summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorKP Singh <kpsingh@google.com>2020-11-06 11:37:43 +0100
committerAlexei Starovoitov <ast@kernel.org>2020-11-06 17:08:37 +0100
commit3ca1032ab7ab010eccb107aa515598788f7d93bb (patch)
treee09a5bff5dfa40b270ce5fe937ec1e0a9af7ff45
parentbpftool: Add support for task local storage (diff)
downloadlinux-3ca1032ab7ab010eccb107aa515598788f7d93bb.tar.xz
linux-3ca1032ab7ab010eccb107aa515598788f7d93bb.zip
bpf: Implement get_current_task_btf and RET_PTR_TO_BTF_ID
The currently available bpf_get_current_task returns an unsigned integer which can be used along with BPF_CORE_READ to read data from the task_struct but still cannot be used as an input argument to a helper that accepts an ARG_PTR_TO_BTF_ID of type task_struct. In order to implement this helper a new return type, RET_PTR_TO_BTF_ID, is added. This is similar to RET_PTR_TO_BTF_ID_OR_NULL but does not require checking the nullness of returned pointer. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20201106103747.2780972-6-kpsingh@chromium.org
-rw-r--r--include/linux/bpf.h1
-rw-r--r--include/uapi/linux/bpf.h9
-rw-r--r--kernel/bpf/verifier.c7
-rw-r--r--kernel/trace/bpf_trace.c16
-rw-r--r--tools/include/uapi/linux/bpf.h9
5 files changed, 40 insertions, 2 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2fffd30e13ac..73d5381a5d5c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -310,6 +310,7 @@ enum bpf_return_type {
RET_PTR_TO_BTF_ID_OR_NULL, /* returns a pointer to a btf_id or NULL */
RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL, /* returns a pointer to a valid memory or a btf_id or NULL */
RET_PTR_TO_MEM_OR_BTF_ID, /* returns a pointer to a valid memory or a btf_id */
+ RET_PTR_TO_BTF_ID, /* returns a pointer to a btf_id */
};
/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f4037b2161a6..9879d6793e90 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3779,6 +3779,14 @@ union bpf_attr {
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
+ *
+ * struct task_struct *bpf_get_current_task_btf(void)
+ * Description
+ * Return a BTF pointer to the "current" task.
+ * This pointer can also be used in helpers that accept an
+ * *ARG_PTR_TO_BTF_ID* of type *task_struct*.
+ * Return
+ * Pointer to the current task.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3939,6 +3947,7 @@ union bpf_attr {
FN(redirect_peer), \
FN(task_storage_get), \
FN(task_storage_delete), \
+ FN(get_current_task_btf), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 00960f6a83ec..10da26e55130 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5186,11 +5186,14 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
PTR_TO_BTF_ID : PTR_TO_BTF_ID_OR_NULL;
regs[BPF_REG_0].btf_id = meta.ret_btf_id;
}
- } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL) {
+ } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL ||
+ fn->ret_type == RET_PTR_TO_BTF_ID) {
int ret_btf_id;
mark_reg_known_zero(env, regs, BPF_REG_0);
- regs[BPF_REG_0].type = PTR_TO_BTF_ID_OR_NULL;
+ regs[BPF_REG_0].type = fn->ret_type == RET_PTR_TO_BTF_ID ?
+ PTR_TO_BTF_ID :
+ PTR_TO_BTF_ID_OR_NULL;
ret_btf_id = *fn->ret_btf_id;
if (ret_btf_id == 0) {
verbose(env, "invalid return type %d of func %s#%d\n",
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 4517c8b66518..e4515b0f62a8 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1022,6 +1022,20 @@ const struct bpf_func_proto bpf_get_current_task_proto = {
.ret_type = RET_INTEGER,
};
+BPF_CALL_0(bpf_get_current_task_btf)
+{
+ return (unsigned long) current;
+}
+
+BTF_ID_LIST_SINGLE(bpf_get_current_btf_ids, struct, task_struct)
+
+static const struct bpf_func_proto bpf_get_current_task_btf_proto = {
+ .func = bpf_get_current_task_btf,
+ .gpl_only = true,
+ .ret_type = RET_PTR_TO_BTF_ID,
+ .ret_btf_id = &bpf_get_current_btf_ids[0],
+};
+
BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
@@ -1265,6 +1279,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_current_pid_tgid_proto;
case BPF_FUNC_get_current_task:
return &bpf_get_current_task_proto;
+ case BPF_FUNC_get_current_task_btf:
+ return &bpf_get_current_task_btf_proto;
case BPF_FUNC_get_current_uid_gid:
return &bpf_get_current_uid_gid_proto;
case BPF_FUNC_get_current_comm:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index f4037b2161a6..9879d6793e90 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3779,6 +3779,14 @@ union bpf_attr {
* 0 on success.
*
* **-ENOENT** if the bpf_local_storage cannot be found.
+ *
+ * struct task_struct *bpf_get_current_task_btf(void)
+ * Description
+ * Return a BTF pointer to the "current" task.
+ * This pointer can also be used in helpers that accept an
+ * *ARG_PTR_TO_BTF_ID* of type *task_struct*.
+ * Return
+ * Pointer to the current task.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3939,6 +3947,7 @@ union bpf_attr {
FN(redirect_peer), \
FN(task_storage_get), \
FN(task_storage_delete), \
+ FN(get_current_task_btf), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper