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authorChuyi Zhou <zhouchuyi@bytedance.com>2023-11-07 21:22:03 +0800
committerMartin KaFai Lau <martin.lau@kernel.org>2023-11-07 15:24:25 -0800
commit0de4f50de25af79c2a46db55d70cdbd8f985c6d1 (patch)
tree02dcfa685f6f84672356ac0c8f1fe8716160eb77 /kernel/bpf
parentd84b139f53e8fa8048f16814c6b2a53d7bc15c3d (diff)
bpf: Let verifier consider {task,cgroup} is trusted in bpf_iter_reg
BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) in verifier.c wanted to teach BPF verifier that bpf_iter__task -> task is a trusted ptr. But it doesn't work well. The reason is, bpf_iter__task -> task would go through btf_ctx_access() which enforces the reg_type of 'task' is ctx_arg_info->reg_type, and in task_iter.c, we actually explicitly declare that the ctx_arg_info->reg_type is PTR_TO_BTF_ID_OR_NULL. Actually we have a previous case like this[1] where PTR_TRUSTED is added to the arg flag for map_iter. This patch sets ctx_arg_info->reg_type is PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED in task_reg_info. Similarly, bpf_cgroup_reg_info -> cgroup is also PTR_TRUSTED since we are under the protection of cgroup_mutex and we would check cgroup_is_dead() in __cgroup_iter_seq_show(). This patch is to improve the user experience of the newly introduced bpf_iter_css_task kfunc before hitting the mainline. The Fixes tag is pointing to the commit introduced the bpf_iter_css_task kfunc. Link[1]:https://lore.kernel.org/all/20230706133932.45883-3-aspsk@isovalent.com/ Fixes: 9c66dc94b62a ("bpf: Introduce css_task open-coded iterator kfuncs") Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231107132204.912120-2-zhouchuyi@bytedance.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/cgroup_iter.c2
-rw-r--r--kernel/bpf/task_iter.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c
index d1b5c5618dd7..f04a468cf6a7 100644
--- a/kernel/bpf/cgroup_iter.c
+++ b/kernel/bpf/cgroup_iter.c
@@ -282,7 +282,7 @@ static struct bpf_iter_reg bpf_cgroup_reg_info = {
.ctx_arg_info_size = 1,
.ctx_arg_info = {
{ offsetof(struct bpf_iter__cgroup, cgroup),
- PTR_TO_BTF_ID_OR_NULL },
+ PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
},
.seq_info = &cgroup_iter_seq_info,
};
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 4e156dca48de..26082b97894d 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -704,7 +704,7 @@ static struct bpf_iter_reg task_reg_info = {
.ctx_arg_info_size = 1,
.ctx_arg_info = {
{ offsetof(struct bpf_iter__task, task),
- PTR_TO_BTF_ID_OR_NULL },
+ PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
},
.seq_info = &task_seq_info,
.fill_link_info = bpf_iter_fill_link_info,