bpf_task_from_pid() that currently exists looks up the
struct task_struct corresponding to the pid in the root pid
namespace (init_pid_ns).
This patch adds bpf_task_from_vpid() which looks up the
struct task_struct corresponding to vpid in the pid namespace
of the current process.
This is useful for getting information about other processes
in the same pid namespace.
Signed-off-by: Juntong Deng <juntong.deng@xxxxxxxxxxx>
---
kernel/bpf/helpers.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 4053f279ed4c..e977c12d60e1 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2521,6 +2521,25 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid)
return p;
}
+/**
+ * bpf_task_from_vpid - Find a struct task_struct from its vpid by looking it up
+ * in the pid namespace of the current task. If a task is returned, it must
+ * either be stored in a map, or released with bpf_task_release().
+ * @vpid: The vpid of the task being looked up.
+ */
+__bpf_kfunc struct task_struct *bpf_task_from_vpid(s32 vpid)
+{
+ struct task_struct *p;
+
+ rcu_read_lock();
+ p = find_task_by_vpid(vpid);
+ if (p)
+ p = bpf_task_acquire(p);
+ rcu_read_unlock();
+
+ return p;
+}
+
/**
* bpf_dynptr_slice() - Obtain a read-only pointer to the dynptr data.
* @p: The dynptr whose data slice to retrieve
@@ -3034,6 +3053,7 @@ BTF_ID_FLAGS(func, bpf_task_under_cgroup, KF_RCU)
BTF_ID_FLAGS(func, bpf_task_get_cgroup1, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
#endif
BTF_ID_FLAGS(func, bpf_task_from_pid, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_task_from_vpid, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_throw)
BTF_KFUNCS_END(generic_btf_ids)
--
2.39.5
