linux-kernel - [RFC PATCH bpf-next 2/4] bpf: add BPF_F_DESTRUCTIVE flag for BPF_PROG

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Message-Id: <20220711083220.2175036-3-asavkov@redhat.com>
Date:   Mon, 11 Jul 2022 10:32:18 +0200
From:   Artem Savkov <asavkov@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Andrea Arcangeli <aarcange@...hat.com>,
        Artem Savkov <asavkov@...hat.com>
Subject: [RFC PATCH bpf-next 2/4] bpf: add BPF_F_DESTRUCTIVE flag for BPF_PROG_LOAD

Add a BPF_F_DESTRUCTIVE will be required to be supplied to
BPF_PROG_LOAD for programs to utilize destructive helpers such as
bpf_panic().

Signed-off-by: Artem Savkov <asavkov@...hat.com>
---
 include/linux/bpf.h            | 1 +
 include/uapi/linux/bpf.h       | 6 ++++++
 kernel/bpf/syscall.c           | 4 +++-
 tools/include/uapi/linux/bpf.h | 6 ++++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 77972724bed7..43c008e3587a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1041,6 +1041,7 @@ struct bpf_prog_aux {
 	bool sleepable;
 	bool tail_call_reachable;
 	bool xdp_has_frags;
+	bool destructive;
 	bool use_bpf_prog_pack;
 	/* BTF_KIND_FUNC_PROTO for valid attach_btf_id */
 	const struct btf_type *attach_func_proto;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e81362891596..4423874b5da4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1121,6 +1121,12 @@ enum bpf_link_type {
  */
 #define BPF_F_XDP_HAS_FRAGS	(1U << 5)
 
+/* If BPF_F_DESTRUCTIVE is used in BPF_PROG_LOAD command, the loaded program
+ * will be able to perform destructive operations such as calling bpf_panic()
+ * helper.
+ */
+#define BPF_F_DESTRUCTIVE	(1U << 6)
+
 /* link_create.kprobe_multi.flags used in LINK_CREATE command for
  * BPF_TRACE_KPROBE_MULTI attach type to create return probe.
  */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 1ce6541d90e1..779feac2dc7d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2449,7 +2449,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 				 BPF_F_TEST_STATE_FREQ |
 				 BPF_F_SLEEPABLE |
 				 BPF_F_TEST_RND_HI32 |
-				 BPF_F_XDP_HAS_FRAGS))
+				 BPF_F_XDP_HAS_FRAGS |
+				 BPF_F_DESTRUCTIVE))
 		return -EINVAL;
 
 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) &&
@@ -2536,6 +2537,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 	prog->aux->offload_requested = !!attr->prog_ifindex;
 	prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE;
 	prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS;
+	prog->aux->destructive = attr->prog_flags & BPF_F_DESTRUCTIVE;
 
 	err = security_bpf_prog_alloc(prog->aux);
 	if (err)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index e81362891596..4423874b5da4 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1121,6 +1121,12 @@ enum bpf_link_type {
  */
 #define BPF_F_XDP_HAS_FRAGS	(1U << 5)
 
+/* If BPF_F_DESTRUCTIVE is used in BPF_PROG_LOAD command, the loaded program
+ * will be able to perform destructive operations such as calling bpf_panic()
+ * helper.
+ */
+#define BPF_F_DESTRUCTIVE	(1U << 6)
+
 /* link_create.kprobe_multi.flags used in LINK_CREATE command for
  * BPF_TRACE_KPROBE_MULTI attach type to create return probe.
  */
-- 
2.35.3