Commit 675c3596 authored by Juntong Deng's avatar Juntong Deng Committed by Alexei Starovoitov
Browse files

bpf: Add bpf_task_from_vpid() kfunc 



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: default avatarJuntong Deng <juntong.deng@outlook.com>
Link: https://lore.kernel.org/r/AM6PR03MB5848E50DA58F79CDE65433C399442@AM6PR03MB5848.eurprd03.prod.outlook.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 1477d31b

kernel/bpf/helpers.c

+20 −0
Original line number Diff line number Diff line
@@ -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)