[PATCH bpf-next v8 0/9] bpf: getsockopt and setsockopt hooks

[PATCH bpf-next v8 0/9] bpf: getsockopt and setsockopt hooks

[Stanislav Fomichev]

This series implements two new per-cgroup hooks: getsockopt and
setsockopt along with a new sockopt program type. The idea is pretty
similar to recently introduced cgroup sysctl hooks, but
implementation is simpler (no need to convert to/from strings).

What this can be applied to:
* move business logic of what tos/priority/etc can be set by
  containers (either pass or reject)
* handle existing options (or introduce new ones) differently by
  propagating some information in cgroup/socket local storage

Compared to a simple syscall/{g,s}etsockopt tracepoint, those
hooks are context aware. Meaning, they can access underlying socket
and use cgroup and socket local storage.

Stanislav Fomichev (9):
  bpf: implement getsockopt and setsockopt hooks
  bpf: sync bpf.h to tools/
  libbpf: support sockopt hooks
  selftests/bpf: test sockopt section name
  selftests/bpf: add sockopt test
  selftests/bpf: add sockopt test that exercises sk helpers
  selftests/bpf: add sockopt test that exercises BPF_F_ALLOW_MULTI
  bpf: add sockopt documentation
  bpftool: support cgroup sockopt

 Documentation/bpf/index.rst                   |   1 +
 Documentation/bpf/prog_cgroup_sockopt.rst     |  82 ++
 include/linux/bpf-cgroup.h                    |  43 +
 include/linux/bpf.h                           |   2 +
 include/linux/bpf_types.h                     |   1 +
 include/linux/filter.h                        |  14 +
 include/uapi/linux/bpf.h                      |  14 +
 kernel/bpf/cgroup.c                           | 317 +++++++
 kernel/bpf/core.c                             |   9 +
 kernel/bpf/syscall.c                          |  19 +
 kernel/bpf/verifier.c                         |  13 +
 net/core/filter.c                             |   2 +-
 net/socket.c                                  |  16 +
 .../bpftool/Documentation/bpftool-cgroup.rst  |   7 +-
 .../bpftool/Documentation/bpftool-prog.rst    |   3 +-
 tools/bpf/bpftool/bash-completion/bpftool     |   9 +-
 tools/bpf/bpftool/cgroup.c                    |   5 +-
 tools/bpf/bpftool/main.h                      |   1 +
 tools/bpf/bpftool/prog.c                      |   3 +-
 tools/include/uapi/linux/bpf.h                |  14 +
 tools/lib/bpf/libbpf.c                        |   5 +
 tools/lib/bpf/libbpf_probes.c                 |   1 +
 tools/testing/selftests/bpf/.gitignore        |   3 +
 tools/testing/selftests/bpf/Makefile          |   6 +-
 .../selftests/bpf/progs/sockopt_multi.c       |  53 ++
 .../testing/selftests/bpf/progs/sockopt_sk.c  |  91 ++
 .../selftests/bpf/test_section_names.c        |  10 +
 tools/testing/selftests/bpf/test_sockopt.c    | 892 ++++++++++++++++++
 .../selftests/bpf/test_sockopt_multi.c        | 276 ++++++
 tools/testing/selftests/bpf/test_sockopt_sk.c | 185 ++++
 30 files changed, 2087 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/bpf/prog_cgroup_sockopt.rst
 create mode 100644 tools/testing/selftests/bpf/progs/sockopt_multi.c
 create mode 100644 tools/testing/selftests/bpf/progs/sockopt_sk.c
 create mode 100644 tools/testing/selftests/bpf/test_sockopt.c
 create mode 100644 tools/testing/selftests/bpf/test_sockopt_multi.c
 create mode 100644 tools/testing/selftests/bpf/test_sockopt_sk.c

-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 1/9] bpf: implement getsockopt and setsockopt hooks

[Stanislav Fomichev]

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_prog_array_is_empty that exits early if there is nothing
attached to a cgroup. Note, however, that there is a race between
__cgroup_bpf_prog_array_is_empty 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.

The return code of the BPF program is handled as follows:
* 0: EPERM
* 1: success, continue with next BPF program in the cgroup chain

v8:
* use s32 for optlen (Andrii Nakryiko)

v7:
* return only 0 or 1 (Alexei Starovoitov)
* always run all progs (Alexei Starovoitov)
* use optval=0 as kernel bypass in setsockopt (Alexei Starovoitov)
  (decided to use optval=-1 instead, optval=0 might be a valid input)
* call getsockopt hook after kernel handlers (Alexei Starovoitov)

v6:
* rework cgroup chaining; stop as soon as bpf program returns
  0 or 2; see patch with the documentation for the details
* drop Andrii's and Martin's Acked-by (not sure they are comfortable
  with the new state of things)

v5:
* skip copy_to_user() and put_user() when ret == 0 (Martin Lau)

v4:
* don't export bpf_sk_fullsock helper (Martin Lau)
* size != sizeof(__u64) for uapi pointers (Martin Lau)
* offsetof instead of bpf_ctx_range when checking ctx access (Martin Lau)

v3:
* typos in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY comments (Andrii Nakryiko)
* reverse christmas tree in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY (Andrii
  Nakryiko)
* use __bpf_md_ptr instead of __u32 for optval{,_end} (Martin Lau)
* use BPF_FIELD_SIZEOF() for consistency (Martin Lau)
* new CG_SOCKOPT_ACCESS macro to wrap repeated parts

v2:
* moved bpf_sockopt_kern fields around to remove a hole (Martin Lau)
* aligned bpf_sockopt_kern->buf to 8 bytes (Martin Lau)
* bpf_prog_array_is_empty instead of bpf_prog_array_length (Martin Lau)
* added [0,2] return code check to verifier (Martin Lau)
* dropped unused buf[64] from the stack (Martin Lau)
* use PTR_TO_SOCKET for bpf_sockopt->sk (Martin Lau)
* dropped bpf_target_off from ctx rewrites (Martin Lau)
* use return code for kernel bypass (Martin Lau & Andrii Nakryiko)

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 include/linux/bpf-cgroup.h |  43 +++++
 include/linux/bpf.h        |   2 +
 include/linux/bpf_types.h  |   1 +
 include/linux/filter.h     |  14 ++
 include/uapi/linux/bpf.h   |  14 ++
 kernel/bpf/cgroup.c        | 317 +++++++++++++++++++++++++++++++++++++
 kernel/bpf/core.c          |   9 ++
 kernel/bpf/syscall.c       |  19 +++
 kernel/bpf/verifier.c      |  13 ++
 net/core/filter.c          |   2 +-
 net/socket.c               |  16 ++
 11 files changed, 449 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index bd79ae32909a..709d7c3ffdc3 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -124,6 +124,14 @@ 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,
+				       int optlen);
+int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
+				       int optname, char __user *optval,
+				       int __user *optlen, int max_optlen,
+				       int retval);
+
 static inline enum bpf_cgroup_storage_type cgroup_storage_type(
 	struct bpf_map *map)
 {
@@ -286,6 +294,36 @@ 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_GETSOCKOPT_MAX_OPTLEN(optlen)			       \
+({									       \
+	int __ret = 0;							       \
+	if (cgroup_bpf_enabled)						       \
+		get_user(__ret, optlen);				       \
+	__ret;								       \
+})
+
+#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, optlen,   \
+				       max_optlen, retval)		       \
+({									       \
+	int __ret = retval;						       \
+	if (cgroup_bpf_enabled)						       \
+		__ret = __cgroup_bpf_run_filter_getsockopt(sock, level,	       \
+							   optname, optval,    \
+							   optlen, max_optlen, \
+							   retval);	       \
+	__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,
@@ -357,6 +395,11 @@ 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_GETSOCKOPT_MAX_OPTLEN(optlen) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname, optval, \
+				       optlen, max_optlen, retval) ({ retval; })
+#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 a62e7889b0b6..18f4cc2c6acd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -518,6 +518,7 @@ struct bpf_prog_array {
 struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags);
 void bpf_prog_array_free(struct bpf_prog_array *progs);
 int bpf_prog_array_length(struct bpf_prog_array *progs);
+bool bpf_prog_array_is_empty(struct bpf_prog_array *array);
 int bpf_prog_array_copy_to_user(struct bpf_prog_array *progs,
 				__u32 __user *prog_ids, u32 cnt);
 
@@ -1051,6 +1052,7 @@ 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_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..98f8a1210117 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1199,4 +1199,18 @@ struct bpf_sysctl_kern {
 	u64 tmp_reg;
 };
 
+struct bpf_sockopt_kern {
+	struct sock	*sk;
+	u8		*optval;
+	u8		*optval_end;
+	s32		level;
+	s32		optname;
+	s32		optlen;
+	s32		retval;
+
+	/* Small on-stack optval buffer to avoid small allocations.
+	 */
+	u8 buf[64] __aligned(8);
+};
+
 #endif /* __LINUX_FILTER_H__ */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b077507efa3f..a396b516a2b2 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 {
@@ -194,6 +195,8 @@ enum bpf_attach_type {
 	BPF_CGROUP_SYSCTL,
 	BPF_CGROUP_UDP4_RECVMSG,
 	BPF_CGROUP_UDP6_RECVMSG,
+	BPF_CGROUP_GETSOCKOPT,
+	BPF_CGROUP_SETSOCKOPT,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -3541,4 +3544,15 @@ struct bpf_sysctl {
 				 */
 };
 
+struct bpf_sockopt {
+	__bpf_md_ptr(struct bpf_sock *, sk);
+	__bpf_md_ptr(void *, optval);
+	__bpf_md_ptr(void *, optval_end);
+
+	__s32	level;
+	__s32	optname;
+	__s32	optlen;
+	__s32	retval;
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index c225c42e114a..255153f2d8e9 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -15,6 +15,7 @@
 #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);
@@ -921,6 +922,185 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
 }
 EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
 
+static bool __cgroup_bpf_prog_array_is_empty(struct cgroup *cgrp,
+					     enum bpf_attach_type attach_type)
+{
+	struct bpf_prog_array *prog_array;
+	bool empty;
+
+	rcu_read_lock();
+	prog_array = rcu_dereference(cgrp->bpf.effective[attach_type]);
+	empty = bpf_prog_array_is_empty(prog_array);
+	rcu_read_unlock();
+
+	return empty;
+}
+
+static int sockopt_alloc_buf(struct bpf_sockopt_kern *ctx, int max_optlen)
+{
+	if (unlikely(max_optlen > PAGE_SIZE) || max_optlen < 0)
+		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,
+				       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_enabled ||
+	    __cgroup_bpf_prog_array_is_empty(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) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	lock_sock(sk);
+	ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_SETSOCKOPT],
+				 &ctx, BPF_PROG_RUN);
+	release_sock(sk);
+
+	if (!ret) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	if (ctx.optlen == -1)
+		/* optlen set to -1, bypass kernel */
+		ret = 1;
+	else if (ctx.optlen == optlen)
+		/* optlen not changed, run kernel handler */
+		ret = 0;
+	else
+		/* any other value is rejected */
+		ret = -EFAULT;
+
+out:
+	sockopt_free_buf(&ctx);
+	return ret;
+}
+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, int max_optlen,
+				       int retval)
+{
+	struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
+	struct bpf_sockopt_kern ctx = {
+		.sk = sk,
+		.level = level,
+		.optname = optname,
+		.retval = retval,
+	};
+	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_enabled ||
+	    __cgroup_bpf_prog_array_is_empty(cgrp, BPF_CGROUP_GETSOCKOPT))
+		return retval;
+
+	ret = sockopt_alloc_buf(&ctx, max_optlen);
+	if (ret)
+		return ret;
+
+	if (!retval) {
+		/* If kernel getsockopt finished successfully,
+		 * copy whatever was returned to the user back
+		 * into our temporary buffer. Set optlen to the
+		 * one that kernel returned as well to let
+		 * BPF programs inspect the value.
+		 */
+
+		if (get_user(ctx.optlen, optlen)) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		if (ctx.optlen > max_optlen)
+			ctx.optlen = max_optlen;
+
+		if (copy_from_user(ctx.optval, optval, ctx.optlen) != 0) {
+			ret = -EFAULT;
+			goto out;
+		}
+	}
+
+	lock_sock(sk);
+	ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
+				 &ctx, BPF_PROG_RUN);
+	release_sock(sk);
+
+	if (!ret) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	if (ctx.optlen > max_optlen) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	/* BPF programs only allowed to set retval to 0, not some
+	 * arbitrary value.
+	 */
+	if (ctx.retval != 0 && ctx.retval != retval) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	if (copy_to_user(optval, ctx.optval, ctx.optlen) ||
+	    put_user(ctx.optlen, optlen)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	ret = ctx.retval;
+
+out:
+	sockopt_free_buf(&ctx);
+	return ret;
+}
+EXPORT_SYMBOL(__cgroup_bpf_run_filter_getsockopt);
+
 static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
 			      size_t *lenp)
 {
@@ -1181,3 +1361,140 @@ const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
 
 const struct bpf_prog_ops cg_sysctl_prog_ops = {
 };
+
+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_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, retval):
+			if (size != size_default)
+				return false;
+			return prog->expected_attach_type ==
+				BPF_CGROUP_GETSOCKOPT;
+		case offsetof(struct bpf_sockopt, optlen):
+			return size == size_default;
+		default:
+			return false;
+		}
+	}
+
+	switch (off) {
+	case offsetof(struct bpf_sockopt, sk):
+		if (size != sizeof(__u64))
+			return false;
+		info->reg_type = PTR_TO_SOCKET;
+		break;
+	case offsetof(struct bpf_sockopt, optval):
+		if (size != sizeof(__u64))
+			return false;
+		info->reg_type = PTR_TO_PACKET;
+		break;
+	case offsetof(struct bpf_sockopt, optval_end):
+		if (size != sizeof(__u64))
+			return false;
+		info->reg_type = PTR_TO_PACKET_END;
+		break;
+	case offsetof(struct bpf_sockopt, retval):
+		if (size != size_default)
+			return false;
+		return prog->expected_attach_type == BPF_CGROUP_GETSOCKOPT;
+	default:
+		if (size != size_default)
+			return false;
+		break;
+	}
+	return true;
+}
+
+#define CG_SOCKOPT_ACCESS_FIELD(T, F)					\
+	T(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, F),			\
+	  si->dst_reg, si->src_reg,					\
+	  offsetof(struct bpf_sockopt_kern, F))
+
+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++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, sk);
+		break;
+	case offsetof(struct bpf_sockopt, level):
+		*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, level);
+		break;
+	case offsetof(struct bpf_sockopt, optname):
+		*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optname);
+		break;
+	case offsetof(struct bpf_sockopt, optlen):
+		if (type == BPF_WRITE)
+			*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_STX_MEM, optlen);
+		else
+			*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optlen);
+		break;
+	case offsetof(struct bpf_sockopt, retval):
+		if (type == BPF_WRITE)
+			*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_STX_MEM, retval);
+		else
+			*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, retval);
+		break;
+	case offsetof(struct bpf_sockopt, optval):
+		*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optval);
+		break;
+	case offsetof(struct bpf_sockopt, optval_end):
+		*insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, 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/core.c b/kernel/bpf/core.c
index ad3be85f1411..accc3e2e4098 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1809,6 +1809,15 @@ int bpf_prog_array_length(struct bpf_prog_array *array)
 	return cnt;
 }
 
+bool bpf_prog_array_is_empty(struct bpf_prog_array *array)
+{
+	struct bpf_prog_array_item *item;
+
+	for (item = array->items; item->prog; item++)
+		if (item->prog != &dummy_bpf_prog.prog)
+			return false;
+	return true;
+}
 
 static bool bpf_prog_array_copy_core(struct bpf_prog_array *array,
 				     u32 *prog_ids,
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7713cf39795a..b0f545e07425 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1590,6 +1590,14 @@ 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;
 	}
@@ -1840,6 +1848,7 @@ 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 &&
@@ -1912,6 +1921,10 @@ 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;
 	}
@@ -1995,6 +2008,10 @@ 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 0e079b2298f8..08231e0449f8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2215,6 +2215,18 @@ 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;
 	}
@@ -6066,6 +6078,7 @@ static int check_return_code(struct bpf_verifier_env *env)
 	case BPF_PROG_TYPE_SOCK_OPS:
 	case BPF_PROG_TYPE_CGROUP_DEVICE:
 	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 		break;
 	default:
 		return 0;
diff --git a/net/core/filter.c b/net/core/filter.c
index 2014d76e0d2a..dc8534be12fc 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5651,7 +5651,7 @@ 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 963df5dbdd54..18d7ce2d8b37 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2063,6 +2063,15 @@ 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,
@@ -2093,6 +2102,7 @@ static int __sys_getsockopt(int fd, int level, int optname,
 {
 	int err, fput_needed;
 	struct socket *sock;
+	int max_optlen;
 
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
 	if (sock != NULL) {
@@ -2100,6 +2110,8 @@ static int __sys_getsockopt(int fd, int level, int optname,
 		if (err)
 			goto out_put;
 
+		max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen);
+
 		if (level == SOL_SOCKET)
 			err =
 			    sock_getsockopt(sock, level, optname, optval,
@@ -2108,6 +2120,10 @@ static int __sys_getsockopt(int fd, int level, int optname,
 			err =
 			    sock->ops->getsockopt(sock, level, optname, optval,
 						  optlen);
+
+		err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, optname,
+						     optval, optlen,
+						     max_optlen, err);
 out_put:
 		fput_light(sock->file, fput_needed);
 	}
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 2/9] bpf: sync bpf.h to tools/

[Stanislav Fomichev]

Export new prog type and hook points to the libbpf.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/include/uapi/linux/bpf.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b077507efa3f..a396b516a2b2 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/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 {
@@ -194,6 +195,8 @@ enum bpf_attach_type {
 	BPF_CGROUP_SYSCTL,
 	BPF_CGROUP_UDP4_RECVMSG,
 	BPF_CGROUP_UDP6_RECVMSG,
+	BPF_CGROUP_GETSOCKOPT,
+	BPF_CGROUP_SETSOCKOPT,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -3541,4 +3544,15 @@ struct bpf_sysctl {
 				 */
 };
 
+struct bpf_sockopt {
+	__bpf_md_ptr(struct bpf_sock *, sk);
+	__bpf_md_ptr(void *, optval);
+	__bpf_md_ptr(void *, optval_end);
+
+	__s32	level;
+	__s32	optname;
+	__s32	optlen;
+	__s32	retval;
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 3/9] libbpf: support sockopt hooks

[Stanislav Fomichev]

Make libbpf aware of new sockopt hooks so it can derive prog type
and hook point from the section names.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/lib/bpf/libbpf.c        | 5 +++++
 tools/lib/bpf/libbpf_probes.c | 1 +
 2 files changed, 6 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 68f45a96769f..cacbd038ac79 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2646,6 +2646,7 @@ static bool bpf_prog_type__needs_kver(enum bpf_prog_type type)
 	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
 	case BPF_PROG_TYPE_PERF_EVENT:
 	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 		return false;
 	case BPF_PROG_TYPE_KPROBE:
 	default:
@@ -3604,6 +3605,10 @@ static const struct {
 						BPF_CGROUP_UDP6_RECVMSG),
 	BPF_EAPROG_SEC("cgroup/sysctl",		BPF_PROG_TYPE_CGROUP_SYSCTL,
 						BPF_CGROUP_SYSCTL),
+	BPF_EAPROG_SEC("cgroup/getsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_GETSOCKOPT),
+	BPF_EAPROG_SEC("cgroup/setsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_SETSOCKOPT),
 };
 
 #undef BPF_PROG_SEC_IMPL
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 6635a31a7a16..ace1a0708d99 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -101,6 +101,7 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
 	case BPF_PROG_TYPE_SK_REUSEPORT:
 	case BPF_PROG_TYPE_FLOW_DISSECTOR:
 	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 	default:
 		break;
 	}
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 4/9] selftests/bpf: test sockopt section name

[Stanislav Fomichev]

Add tests that make sure libbpf section detection works.

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/testing/selftests/bpf/test_section_names.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_section_names.c b/tools/testing/selftests/bpf/test_section_names.c
index dee2f2eceb0f..29833aeaf0de 100644
--- a/tools/testing/selftests/bpf/test_section_names.c
+++ b/tools/testing/selftests/bpf/test_section_names.c
@@ -134,6 +134,16 @@ static struct sec_name_test tests[] = {
 		{0, BPF_PROG_TYPE_CGROUP_SYSCTL, BPF_CGROUP_SYSCTL},
 		{0, BPF_CGROUP_SYSCTL},
 	},
+	{
+		"cgroup/getsockopt",
+		{0, BPF_PROG_TYPE_CGROUP_SOCKOPT, BPF_CGROUP_GETSOCKOPT},
+		{0, BPF_CGROUP_GETSOCKOPT},
+	},
+	{
+		"cgroup/setsockopt",
+		{0, BPF_PROG_TYPE_CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT},
+		{0, BPF_CGROUP_SETSOCKOPT},
+	},
 };
 
 static int test_prog_type_by_name(const struct sec_name_test *test)
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 5/9] selftests/bpf: add sockopt test

[Stanislav Fomichev]

Add sockopt selftests:
* require proper expected_attach_type
* enforce context field read/write access
* test bpf_sockopt_handled handler
* test EPERM
* test limiting optlen from getsockopt
* test out-of-bounds access

v7:
* remove return 2; test retval=0 and optlen=-1

v3:
* use DW for optval{,_end} loads

v2:
* use return code 2 for kernel bypass

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/testing/selftests/bpf/.gitignore     |   1 +
 tools/testing/selftests/bpf/Makefile       |   3 +-
 tools/testing/selftests/bpf/test_sockopt.c | 892 +++++++++++++++++++++
 3 files changed, 895 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/test_sockopt.c

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index 7470327edcfe..3fe92601223d 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -39,3 +39,4 @@ libbpf.so.*
 test_hashmap
 test_btf_dump
 xdping
+test_sockopt
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index f2dbe2043067..afd7b3d298d8 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -26,7 +26,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_sock test_btf test_sockmap get_cgroup_id_user test_socket_cookie \
 	test_cgroup_storage test_select_reuseport test_section_names \
 	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
-	test_btf_dump test_cgroup_attach xdping
+	test_btf_dump test_cgroup_attach xdping test_sockopt
 
 BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
 TEST_GEN_FILES = $(BPF_OBJ_FILES)
@@ -103,6 +103,7 @@ $(OUTPUT)/test_netcnt: cgroup_helpers.c
 $(OUTPUT)/test_sock_fields: cgroup_helpers.c
 $(OUTPUT)/test_sysctl: cgroup_helpers.c
 $(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
+$(OUTPUT)/test_sockopt: cgroup_helpers.c
 
 .PHONY: force
 
diff --git a/tools/testing/selftests/bpf/test_sockopt.c b/tools/testing/selftests/bpf/test_sockopt.c
new file mode 100644
index 000000000000..0c4196eecc45
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sockopt.c
@@ -0,0 +1,892 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <linux/filter.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "bpf_rlimit.h"
+#include "bpf_util.h"
+#include "cgroup_helpers.h"
+
+#define CG_PATH				"/sockopt"
+
+static char bpf_log_buf[4096];
+static bool verbose;
+
+enum sockopt_test_error {
+	OK = 0,
+	DENY_LOAD,
+	DENY_ATTACH,
+	EPERM_GETSOCKOPT,
+	EFAULT_GETSOCKOPT,
+	EPERM_SETSOCKOPT,
+	EFAULT_SETSOCKOPT,
+};
+
+static struct sockopt_test {
+	const char			*descr;
+	const struct bpf_insn		insns[64];
+	enum bpf_attach_type		attach_type;
+	enum bpf_attach_type		expected_attach_type;
+
+	int				level;
+	int				optname;
+
+	const char			set_optval[64];
+	socklen_t			set_optlen;
+
+	const char			get_optval[64];
+	socklen_t			get_optlen;
+	socklen_t			get_optlen_ret;
+
+	enum sockopt_test_error		error;
+} tests[] = {
+
+	/* ==================== getsockopt ====================  */
+
+	{
+		.descr = "getsockopt: no expected_attach_type",
+		.insns = {
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = 0,
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "getsockopt: wrong expected_attach_type",
+		.insns = {
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+		.error = DENY_ATTACH,
+	},
+	{
+		.descr = "getsockopt: bypass bpf hook",
+		.insns = {
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.set_optval = { 1 << 3 },
+		.set_optlen = 1,
+
+		.get_optval = { 1 << 3 },
+		.get_optlen = 1,
+	},
+	{
+		.descr = "getsockopt: return EPERM from bpf hook",
+		.insns = {
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.get_optlen = 1,
+		.error = EPERM_GETSOCKOPT,
+	},
+	{
+		.descr = "getsockopt: no optval bounds check, deny loading",
+		.insns = {
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+
+			/* ctx->optval[0] = 0x80 */
+			BPF_MOV64_IMM(BPF_REG_0, 0x80),
+			BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_0, 0),
+
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "getsockopt: read ctx->level",
+		.insns = {
+			/* r6 = ctx->level */
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, level)),
+
+			/* if (ctx->level == 123) { */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 123, 4),
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } else { */
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.level = 123,
+
+		.get_optlen = 1,
+	},
+	{
+		.descr = "getsockopt: deny writing to ctx->level",
+		.insns = {
+			/* ctx->level = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, level)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "getsockopt: read ctx->optname",
+		.insns = {
+			/* r6 = ctx->optname */
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optname)),
+
+			/* if (ctx->optname == 123) { */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 123, 4),
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } else { */
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.optname = 123,
+
+		.get_optlen = 1,
+	},
+	{
+		.descr = "getsockopt: deny writing to ctx->optname",
+		.insns = {
+			/* ctx->optname = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optname)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "getsockopt: read ctx->optlen",
+		.insns = {
+			/* r6 = ctx->optlen */
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optlen)),
+
+			/* if (ctx->optlen == 64) { */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 64, 4),
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } else { */
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.get_optlen = 64,
+	},
+	{
+		.descr = "getsockopt: deny bigger ctx->optlen",
+		.insns = {
+			/* ctx->optlen = 65 */
+			BPF_MOV64_IMM(BPF_REG_0, 65),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.get_optlen = 64,
+
+		.error = EFAULT_GETSOCKOPT,
+	},
+	{
+		.descr = "getsockopt: deny arbitrary ctx->retval",
+		.insns = {
+			/* ctx->retval = 123 */
+			BPF_MOV64_IMM(BPF_REG_0, 123),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.get_optlen = 64,
+
+		.error = EFAULT_GETSOCKOPT,
+	},
+	{
+		.descr = "getsockopt: support smaller ctx->optlen",
+		.insns = {
+			/* ctx->optlen = 32 */
+			BPF_MOV64_IMM(BPF_REG_0, 32),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.get_optlen = 64,
+		.get_optlen_ret = 32,
+	},
+	{
+		.descr = "getsockopt: deny writing to ctx->optval",
+		.insns = {
+			/* ctx->optval = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optval)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "getsockopt: deny writing to ctx->optval_end",
+		.insns = {
+			/* ctx->optval_end = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optval_end)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "getsockopt: rewrite value",
+		.insns = {
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+			/* r2 = ctx->optval */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_6),
+			/* r6 = ctx->optval + 1 */
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 1),
+
+			/* r7 = ctx->optval_end */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval_end)),
+
+			/* if (ctx->optval + 1 <= ctx->optval_end) { */
+			BPF_JMP_REG(BPF_JGT, BPF_REG_6, BPF_REG_7, 1),
+			/* ctx->optval[0] = 0xF0 */
+			BPF_ST_MEM(BPF_B, BPF_REG_2, 0, 0xF0),
+			/* } */
+
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+
+			/* return 1*/
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_GETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.get_optval = { 0xF0 },
+		.get_optlen = 1,
+	},
+
+	/* ==================== setsockopt ====================  */
+
+	{
+		.descr = "setsockopt: no expected_attach_type",
+		.insns = {
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = 0,
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: wrong expected_attach_type",
+		.insns = {
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_GETSOCKOPT,
+		.error = DENY_ATTACH,
+	},
+	{
+		.descr = "setsockopt: bypass bpf hook",
+		.insns = {
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.set_optval = { 1 << 3 },
+		.set_optlen = 1,
+
+		.get_optval = { 1 << 3 },
+		.get_optlen = 1,
+	},
+	{
+		.descr = "setsockopt: return EPERM from bpf hook",
+		.insns = {
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.set_optlen = 1,
+		.error = EPERM_SETSOCKOPT,
+	},
+	{
+		.descr = "setsockopt: no optval bounds check, deny loading",
+		.insns = {
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+
+			/* r0 = ctx->optval[0] */
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6, 0),
+
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: read ctx->level",
+		.insns = {
+			/* r6 = ctx->level */
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, level)),
+
+			/* if (ctx->level == 123) { */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 123, 4),
+			/* ctx->optlen = -1 */
+			BPF_MOV64_IMM(BPF_REG_0, -1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } else { */
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.level = 123,
+
+		.set_optlen = 1,
+	},
+	{
+		.descr = "setsockopt: deny writing to ctx->level",
+		.insns = {
+			/* ctx->level = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, level)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: read ctx->optname",
+		.insns = {
+			/* r6 = ctx->optname */
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optname)),
+
+			/* if (ctx->optname == 123) { */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 123, 4),
+			/* ctx->optlen = -1 */
+			BPF_MOV64_IMM(BPF_REG_0, -1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } else { */
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.optname = 123,
+
+		.set_optlen = 1,
+	},
+	{
+		.descr = "setsockopt: deny writing to ctx->optname",
+		.insns = {
+			/* ctx->optname = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optname)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: read ctx->optlen",
+		.insns = {
+			/* r6 = ctx->optlen */
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optlen)),
+
+			/* if (ctx->optlen == 64) { */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 64, 4),
+			/* ctx->optlen = -1 */
+			BPF_MOV64_IMM(BPF_REG_0, -1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } else { */
+			/* return 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.set_optlen = 64,
+	},
+	{
+		.descr = "setsockopt: ctx->optlen == -1 is ok",
+		.insns = {
+			/* ctx->optlen = -1 */
+			BPF_MOV64_IMM(BPF_REG_0, -1),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.set_optlen = 64,
+	},
+	{
+		.descr = "setsockopt: deny ctx->optlen != input optlen",
+		.insns = {
+			/* ctx->optlen = 32 */
+			BPF_MOV64_IMM(BPF_REG_0, 32),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optlen)),
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.set_optlen = 64,
+
+		.error = EFAULT_SETSOCKOPT,
+	},
+	{
+		.descr = "setsockopt: deny ctx->retval",
+		.insns = {
+			/* ctx->retval = 0 */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, retval)),
+
+			/* return 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.get_optlen = 64,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: deny writing to ctx->optval",
+		.insns = {
+			/* ctx->optval = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optval)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: deny writing to ctx->optval_end",
+		.insns = {
+			/* ctx->optval_end = 1 */
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0,
+				    offsetof(struct bpf_sockopt, optval_end)),
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.error = DENY_LOAD,
+	},
+	{
+		.descr = "setsockopt: allow IP_TOS <= 128",
+		.insns = {
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+			/* r7 = ctx->optval + 1 */
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_6),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
+
+			/* r8 = ctx->optval_end */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval_end)),
+
+			/* if (ctx->optval + 1 <= ctx->optval_end) { */
+			BPF_JMP_REG(BPF_JGT, BPF_REG_7, BPF_REG_8, 4),
+
+			/* r9 = ctx->optval[0] */
+			BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_6, 0),
+
+			/* if (ctx->optval[0] < 128) */
+			BPF_JMP_IMM(BPF_JGT, BPF_REG_9, 128, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } */
+
+			/* } else { */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.set_optval = { 0x80 },
+		.set_optlen = 1,
+		.get_optval = { 0x80 },
+		.get_optlen = 1,
+	},
+	{
+		.descr = "setsockopt: deny IP_TOS > 128",
+		.insns = {
+			/* r6 = ctx->optval */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval)),
+			/* r7 = ctx->optval + 1 */
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_6),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
+
+			/* r8 = ctx->optval_end */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_1,
+				    offsetof(struct bpf_sockopt, optval_end)),
+
+			/* if (ctx->optval + 1 <= ctx->optval_end) { */
+			BPF_JMP_REG(BPF_JGT, BPF_REG_7, BPF_REG_8, 4),
+
+			/* r9 = ctx->optval[0] */
+			BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_6, 0),
+
+			/* if (ctx->optval[0] < 128) */
+			BPF_JMP_IMM(BPF_JGT, BPF_REG_9, 128, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_A(1),
+			/* } */
+
+			/* } else { */
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* } */
+
+			BPF_EXIT_INSN(),
+		},
+		.attach_type = BPF_CGROUP_SETSOCKOPT,
+		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
+
+		.level = SOL_IP,
+		.optname = IP_TOS,
+
+		.set_optval = { 0x81 },
+		.set_optlen = 1,
+		.get_optval = { 0x00 },
+		.get_optlen = 1,
+
+		.error = EPERM_SETSOCKOPT,
+	},
+};
+
+static int load_prog(const struct bpf_insn *insns,
+		     enum bpf_attach_type expected_attach_type)
+{
+	struct bpf_load_program_attr attr = {
+		.prog_type = BPF_PROG_TYPE_CGROUP_SOCKOPT,
+		.expected_attach_type = expected_attach_type,
+		.insns = insns,
+		.license = "GPL",
+		.log_level = 2,
+	};
+	int fd;
+
+	for (;
+	     insns[attr.insns_cnt].code != (BPF_JMP | BPF_EXIT);
+	     attr.insns_cnt++) {
+	}
+	attr.insns_cnt++;
+
+	fd = bpf_load_program_xattr(&attr, bpf_log_buf, sizeof(bpf_log_buf));
+	if (verbose && fd < 0)
+		fprintf(stderr, "%s\n", bpf_log_buf);
+
+	return fd;
+}
+
+static int run_test(int cgroup_fd, struct sockopt_test *test)
+{
+	int sock_fd, err, prog_fd;
+	void *optval = NULL;
+	int ret = 0;
+
+	prog_fd = load_prog(test->insns, test->expected_attach_type);
+	if (prog_fd < 0) {
+		if (test->error == DENY_LOAD)
+			return 0;
+
+		log_err("Failed to load BPF program");
+		return -1;
+	}
+
+	err = bpf_prog_attach(prog_fd, cgroup_fd, test->attach_type, 0);
+	if (err < 0) {
+		if (test->error == DENY_ATTACH)
+			goto close_prog_fd;
+
+		log_err("Failed to attach BPF program");
+		ret = -1;
+		goto close_prog_fd;
+	}
+
+	sock_fd = socket(AF_INET, SOCK_STREAM, 0);
+	if (sock_fd < 0) {
+		log_err("Failed to create AF_INET socket");
+		ret = -1;
+		goto detach_prog;
+	}
+
+	if (test->set_optlen) {
+		err = setsockopt(sock_fd, test->level, test->optname,
+				 test->set_optval, test->set_optlen);
+		if (err) {
+			if (errno == EPERM && test->error == EPERM_SETSOCKOPT)
+				goto close_sock_fd;
+			if (errno == EFAULT && test->error == EFAULT_SETSOCKOPT)
+				goto free_optval;
+
+			log_err("Failed to call setsockopt");
+			ret = -1;
+			goto close_sock_fd;
+		}
+	}
+
+	if (test->get_optlen) {
+		optval = malloc(test->get_optlen);
+		socklen_t optlen = test->get_optlen;
+		socklen_t expected_get_optlen = test->get_optlen_ret ?:
+			test->get_optlen;
+
+		err = getsockopt(sock_fd, test->level, test->optname,
+				 optval, &optlen);
+		if (err) {
+			if (errno == EPERM && test->error == EPERM_GETSOCKOPT)
+				goto free_optval;
+			if (errno == EFAULT && test->error == EFAULT_GETSOCKOPT)
+				goto free_optval;
+
+			log_err("Failed to call getsockopt");
+			ret = -1;
+			goto free_optval;
+		}
+
+		if (optlen != expected_get_optlen) {
+			errno = 0;
+			log_err("getsockopt returned unexpected optlen");
+			ret = -1;
+			goto free_optval;
+		}
+
+		if (memcmp(optval, test->get_optval, optlen) != 0) {
+			errno = 0;
+			log_err("getsockopt returned unexpected optval");
+			ret = -1;
+			goto free_optval;
+		}
+	}
+
+	ret = test->error != OK;
+
+free_optval:
+	free(optval);
+close_sock_fd:
+	close(sock_fd);
+detach_prog:
+	bpf_prog_detach2(prog_fd, cgroup_fd, test->attach_type);
+close_prog_fd:
+	close(prog_fd);
+	return ret;
+}
+
+int main(int args, char **argv)
+{
+	int err = EXIT_FAILURE, error_cnt = 0;
+	int cgroup_fd, i;
+
+	if (setup_cgroup_environment())
+		goto cleanup_obj;
+
+	cgroup_fd = create_and_get_cgroup(CG_PATH);
+	if (cgroup_fd < 0)
+		goto cleanup_cgroup_env;
+
+	if (join_cgroup(CG_PATH))
+		goto cleanup_cgroup;
+
+	for (i = 0; i < ARRAY_SIZE(tests); i++) {
+		int err = run_test(cgroup_fd, &tests[i]);
+
+		if (err)
+			error_cnt++;
+
+		printf("#%d %s: %s\n", i, err ? "FAIL" : "PASS",
+		       tests[i].descr);
+	}
+
+	printf("Summary: %ld PASSED, %d FAILED\n",
+	       ARRAY_SIZE(tests) - error_cnt, error_cnt);
+	err = error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;
+
+cleanup_cgroup:
+	close(cgroup_fd);
+cleanup_cgroup_env:
+	cleanup_cgroup_environment();
+cleanup_obj:
+	return err;
+}
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 6/9] selftests/bpf: add sockopt test that exercises sk helpers

[Stanislav Fomichev]

socktop test that introduces new SOL_CUSTOM sockopt level and
stores whatever users sets in sk storage. Whenever getsockopt
is called, the original value is retrieved.

v7:
* use retval=0 and optlen-1

v6:
* test 'ret=1' use-case as well (Alexei Starovoitov)

v4:
* don't call bpf_sk_fullsock helper

v3:
* drop (__u8 *)(long) casts for optval{,_end}

v2:
* new test

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/testing/selftests/bpf/.gitignore        |   1 +
 tools/testing/selftests/bpf/Makefile          |   3 +-
 .../testing/selftests/bpf/progs/sockopt_sk.c  |  91 +++++++++
 tools/testing/selftests/bpf/test_sockopt_sk.c | 185 ++++++++++++++++++
 4 files changed, 279 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/sockopt_sk.c
 create mode 100644 tools/testing/selftests/bpf/test_sockopt_sk.c

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index 3fe92601223d..8ac076c311d4 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -40,3 +40,4 @@ test_hashmap
 test_btf_dump
 xdping
 test_sockopt
+test_sockopt_sk
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index afd7b3d298d8..1210b4e98d27 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -26,7 +26,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_sock test_btf test_sockmap get_cgroup_id_user test_socket_cookie \
 	test_cgroup_storage test_select_reuseport test_section_names \
 	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
-	test_btf_dump test_cgroup_attach xdping test_sockopt
+	test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk
 
 BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
 TEST_GEN_FILES = $(BPF_OBJ_FILES)
@@ -104,6 +104,7 @@ $(OUTPUT)/test_sock_fields: cgroup_helpers.c
 $(OUTPUT)/test_sysctl: cgroup_helpers.c
 $(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
 $(OUTPUT)/test_sockopt: cgroup_helpers.c
+$(OUTPUT)/test_sockopt_sk: cgroup_helpers.c
 
 .PHONY: force
 
diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c b/tools/testing/selftests/bpf/progs/sockopt_sk.c
new file mode 100644
index 000000000000..ad4c5db2bc29
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <netinet/in.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;
+
+#define SOL_CUSTOM			0xdeadbeef
+
+struct sockopt_sk {
+	__u8 val;
+};
+
+struct bpf_map_def SEC("maps") socket_storage_map = {
+	.type = BPF_MAP_TYPE_SK_STORAGE,
+	.key_size = sizeof(int),
+	.value_size = sizeof(struct sockopt_sk),
+	.map_flags = BPF_F_NO_PREALLOC,
+};
+BPF_ANNOTATE_KV_PAIR(socket_storage_map, int, struct sockopt_sk);
+
+SEC("cgroup/getsockopt")
+int _getsockopt(struct bpf_sockopt *ctx)
+{
+	__u8 *optval_end = ctx->optval_end;
+	__u8 *optval = ctx->optval;
+	struct sockopt_sk *storage;
+
+	if (ctx->level == SOL_IP && ctx->optname == IP_TOS)
+		/* Not interested in SOL_IP:IP_TOS;
+		 * let next BPF program in the cgroup chain or kernel
+		 * handle it.
+		 */
+		return 1;
+
+	if (ctx->level != SOL_CUSTOM)
+		return 0; /* EPERM, deny everything except custom level */
+
+	if (optval + 1 > optval_end)
+		return 0; /* EPERM, bounds check */
+
+	storage = bpf_sk_storage_get(&socket_storage_map, ctx->sk, 0,
+				     BPF_SK_STORAGE_GET_F_CREATE);
+	if (!storage)
+		return 0; /* EPERM, couldn't get sk storage */
+
+	if (!ctx->retval)
+		return 0; /* EPERM, kernel should not have handled
+			   * SOL_CUSTOM, something is wrong!
+			   */
+	ctx->retval = 0; /* Reset system call return value to zero */
+
+	optval[0] = storage->val;
+	ctx->optlen = 1;
+
+	return 1;
+}
+
+SEC("cgroup/setsockopt")
+int _setsockopt(struct bpf_sockopt *ctx)
+{
+	__u8 *optval_end = ctx->optval_end;
+	__u8 *optval = ctx->optval;
+	struct sockopt_sk *storage;
+
+	if (ctx->level == SOL_IP && ctx->optname == IP_TOS)
+		/* Not interested in SOL_IP:IP_TOS;
+		 * let next BPF program in the cgroup chain or kernel
+		 * handle it.
+		 */
+		return 1;
+
+	if (ctx->level != SOL_CUSTOM)
+		return 0; /* EPERM, deny everything except custom level */
+
+	if (optval + 1 > optval_end)
+		return 0; /* EPERM, bounds check */
+
+	storage = bpf_sk_storage_get(&socket_storage_map, ctx->sk, 0,
+				     BPF_SK_STORAGE_GET_F_CREATE);
+	if (!storage)
+		return 0; /* EPERM, couldn't get sk storage */
+
+	storage->val = optval[0];
+	ctx->optlen = -1; /* BPF has consumed this option, don't call kernel
+			   * setsockopt handler.
+			   */
+
+	return 1;
+}
diff --git a/tools/testing/selftests/bpf/test_sockopt_sk.c b/tools/testing/selftests/bpf/test_sockopt_sk.c
new file mode 100644
index 000000000000..67558e2c5427
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sockopt_sk.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <linux/filter.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "bpf_rlimit.h"
+#include "bpf_util.h"
+#include "cgroup_helpers.h"
+
+#define CG_PATH				"/sockopt"
+
+#define SOL_CUSTOM			0xdeadbeef
+
+static int getsetsockopt(void)
+{
+	int fd, err;
+	char buf[4] = {};
+	socklen_t optlen;
+
+	fd = socket(AF_INET, SOCK_STREAM, 0);
+	if (fd < 0) {
+		log_err("Failed to create socket");
+		return -1;
+	}
+
+	/* IP_TOS - BPF bypass */
+
+	buf[0] = 0x08;
+	err = setsockopt(fd, SOL_IP, IP_TOS, buf, 1);
+	if (err) {
+		log_err("Failed to call setsockopt(IP_TOS)");
+		goto err;
+	}
+
+	buf[0] = 0x00;
+	optlen = 1;
+	err = getsockopt(fd, SOL_IP, IP_TOS, buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(IP_TOS)");
+		goto err;
+	}
+
+	if (buf[0] != 0x08) {
+		log_err("Unexpected getsockopt(IP_TOS) buf[0] 0x%02x != 0x08",
+			buf[0]);
+		goto err;
+	}
+
+	/* IP_TTL - EPERM */
+
+	buf[0] = 1;
+	err = setsockopt(fd, SOL_IP, IP_TTL, buf, 1);
+	if (!err || errno != EPERM) {
+		log_err("Unexpected success from setsockopt(IP_TTL)");
+		goto err;
+	}
+
+	/* SOL_CUSTOM - handled by BPF */
+
+	buf[0] = 0x01;
+	err = setsockopt(fd, SOL_CUSTOM, 0, buf, 1);
+	if (err) {
+		log_err("Failed to call setsockopt");
+		goto err;
+	}
+
+	buf[0] = 0x00;
+	optlen = 4;
+	err = getsockopt(fd, SOL_CUSTOM, 0, buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt");
+		goto err;
+	}
+
+	if (optlen != 1) {
+		log_err("Unexpected optlen %d != 1", optlen);
+		goto err;
+	}
+	if (buf[0] != 0x01) {
+		log_err("Unexpected buf[0] 0x%02x != 0x01", buf[0]);
+		goto err;
+	}
+
+	close(fd);
+	return 0;
+err:
+	close(fd);
+	return -1;
+}
+
+static int prog_attach(struct bpf_object *obj, int cgroup_fd, const char *title)
+{
+	enum bpf_attach_type attach_type;
+	enum bpf_prog_type prog_type;
+	struct bpf_program *prog;
+	int err;
+
+	err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
+	if (err) {
+		log_err("Failed to deduct types for %s BPF program", title);
+		return -1;
+	}
+
+	prog = bpf_object__find_program_by_title(obj, title);
+	if (!prog) {
+		log_err("Failed to find %s BPF program", title);
+		return -1;
+	}
+
+	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd,
+			      attach_type, 0);
+	if (err) {
+		log_err("Failed to attach %s BPF program", title);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int run_test(int cgroup_fd)
+{
+	struct bpf_prog_load_attr attr = {
+		.file = "./sockopt_sk.o",
+	};
+	struct bpf_object *obj;
+	int ignored;
+	int err;
+
+	err = bpf_prog_load_xattr(&attr, &obj, &ignored);
+	if (err) {
+		log_err("Failed to load BPF object");
+		return -1;
+	}
+
+	err = prog_attach(obj, cgroup_fd, "cgroup/getsockopt");
+	if (err)
+		goto close_bpf_object;
+
+	err = prog_attach(obj, cgroup_fd, "cgroup/setsockopt");
+	if (err)
+		goto close_bpf_object;
+
+	err = getsetsockopt();
+
+close_bpf_object:
+	bpf_object__close(obj);
+	return err;
+}
+
+int main(int args, char **argv)
+{
+	int cgroup_fd;
+	int err = EXIT_SUCCESS;
+
+	if (setup_cgroup_environment())
+		goto cleanup_obj;
+
+	cgroup_fd = create_and_get_cgroup(CG_PATH);
+	if (cgroup_fd < 0)
+		goto cleanup_cgroup_env;
+
+	if (join_cgroup(CG_PATH))
+		goto cleanup_cgroup;
+
+	if (run_test(cgroup_fd))
+		err = EXIT_FAILURE;
+
+	printf("test_sockopt_sk: %s\n",
+	       err == EXIT_SUCCESS ? "PASSED" : "FAILED");
+
+cleanup_cgroup:
+	close(cgroup_fd);
+cleanup_cgroup_env:
+	cleanup_cgroup_environment();
+cleanup_obj:
+	return err;
+}
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 7/9] selftests/bpf: add sockopt test that exercises BPF_F_ALLOW_MULTI

[Stanislav Fomichev]

sockopt test that verifies chaining behavior.

v7:
* rework the test to verify cgroup getsockopt chaining

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/testing/selftests/bpf/.gitignore        |   1 +
 tools/testing/selftests/bpf/Makefile          |   4 +-
 .../selftests/bpf/progs/sockopt_multi.c       |  53 ++++
 .../selftests/bpf/test_sockopt_multi.c        | 276 ++++++++++++++++++
 4 files changed, 333 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/sockopt_multi.c
 create mode 100644 tools/testing/selftests/bpf/test_sockopt_multi.c

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index 8ac076c311d4..a2f7f79c7908 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -41,3 +41,4 @@ test_btf_dump
 xdping
 test_sockopt
 test_sockopt_sk
+test_sockopt_multi
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 1210b4e98d27..5615a5f13ce4 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -26,7 +26,8 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_sock test_btf test_sockmap get_cgroup_id_user test_socket_cookie \
 	test_cgroup_storage test_select_reuseport test_section_names \
 	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
-	test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk
+	test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk \
+	test_sockopt_multi
 
 BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
 TEST_GEN_FILES = $(BPF_OBJ_FILES)
@@ -105,6 +106,7 @@ $(OUTPUT)/test_sysctl: cgroup_helpers.c
 $(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
 $(OUTPUT)/test_sockopt: cgroup_helpers.c
 $(OUTPUT)/test_sockopt_sk: cgroup_helpers.c
+$(OUTPUT)/test_sockopt_multi: cgroup_helpers.c
 
 .PHONY: force
 
diff --git a/tools/testing/selftests/bpf/progs/sockopt_multi.c b/tools/testing/selftests/bpf/progs/sockopt_multi.c
new file mode 100644
index 000000000000..1529fe3afe9f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sockopt_multi.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <netinet/in.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;
+
+SEC("cgroup/getsockopt/child")
+int _getsockopt_child(struct bpf_sockopt *ctx)
+{
+	__u8 *optval_end = ctx->optval_end;
+	__u8 *optval = ctx->optval;
+
+	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
+		return 1;
+
+	if (optval + 1 > optval_end)
+		return 0; /* EPERM, bounds check */
+
+	if (optval[0] != 0x80)
+		return 0; /* EPERM, unexpected optval from the kernel */
+
+	ctx->retval = 0; /* Reset system call return value to zero */
+
+	optval[0] = 0x90;
+	ctx->optlen = 1;
+
+	return 1;
+}
+
+SEC("cgroup/getsockopt/parent")
+int _getsockopt_parent(struct bpf_sockopt *ctx)
+{
+	__u8 *optval_end = ctx->optval_end;
+	__u8 *optval = ctx->optval;
+
+	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
+		return 1;
+
+	if (optval + 1 > optval_end)
+		return 0; /* EPERM, bounds check */
+
+	if (optval[0] != 0x90)
+		return 0; /* EPERM, unexpected optval from the kernel */
+
+	ctx->retval = 0; /* Reset system call return value to zero */
+
+	optval[0] = 0xA0;
+	ctx->optlen = 1;
+
+	return 1;
+}
diff --git a/tools/testing/selftests/bpf/test_sockopt_multi.c b/tools/testing/selftests/bpf/test_sockopt_multi.c
new file mode 100644
index 000000000000..71acdc861a55
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sockopt_multi.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <error.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <linux/filter.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "bpf_rlimit.h"
+#include "bpf_util.h"
+#include "cgroup_helpers.h"
+
+static int prog_attach(struct bpf_object *obj, int cgroup_fd, const char *title)
+{
+	enum bpf_attach_type attach_type;
+	enum bpf_prog_type prog_type;
+	struct bpf_program *prog;
+	int err;
+
+	err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
+	if (err) {
+		log_err("Failed to deduct types for %s BPF program", title);
+		return -1;
+	}
+
+	prog = bpf_object__find_program_by_title(obj, title);
+	if (!prog) {
+		log_err("Failed to find %s BPF program", title);
+		return -1;
+	}
+
+	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd,
+			      attach_type, BPF_F_ALLOW_MULTI);
+	if (err) {
+		log_err("Failed to attach %s BPF program", title);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int prog_detach(struct bpf_object *obj, int cgroup_fd, const char *title)
+{
+	enum bpf_attach_type attach_type;
+	enum bpf_prog_type prog_type;
+	struct bpf_program *prog;
+	int err;
+
+	err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
+	if (err)
+		return -1;
+
+	prog = bpf_object__find_program_by_title(obj, title);
+	if (!prog)
+		return -1;
+
+	err = bpf_prog_detach2(bpf_program__fd(prog), cgroup_fd,
+			       attach_type);
+	if (err)
+		return -1;
+
+	return 0;
+}
+
+static int run_test(struct bpf_object *obj, int cg_parent, int cg_child,
+		    int sock_fd)
+{
+	socklen_t optlen;
+	__u8 buf;
+	int err;
+
+	/* Set IP_TOS to the expected value (0x80). */
+
+	buf = 0x80;
+	err = setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1);
+	if (err < 0) {
+		log_err("Failed to call setsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	buf = 0x00;
+	optlen = 1;
+	err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	if (buf != 0x80) {
+		log_err("Unexpected getsockopt 0x%x != 0x80 without BPF", buf);
+		err = -1;
+		goto detach;
+	}
+
+	/* Attach child program and make sure it returns new value:
+	 * - kernel:      -> 0x80
+	 * - child:  0x80 -> 0x90
+	 */
+
+	err = prog_attach(obj, cg_child, "cgroup/getsockopt/child");
+	if (err)
+		goto detach;
+
+	buf = 0x00;
+	optlen = 1;
+	err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	if (buf != 0x90) {
+		log_err("Unexpected getsockopt 0x%x != 0x90", buf);
+		err = -1;
+		goto detach;
+	}
+
+	/* Attach parent program and make sure it returns new value:
+	 * - kernel:      -> 0x80
+	 * - child:  0x80 -> 0x90
+	 * - parent: 0x90 -> 0xA0
+	 */
+
+	err = prog_attach(obj, cg_parent, "cgroup/getsockopt/parent");
+	if (err)
+		goto detach;
+
+	buf = 0x00;
+	optlen = 1;
+	err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	if (buf != 0xA0) {
+		log_err("Unexpected getsockopt 0x%x != 0xA0", buf);
+		err = -1;
+		goto detach;
+	}
+
+	/* Setting unexpected initial sockopt should return EPERM:
+	 * - kernel: -> 0x40
+	 * - child:  unexpected 0x40, EPERM
+	 * - parent: unexpected 0x40, EPERM
+	 */
+
+	buf = 0x40;
+	if (setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1) < 0) {
+		log_err("Failed to call setsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	buf = 0x00;
+	optlen = 1;
+	err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
+	if (!err) {
+		log_err("Unexpected success from getsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	/* Detach child program and make sure we still get EPERM:
+	 * - kernel: -> 0x40
+	 * - parent: unexpected 0x40, EPERM
+	 */
+
+	err = prog_detach(obj, cg_child, "cgroup/getsockopt/child");
+	if (err) {
+		log_err("Failed to detach child program");
+		goto detach;
+	}
+
+	buf = 0x00;
+	optlen = 1;
+	err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
+	if (!err) {
+		log_err("Unexpected success from getsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	/* Set initial value to the one the parent program expects:
+	 * - kernel:      -> 0x90
+	 * - parent: 0x90 -> 0xA0
+	 */
+
+	buf = 0x90;
+	err = setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1);
+	if (err < 0) {
+		log_err("Failed to call setsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	buf = 0x00;
+	optlen = 1;
+	err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
+	if (err) {
+		log_err("Failed to call getsockopt(IP_TOS)");
+		goto detach;
+	}
+
+	if (buf != 0xA0) {
+		log_err("Unexpected getsockopt 0x%x != 0xA0", buf);
+		err = -1;
+		goto detach;
+	}
+
+detach:
+	prog_detach(obj, cg_child, "cgroup/getsockopt/child");
+	prog_detach(obj, cg_parent, "cgroup/getsockopt/parent");
+
+	return err;
+}
+
+int main(int argc, char **argv)
+{
+	struct bpf_prog_load_attr attr = {
+		.file = "./sockopt_multi.o",
+	};
+	int cg_parent = -1, cg_child = -1;
+	struct bpf_object *obj = NULL;
+	int sock_fd = -1;
+	int err = -1;
+	int ignored;
+
+	if (setup_cgroup_environment()) {
+		log_err("Failed to setup cgroup environment\n");
+		goto out;
+	}
+
+	cg_parent = create_and_get_cgroup("/parent");
+	if (cg_parent < 0) {
+		log_err("Failed to create cgroup /parent\n");
+		goto out;
+	}
+
+	cg_child = create_and_get_cgroup("/parent/child");
+	if (cg_child < 0) {
+		log_err("Failed to create cgroup /parent/child\n");
+		goto out;
+	}
+
+	if (join_cgroup("/parent/child")) {
+		log_err("Failed to join cgroup /parent/child\n");
+		goto out;
+	}
+
+	err = bpf_prog_load_xattr(&attr, &obj, &ignored);
+	if (err) {
+		log_err("Failed to load BPF object");
+		goto out;
+	}
+
+	sock_fd = socket(AF_INET, SOCK_STREAM, 0);
+	if (sock_fd < 0) {
+		log_err("Failed to create socket");
+		goto out;
+	}
+
+	if (run_test(obj, cg_parent, cg_child, sock_fd))
+		err = -1;
+
+out:
+	close(sock_fd);
+	bpf_object__close(obj);
+	close(cg_child);
+	close(cg_parent);
+
+	printf("test_sockopt_multi: %s\n", err ? "FAILED" : "PASSED");
+	return err ? EXIT_FAILURE : EXIT_SUCCESS;
+}
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 8/9] bpf: add sockopt documentation

[Stanislav Fomichev]

Provide user documentation about sockopt prog type and cgroup hooks.

v7:
* add description for retval=0 and optlen=-1

v6:
* describe cgroup chaining, add example

v2:
* use return code 2 for kernel bypass

Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 Documentation/bpf/index.rst               |  1 +
 Documentation/bpf/prog_cgroup_sockopt.rst | 82 +++++++++++++++++++++++
 2 files changed, 83 insertions(+)
 create mode 100644 Documentation/bpf/prog_cgroup_sockopt.rst

diff --git a/Documentation/bpf/index.rst b/Documentation/bpf/index.rst
index d3fe4cac0c90..801a6ed3f2e5 100644
--- a/Documentation/bpf/index.rst
+++ b/Documentation/bpf/index.rst
@@ -42,6 +42,7 @@ Program types
 .. toctree::
    :maxdepth: 1
 
+   prog_cgroup_sockopt
    prog_cgroup_sysctl
    prog_flow_dissector
 
diff --git a/Documentation/bpf/prog_cgroup_sockopt.rst b/Documentation/bpf/prog_cgroup_sockopt.rst
new file mode 100644
index 000000000000..24985740711a
--- /dev/null
+++ b/Documentation/bpf/prog_cgroup_sockopt.rst
@@ -0,0 +1,82 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+BPF_PROG_TYPE_CGROUP_SOCKOPT
+============================
+
+``BPF_PROG_TYPE_CGROUP_SOCKOPT`` program type can be attached to two
+cgroup hooks:
+
+* ``BPF_CGROUP_GETSOCKOPT`` - called every time process executes ``getsockopt``
+  system call.
+* ``BPF_CGROUP_SETSOCKOPT`` - called every time process executes ``setsockopt``
+  system call.
+
+The context (``struct bpf_sockopt``) has associated socket (``sk``) and
+all input arguments: ``level``, ``optname``, ``optval`` and ``optlen``.
+
+BPF_CGROUP_SETSOCKOPT
+=====================
+
+``BPF_CGROUP_SETSOCKOPT`` is triggered *before* the kernel handling of
+sockopt and it has mostly read-only context (it can modify only ``optlen``).
+This hook has access to cgroup and socket local storage.
+
+If BPF program sets ``optlen`` to -1, the control will be returned
+back to the userspace after all other BPF programs in the cgroup
+chain finish (i.e. kernel ``setsockopt`` handling will *not* be executed).
+
+Note, that the only acceptable value to set to ``optlen`` is -1. Any
+other value will trigger ``EFAULT``.
+
+Return Type
+-----------
+
+* ``0`` - reject the syscall, ``EPERM`` will be returned to the userspace.
+* ``1`` - success, continue with next BPF program in the cgroup chain.
+
+BPF_CGROUP_GETSOCKOPT
+=====================
+
+``BPF_CGROUP_GETSOCKOPT`` is triggered *after* the kernel handing of
+sockopt. The BPF hook can observe ``optval``, ``optlen`` and ``retval``
+if it's interested in whatever kernel has returned. BPF hook can override
+the values above, adjust ``optlen`` and reset ``retval`` to 0. If ``optlen``
+has been increased above initial ``setsockopt`` value (i.e. userspace
+buffer is too small), ``EFAULT`` is returned.
+
+Note, that the only acceptable value to set to ``retval`` is 0 and the
+original value that the kernel returned. Any other value will trigger
+``EFAULT``.
+
+Return Type
+-----------
+
+* ``0`` - reject the syscall, ``EPERM`` will be returned to the userspace.
+* ``1`` - success: copy ``optval`` and ``optlen`` to userspace, return
+  ``retval`` from the syscall (note that this can be overwritten by
+  the BPF program from the parent cgroup).
+
+Cgroup Inheritance
+==================
+
+Suppose, there is the following cgroup hierarchy where each cgroup
+has ``BPF_CGROUP_GETSOCKOPT`` attached at each level with
+``BPF_F_ALLOW_MULTI`` flag::
+
+  A (root, parent)
+   \
+    B (child)
+
+When the application calls ``getsockopt`` syscall from the cgroup B,
+the programs are executed from the bottom up: B, A. First program
+(B) sees the result of kernel's ``getsockopt``. It can optionally
+adjust ``optval``, ``optlen`` and reset ``retval`` to 0. After that
+control will be passed to the second (A) program which will see the
+same context as B including any potential modifications.
+
+Example
+=======
+
+See ``tools/testing/selftests/bpf/progs/sockopt_sk.c`` for an example
+of BPF program that handles socket options.
-- 
2.22.0.410.gd8fdbe21b5-goog

[PATCH bpf-next v8 9/9] bpftool: support cgroup sockopt

[Stanislav Fomichev]

Support sockopt prog type and cgroup hooks in the bpftool.

Cc: Martin Lau <kafai@fb.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 tools/bpf/bpftool/Documentation/bpftool-cgroup.rst | 7 +++++--
 tools/bpf/bpftool/Documentation/bpftool-prog.rst   | 3 ++-
 tools/bpf/bpftool/bash-completion/bpftool          | 9 ++++++---
 tools/bpf/bpftool/cgroup.c                         | 5 ++++-
 tools/bpf/bpftool/main.h                           | 1 +
 tools/bpf/bpftool/prog.c                           | 3 ++-
 6 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
index 324df15bf4cc..6ac98f08e9d0 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
@@ -30,7 +30,8 @@ CGROUP COMMANDS
 |	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
 |	*ATTACH_TYPE* := { **ingress** | **egress** | **sock_create** | **sock_ops** | **device** |
 |		**bind4** | **bind6** | **post_bind4** | **post_bind6** | **connect4** | **connect6** |
-|		**sendmsg4** | **sendmsg6** | **recvmsg4** | **recvmsg6** | **sysctl** }
+|		**sendmsg4** | **sendmsg6** | **recvmsg4** | **recvmsg6** | **sysctl** |
+|		**getsockopt** | **setsockopt** }
 |	*ATTACH_FLAGS* := { **multi** | **override** }
 
 DESCRIPTION
@@ -91,7 +92,9 @@ DESCRIPTION
                   an unconnected udp4 socket (since 5.2);
 		  **recvmsg6** call to recvfrom(2), recvmsg(2), recvmmsg(2) for
                   an unconnected udp6 socket (since 5.2);
-		  **sysctl** sysctl access (since 5.2).
+		  **sysctl** sysctl access (since 5.2);
+		  **getsockopt** call to getsockopt (since 5.3);
+		  **setsockopt** call to setsockopt (since 5.3).
 
 	**bpftool cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
 		  Detach *PROG* from the cgroup *CGROUP* and attach type
diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index 55dd06517a3b..1df637f85f94 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -40,7 +40,8 @@ PROG COMMANDS
 |		**lwt_seg6local** | **sockops** | **sk_skb** | **sk_msg** | **lirc_mode2** |
 |		**cgroup/bind4** | **cgroup/bind6** | **cgroup/post_bind4** | **cgroup/post_bind6** |
 |		**cgroup/connect4** | **cgroup/connect6** | **cgroup/sendmsg4** | **cgroup/sendmsg6** |
-|		**cgroup/recvmsg4** | **cgroup/recvmsg6** | **cgroup/sysctl**
+|		**cgroup/recvmsg4** | **cgroup/recvmsg6** | **cgroup/sysctl** |
+|		**cgroup/getsockopt** | **cgroup/setsockopt**
 |	}
 |       *ATTACH_TYPE* := {
 |		**msg_verdict** | **stream_verdict** | **stream_parser** | **flow_dissector**
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index c98cb99867f6..08f35c787ab6 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -379,7 +379,8 @@ _bpftool()
                                 cgroup/sendmsg4 cgroup/sendmsg6 \
                                 cgroup/recvmsg4 cgroup/recvmsg6 \
                                 cgroup/post_bind4 cgroup/post_bind6 \
-                                cgroup/sysctl" -- \
+                                cgroup/sysctl cgroup/getsockopt \
+                                cgroup/setsockopt" -- \
                                                    "$cur" ) )
                             return 0
                             ;;
@@ -689,7 +690,8 @@ _bpftool()
                 attach|detach)
                     local ATTACH_TYPES='ingress egress sock_create sock_ops \
                         device bind4 bind6 post_bind4 post_bind6 connect4 \
-                        connect6 sendmsg4 sendmsg6 recvmsg4 recvmsg6 sysctl'
+                        connect6 sendmsg4 sendmsg6 recvmsg4 recvmsg6 sysctl \
+                        getsockopt setsockopt'
                     local ATTACH_FLAGS='multi override'
                     local PROG_TYPE='id pinned tag'
                     case $prev in
@@ -699,7 +701,8 @@ _bpftool()
                             ;;
                         ingress|egress|sock_create|sock_ops|device|bind4|bind6|\
                         post_bind4|post_bind6|connect4|connect6|sendmsg4|\
-                        sendmsg6|recvmsg4|recvmsg6|sysctl)
+                        sendmsg6|recvmsg4|recvmsg6|sysctl|getsockopt|\
+                        setsockopt)
                             COMPREPLY=( $( compgen -W "$PROG_TYPE" -- \
                                 "$cur" ) )
                             return 0
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c
index 1bb2a751107a..24937891bc48 100644
--- a/tools/bpf/bpftool/cgroup.c
+++ b/tools/bpf/bpftool/cgroup.c
@@ -26,7 +26,8 @@
 	"                        sock_ops | device | bind4 | bind6 |\n"	       \
 	"                        post_bind4 | post_bind6 | connect4 |\n"       \
 	"                        connect6 | sendmsg4 | sendmsg6 |\n"           \
-	"                        recvmsg4 | recvmsg6 | sysctl }"
+	"                        recvmsg4 | recvmsg6 | sysctl |\n"	       \
+	"                        getsockopt | setsockopt }"
 
 static const char * const attach_type_strings[] = {
 	[BPF_CGROUP_INET_INGRESS] = "ingress",
@@ -45,6 +46,8 @@ static const char * const attach_type_strings[] = {
 	[BPF_CGROUP_SYSCTL] = "sysctl",
 	[BPF_CGROUP_UDP4_RECVMSG] = "recvmsg4",
 	[BPF_CGROUP_UDP6_RECVMSG] = "recvmsg6",
+	[BPF_CGROUP_GETSOCKOPT] = "getsockopt",
+	[BPF_CGROUP_SETSOCKOPT] = "setsockopt",
 	[__MAX_BPF_ATTACH_TYPE] = NULL,
 };
 
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index fddec15c454a..fb0ba77e6722 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -74,6 +74,7 @@ static const char * const prog_type_name[] = {
 	[BPF_PROG_TYPE_SK_REUSEPORT]		= "sk_reuseport",
 	[BPF_PROG_TYPE_FLOW_DISSECTOR]		= "flow_dissector",
 	[BPF_PROG_TYPE_CGROUP_SYSCTL]		= "cgroup_sysctl",
+	[BPF_PROG_TYPE_CGROUP_SOCKOPT]		= "cgroup_sockopt",
 };
 
 extern const char * const map_type_name[];
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index f1a831f05010..9b0db5d14e31 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1071,7 +1071,8 @@ static int do_help(int argc, char **argv)
 		"                 cgroup/bind4 | cgroup/bind6 | cgroup/post_bind4 |\n"
 		"                 cgroup/post_bind6 | cgroup/connect4 | cgroup/connect6 |\n"
 		"                 cgroup/sendmsg4 | cgroup/sendmsg6 | cgroup/recvmsg4 |\n"
-		"                 cgroup/recvmsg6 }\n"
+		"                 cgroup/recvmsg6 | cgroup/getsockopt |\n"
+		"                 cgroup/setsockopt }\n"
 		"       ATTACH_TYPE := { msg_verdict | stream_verdict | stream_parser |\n"
 		"                        flow_dissector }\n"
 		"       " HELP_SPEC_OPTIONS "\n"
-- 
2.22.0.410.gd8fdbe21b5-goog

Re: [PATCH bpf-next v8 1/9] bpf: implement getsockopt and setsockopt hooks

[Andrii Nakryiko]

On Mon, Jun 24, 2019 at 1:11 PM Stanislav Fomichev <sdf@google.com> 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_prog_array_is_empty that exits early if there is nothing
> attached to a cgroup. Note, however, that there is a race between
> __cgroup_bpf_prog_array_is_empty 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.
>
> The return code of the BPF program is handled as follows:
> * 0: EPERM
> * 1: success, continue with next BPF program in the cgroup chain
>
> v8:
> * use s32 for optlen (Andrii Nakryiko)
>
> v7:
> * return only 0 or 1 (Alexei Starovoitov)
> * always run all progs (Alexei Starovoitov)
> * use optval=0 as kernel bypass in setsockopt (Alexei Starovoitov)
>   (decided to use optval=-1 instead, optval=0 might be a valid input)
> * call getsockopt hook after kernel handlers (Alexei Starovoitov)
>
> v6:
> * rework cgroup chaining; stop as soon as bpf program returns
>   0 or 2; see patch with the documentation for the details
> * drop Andrii's and Martin's Acked-by (not sure they are comfortable
>   with the new state of things)
>
> v5:
> * skip copy_to_user() and put_user() when ret == 0 (Martin Lau)
>
> v4:
> * don't export bpf_sk_fullsock helper (Martin Lau)
> * size != sizeof(__u64) for uapi pointers (Martin Lau)
> * offsetof instead of bpf_ctx_range when checking ctx access (Martin Lau)
>
> v3:
> * typos in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY comments (Andrii Nakryiko)
> * reverse christmas tree in BPF_PROG_CGROUP_SOCKOPT_RUN_ARRAY (Andrii
>   Nakryiko)
> * use __bpf_md_ptr instead of __u32 for optval{,_end} (Martin Lau)
> * use BPF_FIELD_SIZEOF() for consistency (Martin Lau)
> * new CG_SOCKOPT_ACCESS macro to wrap repeated parts
>
> v2:
> * moved bpf_sockopt_kern fields around to remove a hole (Martin Lau)
> * aligned bpf_sockopt_kern->buf to 8 bytes (Martin Lau)
> * bpf_prog_array_is_empty instead of bpf_prog_array_length (Martin Lau)
> * added [0,2] return code check to verifier (Martin Lau)
> * dropped unused buf[64] from the stack (Martin Lau)
> * use PTR_TO_SOCKET for bpf_sockopt->sk (Martin Lau)
> * dropped bpf_target_off from ctx rewrites (Martin Lau)
> * use return code for kernel bypass (Martin Lau & Andrii Nakryiko)
>
> Cc: Martin Lau <kafai@fb.com>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>
> ---

Acked-by: Andrii Nakryiko <andriin@fb.com>

Re: [PATCH bpf-next v8 1/9] bpf: implement getsockopt and setsockopt hooks

[Alexei Starovoitov]

On Mon, Jun 24, 2019 at 09:24:21AM -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.

getsockopt side looks good to me.
I tried to convince myself that readonly setsockopt is fine for now,
but it feels we need to make it writeable from the start.
I agree with your reasoning that doing copy_to_user is no good,
but we can do certainly do set_fs(KERNEL_DS) game.
The same way as kernel_setsockopt() is doing.
It seems quite useful to modify 'optval' before passing it to kernel.
Then bpf prog would be able to specify sane values for SO_SNDBUF
instead of rejecting them.
The alternative would be to allow bpf prog to call setsockopt
from inside, but sock is locked when prog is running,
so unlocking within helper is not going to be clean.
wdyt?

Re: [PATCH bpf-next v8 1/9] bpf: implement getsockopt and setsockopt hooks

[Stanislav Fomichev]

On 06/26, Alexei Starovoitov wrote:
> On Mon, Jun 24, 2019 at 09:24:21AM -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.
> 
> getsockopt side looks good to me.
> I tried to convince myself that readonly setsockopt is fine for now,
> but it feels we need to make it writeable from the start.
> I agree with your reasoning that doing copy_to_user is no good,
> but we can do certainly do set_fs(KERNEL_DS) game.
> The same way as kernel_setsockopt() is doing.
> It seems quite useful to modify 'optval' before passing it to kernel.
> Then bpf prog would be able to specify sane values for SO_SNDBUF
> instead of rejecting them.
> The alternative would be to allow bpf prog to call setsockopt
> from inside, but sock is locked when prog is running,
> so unlocking within helper is not going to be clean.
> wdyt?
Sure, I can take a look if you think that it would be useful in general.
Looks like set_fs should do the trick.

(I was thinking about exporting something like the existing bpf_setsockopt
to a setsockopt hooks, but I agree, it comes with its own bag
of problems).

Re: [PATCH bpf-next v8 1/9] bpf: implement getsockopt and setsockopt hooks

[Alexei Starovoitov]

On Wed, Jun 26, 2019 at 12:10:21PM -0700, Stanislav Fomichev wrote:
> On 06/26, Alexei Starovoitov wrote:
> > On Mon, Jun 24, 2019 at 09:24:21AM -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.
> > 
> > getsockopt side looks good to me.
> > I tried to convince myself that readonly setsockopt is fine for now,
> > but it feels we need to make it writeable from the start.
> > I agree with your reasoning that doing copy_to_user is no good,
> > but we can do certainly do set_fs(KERNEL_DS) game.
> > The same way as kernel_setsockopt() is doing.
> > It seems quite useful to modify 'optval' before passing it to kernel.
> > Then bpf prog would be able to specify sane values for SO_SNDBUF
> > instead of rejecting them.
> > The alternative would be to allow bpf prog to call setsockopt
> > from inside, but sock is locked when prog is running,
> > so unlocking within helper is not going to be clean.
> > wdyt?
> Sure, I can take a look if you think that it would be useful in general.
> Looks like set_fs should do the trick.

Thanks. I think it's useful.
For example see the recent sack steam issue and Eric's workaround
for older kernel to add 128k to sk_sndbuf.
If we had an ability to do adjust SO_SNDBUF from cgroup-bpf prog
when user space is doing setsockopt we could have mitigated it by
rolling bpf prog instead of patching and rebooting the kernels.
That's a bit of a stretch use case, of course.
My feeling that if not today, but really soon people will find
solid use cases for adjusting sockopt values via cgroup-bpf.