On Mon, May 01, 2023 at 10:20:58AM +0300, Andrew Melnychenko wrote:
> eBPF RSS program and maps may now be passed during initialization.
> Initially was implemented for libvirt to launch qemu without permissions,
> and initialized eBPF program through the helper.
>
> Signed-off-by: Andrew Melnychenko <and...@daynix.com>
> ---
> hw/net/virtio-net.c | 96 +++++++++++++++++++++++++++++++---
> include/hw/virtio/virtio-net.h | 1 +
> 2 files changed, 91 insertions(+), 6 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 53e1c326433..9b3a997d872 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -42,6 +42,7 @@
> #include "sysemu/sysemu.h"
> #include "trace.h"
> #include "monitor/qdev.h"
> +#include "monitor/monitor.h"
> #include "hw/pci/pci_device.h"
> #include "net_rx_pkt.h"
> #include "hw/virtio/vhost.h"
> @@ -1305,14 +1306,96 @@ static void virtio_net_detach_epbf_rss(VirtIONet *n)
> virtio_net_attach_ebpf_to_backend(n->nic, -1);
> }
>
> -static bool virtio_net_load_ebpf(VirtIONet *n)
> +static int virtio_net_get_ebpf_rss_fds(char *str, char *fds[], int nfds,
> + Error **errp)
> {
> - if (!virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
> - /* backend does't support steering ebpf */
> - return false;
> + char *ptr = str;
> + char *cur = NULL;
> + size_t len = strlen(str);
> + int i = 0;
> +
> + for (; i < nfds && ptr < str + len;) {
> + cur = strchr(ptr, ':');
> +
> + if (cur == NULL) {
> + fds[i] = g_strdup(ptr);
> + } else {
> + fds[i] = g_strndup(ptr, cur - ptr);
> + }
> +
> + i++;
> + if (cur == NULL) {
> + break;
> + } else {
> + ptr = cur + 1;
> + }
> + }
> +
> + if (cur != NULL) {
> + /* the string contains more arguments */
> + error_setg(errp,
> + "Too many eBPF file descriptors for RSS provided.");
> + } else if (i < nfds) {
> + error_setg(errp,
> + "Not enough eBPF file descriptors for RSS were
> provided.");
> + }
> +
> + return i;
> +}
This whole method could be replaced by a call to g_strsplit in
the caller....
> +
> +static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error **errp)
> +{
> + char *fds_strs[EBPF_RSS_MAX_FDS];
g_autoptr(GStrv) fds_strs = g_strsplit(n->ebpf_rss_fds, ",", 0);
> + int fds[EBPF_RSS_MAX_FDS];
Left as uninitialized stack memory.
> + int nfds;
> + int ret = true;
> + int i = 0;
> +
> + ERRP_GUARD();
> +
> + nfds = virtio_net_get_ebpf_rss_fds(n->ebpf_rss_fds,
> + fds_strs, EBPF_RSS_MAX_FDS, errp);
> + if (*errp) {
> + ret = false;
> + goto exit;
> }
Replace with
if (g_strv_length(fds_strs) != EBPF_RSS_MAX_FDS) {
error_setg(errp,
"Expected %d file descriptors but got %d",
EBPF_RSS_MAX_FDS, g_strv_length(fds_strs));
return false;
}
>
> - return ebpf_rss_load(&n->ebpf_rss);
> + for (i = 0; i < nfds; i++) {
> + fds[i] = monitor_fd_param(monitor_cur(), fds_strs[i], errp);
> + if (*errp) {
> + ret = false;
> + goto exit;
This can break out of the loop before all elements in 'fds' are
initialized.
> + }
> + }
> +
> + ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]);
> +
> +exit:
> + if (!ret || *errp) {
> + for (i = 0; i < nfds; i++) {
> + close(fds[i]);
> + }
> + }
This now calls close() on uninitialized memory, killing
arbitary FDs QEMU has open elsewhere.
> +
> + for (i = 0; i < nfds; i++) {
> + g_free(fds_strs[i]);
> + }
Not required if we use g_autoptr(GStrv)
> +
> + return ret;
> +}
> +
> +static bool virtio_net_load_ebpf(VirtIONet *n, Error **errp)
> +{
> + bool ret = false;
> +
> + if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
> + if (!(n->ebpf_rss_fds
> + && virtio_net_load_ebpf_fds(n, errp))) {
> + ret = ebpf_rss_load(&n->ebpf_rss);
> + }
> + }
> +
> + return ret;
> }
>
> static void virtio_net_unload_ebpf(VirtIONet *n)
> @@ -3738,7 +3821,7 @@ static void virtio_net_device_realize(DeviceState *dev,
> Error **errp)
> net_rx_pkt_init(&n->rx_pkt);
>
> if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) {
> - virtio_net_load_ebpf(n);
> + virtio_net_load_ebpf(n, errp);
> }
> }
>
> @@ -3900,6 +3983,7 @@ static Property virtio_net_properties[] = {
> VIRTIO_NET_F_RSS, false),
> DEFINE_PROP_BIT64("hash", VirtIONet, host_features,
> VIRTIO_NET_F_HASH_REPORT, false),
> + DEFINE_PROP_STRING("ebpf_rss_fds", VirtIONet, ebpf_rss_fds),
> DEFINE_PROP_BIT64("guest_rsc_ext", VirtIONet, host_features,
> VIRTIO_NET_F_RSC_EXT, false),
> DEFINE_PROP_UINT32("rsc_interval", VirtIONet, rsc_timeout,
> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
> index ef234ffe7ef..e10ce88f918 100644
> --- a/include/hw/virtio/virtio-net.h
> +++ b/include/hw/virtio/virtio-net.h
> @@ -219,6 +219,7 @@ struct VirtIONet {
> VirtioNetRssData rss_data;
> struct NetRxPkt *rx_pkt;
> struct EBPFRSSContext ebpf_rss;
> + char *ebpf_rss_fds;
> };
>
> size_t virtio_net_handle_ctrl_iov(VirtIODevice *vdev,
> --
> 2.39.1
>
With regards,
Daniel
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