On 8/25/22 5:37 PM, Kui-Feng Lee wrote:
Allow creating an iterator that loops through resources of one
thread/process.
People could only create iterators to loop through all resources of
files, vma, and tasks in the system, even though they were interested
in only the resources of a specific task or process. Passing the
additional parameters, people can now create an iterator to go
through all resources or only the resources of a task.
Signed-off-by: Kui-Feng Lee <kuifeng@xxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
---
include/linux/bpf.h | 25 +++++++
include/uapi/linux/bpf.h | 6 ++
kernel/bpf/task_iter.c | 128 ++++++++++++++++++++++++++-------
tools/include/uapi/linux/bpf.h | 6 ++
4 files changed, 141 insertions(+), 24 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 9c1674973e03..31ac2c1181f5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1730,6 +1730,27 @@ int bpf_obj_get_user(const char __user *pathname, int flags);
extern int bpf_iter_ ## target(args); \
int __init bpf_iter_ ## target(args) { return 0; }
+/*
+ * The task type of iterators.
+ *
+ * For BPF task iterators, they can be parameterized with various
+ * parameters to visit only some of tasks.
+ *
+ * BPF_TASK_ITER_ALL (default)
+ * Iterate over resources of every task.
+ *
+ * BPF_TASK_ITER_TID
+ * Iterate over resources of a task/tid.
+ *
+ * BPF_TASK_ITER_TGID
+ * Iterate over resources of every task of a process / task group.
+ */
+enum bpf_iter_task_type {
+ BPF_TASK_ITER_ALL = 0,
+ BPF_TASK_ITER_TID,
+ BPF_TASK_ITER_TGID,
+};
+
struct bpf_iter_aux_info {
/* for map_elem iter */
struct bpf_map *map;
@@ -1739,6 +1760,10 @@ struct bpf_iter_aux_info {
struct cgroup *start; /* starting cgroup */
enum bpf_cgroup_iter_order order;
} cgroup;
+ struct {
+ enum bpf_iter_task_type type;
+ u32 pid;
+ } task;
};
typedef int (*bpf_iter_attach_target_t)(struct bpf_prog *prog,
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 0f61f09f467a..385deab984e1 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -110,6 +110,12 @@ union bpf_iter_link_info {
__u32 cgroup_fd;
__u64 cgroup_id;
} cgroup;
+ /* Parameters of task iterators. */
+ struct {
+ __u32 tid;
+ __u32 pid;
+ __u32 pid_fd;
+ } task;
};
/* BPF syscall commands, see bpf(2) man-page for more details. */
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index 8c921799def4..1200cfde71e3 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -12,6 +12,8 @@
struct bpf_iter_seq_task_common {
struct pid_namespace *ns;
+ enum bpf_iter_task_type type;
+ u32 pid;
};
struct bpf_iter_seq_task_info {
@@ -22,24 +24,54 @@ struct bpf_iter_seq_task_info {
u32 tid;
};
-static struct task_struct *task_seq_get_next(struct pid_namespace *ns,
+static bool matched_task(struct task_struct *task,
+ struct bpf_iter_seq_task_common *common,
+ bool skip_if_dup_file)
+{
+ /* Should not have the same 'files' if skip_if_dup_file is true */
+ bool diff_files_if =
+ !skip_if_dup_file ||
+ (thread_group_leader(task) &&
+ task->files != task->group_leader->files);
Should this be
!skip_if_dup_file || thread_group_leader(task) ||
task->files != task->group_leader->files
?
+ /* Should have the given tgid if the type is BPF_TASK_ITER_TGI */
BPF_TASK_ITER_TGID?
+ bool have_tgid_if =
+ common->type != BPF_TASK_ITER_TGID ||
+ __task_pid_nr_ns(task, PIDTYPE_TGID,
+ common->ns) == common->pid;
+ return diff_files_if && have_tgid_if;
+}
+
+
+static struct task_struct *task_seq_get_next(struct bpf_iter_seq_task_common *common,
u32 *tid,
bool skip_if_dup_files)
{
struct task_struct *task = NULL;
struct pid *pid;
+ if (common->type == BPF_TASK_ITER_TID) {
+ if (*tid && *tid != common->pid)
+ return NULL;
+ rcu_read_lock();
+ pid = find_pid_ns(common->pid, common->ns);
+ if (pid) {
+ task = get_pid_task(pid, PIDTYPE_PID);
+ *tid = common->pid;
+ }
+ rcu_read_unlock();
+ return task;
+ }
+
rcu_read_lock();
retry:
- pid = find_ge_pid(*tid, ns);
+ pid = find_ge_pid(*tid, common->ns);
if (pid) {
- *tid = pid_nr_ns(pid, ns);
+ *tid = pid_nr_ns(pid, common->ns);
task = get_pid_task(pid, PIDTYPE_PID);
if (!task) {
++*tid;
goto retry;
- } else if (skip_if_dup_files && !thread_group_leader(task) &&
- task->files == task->group_leader->files) {
+ } else if (!matched_task(task, common, skip_if_dup_files)) {
put_task_struct(task);
task = NULL;
++*tid;
@@ -56,7 +88,7 @@ static void *task_seq_start(struct seq_file *seq, loff_t *pos)
struct bpf_iter_seq_task_info *info = seq->private;
struct task_struct *task;
- task = task_seq_get_next(info->common.ns, &info->tid, false);
+ task = task_seq_get_next(&info->common, &info->tid, false);
if (!task)
return NULL;
[...]
