[PATCH v2 bpf-next 0/2] libbpf: add support for privileged/unprivileged control separation

[PATCH v2 bpf-next 0/2] libbpf: add support for privileged/unprivileged control separation

[mariusz.dudek]

From: Mariusz Dudek <mariuszx.dudek@intel.com>

This patch series adds support for separation of eBPF program
load and xsk socket creation. In for example a Kubernetes
environment you can have an AF_XDP CNI or daemonset that is 
responsible for launching pods that execute an application 
using AF_XDP sockets. It is desirable that the pod runs with
as low privileges as possible, CAP_NET_RAW in this case, 
and that all operations that require privileges are contained
in the CNI or daemonset.
	
In this case, you have to be able separate ePBF program load from
xsk socket creation.

Currently, this will not work with the xsk_socket__create APIs
because you need to have CAP_NET_ADMIN privileges to load eBPF
program and CAP_SYS_ADMIN privileges to create update xsk_bpf_maps.
To be exact xsk_set_bpf_maps does not need those privileges but
it takes the prog_fd and xsks_map_fd and those are known only to
process that was loading eBPF program. The api bpf_prog_get_fd_by_id
that looks up the fd of the prog using an prog_id and
bpf_map_get_fd_by_id that looks for xsks_map_fd usinb map_id both
requires CAP_SYS_ADMIN.

With this patch, the pod can be run with CAP_NET_RAW capability
only. In case your umem is larger or equal process limit for
MEMLOCK you need either increase the limit or CAP_IPC_LOCK capability. 
Without this patch in case of insufficient rights ENOPERM is
returned by xsk_socket__create.

To resolve this privileges issue two new APIs are introduced:
- xsk_setup_xdp_prog - prepares bpf program if given and
loads it on a selected network interface or loads the built in
XDP program, if no XDP program is supplied. It can also return
xsks_map_fd which is needed by unprivileged process to update
xsks_map with AF_XDP socket "fd"
- xsk_sokcet__update_xskmap - inserts an AF_XDP socket into an
xskmap for a particular xsk_socket

Usage example:
int xsk_setup_xdp_prog(int ifindex, struct bpf_prog_cfg *cfg,
		int *xsks_map_fd)

if cfg == NULL, then the default program is loaded.

Instead of NULL user can pass pointer to struct
bpf_prog_cfg and provide own bpf program. 

int xsk_socket__update_xskmap(struct xsk_socket *xsk, int xsks_map_fd);

Inserts AF_XDP socket "fd" into the xskmap.

The first patch introduces the new APIs. The second patch provides
a new sample applications working as control and modification to
existing xdpsock application to work with less privileges.

This patch set is based on bpf-next commit 09a3dac7b579
("bpf: Fix NULL dereference in bpf_task_storage")

Since v1:
- struct bpf_prog_cfg improved for backward/forward compatibility
- API xsk_update_xskmap renamed to xsk_socket__update_xskmap
- commit message formatting fixed

Mariusz Dudek (2):
  libbpf: separate XDP program load with xsk socket creation
  samples/bpf: sample application for eBPF load and socket creation
    split

 samples/bpf/Makefile            |   4 +-
 samples/bpf/xdpsock.h           |   8 ++
 samples/bpf/xdpsock_ctrl_proc.c | 184 ++++++++++++++++++++++++++++++++
 samples/bpf/xdpsock_user.c      | 146 +++++++++++++++++++++++--
 tools/lib/bpf/libbpf.map        |   2 +
 tools/lib/bpf/xsk.c             | 160 ++++++++++++++++++++++-----
 tools/lib/bpf/xsk.h             |  15 +++
 7 files changed, 483 insertions(+), 36 deletions(-)
 create mode 100644 samples/bpf/xdpsock_ctrl_proc.c

-- 
2.20.1

[PATCH v2 bpf-next 1/2] libbpf: separate XDP program load with xsk socket creation

[mariusz.dudek]

From: Mariusz Dudek <mariuszx.dudek@intel.com>

Add support for separation of eBPF program load and xsk socket
creation.

This is needed for use-case when you want to privide as little
privileges as possible to the data plane application that will
handle xsk socket creation and incoming traffic.

With this patch the data entity container can be run with only
CAP_NET_RAW capability to fulfill its purpose of creating xsk
socket and handling packages. In case your umem is larger or
equal process limit for MEMLOCK you need either increase the
limit or CAP_IPC_LOCK capability.

To resolve privileges issue two APIs are introduced:

- xsk_setup_xdp_prog - prepares bpf program if given and
loads it on a selected network interface or loads the built in
XDP program, if no XDP program is supplied. It can also return
xsks_map_fd which is needed by unprivileged process to update
xsks_map with AF_XDP socket "fd"

- xsk_socket__update_xskmap - inserts an AF_XDP socket into an xskmap
for a particular xsk_socket

Signed-off-by: Mariusz Dudek <mariuszx.dudek@intel.com>
---
 tools/lib/bpf/libbpf.map |   2 +
 tools/lib/bpf/xsk.c      | 160 ++++++++++++++++++++++++++++++++-------
 tools/lib/bpf/xsk.h      |  15 ++++
 3 files changed, 151 insertions(+), 26 deletions(-)

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 29ff4807b909..73aa12388055 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -336,6 +336,8 @@ LIBBPF_0.2.0 {
 		perf_buffer__epoll_fd;
 		perf_buffer__consume_buffer;
 		xsk_socket__create_shared;
+		xsk_setup_xdp_prog;
+		xsk_socket__update_xskmap;
 } LIBBPF_0.1.0;
 
 LIBBPF_0.3.0 {
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index e3c98c007825..88b8e01fafe7 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -351,13 +351,8 @@ int xsk_umem__create_v0_0_2(struct xsk_umem **umem_ptr, void *umem_area,
 COMPAT_VERSION(xsk_umem__create_v0_0_2, xsk_umem__create, LIBBPF_0.0.2)
 DEFAULT_VERSION(xsk_umem__create_v0_0_4, xsk_umem__create, LIBBPF_0.0.4)
 
-static int xsk_load_xdp_prog(struct xsk_socket *xsk)
+static int get_bpf_prog(struct bpf_prog_cfg_opts *cfg_ptr, int xsks_map_fd)
 {
-	static const int log_buf_size = 16 * 1024;
-	struct xsk_ctx *ctx = xsk->ctx;
-	char log_buf[log_buf_size];
-	int err, prog_fd;
-
 	/* This is the C-program:
 	 * SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx)
 	 * {
@@ -382,7 +377,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* *(u32 *)(r10 - 4) = r2 */
 		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -4),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsks_map_fd),
 		/* r3 = XDP_PASS */
 		BPF_MOV64_IMM(BPF_REG_3, 2),
 		/* call bpf_redirect_map */
@@ -394,7 +389,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* r2 += -4 */
 		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsks_map_fd),
 		/* call bpf_map_lookup_elem */
 		BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
 		/* r1 = r0 */
@@ -406,7 +401,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* r2 = *(u32 *)(r10 - 4) */
 		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, -4),
 		/* r1 = xskmap[] */
-		BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd),
+		BPF_LD_MAP_FD(BPF_REG_1, xsks_map_fd),
 		/* r3 = 0 */
 		BPF_MOV64_IMM(BPF_REG_3, 0),
 		/* call bpf_redirect_map */
@@ -414,17 +409,42 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk)
 		/* The jumps are to this instruction */
 		BPF_EXIT_INSN(),
 	};
-	size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn);
 
-	prog_fd = bpf_load_program(BPF_PROG_TYPE_XDP, prog, insns_cnt,
-				   "LGPL-2.1 or BSD-2-Clause", 0, log_buf,
+	cfg_ptr->prog = malloc(sizeof(prog));
+	if (!cfg_ptr->prog)
+		return -ENOMEM;
+	memcpy(cfg_ptr->prog, prog, sizeof(prog));
+	cfg_ptr->license = "LGPL-2.1 or BSD-2-Clause";
+	cfg_ptr->insns_cnt = sizeof(prog) / sizeof(struct bpf_insn);
+
+	return 0;
+}
+
+static int xsk_load_xdp_prog(struct xsk_socket *xsk, struct bpf_prog_cfg_opts *user_cfg)
+{
+	static const int log_buf_size = 16 * 1024;
+	struct xsk_ctx *ctx = xsk->ctx;
+	char log_buf[log_buf_size];
+	struct bpf_prog_cfg_opts cfg;
+	int err, prog_fd;
+
+	if (user_cfg && user_cfg->insns_cnt) {
+		cfg = *user_cfg;
+	} else {
+		err = get_bpf_prog(&cfg, ctx->xsks_map_fd);
+		if (err)
+			return err;
+	}
+
+	prog_fd = bpf_load_program(BPF_PROG_TYPE_XDP, cfg.prog, cfg.insns_cnt,
+				   cfg.license, 0, log_buf,
 				   log_buf_size);
 	if (prog_fd < 0) {
 		pr_warn("BPF log buffer:\n%s", log_buf);
 		return prog_fd;
 	}
 
-	err = bpf_set_link_xdp_fd(xsk->ctx->ifindex, prog_fd,
+	err = bpf_set_link_xdp_fd(ctx->ifindex, prog_fd,
 				  xsk->config.xdp_flags);
 	if (err) {
 		close(prog_fd);
@@ -566,8 +586,43 @@ static int xsk_set_bpf_maps(struct xsk_socket *xsk)
 				   &xsk->fd, 0);
 }
 
-static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
+static int xsk_create_xsk_struct(int ifindex, struct xsk_socket *xsk)
+{
+	char ifname[IFNAMSIZ];
+	struct xsk_ctx *ctx;
+	char *interface;
+	int res = -1;
+
+	ctx = calloc(1, sizeof(*ctx));
+	if (!ctx)
+		goto error_ctx;
+
+	interface = if_indextoname(ifindex, &ifname[0]);
+	if (!interface) {
+		res = -errno;
+		goto error_ifindex;
+	}
+
+	ctx->ifindex = ifindex;
+	strncpy(ctx->ifname, ifname, IFNAMSIZ - 1);
+	ctx->ifname[IFNAMSIZ - 1] = 0;
+
+	xsk->ctx = ctx;
+
+	return 0;
+
+error_ifindex:
+	free(ctx);
+error_ctx:
+	return res;
+}
+
+static int __xsk_setup_xdp_prog(struct xsk_socket *_xdp,
+				struct bpf_prog_cfg_opts *cfg,
+				bool force_set_map,
+				int *xsks_map_fd)
 {
+	struct xsk_socket *xsk = _xdp;
 	struct xsk_ctx *ctx = xsk->ctx;
 	__u32 prog_id = 0;
 	int err;
@@ -578,14 +633,17 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
 		return err;
 
 	if (!prog_id) {
-		err = xsk_create_bpf_maps(xsk);
-		if (err)
-			return err;
+		if (!cfg || !cfg->insns_cnt) {
+			err = xsk_create_bpf_maps(xsk);
+			if (err)
+				return err;
+		} else {
+			ctx->xsks_map_fd = cfg->xsks_map_fd;
+		}
 
-		err = xsk_load_xdp_prog(xsk);
+		err = xsk_load_xdp_prog(xsk, cfg);
 		if (err) {
-			xsk_delete_bpf_maps(xsk);
-			return err;
+			goto err_load_xdp_prog;
 		}
 	} else {
 		ctx->prog_fd = bpf_prog_get_fd_by_id(prog_id);
@@ -598,15 +656,29 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
 		}
 	}
 
-	if (xsk->rx)
+	if (xsk->rx || force_set_map) {
 		err = xsk_set_bpf_maps(xsk);
-	if (err) {
-		xsk_delete_bpf_maps(xsk);
-		close(ctx->prog_fd);
-		return err;
+		if (err) {
+			if (!prog_id) {
+				goto err_set_bpf_maps;
+			} else {
+				close(ctx->prog_fd);
+				return err;
+			}
+		}
 	}
+	if (xsks_map_fd)
+		*xsks_map_fd = ctx->xsks_map_fd;
 
 	return 0;
+
+err_set_bpf_maps:
+	close(ctx->prog_fd);
+	bpf_set_link_xdp_fd(ctx->ifindex, -1, 0);
+err_load_xdp_prog:
+	xsk_delete_bpf_maps(xsk);
+
+	return err;
 }
 
 static struct xsk_ctx *xsk_get_ctx(struct xsk_umem *umem, int ifindex,
@@ -689,6 +761,42 @@ static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk,
 	return ctx;
 }
 
+static void xsk_destroy_xsk_struct(struct xsk_socket *xsk)
+{
+	free(xsk->ctx);
+	free(xsk);
+}
+
+int xsk_socket__update_xskmap(struct xsk_socket *xsk, int fd)
+{
+	xsk->ctx->xsks_map_fd = fd;
+	return xsk_set_bpf_maps(xsk);
+}
+
+int xsk_setup_xdp_prog(int ifindex, struct bpf_prog_cfg_opts *opts,
+		       int *xsks_map_fd)
+{
+	struct xsk_socket *xsk;
+	int res = -1;
+
+	if (!OPTS_VALID(opts, bpf_prog_cfg_opts))
+		return -EINVAL;
+
+	xsk = calloc(1, sizeof(*xsk));
+	if (!xsk)
+		return res;
+
+	res = xsk_create_xsk_struct(ifindex, xsk);
+	if (res)
+		return -EINVAL;
+
+	res = __xsk_setup_xdp_prog(xsk, opts, false, xsks_map_fd);
+
+	xsk_destroy_xsk_struct(xsk);
+
+	return res;
+}
+
 int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 			      const char *ifname,
 			      __u32 queue_id, struct xsk_umem *umem,
@@ -838,7 +946,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
 	ctx->prog_fd = -1;
 
 	if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
-		err = xsk_setup_xdp_prog(xsk);
+		err = __xsk_setup_xdp_prog(xsk, NULL, false, NULL);
 		if (err)
 			goto out_mmap_tx;
 	}
diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
index 1069c46364ff..c852ec742437 100644
--- a/tools/lib/bpf/xsk.h
+++ b/tools/lib/bpf/xsk.h
@@ -201,6 +201,21 @@ struct xsk_umem_config {
 	__u32 flags;
 };
 
+struct bpf_prog_cfg_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	struct bpf_insn *prog;
+	const char *license;
+	size_t insns_cnt;
+	int xsks_map_fd;
+};
+#define bpf_prog_cfg_opts__last_field xsks_map_fd
+
+LIBBPF_API int xsk_setup_xdp_prog(int ifindex,
+				  struct bpf_prog_cfg_opts *opts,
+				  int *xsks_map_fd);
+LIBBPF_API int xsk_socket__update_xskmap(struct xsk_socket *xsk,
+				 int xsks_map_fd);
+
 /* Flags for the libbpf_flags field. */
 #define XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD (1 << 0)
 
-- 
2.20.1

Re: [PATCH v2 bpf-next 1/2] libbpf: separate XDP program load with xsk socket creation

[Andrii Nakryiko]

On Thu, Nov 12, 2020 at 12:58 AM <mariusz.dudek@gmail.com> wrote:
>
> From: Mariusz Dudek <mariuszx.dudek@intel.com>
>
> Add support for separation of eBPF program load and xsk socket
> creation.
>
> This is needed for use-case when you want to privide as little
> privileges as possible to the data plane application that will
> handle xsk socket creation and incoming traffic.
>
> With this patch the data entity container can be run with only
> CAP_NET_RAW capability to fulfill its purpose of creating xsk
> socket and handling packages. In case your umem is larger or
> equal process limit for MEMLOCK you need either increase the
> limit or CAP_IPC_LOCK capability.
>
> To resolve privileges issue two APIs are introduced:
>
> - xsk_setup_xdp_prog - prepares bpf program if given and
> loads it on a selected network interface or loads the built in
> XDP program, if no XDP program is supplied. It can also return
> xsks_map_fd which is needed by unprivileged process to update
> xsks_map with AF_XDP socket "fd"
>
> - xsk_socket__update_xskmap - inserts an AF_XDP socket into an xskmap
> for a particular xsk_socket
>
> Signed-off-by: Mariusz Dudek <mariuszx.dudek@intel.com>
> ---
>  tools/lib/bpf/libbpf.map |   2 +
>  tools/lib/bpf/xsk.c      | 160 ++++++++++++++++++++++++++++++++-------
>  tools/lib/bpf/xsk.h      |  15 ++++
>  3 files changed, 151 insertions(+), 26 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 29ff4807b909..73aa12388055 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -336,6 +336,8 @@ LIBBPF_0.2.0 {
>                 perf_buffer__epoll_fd;
>                 perf_buffer__consume_buffer;
>                 xsk_socket__create_shared;
> +               xsk_setup_xdp_prog;
> +               xsk_socket__update_xskmap;
>  } LIBBPF_0.1.0;


New APIs have to go into LIBBPF_0.3.0 section now.

>
>  LIBBPF_0.3.0 {

[...]

> +static int __xsk_setup_xdp_prog(struct xsk_socket *_xdp,
> +                               struct bpf_prog_cfg_opts *cfg,
> +                               bool force_set_map,
> +                               int *xsks_map_fd)
>  {
> +       struct xsk_socket *xsk = _xdp;
>         struct xsk_ctx *ctx = xsk->ctx;
>         __u32 prog_id = 0;
>         int err;
> @@ -578,14 +633,17 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
>                 return err;
>
>         if (!prog_id) {
> -               err = xsk_create_bpf_maps(xsk);
> -               if (err)
> -                       return err;
> +               if (!cfg || !cfg->insns_cnt) {

you can't do this, use OPTS_GET() macro to access fields of opts struct.

> +                       err = xsk_create_bpf_maps(xsk);
> +                       if (err)
> +                               return err;
> +               } else {
> +                       ctx->xsks_map_fd = cfg->xsks_map_fd;

same

> +               }
>
> -               err = xsk_load_xdp_prog(xsk);
> +               err = xsk_load_xdp_prog(xsk, cfg);
>                 if (err) {
> -                       xsk_delete_bpf_maps(xsk);
> -                       return err;
> +                       goto err_load_xdp_prog;
>                 }
>         } else {
>                 ctx->prog_fd = bpf_prog_get_fd_by_id(prog_id);

[...]

>  int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
>                               const char *ifname,
>                               __u32 queue_id, struct xsk_umem *umem,
> @@ -838,7 +946,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
>         ctx->prog_fd = -1;
>
>         if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
> -               err = xsk_setup_xdp_prog(xsk);
> +               err = __xsk_setup_xdp_prog(xsk, NULL, false, NULL);
>                 if (err)
>                         goto out_mmap_tx;
>         }
> diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
> index 1069c46364ff..c852ec742437 100644
> --- a/tools/lib/bpf/xsk.h
> +++ b/tools/lib/bpf/xsk.h
> @@ -201,6 +201,21 @@ struct xsk_umem_config {
>         __u32 flags;
>  };
>
> +struct bpf_prog_cfg_opts {

The name of this struct doesn't really match an API it's used in, it
looks to be related to struct bpf_program, which is extremely
misleading. Why didn't you go with something like
xdp_setup_xdp_prog_opts?

Also, so far we've been following the convention that non-optional
parameters are passed directly as function arguments, with all the
optional things put into opts. Looking at this struct, prog and
insns_cnt look non-optional. Not sure about the license. Also, it
seems strange to have xsks_map_fd in opts struct and as an output
parameter... If that's really in/out param, you can do OPTS_SET() and
pass it back through the same opts struct.

But in general, I'm also surprised that this API is using the bpf_insn
array as an input. Do people really construct such a low-level set of
instructions manually? Seems like a rather painful API.

Björn, Magnus, please take a look as well and chime in on API design
(I have too little context on XSK use cases).


> +       size_t sz; /* size of this struct for forward/backward compatibility */
> +       struct bpf_insn *prog;
> +       const char *license;
> +       size_t insns_cnt;
> +       int xsks_map_fd;
> +};
> +#define bpf_prog_cfg_opts__last_field xsks_map_fd
> +
> +LIBBPF_API int xsk_setup_xdp_prog(int ifindex,
> +                                 struct bpf_prog_cfg_opts *opts,
> +                                 int *xsks_map_fd);
> +LIBBPF_API int xsk_socket__update_xskmap(struct xsk_socket *xsk,
> +                                int xsks_map_fd);
> +
>  /* Flags for the libbpf_flags field. */
>  #define XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD (1 << 0)
>
> --
> 2.20.1
>

Re: [PATCH v2 bpf-next 1/2] libbpf: separate XDP program load with xsk socket creation

[Magnus Karlsson]

On Thu, Nov 12, 2020 at 8:12 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Nov 12, 2020 at 12:58 AM <mariusz.dudek@gmail.com> wrote:
> >
> > From: Mariusz Dudek <mariuszx.dudek@intel.com>
> >
> > Add support for separation of eBPF program load and xsk socket
> > creation.
> >
> > This is needed for use-case when you want to privide as little
> > privileges as possible to the data plane application that will
> > handle xsk socket creation and incoming traffic.
> >
> > With this patch the data entity container can be run with only
> > CAP_NET_RAW capability to fulfill its purpose of creating xsk
> > socket and handling packages. In case your umem is larger or
> > equal process limit for MEMLOCK you need either increase the
> > limit or CAP_IPC_LOCK capability.
> >
> > To resolve privileges issue two APIs are introduced:
> >
> > - xsk_setup_xdp_prog - prepares bpf program if given and
> > loads it on a selected network interface or loads the built in
> > XDP program, if no XDP program is supplied. It can also return
> > xsks_map_fd which is needed by unprivileged process to update
> > xsks_map with AF_XDP socket "fd"
> >
> > - xsk_socket__update_xskmap - inserts an AF_XDP socket into an xskmap
> > for a particular xsk_socket
> >
> > Signed-off-by: Mariusz Dudek <mariuszx.dudek@intel.com>
> > ---
> >  tools/lib/bpf/libbpf.map |   2 +
> >  tools/lib/bpf/xsk.c      | 160 ++++++++++++++++++++++++++++++++-------
> >  tools/lib/bpf/xsk.h      |  15 ++++
> >  3 files changed, 151 insertions(+), 26 deletions(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> > index 29ff4807b909..73aa12388055 100644
> > --- a/tools/lib/bpf/libbpf.map
> > +++ b/tools/lib/bpf/libbpf.map
> > @@ -336,6 +336,8 @@ LIBBPF_0.2.0 {
> >                 perf_buffer__epoll_fd;
> >                 perf_buffer__consume_buffer;
> >                 xsk_socket__create_shared;
> > +               xsk_setup_xdp_prog;
> > +               xsk_socket__update_xskmap;
> >  } LIBBPF_0.1.0;
>
>
> New APIs have to go into LIBBPF_0.3.0 section now.
>
> >
> >  LIBBPF_0.3.0 {
>
> [...]
>
> > +static int __xsk_setup_xdp_prog(struct xsk_socket *_xdp,
> > +                               struct bpf_prog_cfg_opts *cfg,
> > +                               bool force_set_map,
> > +                               int *xsks_map_fd)
> >  {
> > +       struct xsk_socket *xsk = _xdp;
> >         struct xsk_ctx *ctx = xsk->ctx;
> >         __u32 prog_id = 0;
> >         int err;
> > @@ -578,14 +633,17 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
> >                 return err;
> >
> >         if (!prog_id) {
> > -               err = xsk_create_bpf_maps(xsk);
> > -               if (err)
> > -                       return err;
> > +               if (!cfg || !cfg->insns_cnt) {
>
> you can't do this, use OPTS_GET() macro to access fields of opts struct.
>
> > +                       err = xsk_create_bpf_maps(xsk);
> > +                       if (err)
> > +                               return err;
> > +               } else {
> > +                       ctx->xsks_map_fd = cfg->xsks_map_fd;
>
> same
>
> > +               }
> >
> > -               err = xsk_load_xdp_prog(xsk);
> > +               err = xsk_load_xdp_prog(xsk, cfg);
> >                 if (err) {
> > -                       xsk_delete_bpf_maps(xsk);
> > -                       return err;
> > +                       goto err_load_xdp_prog;
> >                 }
> >         } else {
> >                 ctx->prog_fd = bpf_prog_get_fd_by_id(prog_id);
>
> [...]
>
> >  int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
> >                               const char *ifname,
> >                               __u32 queue_id, struct xsk_umem *umem,
> > @@ -838,7 +946,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
> >         ctx->prog_fd = -1;
> >
> >         if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
> > -               err = xsk_setup_xdp_prog(xsk);
> > +               err = __xsk_setup_xdp_prog(xsk, NULL, false, NULL);
> >                 if (err)
> >                         goto out_mmap_tx;
> >         }
> > diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
> > index 1069c46364ff..c852ec742437 100644
> > --- a/tools/lib/bpf/xsk.h
> > +++ b/tools/lib/bpf/xsk.h
> > @@ -201,6 +201,21 @@ struct xsk_umem_config {
> >         __u32 flags;
> >  };
> >
> > +struct bpf_prog_cfg_opts {
>
> The name of this struct doesn't really match an API it's used in, it
> looks to be related to struct bpf_program, which is extremely
> misleading. Why didn't you go with something like
> xdp_setup_xdp_prog_opts?
>
> Also, so far we've been following the convention that non-optional
> parameters are passed directly as function arguments, with all the
> optional things put into opts. Looking at this struct, prog and
> insns_cnt look non-optional. Not sure about the license. Also, it
> seems strange to have xsks_map_fd in opts struct and as an output
> parameter... If that's really in/out param, you can do OPTS_SET() and
> pass it back through the same opts struct.
>
> But in general, I'm also surprised that this API is using the bpf_insn
> array as an input. Do people really construct such a low-level set of
> instructions manually? Seems like a rather painful API.
>
> Björn, Magnus, please take a look as well and chime in on API design
> (I have too little context on XSK use cases).

Yes, it is much too macho to write an eBPF program directly using
assembly :-). My suggestion is to get rid of this whole struct
bpf_prog_cfg_opts completely and the parameter in the call. There is
no reason to provide functionality to load your own program in this
API as it is already so easy using the existing libbpf APIs e.g., with
bpf_prog_load_xattr() followed by bpf_set_link_xdp_fd(). So I suggest
the following:

LIBBPF_API int xsk_setup_default_prog(int ifindex, int *xsks_map_fd);

It is strictly a helper function for setting up the default XDP
program from a process that has the privilege to do this.

Thanks Andrii for taking a look at this and thanks Mariusz for taking
a stab at this.

>
> > +       size_t sz; /* size of this struct for forward/backward compatibility */
> > +       struct bpf_insn *prog;
> > +       const char *license;
> > +       size_t insns_cnt;
> > +       int xsks_map_fd;
> > +};
> > +#define bpf_prog_cfg_opts__last_field xsks_map_fd
> > +
> > +LIBBPF_API int xsk_setup_xdp_prog(int ifindex,
> > +                                 struct bpf_prog_cfg_opts *opts,
> > +                                 int *xsks_map_fd);
> > +LIBBPF_API int xsk_socket__update_xskmap(struct xsk_socket *xsk,
> > +                                int xsks_map_fd);
> > +
> >  /* Flags for the libbpf_flags field. */
> >  #define XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD (1 << 0)
> >
> > --
> > 2.20.1
> >

[PATCH v2 bpf-next 2/2] samples/bpf: sample application for eBPF load and socket creation split

[mariusz.dudek]

From: Mariusz Dudek <mariuszx.dudek@intel.com>

Introduce a sample program to demonstrate the control and data
plane split. For the control plane part a new program called
xdpsock_ctrl_proc is introduced. For the data plane part, some code
was added to xdpsock_user.c to act as the data plane entity.

Application xdpsock_ctrl_proc works as control entity with sudo
privileges (CAP_SYS_ADMIN and CAP_NET_ADMIN are sufficient) and the
extended xdpsock as data plane entity with CAP_NET_RAW capability
only.

Usage example:

sudo ./samples/bpf/xdpsock_ctrl_proc -i <interface>

sudo ./samples/bpf/xdpsock -i <interface> -q <queue_id>
	-n <interval> -N -l -R

Signed-off-by: Mariusz Dudek <mariuszx.dudek@intel.com>
---
 samples/bpf/Makefile            |   4 +-
 samples/bpf/xdpsock.h           |   8 ++
 samples/bpf/xdpsock_ctrl_proc.c | 184 ++++++++++++++++++++++++++++++++
 samples/bpf/xdpsock_user.c      | 146 +++++++++++++++++++++++--
 4 files changed, 332 insertions(+), 10 deletions(-)
 create mode 100644 samples/bpf/xdpsock_ctrl_proc.c

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index aeebf5d12f32..8fb8be1c0144 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -48,6 +48,7 @@ tprogs-y += syscall_tp
 tprogs-y += cpustat
 tprogs-y += xdp_adjust_tail
 tprogs-y += xdpsock
+tprogs-y += xdpsock_ctrl_proc
 tprogs-y += xsk_fwd
 tprogs-y += xdp_fwd
 tprogs-y += task_fd_query
@@ -105,6 +106,7 @@ syscall_tp-objs := syscall_tp_user.o
 cpustat-objs := cpustat_user.o
 xdp_adjust_tail-objs := xdp_adjust_tail_user.o
 xdpsock-objs := xdpsock_user.o
+xdpsock_ctrl_proc-objs := xdpsock_ctrl_proc.o
 xsk_fwd-objs := xsk_fwd.o
 xdp_fwd-objs := xdp_fwd_user.o
 task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS)
@@ -204,7 +206,7 @@ TPROGLDLIBS_tracex4		+= -lrt
 TPROGLDLIBS_trace_output	+= -lrt
 TPROGLDLIBS_map_perf_test	+= -lrt
 TPROGLDLIBS_test_overhead	+= -lrt
-TPROGLDLIBS_xdpsock		+= -pthread
+TPROGLDLIBS_xdpsock		+= -pthread -lcap
 TPROGLDLIBS_xsk_fwd		+= -pthread
 
 # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
diff --git a/samples/bpf/xdpsock.h b/samples/bpf/xdpsock.h
index b7eca15c78cc..fd70cce60712 100644
--- a/samples/bpf/xdpsock.h
+++ b/samples/bpf/xdpsock.h
@@ -8,4 +8,12 @@
 
 #define MAX_SOCKS 4
 
+#define SOCKET_NAME "sock_cal_bpf_fd"
+#define MAX_NUM_OF_CLIENTS 10
+
+#define CLOSE_CONN  1
+
+typedef __u64 u64;
+typedef __u32 u32;
+
 #endif /* XDPSOCK_H */
diff --git a/samples/bpf/xdpsock_ctrl_proc.c b/samples/bpf/xdpsock_ctrl_proc.c
new file mode 100644
index 000000000000..c841aca59a96
--- /dev/null
+++ b/samples/bpf/xdpsock_ctrl_proc.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2017 - 2018 Intel Corporation. */
+
+#include <errno.h>
+#include <getopt.h>
+#include <libgen.h>
+#include <net/if.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include <bpf/bpf.h>
+#include <bpf/xsk.h>
+#include "xdpsock.h"
+
+static const char *opt_if = "";
+
+static struct option long_options[] = {
+	{"interface", required_argument, 0, 'i'},
+	{0, 0, 0, 0}
+};
+
+static void usage(const char *prog)
+{
+	const char *str =
+		"  Usage: %s [OPTIONS]\n"
+		"  Options:\n"
+		"  -i, --interface=n	Run on interface n\n"
+		"\n";
+	fprintf(stderr, "%s\n", str);
+
+	exit(0);
+}
+
+static void parse_command_line(int argc, char **argv)
+{
+	int option_index, c;
+
+	opterr = 0;
+
+	for (;;) {
+		c = getopt_long(argc, argv, "i:",
+				long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'i':
+			opt_if = optarg;
+			break;
+		default:
+			usage(basename(argv[0]));
+		}
+	}
+}
+
+static int send_xsks_map_fd(int sock, int fd)
+{
+	char cmsgbuf[CMSG_SPACE(sizeof(int))];
+	struct msghdr msg;
+	struct iovec iov;
+	int value = 0;
+
+	if (fd == -1) {
+		fprintf(stderr, "Incorrect fd = %d\n", fd);
+		return -1;
+	}
+	iov.iov_base = &value;
+	iov.iov_len = sizeof(int);
+
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	msg.msg_flags = 0;
+	msg.msg_control = cmsgbuf;
+	msg.msg_controllen = CMSG_LEN(sizeof(int));
+
+	struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+	cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+
+	*(int *)CMSG_DATA(cmsg) = fd;
+	int ret = sendmsg(sock, &msg, 0);
+
+	if (ret == -1) {
+		fprintf(stderr, "Sendmsg failed with %s", strerror(errno));
+		return -errno;
+	}
+
+	return ret;
+}
+
+int
+main(int argc, char **argv)
+{
+	struct sockaddr_un server;
+	int listening = 1;
+	int rval, msgsock;
+	int ifindex = 0;
+	int flag = 1;
+	int cmd = 0;
+	int sock;
+	int err;
+	int xsks_map_fd;
+
+	parse_command_line(argc, argv);
+
+	ifindex = if_nametoindex(opt_if);
+	if (ifindex == 0)
+		return -errno;
+
+	sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (sock < 0) {
+		fprintf(stderr, "Opening socket stream failed: %s", strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	server.sun_family = AF_UNIX;
+	strcpy(server.sun_path, SOCKET_NAME);
+
+	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(int));
+
+	if (bind(sock, (struct sockaddr *)&server, sizeof(struct sockaddr_un))) {
+		fprintf(stderr, "Binding to socket stream failed: %s", strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	listen(sock, MAX_NUM_OF_CLIENTS);
+
+	err = xsk_setup_xdp_prog(ifindex, NULL, &xsks_map_fd);
+	if (err) {
+		fprintf(stderr, "Setup of xdp program failed\n");
+		goto close_sock;
+	}
+
+	while (listening) {
+		msgsock = accept(sock, 0, 0);
+		if (msgsock == -1) {
+			fprintf(stderr, "Error accepting connection: %s", strerror(errno));
+			err = -errno;
+			goto close_sock;
+		}
+		err = send_xsks_map_fd(msgsock, xsks_map_fd);
+		if (err <= 0) {
+			fprintf(stderr, "Error %d sending xsks_map_fd\n", err);
+			goto cleanup;
+		}
+		do {
+			rval = read(msgsock, &cmd, sizeof(int));
+			if (rval < 0) {
+				fprintf(stderr, "Error reading stream message");
+			} else {
+				if (cmd != CLOSE_CONN)
+					fprintf(stderr, "Recv unknown cmd = %d\n", cmd);
+				listening = 0;
+				break;
+			}
+		} while (rval > 0);
+	}
+	close(msgsock);
+	close(sock);
+	unlink(SOCKET_NAME);
+
+	/* Unset fd for given ifindex */
+	err = bpf_set_link_xdp_fd(ifindex, -1, 0);
+	if (err) {
+		fprintf(stderr, "Error when unsetting bpf prog_fd for ifindex(%d)\n", ifindex);
+		return err;
+	}
+
+	return 0;
+
+cleanup:
+	close(msgsock);
+close_sock:
+	close(sock);
+	unlink(SOCKET_NAME);
+	return err;
+}
diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index 1149e94ca32f..9f24b940d363 100644
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -24,10 +24,12 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/capability.h>
 #include <sys/mman.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
 #include <sys/types.h>
+#include <sys/un.h>
 #include <time.h>
 #include <unistd.h>
 
@@ -95,6 +97,7 @@ static int opt_timeout = 1000;
 static bool opt_need_wakeup = true;
 static u32 opt_num_xsks = 1;
 static u32 prog_id;
+static bool opt_reduced_cap;
 
 struct xsk_ring_stats {
 	unsigned long rx_npkts;
@@ -153,6 +156,7 @@ struct xsk_socket_info {
 
 static int num_socks;
 struct xsk_socket_info *xsks[MAX_SOCKS];
+int sock;
 
 static unsigned long get_nsecs(void)
 {
@@ -460,6 +464,7 @@ static void *poller(void *arg)
 static void remove_xdp_program(void)
 {
 	u32 curr_prog_id = 0;
+	int cmd = CLOSE_CONN;
 
 	if (bpf_get_link_xdp_id(opt_ifindex, &curr_prog_id, opt_xdp_flags)) {
 		printf("bpf_get_link_xdp_id failed\n");
@@ -471,6 +476,13 @@ static void remove_xdp_program(void)
 		printf("couldn't find a prog id on a given interface\n");
 	else
 		printf("program on interface changed, not removing\n");
+
+	if (opt_reduced_cap) {
+		if (write(sock, &cmd, sizeof(int)) < 0) {
+			fprintf(stderr, "Error writing into stream socket: %s", strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+	}
 }
 
 static void int_exit(int sig)
@@ -853,7 +865,7 @@ static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem,
 	xsk->umem = umem;
 	cfg.rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
 	cfg.tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS;
-	if (opt_num_xsks > 1)
+	if (opt_num_xsks > 1 || opt_reduced_cap)
 		cfg.libbpf_flags = XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD;
 	else
 		cfg.libbpf_flags = 0;
@@ -911,6 +923,7 @@ static struct option long_options[] = {
 	{"quiet", no_argument, 0, 'Q'},
 	{"app-stats", no_argument, 0, 'a'},
 	{"irq-string", no_argument, 0, 'I'},
+	{"reduce-cap", no_argument, 0, 'R'},
 	{0, 0, 0, 0}
 };
 
@@ -933,7 +946,7 @@ static void usage(const char *prog)
 		"  -m, --no-need-wakeup Turn off use of driver need wakeup flag.\n"
 		"  -f, --frame-size=n   Set the frame size (must be a power of two in aligned mode, default is %d).\n"
 		"  -u, --unaligned	Enable unaligned chunk placement\n"
-		"  -M, --shared-umem	Enable XDP_SHARED_UMEM\n"
+		"  -M, --shared-umem	Enable XDP_SHARED_UMEM (cannot be used with -R)\n"
 		"  -F, --force		Force loading the XDP prog\n"
 		"  -d, --duration=n	Duration in secs to run command.\n"
 		"			Default: forever.\n"
@@ -949,6 +962,7 @@ static void usage(const char *prog)
 		"  -Q, --quiet          Do not display any stats.\n"
 		"  -a, --app-stats	Display application (syscall) statistics.\n"
 		"  -I, --irq-string	Display driver interrupt statistics for interface associated with irq-string.\n"
+		"  -R, --reduce-cap	Use reduced capabilities (cannot be used with -M)\n"
 		"\n";
 	fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SIZE,
 		opt_batch_size, MIN_PKT_SIZE, MIN_PKT_SIZE,
@@ -964,7 +978,7 @@ static void parse_command_line(int argc, char **argv)
 	opterr = 0;
 
 	for (;;) {
-		c = getopt_long(argc, argv, "Frtli:q:pSNn:czf:muMd:b:C:s:P:xQaI:",
+		c = getopt_long(argc, argv, "Frtli:q:pSNn:czf:muMd:b:C:s:P:xQaI:R",
 				long_options, &option_index);
 		if (c == -1)
 			break;
@@ -1063,6 +1077,9 @@ static void parse_command_line(int argc, char **argv)
 				usage(basename(argv[0]));
 			}
 
+			break;
+		case 'R':
+			opt_reduced_cap = true;
 			break;
 		default:
 			usage(basename(argv[0]));
@@ -1085,6 +1102,11 @@ static void parse_command_line(int argc, char **argv)
 			opt_xsk_frame_size);
 		usage(basename(argv[0]));
 	}
+
+	if (opt_reduced_cap && opt_num_xsks > 1) {
+		fprintf(stderr, "ERROR: -M and -R cannot be used together\n");
+		usage(basename(argv[0]));
+	}
 }
 
 static void kick_tx(struct xsk_socket_info *xsk)
@@ -1461,26 +1483,117 @@ static void enter_xsks_into_map(struct bpf_object *obj)
 	}
 }
 
+static int recv_xsks_map_fd_from_ctrl_node(int sock, int *_fd)
+{
+	char cms[CMSG_SPACE(sizeof(int))];
+	struct cmsghdr *cmsg;
+	struct msghdr msg;
+	struct iovec iov;
+	int value;
+	int len;
+
+	iov.iov_base = &value;
+	iov.iov_len = sizeof(int);
+
+	msg.msg_name = 0;
+	msg.msg_namelen = 0;
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	msg.msg_flags = 0;
+	msg.msg_control = (caddr_t)cms;
+	msg.msg_controllen = sizeof(cms);
+
+	len = recvmsg(sock, &msg, 0);
+
+	if (len < 0) {
+		fprintf(stderr, "Recvmsg failed length incorrect.\n");
+		return -EINVAL;
+	}
+
+	if (len == 0) {
+		fprintf(stderr, "Recvmsg failed no data\n");
+		return -EINVAL;
+	}
+
+	cmsg = CMSG_FIRSTHDR(&msg);
+	*_fd = *(int *)CMSG_DATA(cmsg);
+
+	return 0;
+}
+
+static int
+recv_xsks_map_fd(int *xsks_map_fd)
+{
+	struct sockaddr_un server;
+	int err;
+
+	sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (sock < 0) {
+		fprintf(stderr, "Error opening socket stream: %s", strerror(errno));
+		return errno;
+	}
+
+	server.sun_family = AF_UNIX;
+	strcpy(server.sun_path, SOCKET_NAME);
+
+	if (connect(sock, (struct sockaddr *)&server, sizeof(struct sockaddr_un)) < 0) {
+		close(sock);
+		fprintf(stderr, "Error connecting stream socket: %s", strerror(errno));
+		return errno;
+	}
+
+	err = recv_xsks_map_fd_from_ctrl_node(sock, xsks_map_fd);
+	if (err) {
+		fprintf(stderr, "Error %d recieving fd\n", err);
+		return err;
+	}
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
+	struct __user_cap_header_struct hdr = { _LINUX_CAPABILITY_VERSION_3, 0 };
+	struct __user_cap_data_struct data[2] = { { 0 } };
 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 	bool rx = false, tx = false;
 	struct xsk_umem_info *umem;
 	struct bpf_object *obj;
+	int xsks_map_fd = 0;
 	pthread_t pt;
 	int i, ret;
 	void *bufs;
 
 	parse_command_line(argc, argv);
 
-	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
-		fprintf(stderr, "ERROR: setrlimit(RLIMIT_MEMLOCK) \"%s\"\n",
-			strerror(errno));
-		exit(EXIT_FAILURE);
+	if (opt_reduced_cap) {
+		if (capget(&hdr, data)  < 0)
+			fprintf(stderr, "Error getting capabilities\n");
+
+		data->effective &= CAP_TO_MASK(CAP_NET_RAW);
+		data->permitted &= CAP_TO_MASK(CAP_NET_RAW);
+
+		if (capset(&hdr, data) < 0)
+			fprintf(stderr, "Setting capabilities failed\n");
+
+		if (capget(&hdr, data)  < 0) {
+			fprintf(stderr, "Error getting capabilities\n");
+		} else {
+			fprintf(stderr, "Capabilities EFF %x Caps INH %x Caps Per %x\n",
+				data[0].effective, data[0].inheritable, data[0].permitted);
+			fprintf(stderr, "Capabilities EFF %x Caps INH %x Caps Per %x\n",
+				data[1].effective, data[1].inheritable, data[1].permitted);
+		}
+	} else {
+		if (setrlimit(RLIMIT_MEMLOCK, &r)) {
+			fprintf(stderr, "ERROR: setrlimit(RLIMIT_MEMLOCK) \"%s\"\n",
+				strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+
+		if (opt_num_xsks > 1)
+			load_xdp_program(argv, &obj);
 	}
 
-	if (opt_num_xsks > 1)
-		load_xdp_program(argv, &obj);
 
 	/* Reserve memory for the umem. Use hugepages if unaligned chunk mode */
 	bufs = mmap(NULL, NUM_FRAMES * opt_xsk_frame_size,
@@ -1512,6 +1625,21 @@ int main(int argc, char **argv)
 	if (opt_num_xsks > 1 && opt_bench != BENCH_TXONLY)
 		enter_xsks_into_map(obj);
 
+	if (opt_reduced_cap) {
+		ret = recv_xsks_map_fd(&xsks_map_fd);
+		if (ret) {
+			fprintf(stderr, "Error %d receiving xsks_map_fd\n", ret);
+			exit_with_error(ret);
+		}
+		if (xsks[0]->xsk) {
+			ret = xsk_socket__update_xskmap(xsks[0]->xsk, xsks_map_fd);
+			if (ret) {
+				fprintf(stderr, "Update of BPF map failed(%d)\n", ret);
+				exit_with_error(ret);
+			}
+		}
+	}
+
 	signal(SIGINT, int_exit);
 	signal(SIGTERM, int_exit);
 	signal(SIGABRT, int_exit);
-- 
2.20.1