type)
> > > > +{
> > > > + struct bpf_prog_array *prog_array;
> > > > + int nr;
> > > > +
> > > > + rcu_read_lock();
> > > > + prog_array = rcu_dereference(cgrp->bpf.effective[attach_type]);
> > > > + nr = bpf_prog_array_length(prog_array);
> > > Nit. It seems unnecessary to loop through the whole
> > > array if the only signal needed is non-zero.
> > Oh, good point. I guess I'd have to add another helper like
> > bpf_prog_array_is_empty() and return early. Any other suggestions?
> I was thinking to check empty_prog_array on top but it is
> too overkilled, so didn't mention it. I think just return
> early is good enough.
[..]
> I think this non-zero check is good to have before doing lock_sock().
And not before the allocation? I was trying to optimize for both kmalloc
and lock_sock (since, I guess, the majority of the cgroups would not
have any sockopt progs, so there is no point in paying the kmalloc
cost as well).
>
> >
> > > > + rcu_read_unlock();
> > > > +
> > > > + return nr > 0;
> > > > +}
> > > > +
> > > > +static int sockopt_alloc_buf(struct bpf_sockopt_kern *ctx, int max_optlen)
> > > > +{
> > > > + if (unlikely(max_optlen > PAGE_SIZE))
> > > > + return -EINVAL;
> > > > +
> > > > + if (likely(max_optlen <= sizeof(ctx->buf))) {
> > > > + ctx->optval = ctx->buf;
> > > > + } else {
> > > > + ctx->optval = kzalloc(max_optlen, GFP_USER);
> > > > + if (!ctx->optval)
> > > > + return -ENOMEM;
> > > > + }
> > > > +
> > > > + ctx->optval_end = ctx->optval + max_optlen;
> > > > + ctx->optlen = max_optlen;
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static void sockopt_free_buf(struct bpf_sockopt_kern *ctx)
> > > > +{
> > > > + if (unlikely(ctx->optval != ctx->buf))
> > > > + kfree(ctx->optval);
> > > > +}
> > > > +
> > > > +int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int level,
> > > > + int optname, char __user *optval,
> > > > + unsigned int optlen)
> > > > +{
> > > > + struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
> > > > + struct bpf_sockopt_kern ctx = {
> > > > + .sk = sk,
> > > > + .level = level,
> > > > + .optname = optname,
> > > > + };
> > > > + int ret;
> > > > +
> > > > + /* Opportunistic check to see whether we have any BPF program
> > > > + * attached to the hook so we don't waste time allocating
> > > > + * memory and locking the socket.
> > > > + */
> > > > + if (!__cgroup_bpf_has_prog_array(cgrp, BPF_CGROUP_SETSOCKOPT))
> > > > + return 0;
> > > > +
> > > > + ret = sockopt_alloc_buf(&ctx, optlen);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + if (copy_from_user(ctx.optval, optval, optlen) != 0) {
> > > > + sockopt_free_buf(&ctx);
> > > > + return -EFAULT;
> > > > + }
> > > > +
> > > > + lock_sock(sk);
> > > > + ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_SETSOCKOPT],
> > > > + &ctx, BPF_PROG_RUN);
> > > I think the check_return_code() in verifier.c has to be
> > > adjusted also.
> > Good catch! I though that it does the [0,1] check by default.
> btw, just came to my mind, do you have a chance to
> look at how 'ret' is handled in BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY()?
> It can take return values other than 0 or 1. I am thinking
> ctx.handled could also be done in the 'ret' itself also
> but out of my head I think your current way "bpf_sockopt_handled()"
> may be cleaner.
Andrii had the same suggestion. Let me spend some time to look into whether
it's easier to use return code.
> > > > + release_sock(sk);
> > > > +
> > > > + sockopt_free_buf(&ctx);
> > > > +
> > > > + if (!ret)
> > > > + return -EPERM;
> > > > +
> > > > + return ctx.handled ? 1 : 0;
> > > > +}
> > > > +EXPORT_SYMBOL(__cgroup_bpf_run_filter_setsockopt);
> > > > +
> > > > +int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
> > > > + int optname, char __user *optval,
> > > > + int __user *optlen)
> > > > +{
> > > > + struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
> > > > + struct bpf_sockopt_kern ctx = {
> > > > + .sk = sk,
> > > > + .level = level,
> > > > + .optname = optname,
> > > > + };
> > > > + int max_optlen;
> > > > + char buf[64];
> > > hmm... where is it used?
> > It's a leftover from my initial attempt to have a small buffer on the stack.
> > I've since moved it into struct bpf_sockopt_kern. Will remove. Gcc even
> > complains about unused var, not sure how I missed that...
> >
> > > > + int ret;
> > > > +
> > > > + /* Opportunistic check to see whether we have any BPF program
> > > > + * attached to the hook so we don't waste time allocating
> > > > + * memory and locking the socket.
> > > > + */
> > > > + if (!__cgroup_bpf_has_prog_array(cgrp, BPF_CGROUP_GETSOCKOPT))
> > > > + return 0;
> > > > +
> > > > + if (get_user(max_optlen, optlen))
> > > > + return -EFAULT;
> > > > +
> > > > + ret = sockopt_alloc_buf(&ctx, max_optlen);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + lock_sock(sk);
> > > > + ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
> > > > + &ctx, BPF_PROG_RUN);
> > > > + release_sock(sk);
> > > > +
> > > > + if (ctx.optlen > max_optlen) {
> > > > + sockopt_free_buf(&ctx);
> > > > + return -EFAULT;
> > > > + }
> > > > +
> > > > + if (copy_to_user(optval, ctx.optval, ctx.optlen) != 0) {
> > > > + sockopt_free_buf(&ctx);
> > > > + return -EFAULT;
> > > > + }
> > > > +
> > > > + sockopt_free_buf(&ctx);
> > > > +
> > > > + if (put_user(ctx.optlen, optlen))
> > > > + return -EFAULT;
> > > > +
> > > > + if (!ret)
> > > > + return -EPERM;
> > > > +
> > > > + return ctx.handled ? 1 : 0;
> > > > +}
> > > > +EXPORT_SYMBOL(__cgroup_bpf_run_filter_getsockopt);
> > > > +
> > > > static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
> > > > size_t *lenp)
> > > > {
> > > > @@ -1184,3 +1321,154 @@ const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
> > > >
> > > > const struct bpf_prog_ops cg_sysctl_prog_ops = {
> > > > };
> > > > +
> > > > +BPF_CALL_1(bpf_sockopt_handled, struct bpf_sockopt_kern *, ctx)
> > > > +{
> > > > + ctx->handled = true;
> > > > + return 1;
> > > RET_VOID?
> > I was thinking that in the C code the pattern can be:
> > {
> > ...
> > return bpf_sockopt_handled();
> > }
> >
> > That's why I'm retuning 1 from the helper. But I can change it to VOID
> > so that users have to return 1 manually. That's probably cleaner, will
> > change.
> >
> > > > +}
> > > > +
> > > > +static const struct bpf_func_proto bpf_sockopt_handled_proto = {
> > > > + .func = bpf_sockopt_handled,
> > > > + .gpl_only = false,
> > > > + .arg1_type = ARG_PTR_TO_CTX,
> > > > + .ret_type = RET_INTEGER,
> > > > +};
> > > > +
> > > > +static const struct bpf_func_proto *
> > > > +cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > > > +{
> > > > + switch (func_id) {
> > > > + case BPF_FUNC_sockopt_handled:
> > > > + return &bpf_sockopt_handled_proto;
> > > > + case BPF_FUNC_sk_fullsock:
> > > > + return &bpf_sk_fullsock_proto;
> > > > + case BPF_FUNC_sk_storage_get:
> > > > + return &bpf_sk_storage_get_proto;
> > > > + case BPF_FUNC_sk_storage_delete:
> > > > + return &bpf_sk_storage_delete_proto;
> > > > +#ifdef CONFIG_INET
> > > > + case BPF_FUNC_tcp_sock:
> > > > + return &bpf_tcp_sock_proto;
> > > > +#endif
> > > > + default:
> > > > + return cgroup_base_func_proto(func_id, prog);
> > > > + }
> > > > +}
> > > > +
> > > > +static bool cg_sockopt_is_valid_access(int off, int size,
> > > > + enum bpf_access_type type,
> > > > + const struct bpf_prog *prog,
> > > > + struct bpf_insn_access_aux *info)
> > > > +{
> > > > + const int size_default = sizeof(__u32);
> > > > +
> > > > + if (off < 0 || off >= sizeof(struct bpf_sockopt))
> > > > + return false;
> > > > +
> > > > + if (off % size != 0)
> > > > + return false;
> > > > +
> > > > + if (type == BPF_WRITE) {
> > > > + switch (off) {
> > > > + case offsetof(struct bpf_sockopt, optlen):
> > > > + if (size != size_default)
> > > > + return false;
> > > > + return prog->expected_attach_type ==
> > > > + BPF_CGROUP_GETSOCKOPT;
> > > > + default:
> > > > + return false;
> > > > + }
> > > > + }
> > > > +
> > > > + switch (off) {
> > > > + case offsetof(struct bpf_sockopt, sk):
> > > > + if (size != sizeof(__u64))
> > > > + return false;
> > > > + info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
> > > sk cannot be NULL, so the OR_NULL part is not needed.
> > >
> > > I think it should also be PTR_TO_SOCKET instead.
> > I think you're correct. That reminds me of the fact that
> > I haven't properly tested it. Let me add a small C
> > selftest where I test this codepath.
> >
> > > > + break;
> > > > + case bpf_ctx_range(struct bpf_sockopt, optval):
> > > > + if (size != size_default)
> > > > + return false;
> > > > + info->reg_type = PTR_TO_PACKET;
> > > > + break;
> > > > + case bpf_ctx_range(struct bpf_sockopt, optval_end):
> > > > + if (size != size_default)
> > > > + return false;
> > > > + info->reg_type = PTR_TO_PACKET_END;
> > > > + break;
> > > > + default:
> > > > + if (size != size_default)
> > > > + return false;
> > > > + break;
> > > > + }
> > > > + return true;
> > > > +}
> > > > +
> > > > +static u32 cg_sockopt_convert_ctx_access(enum bpf_access_type type,
> > > > + const struct bpf_insn *si,
> > > > + struct bpf_insn *insn_buf,
> > > > + struct bpf_prog *prog,
> > > > + u32 *target_size)
> > > > +{
> > > > + struct bpf_insn *insn = insn_buf;
> > > > +
> > > > + switch (si->off) {
> > > > + case offsetof(struct bpf_sockopt, sk):
> > > > + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, sk),
> > > > + si->dst_reg, si->src_reg,
> > > > + offsetof(struct bpf_sockopt_kern, sk));
> > > > + break;
> > > > + case offsetof(struct bpf_sockopt, level):
> > > > + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
> > > > + bpf_target_off(struct bpf_sockopt_kern,
> > > > + level, 4, target_size));
> > > bpf_target_off() is not needed since there is no narrow load.
> > Good point, will drop it.
> >
> > Thank you for a review!
> >
> > > > + break;
> > > > + case offsetof(struct bpf_sockopt, optname):
> > > > + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
> > > > + bpf_target_off(struct bpf_sockopt_kern,
> > > > + optname, 4, target_size));
> > > > + break;
> > > > + case offsetof(struct bpf_sockopt, optlen):
> > > > + if (type == BPF_WRITE)
> > > > + *insn++ = BPF_STX_MEM(BPF_W, si->dst_reg, si->src_reg,
> > > > + bpf_target_off(struct bpf_sockopt_kern,
> > > > + optlen, 4, target_size));
> > > > + else
> > > > + *insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,
> > > > + bpf_target_off(struct bpf_sockopt_kern,
> > > > + optlen, 4, target_size));
> > > > + break;
> > > > + case offsetof(struct bpf_sockopt, optval):
> > > > + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, optval),
> > > > + si->dst_reg, si->src_reg,
> > > > + offsetof(struct bpf_sockopt_kern, optval));
> > > > + break;
> > > > + case offsetof(struct bpf_sockopt, optval_end):
> > > > + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, optval_end),
> > > > + si->dst_reg, si->src_reg,
> > > > + offsetof(struct bpf_sockopt_kern, optval_end));
> > > > + break;
> > > > + }
> > > > +
> > > > + return insn - insn_buf;
> > > > +}
> > > > +
> > > > +static int cg_sockopt_get_prologue(struct bpf_insn *insn_buf,
> > > > + bool direct_write,
> > > > + const struct bpf_prog *prog)
> > > > +{
> > > > + /* Nothing to do for sockopt argument. The data is kzalloc'ated.
> > > > + */
> > > > + return 0;
> > > > +}
> > > > +
> > > > +const struct bpf_verifier_ops cg_sockopt_verifier_ops = {
> > > > + .get_func_proto = cg_sockopt_func_proto,
> > > > + .is_valid_access = cg_sockopt_is_valid_access,
> > > > + .convert_ctx_access = cg_sockopt_convert_ctx_access,
> > > > + .gen_prologue = cg_sockopt_get_prologue,
> > > > +};
> > > > +
> > > > +const struct bpf_prog_ops cg_sockopt_prog_ops = {
> > > > +};
> > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > > index 4c53cbd3329d..4ad2b5f1905f 100644
> > > > --- a/kernel/bpf/syscall.c
> > > > +++ b/kernel/bpf/syscall.c
> > > > @@ -1596,6 +1596,14 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
> > > > default:
> > > > return -EINVAL;
> > > > }
> > > > + case BPF_PROG_TYPE_CGROUP_SOCKOPT:
> > > > + switch (expected_attach_type) {
> > > > + case BPF_CGROUP_SETSOCKOPT:
> > > > + case BPF_CGROUP_GETSOCKOPT:
> > > > + return 0;
> > > > + default:
> > > > + return -EINVAL;
> > > > + }
> > > > default:
> > > > return 0;
> > > > }
> > > > @@ -1846,6 +1854,7 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
> > > > switch (prog->type) {
> > > > case BPF_PROG_TYPE_CGROUP_SOCK:
> > > > case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
> > > > + case BPF_PROG_TYPE_CGROUP_SOCKOPT:
> > > > return attach_type == prog->expected_attach_type ? 0 : -EINVAL;
> > > > case BPF_PROG_TYPE_CGROUP_SKB:
> > > > return prog->enforce_expected_attach_type &&
> > > > @@ -1916,6 +1925,10 @@ static int bpf_prog_attach(const union bpf_attr *attr)
> > > > case BPF_CGROUP_SYSCTL:
> > > > ptype = BPF_PROG_TYPE_CGROUP_SYSCTL;
> > > > break;
> > > > + case BPF_CGROUP_GETSOCKOPT:
> > > > + case BPF_CGROUP_SETSOCKOPT:
> > > > + ptype = BPF_PROG_TYPE_CGROUP_SOCKOPT;
> > > > + break;
> > > > default:
> > > > return -EINVAL;
> > > > }
> > > > @@ -1997,6 +2010,10 @@ static int bpf_prog_detach(const union bpf_attr *attr)
> > > > case BPF_CGROUP_SYSCTL:
> > > > ptype = BPF_PROG_TYPE_CGROUP_SYSCTL;
> > > > break;
> > > > + case BPF_CGROUP_GETSOCKOPT:
> > > > + case BPF_CGROUP_SETSOCKOPT:
> > > > + ptype = BPF_PROG_TYPE_CGROUP_SOCKOPT;
> > > > + break;
> > > > default:
> > > > return -EINVAL;
> > > > }
> > > > @@ -2031,6 +2048,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
> > > > case BPF_CGROUP_SOCK_OPS:
> > > > case BPF_CGROUP_DEVICE:
> > > > case BPF_CGROUP_SYSCTL:
> > > > + case BPF_CGROUP_GETSOCKOPT:
> > > > + case BPF_CGROUP_SETSOCKOPT:
> > > > break;
> > > > case BPF_LIRC_MODE2:
> > > > return lirc_prog_query(attr, uattr);
> > > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > > > index 5c2cb5bd84ce..b91fde10e721 100644
> > > > --- a/kernel/bpf/verifier.c
> > > > +++ b/kernel/bpf/verifier.c
> > > > @@ -1717,6 +1717,18 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
> > > >
> > > > env->seen_direct_write = true;
> > > > return true;
> > > > +
> > > > + case BPF_PROG_TYPE_CGROUP_SOCKOPT:
> > > > + if (t == BPF_WRITE) {
> > > > + if (env->prog->expected_attach_type ==
> > > > + BPF_CGROUP_GETSOCKOPT) {
> > > > + env->seen_direct_write = true;
> > > > + return true;
> > > > + }
> > > > + return false;
> > > > + }
> > > > + return true;
> > > > +
> > > > default:
> > > > return false;
> > > > }
> > > > diff --git a/net/core/filter.c b/net/core/filter.c
> > > > index 55bfc941d17a..4652c0a005ca 100644
> > > > --- a/net/core/filter.c
> > > > +++ b/net/core/filter.c
> > > > @@ -1835,7 +1835,7 @@ BPF_CALL_1(bpf_sk_fullsock, struct sock *, sk)
> > > > return sk_fullsock(sk) ? (unsigned long)sk : (unsigned long)NULL;
> > > > }
> > > >
> > > > -static const struct bpf_func_proto bpf_sk_fullsock_proto = {
> > > > +const struct bpf_func_proto bpf_sk_fullsock_proto = {
> > > > .func = bpf_sk_fullsock,
> > > > .gpl_only = false,
> > > > .ret_type = RET_PTR_TO_SOCKET_OR_NULL,
> > > > @@ -5636,7 +5636,7 @@ BPF_CALL_1(bpf_tcp_sock, struct sock *, sk)
> > > > return (unsigned long)NULL;
> > > > }
> > > >
> > > > -static const struct bpf_func_proto bpf_tcp_sock_proto = {
> > > > +const struct bpf_func_proto bpf_tcp_sock_proto = {
> > > > .func = bpf_tcp_sock,
> > > > .gpl_only = false,
> > > > .ret_type = RET_PTR_TO_TCP_SOCK_OR_NULL,
> > > > diff --git a/net/socket.c b/net/socket.c
> > > > index 72372dc5dd70..e8654f1f70e6 100644
> > > > --- a/net/socket.c
> > > > +++ b/net/socket.c
> > > > @@ -2069,6 +2069,15 @@ static int __sys_setsockopt(int fd, int level, int optname,
> > > > if (err)
> > > > goto out_put;
> > > >
> > > > + err = BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock->sk, level, optname,
> > > > + optval, optlen);
> > > > + if (err < 0) {
> > > > + goto out_put;
> > > > + } else if (err > 0) {
> > > > + err = 0;
> > > > + goto out_put;
> > > > + }
> > > > +
> > > > if (level == SOL_SOCKET)
> > > > err =
> > > > sock_setsockopt(sock, level, optname, optval,
> > > > @@ -2106,6 +2115,15 @@ static int __sys_getsockopt(int fd, int level, int optname,
> > > > if (err)
> > > > goto out_put;
> > > >
> > > > + err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, optname,
> > > > + optval, optlen);
> > > > + if (err < 0) {
> > > > + goto out_put;
> > > > + } else if (err > 0) {
> > > > + err = 0;
> > > > + goto out_put;
> > > > + }
> > > > +
> > > > if (level == SOL_SOCKET)
> > > > err =
> > > > sock_getsockopt(sock, level, optname, optval,
> > > > --
> > > > 2.22.0.rc1.311.g5d7573a151-goog
> > > >
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