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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773299756; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7TP4pcyGvQDh1DUUtvcRt7y8rlEbVtZORgehPcPMHGA=; b=MiN+78PGb56Rt1v45TvmZ03Q0n6BdUYxTyDo+FkLxCWwfVcS7QrobhhDcMYyUgeeW2lqCf tMsZftKIhGAvVLBZlaFsSg6DmfkDur7Gp/aFQ8fB3LMTRluWZkA5gBsxDbLqtngd5l/H+u udc6/fP5oM1tx7vH3v+v6eSBoqh0NHo= X-MC-Unique: 9kIESzKbPmWOpEAJhjSnNw-1 X-Mimecast-MFC-AGG-ID: 9kIESzKbPmWOpEAJhjSnNw_1773299752 From: Cindy Lu To: lulu@redhat.com, mst@redhat.com, jasowang@redhat.com, zhangckid@gmail.com, lizhijian@fujitsu.com, jmarcin@redhat.com, qemu-devel@nongnu.org Subject: [RFC v2 9/9] net/filter-redirector: check CAP_NET_RAW before creating AF_PACKET Date: Thu, 12 Mar 2026 15:09:37 +0800 Message-ID: <20260312071415.1836655-10-lulu@redhat.com> In-Reply-To: <20260312071415.1836655-1-lulu@redhat.com> References: <20260312071415.1836655-1-lulu@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" Creating an AF_PACKET SOCK_RAW socket requires the CAP_NET_RAW capability. Without it the qemu_socket() call fails with EPERM, producing a generic error that gives no hint about the missing capability. Add an explicit capget()-based check in filter_redirector_netdev_setup() before the socket call. Signed-off-by: Cindy Lu --- net/filter-mirror.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/net/filter-mirror.c b/net/filter-mirror.c index dabf52275a..a07ae61b2d 100644 --- a/net/filter-mirror.c +++ b/net/filter-mirror.c @@ -34,6 +34,8 @@ #include #include #include +#include +#include =20 typedef struct MirrorState MirrorState; DECLARE_INSTANCE_CHECKER(MirrorState, FILTER_MIRROR, @@ -690,6 +692,21 @@ static void filter_redirector_maybe_enable_read_poll(N= etFilterState *nf) } } =20 +static bool filter_redirector_has_cap_net_raw(void) +{ + struct __user_cap_header_struct hdr =3D { + .version =3D _LINUX_CAPABILITY_VERSION_3, + .pid =3D 0, + }; + struct __user_cap_data_struct data[2] =3D {}; + + if (syscall(SYS_capget, &hdr, data) < 0) { + return false; + } + + return data[CAP_NET_RAW >> 5].effective & (1u << (CAP_NET_RAW & 31)); +} + static bool filter_redirector_netdev_setup(NetFilterState *nf, Error **err= p) { MirrorState *s =3D FILTER_REDIRECTOR(nf); @@ -724,6 +741,13 @@ static bool filter_redirector_netdev_setup(NetFilterSt= ate *nf, Error **errp) return false; } =20 + if (!filter_redirector_has_cap_net_raw()) { + error_setg(errp, + "AF_PACKET raw socket requires CAP_NET_RAW; " + "run with 'setcap cap_net_raw+ep ' or as r= oot"); + return false; + } + fd =3D qemu_socket(AF_PACKET, SOCK_RAW | SOCK_NONBLOCK, htons(ETH_P_AL= L)); if (fd < 0) { error_setg_errno(errp, errno, "failed to create AF_PACKET socket"); --=20 2.52.0