Now we can dump all task or children of a specified task.
It's an example how this interface can be expanded for different
use-cases.
v2: Fixes from David Ahern
Add missing break in iter_stop
Fix 8-byte alignment issues
Cc: David Ahern <[email protected]>
Signed-off-by: Andrey Vagin <[email protected]>
---
include/uapi/linux/task_diag.h | 1 +
kernel/taskdiag.c | 117 +++++++++++++++++++++++++++++++++++------
2 files changed, 102 insertions(+), 16 deletions(-)
diff --git a/include/uapi/linux/task_diag.h b/include/uapi/linux/task_diag.h
index 0e659d6..af192db 100644
--- a/include/uapi/linux/task_diag.h
+++ b/include/uapi/linux/task_diag.h
@@ -63,6 +63,7 @@ struct task_diag_creds {
};
#define TASK_DIAG_DUMP_ALL 0
+#define TASK_DIAG_DUMP_CHILDREN 1
struct task_diag_pid {
__u64 show_flags;
diff --git a/kernel/taskdiag.c b/kernel/taskdiag.c
index 5123e12..6dd3361 100644
--- a/kernel/taskdiag.c
+++ b/kernel/taskdiag.c
@@ -184,42 +184,127 @@ err:
return err;
}
+struct task_iter {
+ struct task_diag_pid req;
+ struct pid_namespace *ns;
+ struct netlink_callback *cb;
+ struct task_struct *parent;
+
+ union {
+ struct tgid_iter tgid;
+ struct {
+ unsigned int pos;
+ struct task_struct *task;
+ };
+ };
+};
+
+static void iter_stop(struct task_iter *iter)
+{
+ struct task_struct *task;
+
+ if (iter->parent)
+ put_task_struct(iter->parent);
+
+ switch (iter->req.dump_strategy) {
+ case TASK_DIAG_DUMP_ALL:
+ task = iter->tgid.task;
+ break;
+ default:
+ task = iter->task;
+ }
+ if (task)
+ put_task_struct(task);
+}
+
+static struct task_struct *iter_start(struct task_iter *iter)
+{
+ if (iter->req.pid > 0) {
+ rcu_read_lock();
+ iter->parent = find_task_by_pid_ns(iter->req.pid, iter->ns);
+ if (iter->parent)
+ get_task_struct(iter->parent);
+ rcu_read_unlock();
+ }
+
+ switch (iter->req.dump_strategy) {
+ case TASK_DIAG_DUMP_CHILDREN:
+
+ if (iter->parent == NULL)
+ return ERR_PTR(-ESRCH);
+
+ iter->pos = iter->cb->args[0];
+ iter->task = task_next_child(iter->parent, NULL, iter->pos);
+ return iter->task;
+
+ case TASK_DIAG_DUMP_ALL:
+ iter->tgid.tgid = iter->cb->args[0];
+ iter->tgid.task = NULL;
+ iter->tgid = next_tgid(iter->ns, iter->tgid);
+ return iter->tgid.task;
+ }
+
+ return ERR_PTR(-EINVAL);
+}
+
+static struct task_struct *iter_next(struct task_iter *iter)
+{
+ switch (iter->req.dump_strategy) {
+ case TASK_DIAG_DUMP_CHILDREN:
+ iter->pos++;
+ iter->task = task_next_child(iter->parent, iter->task,
iter->pos);
+ iter->cb->args[0] = iter->pos;
+ return iter->task;
+
+ case TASK_DIAG_DUMP_ALL:
+ iter->tgid.tgid += 1;
+ iter->tgid = next_tgid(iter->ns, iter->tgid);
+ iter->cb->args[0] = iter->tgid.tgid;
+ return iter->tgid.task;
+ }
+
+ return NULL;
+}
+
int taskdiag_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
struct pid_namespace *ns = task_active_pid_ns(current);
- struct tgid_iter iter;
+ struct task_iter iter;
struct nlattr *na;
- struct task_diag_pid req;
+ struct task_struct *task;
int rc;
- if (nlmsg_len(cb->nlh) < GENL_HDRLEN + sizeof(req))
+ if (nlmsg_len(cb->nlh) < GENL_HDRLEN + sizeof(iter.req))
return -EINVAL;
na = nlmsg_data(cb->nlh) + GENL_HDRLEN;
if (na->nla_type < 0)
return -EINVAL;
- memcpy(&req, nla_data(na), sizeof(req));
+ memcpy(&iter.req, nla_data(na), sizeof(iter.req));
- iter.tgid = cb->args[0];
- iter.task = NULL;
- for (iter = next_tgid(ns, iter);
- iter.task;
- iter.tgid += 1, iter = next_tgid(ns, iter)) {
- if (!ptrace_may_access(iter.task, PTRACE_MODE_READ))
- continue;
+ iter.ns = ns;
+ iter.cb = cb;
+ iter.parent = NULL;
- rc = task_diag_fill(iter.task, skb, req.show_flags,
+ task = iter_start(&iter);
+ if (IS_ERR(task))
+ return PTR_ERR(task);
+
+ for (; task; task = iter_next(&iter)) {
+ if (!ptrace_may_access(task, PTRACE_MODE_READ))
+ continue;
+ rc = task_diag_fill(task, skb, iter.req.show_flags,
NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
cb);
if (rc < 0) {
- put_task_struct(iter.task);
- if (rc != -EMSGSIZE)
+ if (rc != -EMSGSIZE) {
+ iter_stop(&iter);
return rc;
+ }
break;
}
}
-
- cb->args[0] = iter.tgid;
+ iter_stop(&iter);
return skb->len;
}
--
2.1.0
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