This patch adds kfuncs bpf_iter_task_{new,next,destroy} which allow
creation and manipulation of struct bpf_iter_task in open-coded iterator
style. BPF programs can use these kfuncs or through bpf_for_each macro to
iterate all processes in the system.
The API design keep consistent with SEC("iter/task"). bpf_iter_task_new()
accepts a specific task and iterating type which allows:
1. iterating all process in the system(BPF_TASK_ITER_ALL_PROCS)
2. iterating all threads in the system(BPF_TASK_ITER_ALL_THREADS)
3. iterating all threads of a specific task(BPF_TASK_ITER_PROC_THREADS)
Signed-off-by: Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx>
---
kernel/bpf/helpers.c | 3 +
kernel/bpf/task_iter.c | 82 +++++++++++++++++++
.../testing/selftests/bpf/bpf_experimental.h | 5 ++
3 files changed, 90 insertions(+)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index cb24c4a916df..690763751f6e 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2555,6 +2555,9 @@ BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_iter_css_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_css_task_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_iter_task_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_task_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_dynptr_adjust)
BTF_ID_FLAGS(func, bpf_dynptr_is_null)
BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 2cfcb4dd8a37..caeddad3d2f1 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -856,6 +856,88 @@ __bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it)
bpf_mem_free(&bpf_global_ma, kit->css_it);
}
+struct bpf_iter_task {
+ __u64 __opaque[3];
+} __attribute__((aligned(8)));
+
+struct bpf_iter_task_kern {
+ struct task_struct *task;
+ struct task_struct *pos;
+ unsigned int flags;
+} __attribute__((aligned(8)));
+
+enum {
+ BPF_TASK_ITER_ALL_PROCS,
+ BPF_TASK_ITER_ALL_THREADS,
+ BPF_TASK_ITER_PROC_THREADS
+};
+
+__bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it,
+ struct task_struct *task, unsigned int flags)
+{
+ struct bpf_iter_task_kern *kit = (void *)it;
+
+ BUILD_BUG_ON(sizeof(struct bpf_iter_task_kern) > sizeof(struct bpf_iter_task));
+ BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) !=
+ __alignof__(struct bpf_iter_task));
+
+ kit->task = kit->pos = NULL;
+ switch (flags) {
+ case BPF_TASK_ITER_ALL_THREADS:
+ case BPF_TASK_ITER_ALL_PROCS:
+ case BPF_TASK_ITER_PROC_THREADS:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (flags == BPF_TASK_ITER_PROC_THREADS)
+ kit->task = task;
+ else
+ kit->task = &init_task;
+ kit->pos = kit->task;
+ kit->flags = flags;
+ return 0;
+}
+
+__bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)
+{
+ struct bpf_iter_task_kern *kit = (void *)it;
+ struct task_struct *pos;
+ unsigned int flags;
+
+ flags = kit->flags;
+ pos = kit->pos;
+
+ if (!pos)
+ goto out;
+
+ if (flags == BPF_TASK_ITER_ALL_PROCS)
+ goto get_next_task;
+
+ kit->pos = next_thread(kit->pos);
+ if (kit->pos == kit->task) {
+ if (flags == BPF_TASK_ITER_PROC_THREADS) {
+ kit->pos = NULL;
+ goto out;
+ }
+ } else
+ goto out;
+
+get_next_task:
+ kit->pos = next_task(kit->pos);
+ kit->task = kit->pos;
+ if (kit->pos == &init_task)
+ kit->pos = NULL;
+
+out:
+ return pos;
+}
+
+__bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it)
+{
+}
+
DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
static void do_mmap_read_unlock(struct irq_work *entry)
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 8b53537e0f27..1ec82997cce7 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -457,5 +457,10 @@ extern int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
extern struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it) __weak __ksym;
extern void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) __weak __ksym;
+struct bpf_iter_task;
+extern int bpf_iter_task_new(struct bpf_iter_task *it,
+ struct task_struct *task, unsigned int flags) __weak __ksym;
+extern struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) __weak __ksym;
+extern void bpf_iter_task_destroy(struct bpf_iter_task *it) __weak __ksym;
#endif
--
2.20.1
