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Merge branch 'bpf-allow-xdp_redirect-for-xdp-dev-bound-programs'

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Lorenzo Bianconi says:

====================
bpf: Allow XDP_REDIRECT for XDP dev-bound programs

In the current implementation if the program is dev-bound to a specific
device, it will not be possible to perform XDP_REDIRECT into a DEVMAP or
CPUMAP even if the program is running in the driver NAPI context.
Fix the issue introducing __bpf_prog_map_compatible utility routine in
order to avoid bpf_prog_is_dev_bound() during the XDP program load.
Continue forbidding to attach a dev-bound program to XDP maps.
====================

Link: https://patch.msgid.link/20250428-xdp-prog-bound-fix-v3-0-c9e9ba3300c7@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Martin KaFai Lau
2025-05-01 12:54:07 -07:00
parent 7b05f43155 3678331ca7
commit 86870d0b8f
3 changed files with 50 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
kernel/bpf/core.c
View File

@@ -2358,8 +2358,8 @@ static unsigned int __bpf_prog_ret0_warn(const void *ctx,
return 0;
}
bool bpf_prog_map_compatible(struct bpf_map *map,
const struct bpf_prog *fp)
static bool __bpf_prog_map_compatible(struct bpf_map *map,
const struct bpf_prog *fp)
{
enum bpf_prog_type prog_type = resolve_prog_type(fp);
bool ret;
@@ -2368,14 +2368,6 @@ bool bpf_prog_map_compatible(struct bpf_map *map,
if (fp->kprobe_override)
return false;
/* XDP programs inserted into maps are not guaranteed to run on
* a particular netdev (and can run outside driver context entirely
* in the case of devmap and cpumap). Until device checks
* are implemented, prohibit adding dev-bound programs to program maps.
*/
if (bpf_prog_is_dev_bound(aux))
return false;
spin_lock(&map->owner.lock);
if (!map->owner.type) {
/* There's no owner yet where we could check for
@@ -2409,6 +2401,19 @@ bool bpf_prog_map_compatible(struct bpf_map *map,
return ret;
}
bool bpf_prog_map_compatible(struct bpf_map *map, const struct bpf_prog *fp)
{
/* XDP programs inserted into maps are not guaranteed to run on
* a particular netdev (and can run outside driver context entirely
* in the case of devmap and cpumap). Until device checks
* are implemented, prohibit adding dev-bound programs to program maps.
*/
if (bpf_prog_is_dev_bound(fp->aux))
return false;
return __bpf_prog_map_compatible(map, fp);
}
static int bpf_check_tail_call(const struct bpf_prog *fp)
{
struct bpf_prog_aux *aux = fp->aux;
@@ -2421,7 +2426,7 @@ static int bpf_check_tail_call(const struct bpf_prog *fp)
if (!map_type_contains_progs(map))
continue;
if (!bpf_prog_map_compatible(map, fp)) {
if (!__bpf_prog_map_compatible(map, fp)) {
ret = -EINVAL;
goto out;
}

22
tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
View File

@@ -351,9 +351,10 @@ void test_xdp_metadata(void)
struct xdp_metadata2 *bpf_obj2 = NULL;
struct xdp_metadata *bpf_obj = NULL;
struct bpf_program *new_prog, *prog;
struct bpf_devmap_val devmap_e = {};
struct bpf_map *prog_arr, *devmap;
struct nstoken *tok = NULL;
__u32 queue_id = QUEUE_ID;
struct bpf_map *prog_arr;
struct xsk tx_xsk = {};
struct xsk rx_xsk = {};
__u32 val, key = 0;
@@ -409,6 +410,13 @@ void test_xdp_metadata(void)
bpf_program__set_ifindex(prog, rx_ifindex);
bpf_program__set_flags(prog, BPF_F_XDP_DEV_BOUND_ONLY);
/* Make sure we can load a dev-bound program that performs
* XDP_REDIRECT into a devmap.
*/
new_prog = bpf_object__find_program_by_name(bpf_obj->obj, "redirect");
bpf_program__set_ifindex(new_prog, rx_ifindex);
bpf_program__set_flags(new_prog, BPF_F_XDP_DEV_BOUND_ONLY);
if (!ASSERT_OK(xdp_metadata__load(bpf_obj), "load skeleton"))
goto out;
@@ -423,6 +431,18 @@ void test_xdp_metadata(void)
"update prog_arr"))
goto out;
/* Make sure we can't add dev-bound programs to devmaps. */
devmap = bpf_object__find_map_by_name(bpf_obj->obj, "dev_map");
if (!ASSERT_OK_PTR(devmap, "no dev_map found"))
goto out;
devmap_e.bpf_prog.fd = val;
if (!ASSERT_ERR(bpf_map__update_elem(devmap, &key, sizeof(key),
&devmap_e, sizeof(devmap_e),
BPF_ANY),
"update dev_map"))
goto out;
/* Attach BPF program to RX interface. */
ret = bpf_xdp_attach(rx_ifindex,

13
tools/testing/selftests/bpf/progs/xdp_metadata.c
View File

@@ -19,6 +19,13 @@ struct {
__type(value, __u32);
} prog_arr SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_DEVMAP);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(struct bpf_devmap_val));
__uint(max_entries, 1);
} dev_map SEC(".maps");
extern int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx,
__u64 *timestamp) __ksym;
extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, __u32 *hash,
@@ -95,4 +102,10 @@ int rx(struct xdp_md *ctx)
return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
}
SEC("xdp")
int redirect(struct xdp_md *ctx)
{
return bpf_redirect_map(&dev_map, ctx->rx_queue_index, XDP_PASS);
}
char _license[] SEC("license") = "GPL";