diff options
| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2022-04-25 03:18:50 +0530 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-04-25 17:31:35 -0700 |
| commit | 8f14852e89113d738c99c375b4c8b8b7e1073df1 (patch) | |
| tree | 22188e2a08e63757bd579685eaec5537b4ead449 /tools | |
| parent | 61df10c7799e27807ad5e459eec9d77cddf8bf45 (diff) | |
bpf: Tag argument to be released in bpf_func_proto
Add a new type flag for bpf_arg_type that when set tells verifier that
for a release function, that argument's register will be the one for
which meta.ref_obj_id will be set, and which will then be released
using release_reference. To capture the regno, introduce a new field
release_regno in bpf_call_arg_meta.
This would be required in the next patch, where we may either pass NULL
or a refcounted pointer as an argument to the release function
bpf_kptr_xchg. Just releasing only when meta.ref_obj_id is set is not
enough, as there is a case where the type of argument needed matches,
but the ref_obj_id is set to 0. Hence, we must enforce that whenever
meta.ref_obj_id is zero, the register that is to be released can only
be NULL for a release function.
Since we now indicate whether an argument is to be released in
bpf_func_proto itself, is_release_function helper has lost its utitlity,
hence refactor code to work without it, and just rely on
meta.release_regno to know when to release state for a ref_obj_id.
Still, the restriction of one release argument and only one ref_obj_id
passed to BPF helper or kfunc remains. This may be lifted in the future.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220424214901.2743946-3-memxor@gmail.com
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/ref_tracking.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/sock.c | 6 |
2 files changed, 4 insertions, 4 deletions
diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c b/tools/testing/selftests/bpf/verifier/ref_tracking.c index fbd682520e47..57a83d763ec1 100644 --- a/tools/testing/selftests/bpf/verifier/ref_tracking.c +++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c @@ -796,7 +796,7 @@ }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = REJECT, - .errstr = "reference has not been acquired before", + .errstr = "R1 must be referenced when passed to release function", }, { /* !bpf_sk_fullsock(sk) is checked but !bpf_tcp_sock(sk) is not checked */ diff --git a/tools/testing/selftests/bpf/verifier/sock.c b/tools/testing/selftests/bpf/verifier/sock.c index 86b24cad27a7..d11d0b28be41 100644 --- a/tools/testing/selftests/bpf/verifier/sock.c +++ b/tools/testing/selftests/bpf/verifier/sock.c @@ -417,7 +417,7 @@ }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = REJECT, - .errstr = "reference has not been acquired before", + .errstr = "R1 must be referenced when passed to release function", }, { "bpf_sk_release(bpf_sk_fullsock(skb->sk))", @@ -436,7 +436,7 @@ }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = REJECT, - .errstr = "reference has not been acquired before", + .errstr = "R1 must be referenced when passed to release function", }, { "bpf_sk_release(bpf_tcp_sock(skb->sk))", @@ -455,7 +455,7 @@ }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = REJECT, - .errstr = "reference has not been acquired before", + .errstr = "R1 must be referenced when passed to release function", }, { "sk_storage_get(map, skb->sk, NULL, 0): value == NULL", |