Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2020-05-15

The following pull-request contains BPF updates for your *net-next* tree.

We've added 37 non-merge commits during the last 1 day(s) which contain
a total of 67 files changed, 741 insertions(+), 252 deletions(-).

The main changes are:

1) bpf_xdp_adjust_tail() now allows to grow the tail as well, from Jesper.

2) bpftool can probe CONFIG_HZ, from Daniel.

3) CAP_BPF is introduced to isolate user processes that use BPF infra and
   to secure BPF networking services by dropping CAP_SYS_ADMIN requirement
   in certain cases, from Alexei.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 33 insertions, 12 deletions

diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 756b63b6f7b3..d2c4d16dadba 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -625,7 +625,7 @@ static int bpf_sk_storage_map_alloc_check(union bpf_attr *attr)
 	    !attr->btf_key_type_id || !attr->btf_value_type_id)
 		return -EINVAL;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!bpf_capable())
 		return -EPERM;
 
 	if (attr->value_size > MAX_VALUE_SIZE)
@@ -978,7 +978,7 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs)
 	/* bpf_sk_storage_map is currently limited to CAP_SYS_ADMIN as
 	 * the map_alloc_check() side also does.
 	 */
-	if (!capable(CAP_SYS_ADMIN))
+	if (!bpf_capable())
 		return ERR_PTR(-EPERM);
 
 	nla_for_each_nested(nla, nla_stgs, rem) {
diff --git a/net/core/dev.c b/net/core/dev.c
index 4c91de39890a..f937a3ff668d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4617,6 +4617,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
 	xdp->data_meta = xdp->data;
 	xdp->data_end = xdp->data + hlen;
 	xdp->data_hard_start = skb->data - skb_headroom(skb);
+
+	/* SKB "head" area always have tailroom for skb_shared_info */
+	xdp->frame_sz  = (void *)skb_end_pointer(skb) - xdp->data_hard_start;
+	xdp->frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+
 	orig_data_end = xdp->data_end;
 	orig_data = xdp->data;
 	eth = (struct ethhdr *)xdp->data;
@@ -4640,14 +4645,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
 		skb_reset_network_header(skb);
 	}
 
-	/* check if bpf_xdp_adjust_tail was used. it can only "shrink"
-	 * pckt.
-	 */
-	off = orig_data_end - xdp->data_end;
+	/* check if bpf_xdp_adjust_tail was used */
+	off = xdp->data_end - orig_data_end;
 	if (off != 0) {
 		skb_set_tail_pointer(skb, xdp->data_end - xdp->data);
-		skb->len -= off;
-
+		skb->len += off; /* positive on grow, negative on shrink */
 	}
 
 	/* check if XDP changed eth hdr such SKB needs update */
diff --git a/net/core/filter.c b/net/core/filter.c
index 5815902bb617..f8a3c7e9d027 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3411,15 +3411,26 @@ static const struct bpf_func_proto bpf_xdp_adjust_head_proto = {
 
 BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset)
 {
+	void *data_hard_end = xdp_data_hard_end(xdp); /* use xdp->frame_sz */
 	void *data_end = xdp->data_end + offset;
 
-	/* only shrinking is allowed for now. */
-	if (unlikely(offset >= 0))
+	/* Notice that xdp_data_hard_end have reserved some tailroom */
+	if (unlikely(data_end > data_hard_end))
 		return -EINVAL;
 
+	/* ALL drivers MUST init xdp->frame_sz, chicken check below */
+	if (unlikely(xdp->frame_sz > PAGE_SIZE)) {
+		WARN_ONCE(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz);
+		return -EINVAL;
+	}
+
 	if (unlikely(data_end < xdp->data + ETH_HLEN))
 		return -EINVAL;
 
+	/* Clear memory area on grow, can contain uninit kernel memory */
+	if (offset > 0)
+		memset(xdp->data_end, 0, offset);
+
 	xdp->data_end = data_end;
 
 	return 0;
@@ -6676,7 +6687,7 @@ static bool cg_skb_is_valid_access(int off, int size,
 		return false;
 	case bpf_ctx_range(struct __sk_buff, data):
 	case bpf_ctx_range(struct __sk_buff, data_end):
-		if (!capable(CAP_SYS_ADMIN))
+		if (!bpf_capable())
 			return false;
 		break;
 	}
@@ -6688,7 +6699,7 @@ static bool cg_skb_is_valid_access(int off, int size,
 		case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]):
 			break;
 		case bpf_ctx_range(struct __sk_buff, tstamp):
-			if (!capable(CAP_SYS_ADMIN))
+			if (!bpf_capable())
 				return false;
 			break;
 		default:
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 4c7ea85486af..490b8f5fa8ee 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/idr.h>
 #include <linux/rhashtable.h>
+#include <linux/bug.h>
 #include <net/page_pool.h>
 
 #include <net/xdp.h>
@@ -496,3 +497,10 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
 	return xdpf;
 }
 EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);
+
+/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
+void xdp_warn(const char *msg, const char *func, const int line)
+{
+	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
+};
+EXPORT_SYMBOL_GPL(xdp_warn);