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5eccd2db |
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14-Dec-2023 |
Andrii Nakryiko <andrii@kernel.org> |
bpf: reuse btf_prepare_func_args() check for main program BTF validation Instead of btf_check_subprog_arg_match(), use btf_prepare_func_args() logic to validate "trustworthiness" of main BPF program's BTF information, if it is present. We ignored results of original BTF check anyway, often times producing confusing and ominously-sounding "reg type unsupported for arg#0 function" message, which has no apparent effect on program correctness and verification process. All the -EFAULT returning sanity checks are already performed in check_btf_info_early(), so there is zero reason to have this duplication of logic between btf_check_subprog_call() and btf_check_subprog_arg_match(). Dropping btf_check_subprog_arg_match() simplifies btf_check_func_arg_match() further removing `bool processing_call` flag. One subtle bit that was done by btf_check_subprog_arg_match() was potentially marking main program's BTF as unreliable. We do this explicitly now with a dedicated simple check, preserving the original behavior, but now based on well factored btf_prepare_func_args() logic. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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6499fe6e |
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10-Apr-2023 |
David Vernet <void@manifault.com> |
bpf: Remove bpf_cgroup_kptr_get() kfunc Now that bpf_cgroup_acquire() is KF_RCU | KF_RET_NULL, bpf_cgroup_kptr_get() is redundant. Let's remove it, and update selftests to instead use bpf_cgroup_acquire() where appropriate. The next patch will update the BPF documentation to not mention bpf_cgroup_kptr_get(). Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230411041633.179404-2-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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1d712839 |
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10-Apr-2023 |
David Vernet <void@manifault.com> |
bpf: Make bpf_cgroup_acquire() KF_RCU | KF_RET_NULL struct cgroup is already an RCU-safe type in the verifier. We can therefore update bpf_cgroup_acquire() to be KF_RCU | KF_RET_NULL, and subsequently remove bpf_cgroup_kptr_get(). This patch does the first of these by updating bpf_cgroup_acquire() to be KF_RCU | KF_RET_NULL, and also updates selftests accordingly. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230411041633.179404-1-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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6c831c46 |
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25-Mar-2023 |
David Vernet <void@manifault.com> |
bpf: Treat KF_RELEASE kfuncs as KF_TRUSTED_ARGS KF_RELEASE kfuncs are not currently treated as having KF_TRUSTED_ARGS, even though they have a superset of the requirements of KF_TRUSTED_ARGS. Like KF_TRUSTED_ARGS, KF_RELEASE kfuncs require a 0-offset argument, and don't allow NULL-able arguments. Unlike KF_TRUSTED_ARGS which require _either_ an argument with ref_obj_id > 0, _or_ (ref->type & BPF_REG_TRUSTED_MODIFIERS) (and no unsafe modifiers allowed), KF_RELEASE only allows for ref_obj_id > 0. Because KF_RELEASE today doesn't automatically imply KF_TRUSTED_ARGS, some of these requirements are enforced in different ways that can make the behavior of the verifier feel unpredictable. For example, a KF_RELEASE kfunc with a NULL-able argument will currently fail in the verifier with a message like, "arg#0 is ptr_or_null_ expected ptr_ or socket" rather than "Possibly NULL pointer passed to trusted arg0". Our intention is the same, but the semantics are different due to implemenetation details that kfunc authors and BPF program writers should not need to care about. Let's make the behavior of the verifier more consistent and intuitive by having KF_RELEASE kfuncs imply the presence of KF_TRUSTED_ARGS. Our eventual goal is to have all kfuncs assume KF_TRUSTED_ARGS by default anyways, so this takes us a step in that direction. Note that it does not make sense to assume KF_TRUSTED_ARGS for all KF_ACQUIRE kfuncs. KF_ACQUIRE kfuncs can have looser semantics than KF_RELEASE, with e.g. KF_RCU | KF_RET_NULL. We may want to have KF_ACQUIRE imply KF_TRUSTED_ARGS _unless_ KF_RCU is specified, but that can be left to another patch set, and there are no such subtleties to address for KF_RELEASE. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20230325213144.486885-4-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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c8ed6685 |
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08-Mar-2023 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: fix lots of silly mistakes pointed out by compiler Once we enable -Wall for BPF sources, compiler will complain about lots of unused variables, variables that are set but never read, etc. Fix all these issues first before enabling -Wall in Makefile. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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20c09d92 |
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02-Mar-2023 |
Alexei Starovoitov <ast@kernel.org> |
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
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8032cad1 |
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13-Feb-2023 |
Joanne Koong <joannelkoong@gmail.com> |
selftests/bpf: Clean up user_ringbuf, cgrp_kfunc, kfunc_dynptr_param tests Clean up user_ringbuf, cgrp_kfunc, and kfunc_dynptr_param tests to use the generic verification tester for checking verifier rejections. The generic verification tester uses btf_decl_tag-based annotations for verifying that the tests fail with the expected log messages. Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Acked-by: David Vernet <void@manifault.com> Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com> Link: https://lore.kernel.org/r/20230214051332.4007131-1-joannelkoong@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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f583ddf1 |
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21-Nov-2022 |
David Vernet <void@manifault.com> |
selftests/bpf: Add cgroup kfunc / kptr selftests This patch adds a selftest suite to validate the cgroup kfuncs that were added in the prior patch. Signed-off-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/r/20221122055458.173143-3-void@manifault.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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