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bpf: Add bpf_task_from_vpid() kfunc

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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@outlook.com>
Link: https://lore.kernel.org/r/AM6PR03MB5848E50DA58F79CDE65433C399442@AM6PR03MB5848.eurprd03.prod.outlook.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Juntong Deng 2024-10-14 10:21:08 +01:00 committed by Alexei Starovoitov
parent 1477d31b1c
commit 675c3596ff
1 changed files with 20 additions and 0 deletions
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20
kernel/bpf/helpers.c
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@ -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)