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| author | Alexei Starovoitov <ast@kernel.org> | 2023-03-03 07:14:46 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-03-03 19:42:20 +0300 |
| commit | 6fcd486b3a0a628c41f12b3a7329a18a2c74b351 (patch) | |
| tree | ac60957b666a5eac1e50dd7bb125bb7c106acb2f /tools/testing/selftests/bpf/verifier/calls.c | |
| parent | 0047d8343f6042c4feea24072ef254d47b8a33b3 (diff) | |
| download | linux-6fcd486b3a0a628c41f12b3a7329a18a2c74b351.tar.xz | |
bpf: Refactor RCU enforcement in the verifier.
bpf_rcu_read_lock/unlock() are only available in clang compiled kernels. Lack
of such key mechanism makes it impossible for sleepable bpf programs to use RCU
pointers.
Allow bpf_rcu_read_lock/unlock() in GCC compiled kernels (though GCC doesn't
support btf_type_tag yet) and allowlist certain field dereferences in important
data structures like tast_struct, cgroup, socket that are used by sleepable
programs either as RCU pointer or full trusted pointer (which is valid outside
of RCU CS). Use BTF_TYPE_SAFE_RCU and BTF_TYPE_SAFE_TRUSTED macros for such
tagging. They will be removed once GCC supports btf_type_tag.
With that refactor check_ptr_to_btf_access(). Make it strict in enforcing
PTR_TRUSTED and PTR_UNTRUSTED while deprecating old PTR_TO_BTF_ID without
modifier flags. There is a chance that this strict enforcement might break
existing programs (especially on GCC compiled kernels), but this cleanup has to
start sooner than later. Note PTR_TO_CTX access still yields old deprecated
PTR_TO_BTF_ID. Once it's converted to strict PTR_TRUSTED or PTR_UNTRUSTED the
kfuncs and helpers will be able to default to KF_TRUSTED_ARGS. KF_RCU will
remain as a weaker version of KF_TRUSTED_ARGS where obj refcnt could be 0.
Adjust rcu_read_lock selftest to run on gcc and clang compiled kernels.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230303041446.3630-7-alexei.starovoitov@gmail.com
Diffstat (limited to 'tools/testing/selftests/bpf/verifier/calls.c')
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/calls.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c index 9a326a800e5c..5702fc9761ef 100644 --- a/tools/testing/selftests/bpf/verifier/calls.c +++ b/tools/testing/selftests/bpf/verifier/calls.c @@ -181,7 +181,7 @@ }, .result_unpriv = REJECT, .result = REJECT, - .errstr = "negative offset ptr_ ptr R1 off=-4 disallowed", + .errstr = "ptr R1 off=-4 disallowed", }, { "calls: invalid kfunc call: PTR_TO_BTF_ID with variable offset", |