[PATCH bpf v2] bpf: Gate dynptr API behind CAP_BPF

[PATCH bpf v2] bpf: Gate dynptr API behind CAP_BPF

[Kumar Kartikeya Dwivedi]

This has been enabled for unprivileged programs for only one kernel
release, hence the expected annoyances due to this move are low. Users
using ringbuf can stick to non-dynptr APIs. The actual use cases dynptr
is meant to serve may not make sense in unprivileged BPF programs.

Hence, gate these helpers behind CAP_BPF and limit use to privileged
BPF programs.

Fixes: 263ae152e962 ("bpf: Add bpf_dynptr_from_mem for local dynptrs")
Fixes: bc34dee65a65 ("bpf: Dynptr support for ring buffers")
Fixes: 13bbbfbea759 ("bpf: Add bpf_dynptr_read and bpf_dynptr_write")
Fixes: 34d4ef5775f7 ("bpf: Add dynptr data slices")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
v2: Rebase on bpf tree
---
 kernel/bpf/helpers.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1f961f9982d2..3814b0fd3a2c 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1627,26 +1627,12 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_ringbuf_discard_proto;
 	case BPF_FUNC_ringbuf_query:
 		return &bpf_ringbuf_query_proto;
-	case BPF_FUNC_ringbuf_reserve_dynptr:
-		return &bpf_ringbuf_reserve_dynptr_proto;
-	case BPF_FUNC_ringbuf_submit_dynptr:
-		return &bpf_ringbuf_submit_dynptr_proto;
-	case BPF_FUNC_ringbuf_discard_dynptr:
-		return &bpf_ringbuf_discard_dynptr_proto;
 	case BPF_FUNC_for_each_map_elem:
 		return &bpf_for_each_map_elem_proto;
 	case BPF_FUNC_loop:
 		return &bpf_loop_proto;
 	case BPF_FUNC_strncmp:
 		return &bpf_strncmp_proto;
-	case BPF_FUNC_dynptr_from_mem:
-		return &bpf_dynptr_from_mem_proto;
-	case BPF_FUNC_dynptr_read:
-		return &bpf_dynptr_read_proto;
-	case BPF_FUNC_dynptr_write:
-		return &bpf_dynptr_write_proto;
-	case BPF_FUNC_dynptr_data:
-		return &bpf_dynptr_data_proto;
 	default:
 		break;
 	}
@@ -1675,6 +1661,20 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_timer_cancel_proto;
 	case BPF_FUNC_kptr_xchg:
 		return &bpf_kptr_xchg_proto;
+	case BPF_FUNC_ringbuf_reserve_dynptr:
+		return &bpf_ringbuf_reserve_dynptr_proto;
+	case BPF_FUNC_ringbuf_submit_dynptr:
+		return &bpf_ringbuf_submit_dynptr_proto;
+	case BPF_FUNC_ringbuf_discard_dynptr:
+		return &bpf_ringbuf_discard_dynptr_proto;
+	case BPF_FUNC_dynptr_from_mem:
+		return &bpf_dynptr_from_mem_proto;
+	case BPF_FUNC_dynptr_read:
+		return &bpf_dynptr_read_proto;
+	case BPF_FUNC_dynptr_write:
+		return &bpf_dynptr_write_proto;
+	case BPF_FUNC_dynptr_data:
+		return &bpf_dynptr_data_proto;
 	default:
 		break;
 	}
--
2.34.1

Re: [PATCH bpf v2] bpf: Gate dynptr API behind CAP_BPF

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Wed, 21 Sep 2022 16:35:50 +0200 you wrote:
> This has been enabled for unprivileged programs for only one kernel
> release, hence the expected annoyances due to this move are low. Users
> using ringbuf can stick to non-dynptr APIs. The actual use cases dynptr
> is meant to serve may not make sense in unprivileged BPF programs.
> 
> Hence, gate these helpers behind CAP_BPF and limit use to privileged
> BPF programs.
> 
> [...]

Here is the summary with links:
  - [bpf,v2] bpf: Gate dynptr API behind CAP_BPF
    https://git.kernel.org/bpf/bpf/c/8addbfc7b308

You are awesome, thank you!
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