netdev - [PATCH bpf v2] libbpf: fix to reject unknown flags in xsk_socket_

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Message-Id: <1552381185-4931-1-git-send-email-magnus.karlsson@intel.com>
Date:   Tue, 12 Mar 2019 09:59:45 +0100
From:   Magnus Karlsson <magnus.karlsson@...el.com>
To:     magnus.karlsson@...el.com, bjorn.topel@...el.com,
        maciejromanfijalkowski@...il.com, ast@...nel.org,
        daniel@...earbox.net, netdev@...r.kernel.org
Cc:     andrii.nakryiko@...il.com
Subject: [PATCH bpf v2] libbpf: fix to reject unknown flags in xsk_socket__create()

In xsk_socket__create(), the libbpf_flags field was not checked for
setting currently unused/unknown flags. This patch fixes that by returning
-EINVAL if the user has set any flag that is not in use at this point
in time.

Fixes: 1cad07884239 ("libbpf: add support for using AF_XDP sockets")
Reviewed-by: Andrii Nakryiko <andrii.nakryiko@...il.com>
Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
---
 tools/lib/bpf/xsk.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index f98ac82..8d0078b 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -126,8 +126,8 @@ static void xsk_set_umem_config(struct xsk_umem_config *cfg,
 	cfg->frame_headroom = usr_cfg->frame_headroom;
 }
 
-static void xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
-				      const struct xsk_socket_config *usr_cfg)
+static int xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
+				     const struct xsk_socket_config *usr_cfg)
 {
 	if (!usr_cfg) {
 		cfg->rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
@@ -135,14 +135,19 @@ static void xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
 		cfg->libbpf_flags = 0;
 		cfg->xdp_flags = 0;
 		cfg->bind_flags = 0;
-		return;
+		return 0;
 	}
 
+	if (usr_cfg->libbpf_flags & ~XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)
+		return -EINVAL;
+
 	cfg->rx_size = usr_cfg->rx_size;
 	cfg->tx_size = usr_cfg->tx_size;
 	cfg->libbpf_flags = usr_cfg->libbpf_flags;
 	cfg->xdp_flags = usr_cfg->xdp_flags;
 	cfg->bind_flags = usr_cfg->bind_flags;
+
+	return 0;
 }
 
 int xsk_umem__create(struct xsk_umem **umem_ptr, void *umem_area, __u64 size,
@@ -557,7 +562,9 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
 	}
 	strncpy(xsk->ifname, ifname, IFNAMSIZ);
 
-	xsk_set_xdp_socket_config(&xsk->config, usr_config);
+	err = xsk_set_xdp_socket_config(&xsk->config, usr_config);
+	if (err)
+		goto out_socket;
 
 	if (rx) {
 		err = setsockopt(xsk->fd, SOL_XDP, XDP_RX_RING,
-- 
2.7.4