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SubjectRe: [PATCH bpf-next] bpf: fix bpf compile error caused by CONFIG_CGROUP_BPF
On Tue, Jul 19, 2022 at 1:49 AM Xu Jia <xujia39@huawei.com> wrote:
>
> We failed to compile when CONFIG_BPF_LSM is enabled but CONFIG_CGROUP_BPF
> is not set. The failings are shown as below:
>
> kernel/bpf/trampoline.o: in function `bpf_trampoline_link_cgroup_shim'
> trampoline.c: undefined reference to `bpf_cgroup_atype_get'
> kernel/bpf/bpf_lsm.o: In function `bpf_lsm_find_cgroup_shim':
> bpf_lsm.c: undefined reference to `__cgroup_bpf_run_lsm_current'
> bpf_lsm.c: undefined reference to `__cgroup_bpf_run_lsm_sock'
> bpf_lsm.c: undefined reference to `__cgroup_bpf_run_lsm_socket'
>
> Fix them by protecting these functions with CONFIG_CGROUP_BPF.

Should be fixed by the following?

https://lore.kernel.org/bpf/20220714185404.3647772-1-sdf@google.com/

> Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor")
> Signed-off-by: Xu Jia <xujia39@huawei.com>
> ---
> include/linux/bpf.h | 12 +++++++++---
> include/linux/bpf_lsm.h | 10 ++++++----
> kernel/bpf/bpf_lsm.c | 2 ++
> kernel/bpf/trampoline.c | 2 ++
> 4 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 2b21f2a3452f..add8895c02cc 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1255,9 +1255,7 @@ struct bpf_dummy_ops {
> int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
> union bpf_attr __user *uattr);
> #endif
> -int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
> - int cgroup_atype);
> -void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog);
> +
> #else
> static inline const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
> {
> @@ -1281,6 +1279,14 @@ static inline int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map,
> {
> return -EINVAL;
> }
> +#endif
> +
> +#if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL) && \
> + defined(CONFIG_CGROUP_BPF)
> +int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
> + int cgroup_atype);
> +void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog);
> +#else
> static inline int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
> int cgroup_atype)
> {
> diff --git a/include/linux/bpf_lsm.h b/include/linux/bpf_lsm.h
> index 4bcf76a9bb06..bed45a0c8a9c 100644
> --- a/include/linux/bpf_lsm.h
> +++ b/include/linux/bpf_lsm.h
> @@ -42,8 +42,6 @@ extern const struct bpf_func_proto bpf_inode_storage_get_proto;
> extern const struct bpf_func_proto bpf_inode_storage_delete_proto;
> void bpf_inode_storage_free(struct inode *inode);
>
> -void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog, bpf_func_t *bpf_func);
> -
> #else /* !CONFIG_BPF_LSM */
>
> static inline bool bpf_lsm_is_sleepable_hook(u32 btf_id)
> @@ -67,11 +65,15 @@ static inline void bpf_inode_storage_free(struct inode *inode)
> {
> }
>
> +#endif /* CONFIG_BPF_LSM */
> +
> +#if defined(CONFIG_BPF_LSM) && defined(CONFIG_BPF_CGROUP)
> +void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog, bpf_func_t *bpf_func);
> +#else
> static inline void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog,
> bpf_func_t *bpf_func)
> {
> }
> -
> -#endif /* CONFIG_BPF_LSM */
> +#endif
>
> #endif /* _LINUX_BPF_LSM_H */
> diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
> index d469b7f3deef..29527828b38b 100644
> --- a/kernel/bpf/bpf_lsm.c
> +++ b/kernel/bpf/bpf_lsm.c
> @@ -63,6 +63,7 @@ BTF_ID(func, bpf_lsm_socket_post_create)
> BTF_ID(func, bpf_lsm_socket_socketpair)
> BTF_SET_END(bpf_lsm_unlocked_sockopt_hooks)
>
> +#ifdef CONFIG_BPF_CGROUP
> void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog,
> bpf_func_t *bpf_func)
> {
> @@ -86,6 +87,7 @@ void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog,
> #endif
> *bpf_func = __cgroup_bpf_run_lsm_current;
> }
> +#endif /* CONFIG_BPF_CGROUP */
>
> int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
> const struct bpf_prog *prog)
> diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
> index 6cd226584c33..127924711935 100644
> --- a/kernel/bpf/trampoline.c
> +++ b/kernel/bpf/trampoline.c
> @@ -525,6 +525,7 @@ static const struct bpf_link_ops bpf_shim_tramp_link_lops = {
> .dealloc = bpf_shim_tramp_link_dealloc,
> };
>
> +#ifdef CONFIG_CGROUP_BPF
> static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog,
> bpf_func_t bpf_func,
> int cgroup_atype)
> @@ -668,6 +669,7 @@ void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog)
>
> bpf_trampoline_put(tr); /* bpf_trampoline_lookup above */
> }
> +#endif /* CONFIG_CGROUP_BPF */
> #endif
>
> struct bpf_trampoline *bpf_trampoline_get(u64 key,
> --
> 2.25.1
>

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