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| author | Alexei Starovoitov <ast@kernel.org> | 2023-03-03 05:14:43 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-03-03 17:42:20 +0100 |
| commit | 20c09d92faeefb8536f705d3a4629e0dc314c8a1 (patch) | |
| tree | f68b08f9877e6905e1bbcaf90ec85d52bc83cc8e /tools | |
| parent | bpf: Mark cgroups and dfl_cgrp fields as trusted. (diff) | |
| download | linux-20c09d92faeefb8536f705d3a4629e0dc314c8a1.tar.xz linux-20c09d92faeefb8536f705d3a4629e0dc314c8a1.zip | |
bpf: Introduce kptr_rcu.
The life time of certain kernel structures like 'struct cgroup' is protected by RCU.
Hence it's safe to dereference them directly from __kptr tagged pointers in bpf maps.
The resulting pointer is MEM_RCU and can be passed to kfuncs that expect KF_RCU.
Derefrence of other kptr-s returns PTR_UNTRUSTED.
For example:
struct map_value {
struct cgroup __kptr *cgrp;
};
SEC("tp_btf/cgroup_mkdir")
int BPF_PROG(test_cgrp_get_ancestors, struct cgroup *cgrp_arg, const char *path)
{
struct cgroup *cg, *cg2;
cg = bpf_cgroup_acquire(cgrp_arg); // cg is PTR_TRUSTED and ref_obj_id > 0
bpf_kptr_xchg(&v->cgrp, cg);
cg2 = v->cgrp; // This is new feature introduced by this patch.
// cg2 is PTR_MAYBE_NULL | MEM_RCU.
// When cg2 != NULL, it's a valid cgroup, but its percpu_ref could be zero
if (cg2)
bpf_cgroup_ancestor(cg2, level); // safe to do.
}
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230303041446.3630-4-alexei.starovoitov@gmail.com
Diffstat (limited to 'tools')
4 files changed, 5 insertions, 5 deletions
diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c index 4ad7fe24966d..b42291ed9586 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c @@ -205,7 +205,7 @@ int BPF_PROG(cgrp_kfunc_get_unreleased, struct cgroup *cgrp, const char *path) } SEC("tp_btf/cgroup_mkdir") -__failure __msg("arg#0 is untrusted_ptr_or_null_ expected ptr_ or socket") +__failure __msg("expects refcounted") int BPF_PROG(cgrp_kfunc_release_untrusted, struct cgroup *cgrp, const char *path) { struct __cgrps_kfunc_map_value *v; diff --git a/tools/testing/selftests/bpf/progs/map_kptr_fail.c b/tools/testing/selftests/bpf/progs/map_kptr_fail.c index e19e2a5f38cf..08f9ec18c345 100644 --- a/tools/testing/selftests/bpf/progs/map_kptr_fail.c +++ b/tools/testing/selftests/bpf/progs/map_kptr_fail.c @@ -281,7 +281,7 @@ int reject_kptr_get_bad_type_match(struct __sk_buff *ctx) } SEC("?tc") -__failure __msg("R1 type=untrusted_ptr_or_null_ expected=percpu_ptr_") +__failure __msg("R1 type=rcu_ptr_or_null_ expected=percpu_ptr_") int mark_ref_as_untrusted_or_null(struct __sk_buff *ctx) { struct map_value *v; @@ -316,7 +316,7 @@ int reject_untrusted_store_to_ref(struct __sk_buff *ctx) } SEC("?tc") -__failure __msg("R2 type=untrusted_ptr_ expected=ptr_") +__failure __msg("R2 must be referenced") int reject_untrusted_xchg(struct __sk_buff *ctx) { struct prog_test_ref_kfunc *p; diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c index 289ed202ec66..9a326a800e5c 100644 --- a/tools/testing/selftests/bpf/verifier/calls.c +++ b/tools/testing/selftests/bpf/verifier/calls.c @@ -243,7 +243,7 @@ }, .result_unpriv = REJECT, .result = REJECT, - .errstr = "R1 must be referenced", + .errstr = "R1 must be", }, { "calls: valid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID", diff --git a/tools/testing/selftests/bpf/verifier/map_kptr.c b/tools/testing/selftests/bpf/verifier/map_kptr.c index 6914904344c0..d775ccb01989 100644 --- a/tools/testing/selftests/bpf/verifier/map_kptr.c +++ b/tools/testing/selftests/bpf/verifier/map_kptr.c @@ -336,7 +336,7 @@ .prog_type = BPF_PROG_TYPE_SCHED_CLS, .fixup_map_kptr = { 1 }, .result = REJECT, - .errstr = "R1 type=untrusted_ptr_or_null_ expected=percpu_ptr_", + .errstr = "R1 type=rcu_ptr_or_null_ expected=percpu_ptr_", }, { "map_kptr: ref: reject off != 0", |