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30897832d8
Adds support for both bpf_{sk, inode}_storage_{get, delete} to be used
in LSM programs. These helpers are not used for tracing programs
(currently) as their usage is tied to the life-cycle of the object and
should only be used where the owning object won't be freed (when the
owning object is passed as an argument to the LSM hook). Thus, they
are safer to use in LSM hooks than tracing. Usage of local storage in
tracing programs will probably follow a per function based whitelist
approach.
Since the UAPI helper signature for bpf_sk_storage expect a bpf_sock,
it, leads to a compilation warning for LSM programs, it's also updated
to accept a void * pointer instead.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200825182919.1118197-7-kpsingh@chromium.org
74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2020 Google LLC.
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*/
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#include <linux/filter.h>
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#include <linux/bpf.h>
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#include <linux/btf.h>
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#include <linux/lsm_hooks.h>
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#include <linux/bpf_lsm.h>
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#include <linux/kallsyms.h>
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#include <linux/bpf_verifier.h>
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#include <net/bpf_sk_storage.h>
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#include <linux/bpf_local_storage.h>
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/* For every LSM hook that allows attachment of BPF programs, declare a nop
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* function where a BPF program can be attached.
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*/
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#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
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noinline RET bpf_lsm_##NAME(__VA_ARGS__) \
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{ \
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return DEFAULT; \
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}
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#include <linux/lsm_hook_defs.h>
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#undef LSM_HOOK
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#define BPF_LSM_SYM_PREFX "bpf_lsm_"
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int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
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const struct bpf_prog *prog)
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{
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if (!prog->gpl_compatible) {
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bpf_log(vlog,
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"LSM programs must have a GPL compatible license\n");
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return -EINVAL;
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}
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if (strncmp(BPF_LSM_SYM_PREFX, prog->aux->attach_func_name,
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sizeof(BPF_LSM_SYM_PREFX) - 1)) {
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bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
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prog->aux->attach_btf_id, prog->aux->attach_func_name);
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return -EINVAL;
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}
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return 0;
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}
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static const struct bpf_func_proto *
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bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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{
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switch (func_id) {
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case BPF_FUNC_inode_storage_get:
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return &bpf_inode_storage_get_proto;
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case BPF_FUNC_inode_storage_delete:
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return &bpf_inode_storage_delete_proto;
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case BPF_FUNC_sk_storage_get:
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return &sk_storage_get_btf_proto;
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case BPF_FUNC_sk_storage_delete:
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return &sk_storage_delete_btf_proto;
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default:
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return tracing_prog_func_proto(func_id, prog);
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}
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}
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const struct bpf_prog_ops lsm_prog_ops = {
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};
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const struct bpf_verifier_ops lsm_verifier_ops = {
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.get_func_proto = bpf_lsm_func_proto,
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.is_valid_access = btf_ctx_access,
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};
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