From c92a7a52243871eb10e0ea2260685def47fb5094 Mon Sep 17 00:00:00 2001 From: David Vernet Date: Wed, 12 Oct 2022 18:20:14 -0500 Subject: bpf: Allow bpf_user_ringbuf_drain() callbacks to return 1 The bpf_user_ringbuf_drain() helper function allows a BPF program to specify a callback that is invoked when draining entries from a BPF_MAP_TYPE_USER_RINGBUF ring buffer map. The API is meant to allow the callback to return 0 if it wants to continue draining samples, and 1 if it's done draining. Unfortunately, bpf_user_ringbuf_drain() landed shortly after commit 1bfe26fb0827 ("bpf: Add verifier support for custom callback return range"), which changed the default behavior of callbacks to only support returning 0. This patch corrects that oversight by allowing bpf_user_ringbuf_drain() callbacks to return 0 or 1. A follow-on patch will update the user_ringbuf selftests to also return 1 from a bpf_user_ringbuf_drain() callback to prevent this from regressing in the future. Fixes: 205715673844 ("bpf: Add bpf_user_ringbuf_drain() helper") Signed-off-by: David Vernet Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221012232015.1510043-2-void@manifault.com --- kernel/bpf/verifier.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6f6d2d511c06..9ab7188d8f68 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6946,6 +6946,7 @@ static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); return 0; } -- cgit v1.2.3 From 6e44b9f375a3135fc4960d76a9ea6720625cad73 Mon Sep 17 00:00:00 2001 From: David Vernet Date: Wed, 12 Oct 2022 18:20:15 -0500 Subject: selftests/bpf: Make bpf_user_ringbuf_drain() selftest callback return 1 In commit 1bfe26fb0827 ("bpf: Add verifier support for custom callback return range"), the verifier was updated to require callbacks to BPF helpers to explicitly specify the range of values that can be returned. bpf_user_ringbuf_drain() was merged after this in commit 205715673844 ("bpf: Add bpf_user_ringbuf_drain() helper"), and this change in default behavior was missed. This patch updates the BPF_MAP_TYPE_USER_RINGBUF selftests to also return 1 from a bpf_user_ringbuf_drain() callback so as to properly test this going forward. Signed-off-by: David Vernet Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221012232015.1510043-3-void@manifault.com --- tools/testing/selftests/bpf/progs/user_ringbuf_success.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/user_ringbuf_success.c b/tools/testing/selftests/bpf/progs/user_ringbuf_success.c index 099c23d9aa21..b39093dd5715 100644 --- a/tools/testing/selftests/bpf/progs/user_ringbuf_success.c +++ b/tools/testing/selftests/bpf/progs/user_ringbuf_success.c @@ -47,14 +47,14 @@ record_sample(struct bpf_dynptr *dynptr, void *context) if (status) { bpf_printk("bpf_dynptr_read() failed: %d\n", status); err = 1; - return 0; + return 1; } } else { sample = bpf_dynptr_data(dynptr, 0, sizeof(*sample)); if (!sample) { bpf_printk("Unexpectedly failed to get sample\n"); err = 2; - return 0; + return 1; } stack_sample = *sample; } -- cgit v1.2.3