bpf: Add support for XDP programs in DEVMAP entries

PATCH Superseded David Ahern 4 participants 13 messages May 29, 2020

Subsystems (9)

Networking Network drivers Kselftest BPF +5 more subsystems

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David Ahern

author

2020-05-29 05:21 UTC #0 lore raw

v3 cover bpf: Add support for XDP programs in DEVMAP entries

Implementation of Daniel's proposal for allowing DEVMAP entries to be a device index, program fd pair.

Programs are run after XDP_REDIRECT and have access to both Rx device and Tx device.

v3
- renamed struct to bpf_devmap_val
- used offsetofend to check for expected map size, modification of Toke's comment
- check for explicit value sizes
- adjusted switch statement in dev_map_run_prog per Andrii's comment
- changed SEC shortcut to xdp_devmap
- changed selftests to use skeleton and new map declaration

v2
- moved dev_map_ext_val definition to uapi to formalize the API for devmap extensions; add bpf_ prefix to the prog_fd and prog_id entries
- changed devmap code to handle struct in a way that it can support future extensions
- fixed subject in libbpf patch

v1
- fixed prog put on invalid program - Toke
- changed write value from id to fd per Toke's comments about capabilities
- add test cases

David Ahern (5):
devmap: Formalize map value as a named struct
bpf: Add support to attach bpf program to a devmap entry
xdp: Add xdp_txq_info to xdp_buff
libbpf: Add SEC name for xdp programs attached to device map
selftest: Add tests for XDP programs in devmap entries

 include/linux/bpf.h                           |   5 +
 include/net/xdp.h                             |   5 +
 include/uapi/linux/bpf.h                      |  12 ++
 kernel/bpf/devmap.c                           | 121 +++++++++++++++---
 net/core/dev.c                                |  18 +++
 net/core/filter.c                             |  17 +++
 tools/include/uapi/linux/bpf.h                |  12 ++
 tools/lib/bpf/libbpf.c                        |   2 +
 .../bpf/prog_tests/xdp_devmap_attach.c        |  89 +++++++++++++
 .../bpf/progs/test_xdp_devmap_helpers.c       |  22 ++++
 .../bpf/progs/test_xdp_with_devmap_helpers.c  |  43 +++++++
 11 files changed, 328 insertions(+), 18 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c

Signature · 1 line

2.21.1 (Apple Git-122.3)

David Ahern

author

2020-05-29 05:21 UTC #1 lore raw

PATCH v3 1/5 devmap: Formalize map value as a named struct

Add 'struct bpf_devmap_val' to the bpf uapi to formalize the expected values that can be passed in for a DEVMAP. Update devmap code to use the struct.

Signed-off-by David Ahern <[email protected]>

---
 include/uapi/linux/bpf.h       |  5 +++++
 kernel/bpf/devmap.c            | 40 +++++++++++++++++++---------------
 tools/include/uapi/linux/bpf.h |  5 +++++
 3 files changed, 33 insertions(+), 17 deletions(-)

include/uapi/linux/bpf.h +5 -0

index 54b93f8b49b8..42c884dfbad9 100644
@@ -3625,6 +3625,11 @@ struct xdp_md {
 	__u32 rx_queue_index;  /* rxq->queue_index  */
 };
 
+/* DEVMAP values */
+struct bpf_devmap_val {
+	__u32 ifindex;   /* device index */
+};
+
 enum sk_action {
 	SK_DROP = 0,
 	SK_PASS,

kernel/bpf/devmap.c +23 ~~-17~~

index a51d9fb7a359..2887fe6d1e1d 100644
@@ -66,6 +66,7 @@ struct bpf_dtab_netdev {
 	struct bpf_dtab *dtab;
 	struct rcu_head rcu;
 	unsigned int idx;
+	struct bpf_devmap_val val;
 };
 
 struct bpf_dtab {

@@ -472,18 +473,15 @@ int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 {
 	struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
-	struct net_device *dev = obj ? obj->dev : NULL;
 
-	return dev ? &dev->ifindex : NULL;
+	return obj ? &obj->val : NULL;
 }
 
 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
 {
 	struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
 								*(u32 *)key);
-	struct net_device *dev = obj ? obj->dev : NULL;
-
-	return dev ? &dev->ifindex : NULL;
+	return obj ? &obj->val : NULL;
 }
 
 static void __dev_map_entry_free(struct rcu_head *rcu)

@@ -541,7 +539,7 @@ static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
 
 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 						    struct bpf_dtab *dtab,
-						    u32 ifindex,
+						    struct bpf_devmap_val *val,
 						    unsigned int idx)
 {
 	struct bpf_dtab_netdev *dev;

@@ -551,16 +549,18 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
-	dev->dev = dev_get_by_index(net, ifindex);
-	if (!dev->dev) {
-		kfree(dev);
-		return ERR_PTR(-EINVAL);
-	}
+	dev->dev = dev_get_by_index(net, val->ifindex);
+	if (!dev->dev)
+		goto err_out;
 
 	dev->idx = idx;
 	dev->dtab = dtab;
+	dev->val.ifindex = val->ifindex;
 
 	return dev;
+err_out:
+	kfree(dev);
+	return ERR_PTR(-EINVAL);
 }
 
 static int __dev_map_update_elem(struct net *net, struct bpf_map *map,

@@ -568,7 +568,7 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 {
 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 	struct bpf_dtab_netdev *dev, *old_dev;
-	u32 ifindex = *(u32 *)value;
+	struct bpf_devmap_val val = { };
 	u32 i = *(u32 *)key;
 
 	if (unlikely(map_flags > BPF_EXIST))

@@ -578,10 +578,13 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 	if (unlikely(map_flags == BPF_NOEXIST))
 		return -EEXIST;
 
-	if (!ifindex) {
+	/* already verified value_size <= sizeof val */
+	memcpy(&val, value, map->value_size);
+
+	if (!val.ifindex) {
 		dev = NULL;
 	} else {
-		dev = __dev_map_alloc_node(net, dtab, ifindex, i);
+		dev = __dev_map_alloc_node(net, dtab, &val, i);
 		if (IS_ERR(dev))
 			return PTR_ERR(dev);
 	}

@@ -609,12 +612,15 @@ static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 {
 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 	struct bpf_dtab_netdev *dev, *old_dev;
-	u32 ifindex = *(u32 *)value;
+	struct bpf_devmap_val val = { };
 	u32 idx = *(u32 *)key;
 	unsigned long flags;
 	int err = -EEXIST;
 
-	if (unlikely(map_flags > BPF_EXIST || !ifindex))
+	/* already verified value_size <= sizeof val */
+	memcpy(&val, value, map->value_size);
+
+	if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
 		return -EINVAL;
 
 	spin_lock_irqsave(&dtab->index_lock, flags);

@@ -623,7 +629,7 @@ static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 	if (old_dev && (map_flags & BPF_NOEXIST))
 		goto out_err;
 
-	dev = __dev_map_alloc_node(net, dtab, ifindex, idx);
+	dev = __dev_map_alloc_node(net, dtab, &val, idx);
 	if (IS_ERR(dev)) {
 		err = PTR_ERR(dev);
 		goto out_err;

tools/include/uapi/linux/bpf.h +5 -0

index 54b93f8b49b8..42c884dfbad9 100644
@@ -3625,6 +3625,11 @@ struct xdp_md {
 	__u32 rx_queue_index;  /* rxq->queue_index  */
 };
 
+/* DEVMAP values */
+struct bpf_devmap_val {
+	__u32 ifindex;   /* device index */
+};
+
 enum sk_action {
 	SK_DROP = 0,
 	SK_PASS,

Signature · 1 line

2.21.1 (Apple Git-122.3)

David Ahern

author

2020-05-29 05:21 UTC #5 lore raw

PATCH v3 2/5 bpf: Add support to attach bpf program to a devmap entry

In reply to David Ahern

Add BPF_XDP_DEVMAP attach type for use with programs associated with a DEVMAP entry.

Allow DEVMAPs to associate a program with a device entry by adding a bpf_prog_fd to 'struct bpf_devmap_val'. Values read show the program id, so the fd and id are a union.

The program associated with the fd must have type XDP with expected attach type BPF_XDP_DEVMAP. When a program is associated with a device index, the program is run on an XDP_REDIRECT and before the buffer is added to the per-cpu queue. At this point rxq data is still valid; the next patch adds tx device information allowing the prorgam to see both ingress and egress device indices.

XDP generic is skb based and XDP programs do not work with skb's. Block the use case by walking maps used by a program that is to be attached via xdpgeneric and fail if any of them are DEVMAP / DEVMAP_HASH with

Quoted 1 line

4-byte values.

Block attach of BPF_XDP_DEVMAP programs to devices.

Signed-off-by David Ahern <[email protected]>

---
 include/linux/bpf.h            |  5 ++
 include/uapi/linux/bpf.h       |  5 ++
 kernel/bpf/devmap.c            | 84 ++++++++++++++++++++++++++++++++--
 net/core/dev.c                 | 18 ++++++++
 tools/include/uapi/linux/bpf.h |  5 ++
 5 files changed, 113 insertions(+), 4 deletions(-)

include/linux/bpf.h +5 -0

index efe8836b5c48..088751bc09aa 100644
@@ -1242,6 +1242,7 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
 		    struct net_device *dev_rx);
 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 			     struct bpf_prog *xdp_prog);
+bool dev_map_can_have_prog(struct bpf_map *map);
 
 struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
 void __cpu_map_flush(void);

@@ -1355,6 +1356,10 @@ static inline struct net_device  *__dev_map_hash_lookup_elem(struct bpf_map *map
 {
 	return NULL;
 }
+static inline bool dev_map_can_have_prog(struct bpf_map *map)
+{
+	return false;
+}
 
 static inline void __dev_flush(void)
 {

include/uapi/linux/bpf.h +5 -0

index 42c884dfbad9..02177049cf66 100644
@@ -224,6 +224,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_GETPEERNAME,
 	BPF_CGROUP_INET4_GETSOCKNAME,
 	BPF_CGROUP_INET6_GETSOCKNAME,
+	BPF_XDP_DEVMAP,
 	__MAX_BPF_ATTACH_TYPE
 };

@@ -3628,6 +3629,10 @@ struct xdp_md {
 /* DEVMAP values */
 struct bpf_devmap_val {
 	__u32 ifindex;   /* device index */
+	union {
+		int   bpf_prog_fd;  /* prog fd on map write */
+		__u32 bpf_prog_id;  /* prog id on map read */
+	};
 };
 
 enum sk_action {

kernel/bpf/devmap.c +80 -4

173 lines not on this page · raw message

net/core/dev.c +18 -0

index ae37586f6ee8..10684833f864 100644
@@ -5420,6 +5420,18 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
 	struct bpf_prog *new = xdp->prog;
 	int ret = 0;
 
+	if (new) {
+		u32 i;
+
+		/* generic XDP does not work with DEVMAPs that can
+		 * have a bpf_prog installed on an entry
+		 */
+		for (i = 0; i < new->aux->used_map_cnt; i++) {
+			if (dev_map_can_have_prog(new->aux->used_maps[i]))
+				return -EINVAL;
+		}
+	}
+
 	switch (xdp->command) {
 	case XDP_SETUP_PROG:
 		rcu_assign_pointer(dev->xdp_prog, new);

@@ -8835,6 +8847,12 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 			return -EINVAL;
 		}
 
+		if (prog->expected_attach_type == BPF_XDP_DEVMAP) {
+			NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP programs can not be attached to a device");
+			bpf_prog_put(prog);
+			return -EINVAL;
+		}
+
 		/* prog->aux->id may be 0 for orphaned device-bound progs */
 		if (prog->aux->id && prog->aux->id == prog_id) {
 			bpf_prog_put(prog);

tools/include/uapi/linux/bpf.h +5 -0

index 42c884dfbad9..02177049cf66 100644
@@ -224,6 +224,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_GETPEERNAME,
 	BPF_CGROUP_INET4_GETSOCKNAME,
 	BPF_CGROUP_INET6_GETSOCKNAME,
+	BPF_XDP_DEVMAP,
 	__MAX_BPF_ATTACH_TYPE
 };

@@ -3628,6 +3629,10 @@ struct xdp_md {
 /* DEVMAP values */
 struct bpf_devmap_val {
 	__u32 ifindex;   /* device index */
+	union {
+		int   bpf_prog_fd;  /* prog fd on map write */
+		__u32 bpf_prog_id;  /* prog id on map read */
+	};
 };
 
 enum sk_action {

Signature · 1 line

2.21.1 (Apple Git-122.3)

David Ahern

author

2020-05-29 05:21 UTC #8 lore raw

PATCH v3 5/5 selftest: Add tests for XDP programs in devmap entries

In reply to David Ahern

Add tests to verify ability to add an XDP program to a entry in a DEVMAP.

Add negative tests to show DEVMAP programs can not be attached to devices as a normal XDP program, and accesses to egress_ifindex require BPF_XDP_DEVMAP attach type.

Signed-off-by David Ahern <[email protected]>

---
 .../bpf/prog_tests/xdp_devmap_attach.c        | 89 +++++++++++++++++++
 .../bpf/progs/test_xdp_devmap_helpers.c       | 22 +++++
 .../bpf/progs/test_xdp_with_devmap_helpers.c  | 43 +++++++++
 3 files changed, 154 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c

tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c new file +89 -0

new file mode 100644
index 000000000000..caeea19f2772
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <uapi/linux/bpf.h>
+#include <linux/if_link.h>
+#include <test_progs.h>
+
+#include "test_xdp_devmap_helpers.skel.h"
+#include "test_xdp_with_devmap_helpers.skel.h"
+
+#define IFINDEX_LO 1
+
+void test_xdp_with_devmap_helpers(void)
+{
+	struct test_xdp_with_devmap_helpers *skel;
+	struct bpf_prog_info info = {};
+	struct bpf_devmap_val val = {
+		.ifindex = IFINDEX_LO,
+	};
+	__u32 id, len = sizeof(info);
+	__u32 duration, idx = 0;
+	int err, dm_fd, map_fd;
+
+
+	skel = test_xdp_with_devmap_helpers__open_and_load();
+	if (CHECK_FAIL(!skel)) {
+		perror("test_xdp_with_devmap_helpers__open_and_load");
+		return;
+	}
+
+	/* can not attach program with DEVMAPs that allow programs
+	 * as xdp generic
+	 */
+	dm_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
+	err = bpf_set_link_xdp_fd(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE);
+	CHECK(err == 0, "Generic attach of program with 8-byte devmap",
+	      "should have failed\n");
+
+	dm_fd = bpf_program__fd(skel->progs.xdp_dummy_dm);
+	map_fd = bpf_map__fd(skel->maps.dm_ports);
+	err = bpf_obj_get_info_by_fd(dm_fd, &info, &len);
+	if (CHECK_FAIL(err))
+		goto out_close;
+
+	val.bpf_prog_fd = dm_fd;
+	err = bpf_map_update_elem(map_fd, &idx, &val, 0);
+	CHECK(err, "Add program to devmap entry",
+	      "err %d errno %d\n", err, errno);
+
+	err = bpf_map_lookup_elem(map_fd, &id, &val);
+	CHECK(err, "Read devmap entry", "err %d errno %d\n", err, errno);
+	CHECK(info.id != val.bpf_prog_id, "Expected program id in devmap entry",
+	      "expected %u read %u\n", info.id, val.bpf_prog_id);
+
+	/* can not attach BPF_XDP_DEVMAP program to a device */
+	err = bpf_set_link_xdp_fd(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE);
+	CHECK(err == 0, "Attach of BPF_XDP_DEVMAP program",
+	      "should have failed\n");
+
+	val.ifindex = 1;
+	val.bpf_prog_fd = bpf_program__fd(skel->progs.xdp_dummy_prog);
+	err = bpf_map_update_elem(map_fd, &idx, &val, 0);
+	CHECK(err == 0, "Add non-BPF_XDP_DEVMAP program to devmap entry",
+	      "should have failed\n");
+
+out_close:
+	test_xdp_with_devmap_helpers__destroy(skel);
+}
+
+void test_neg_xdp_devmap_helpers(void)
+{
+	struct test_xdp_devmap_helpers *skel;
+	__u32 duration;
+
+	skel = test_xdp_devmap_helpers__open_and_load();
+	if (CHECK(skel,
+		  "Load of XDP program accessing egress ifindex without attach type",
+		  "should have failed\n")) {
+		test_xdp_devmap_helpers__destroy(skel);
+	}
+}
+
+
+void test_xdp_devmap_attach(void)
+{
+	if (test__start_subtest("DEVMAP with programs in entries"))
+		test_xdp_with_devmap_helpers();
+
+	if (test__start_subtest("Verifier check of DEVMAP programs"))
+		test_neg_xdp_devmap_helpers();
+}

tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +22 -0

new file mode 100644
index 000000000000..b360ba2bd441
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/* fails to load without expected_attach_type = BPF_XDP_DEVMAP
+ * because of access to egress_ifindex
+ */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp_dm_log")
+int xdpdm_devlog(struct xdp_md *ctx)
+{
+	char fmt[] = "devmap redirect: dev %u -> dev %u len %u\n";
+	void *data_end = (void *)(long)ctx->data_end;
+	void *data = (void *)(long)ctx->data;
+	unsigned int len = data_end - data;
+
+	bpf_trace_printk(fmt, sizeof(fmt),
+			 ctx->ingress_ifindex, ctx->egress_ifindex, len);
+
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c new file +43 -0

43 lines not on this page · raw message

Signature · 1 line

2.21.1 (Apple Git-122.3)

David Ahern

author

2020-05-29 05:21 UTC #6 lore raw

PATCH v3 3/5 xdp: Add xdp_txq_info to xdp_buff

In reply to David Ahern

Add xdp_txq_info as the Tx counterpart to xdp_rxq_info. At the moment only the device is added. Other fields (queue_index) can be added as use cases arise.

From a UAPI perspective, add egress_ifindex to xdp context for bpf programs to see the Tx device.

Update the verifier to only allow accesses to egress_ifindex by XDP programs with BPF_XDP_DEVMAP expected attach type.

Signed-off-by David Ahern <[email protected]>

---
 include/net/xdp.h              |  5 +++++
 include/uapi/linux/bpf.h       |  2 ++
 kernel/bpf/devmap.c            |  3 +++
 net/core/filter.c              | 17 +++++++++++++++++
 tools/include/uapi/linux/bpf.h |  2 ++
 5 files changed, 29 insertions(+)

include/net/xdp.h +5 -0

index 90f11760bd12..d54022959491 100644
@@ -61,12 +61,17 @@ struct xdp_rxq_info {
 	struct xdp_mem_info mem;
 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
 
+struct xdp_txq_info {
+	struct net_device *dev;
+};
+
 struct xdp_buff {
 	void *data;
 	void *data_end;
 	void *data_meta;
 	void *data_hard_start;
 	struct xdp_rxq_info *rxq;
+	struct xdp_txq_info *txq;
 	u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
 };

include/uapi/linux/bpf.h +2 -0

index 02177049cf66..61ae81bf67de 100644
@@ -3624,6 +3624,8 @@ struct xdp_md {
 	/* Below access go through struct xdp_rxq_info */
 	__u32 ingress_ifindex; /* rxq->dev->ifindex */
 	__u32 rx_queue_index;  /* rxq->queue_index  */
+
+	__u32 egress_ifindex;  /* txq->dev->ifindex */
 };
 
 /* DEVMAP values */

kernel/bpf/devmap.c +3 -0

index 3152151d3bb8..defdd22caa4b 100644
@@ -467,8 +467,11 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
 					 struct xdp_buff *xdp,
 					 struct bpf_prog *xdp_prog)
 {
+	struct xdp_txq_info txq = { .dev = dev };
 	u32 act;
 
+	xdp->txq = &txq;
+
 	act = bpf_prog_run_xdp(xdp_prog, xdp);
 	switch (act) {
 	case XDP_PASS:

net/core/filter.c +17 -0

index a6fc23447f12..2e9dbfd8e60c 100644
@@ -7014,6 +7014,13 @@ static bool xdp_is_valid_access(int off, int size,
 				const struct bpf_prog *prog,
 				struct bpf_insn_access_aux *info)
 {
+	if (prog->expected_attach_type != BPF_XDP_DEVMAP) {
+		switch (off) {
+		case offsetof(struct xdp_md, egress_ifindex):
+			return false;
+		}
+	}
+
 	if (type == BPF_WRITE) {
 		if (bpf_prog_is_dev_bound(prog->aux)) {
 			switch (off) {

@@ -7967,6 +7974,16 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type,
 				      offsetof(struct xdp_rxq_info,
 					       queue_index));
 		break;
+	case offsetof(struct xdp_md, egress_ifindex):
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, txq),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct xdp_buff, txq));
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_txq_info, dev),
+				      si->dst_reg, si->dst_reg,
+				      offsetof(struct xdp_txq_info, dev));
+		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
+				      offsetof(struct net_device, ifindex));
+		break;
 	}
 
 	return insn - insn_buf;

tools/include/uapi/linux/bpf.h +2 -0

index 02177049cf66..61ae81bf67de 100644
@@ -3624,6 +3624,8 @@ struct xdp_md {
 	/* Below access go through struct xdp_rxq_info */
 	__u32 ingress_ifindex; /* rxq->dev->ifindex */
 	__u32 rx_queue_index;  /* rxq->queue_index  */
+
+	__u32 egress_ifindex;  /* txq->dev->ifindex */
 };
 
 /* DEVMAP values */

Signature · 1 line

2.21.1 (Apple Git-122.3)

David Ahern

author

2020-05-29 05:21 UTC #7 lore raw

PATCH v3 4/5 libbpf: Add SEC name for xdp programs attached to device map

In reply to David Ahern

Support SEC("xdp_devmap*") as a short cut for loading the program with type BPF_PROG_TYPE_XDP and expected attach type BPF_XDP_DEVMAP.

Signed-off-by David Ahern <[email protected]>

---
 tools/lib/bpf/libbpf.c | 2 ++
 1 file changed, 2 insertions(+)

tools/lib/bpf/libbpf.c +2 -0

index 74d967619dcf..85d4f1c5fc52 100644
@@ -6657,6 +6657,8 @@ static const struct bpf_sec_def section_defs[] = {
 		.expected_attach_type = BPF_TRACE_ITER,
 		.is_attach_btf = true,
 		.attach_fn = attach_iter),
+	BPF_EAPROG_SEC("xdp_devmap",		BPF_PROG_TYPE_XDP,
+						BPF_XDP_DEVMAP),
 	BPF_PROG_SEC("xdp",			BPF_PROG_TYPE_XDP),
 	BPF_PROG_SEC("perf_event",		BPF_PROG_TYPE_PERF_EVENT),
 	BPF_PROG_SEC("lwt_in",			BPF_PROG_TYPE_LWT_IN),

Signature · 1 line

2.21.1 (Apple Git-122.3)

Jesper Dangaard Brouer

2020-05-29 08:23 UTC #2 lore raw

Re: [PATCH v3 bpf-next 1/5] devmap: Formalize map value as a named struct

In reply to David Ahern

Quoted 16 lines · On Thu, 28 May 2020 23:20:53 -0600 David Ahern <[email protected]> wrote:

Add 'struct bpf_devmap_val' to the bpf uapi to formalize the expected values that can be passed in for a DEVMAP. Update devmap code to use the struct.
Signed-off-by David Ahern <[email protected]>
---
 include/uapi/linux/bpf.h       |  5 +++++
 kernel/bpf/devmap.c            | 40 +++++++++++++++++++---------------
 tools/include/uapi/linux/bpf.h |  5 +++++
 3 files changed, 33 insertions(+), 17 deletions(-)
include/uapi/linux/bpf.h +0 -0
index 54b93f8b49b8..42c884dfbad9 100644

include/uapi/linux/bpf.h struct xdp_md { · line 3631

Quoted 7 lines

include/uapi/linux/bpf.h +4 -0

@@ -3625,6 +3625,11 @@ struct xdp_md {
 	__u32 rx_queue_index;  /* rxq->queue_index  */
 };
 
+/* DEVMAP values */
+struct bpf_devmap_val {
+	__u32 ifindex;   /* device index */
+};

We do need this struct bpf_devmap_val, but I think it is wrong to make this UAPI.

A BPF-prog can get this via: #include "vmlinux.h"

Signature · 4 lines

Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

David Ahern

2020-05-29 15:36 UTC #3 lore raw

Re: [PATCH v3 bpf-next 1/5] devmap: Formalize map value as a named struct

Quoted 3 lines · Jesper Dangaard Brouer

We do need this struct bpf_devmap_val, but I think it is wrong to make this UAPI.
A BPF-prog can get this via: #include "vmlinux.h"

sure. I see that now.

I forgot to fold in a small update to the selftests, so I need to send a v4 anyways. I will wait until later in the day in case there are other comments.

Jesper Dangaard Brouer

2020-05-29 16:03 UTC #4 lore raw

Re: [PATCH v3 bpf-next 1/5] devmap: Formalize map value as a named struct

Quoted 10 lines · On Fri, 29 May 2020 09:36:14 -0600 David Ahern <[email protected]> wrote:

Quoted 3 lines · Jesper Dangaard Brouer
We do need this struct bpf_devmap_val, but I think it is wrong to make this UAPI.
A BPF-prog can get this via: #include "vmlinux.h"
sure. I see that now.
I forgot to fold in a small update to the selftests, so I need to send a v4 anyways. I will wait until later in the day in case there are other comments.

I've just posted a patchset on top of this V3, that moves struct bpf_devmap_val, and that demonstrate via code that I mean by leveraging BTF for dynamic config API.

https://lore.kernel.org/netdev/159076794319.1387573.8722376887638960093.stgit@firesoul/

Signature · 4 lines

Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Toke Høiland-Jørgensen

2020-05-29 16:45 UTC #9 lore raw

Re: [PATCH v3 bpf-next 5/5] selftest: Add tests for XDP programs in devmap entries

In reply to David Ahern

Quoted 118 lines · David Ahern

Add tests to verify ability to add an XDP program to a entry in a DEVMAP.

Add negative tests to show DEVMAP programs can not be attached to devices as a normal XDP program, and accesses to egress_ifindex require BPF_XDP_DEVMAP attach type.

Signed-off-by David Ahern <[email protected]>

---
 .../bpf/prog_tests/xdp_devmap_attach.c        | 89 +++++++++++++++++++
 .../bpf/progs/test_xdp_devmap_helpers.c       | 22 +++++
 .../bpf/progs/test_xdp_with_devmap_helpers.c  | 43 +++++++++
 3 files changed, 154 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_with_devmap_helpers.c

tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c new file +89 -0

new file mode 100644
index 000000000000..caeea19f2772
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <uapi/linux/bpf.h>
+#include <linux/if_link.h>
+#include <test_progs.h>
+
+#include "test_xdp_devmap_helpers.skel.h"
+#include "test_xdp_with_devmap_helpers.skel.h"
+
+#define IFINDEX_LO 1
+
+void test_xdp_with_devmap_helpers(void)
+{
+	struct test_xdp_with_devmap_helpers *skel;
+	struct bpf_prog_info info = {};
+	struct bpf_devmap_val val = {
+		.ifindex = IFINDEX_LO,
+	};
+	__u32 id, len = sizeof(info);
+	__u32 duration, idx = 0;
+	int err, dm_fd, map_fd;
+
+
+	skel = test_xdp_with_devmap_helpers__open_and_load();
+	if (CHECK_FAIL(!skel)) {
+		perror("test_xdp_with_devmap_helpers__open_and_load");
+		return;
+	}
+
+	/* can not attach program with DEVMAPs that allow programs
+	 * as xdp generic
+	 */
+	dm_fd = bpf_program__fd(skel->progs.xdp_redir_prog);
+	err = bpf_set_link_xdp_fd(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE);
+	CHECK(err == 0, "Generic attach of program with 8-byte devmap",
+	      "should have failed\n");
+
+	dm_fd = bpf_program__fd(skel->progs.xdp_dummy_dm);
+	map_fd = bpf_map__fd(skel->maps.dm_ports);
+	err = bpf_obj_get_info_by_fd(dm_fd, &info, &len);
+	if (CHECK_FAIL(err))
+		goto out_close;
+
+	val.bpf_prog_fd = dm_fd;
+	err = bpf_map_update_elem(map_fd, &idx, &val, 0);
+	CHECK(err, "Add program to devmap entry",
+	      "err %d errno %d\n", err, errno);
+
+	err = bpf_map_lookup_elem(map_fd, &id, &val);
+	CHECK(err, "Read devmap entry", "err %d errno %d\n", err, errno);
+	CHECK(info.id != val.bpf_prog_id, "Expected program id in devmap entry",
+	      "expected %u read %u\n", info.id, val.bpf_prog_id);
+
+	/* can not attach BPF_XDP_DEVMAP program to a device */
+	err = bpf_set_link_xdp_fd(IFINDEX_LO, dm_fd, XDP_FLAGS_SKB_MODE);
+	CHECK(err == 0, "Attach of BPF_XDP_DEVMAP program",
+	      "should have failed\n");
+
+	val.ifindex = 1;
+	val.bpf_prog_fd = bpf_program__fd(skel->progs.xdp_dummy_prog);
+	err = bpf_map_update_elem(map_fd, &idx, &val, 0);
+	CHECK(err == 0, "Add non-BPF_XDP_DEVMAP program to devmap entry",
+	      "should have failed\n");
+
+out_close:
+	test_xdp_with_devmap_helpers__destroy(skel);
+}
+
+void test_neg_xdp_devmap_helpers(void)
+{
+	struct test_xdp_devmap_helpers *skel;
+	__u32 duration;
+
+	skel = test_xdp_devmap_helpers__open_and_load();
+	if (CHECK(skel,
+		  "Load of XDP program accessing egress ifindex without attach type",
+		  "should have failed\n")) {
+		test_xdp_devmap_helpers__destroy(skel);
+	}
+}
+
+
+void test_xdp_devmap_attach(void)
+{
+	if (test__start_subtest("DEVMAP with programs in entries"))
+		test_xdp_with_devmap_helpers();
+
+	if (test__start_subtest("Verifier check of DEVMAP programs"))
+		test_neg_xdp_devmap_helpers();
+}

tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +0 -0

new file mode 100644
index 000000000000..b360ba2bd441

tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c line 8

Quoted 8 lines

tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +8 -0

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/* fails to load without expected_attach_type = BPF_XDP_DEVMAP
+ * because of access to egress_ifindex
+ */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp_dm_log")

Guess this should be xdp_devmap_log now?

-Toke

Toke Høiland-Jørgensen

Acked-by on the v3 series

2020-05-29 16:46 UTC #12 lore raw

In reply to David Ahern

Quoted 5 lines · David Ahern

Implementation of Daniel's proposal for allowing DEVMAP entries to be a device index, program fd pair.
Programs are run after XDP_REDIRECT and have access to both Rx device and Tx device.

Found one more nit apart from the changes you already said you'd do for v4. So with those fixes, feel free to add my:

Acked-by Toke Høiland-Jørgensen <[email protected]>

David Ahern

2020-05-29 16:48 UTC #10 lore raw

Re: [PATCH v3 bpf-next 5/5] selftest: Add tests for XDP programs in devmap entries

In reply to Toke Høiland-Jørgensen

Quoted 7 lines · Toke Høiland-Jørgensen

Quoted 7 lines
tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +1 -0
new file mode 100644
index 000000000000..b360ba2bd441
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0

Quoted 9 lines

tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c line 8
Quoted 7 lines
tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +7 -0
+/* fails to load without expected_attach_type = BPF_XDP_DEVMAP
+ * because of access to egress_ifindex
+ */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp_dm_log")
Guess this should be xdp_devmap_log now?

no. this program is for negative testing - it should load as an XDP program without the expected_attach_type set. See the comment at the top of the file.

Toke Høiland-Jørgensen

2020-05-29 16:58 UTC #11 lore raw

Re: [PATCH v3 bpf-next 5/5] selftest: Add tests for XDP programs in devmap entries

Quoted 17 lines · David Ahern

Quoted 7 lines · Toke Høiland-Jørgensen
Quoted 7 lines
tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +1 -0
new file mode 100644
index 000000000000..b360ba2bd441
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
Quoted 9 lines
tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c line 8
Quoted 7 lines
tools/testing/selftests/bpf/progs/test_xdp_devmap_helpers.c new file +7 -0
+/* fails to load without expected_attach_type = BPF_XDP_DEVMAP
+ * because of access to egress_ifindex
+ */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp_dm_log")
Guess this should be xdp_devmap_log now?

Quoted 3 lines

no. this program is for negative testing - it should load as an XDP program without the expected_attach_type set. See the comment at the top of the file.

Ah, right, sorry - missed that (obviously) :)

-Toke