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Message-Id: <20191022191751.3780-3-cneirabustos@gmail.com>
Date: Tue, 22 Oct 2019 16:17:48 -0300
From: Carlos Neira <cneirabustos@...il.com>
To: netdev@...r.kernel.org
Cc: yhs@...com, ebiederm@...ssion.com, brouer@...hat.com,
bpf@...r.kernel.org, cneirabustos@...il.com
Subject: [PATCH v15 2/5] bpf: added new helper bpf_get_ns_current_pid_tgid
New bpf helper bpf_get_ns_current_pid_tgid,
This helper will return pid and tgid from current task
which namespace matches dev_t and inode number provided,
this will allows us to instrument a process inside a container.
Signed-off-by: Carlos Neira <cneirabustos@...il.com>
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 20 +++++++++++++++++-
kernel/bpf/core.c | 1 +
kernel/bpf/helpers.c | 45 ++++++++++++++++++++++++++++++++++++++++
kernel/trace/bpf_trace.c | 2 ++
5 files changed, 68 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2c2c29b49845..1d7c86019113 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1082,6 +1082,7 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto;
extern const struct bpf_func_proto bpf_strtol_proto;
extern const struct bpf_func_proto bpf_strtoul_proto;
extern const struct bpf_func_proto bpf_tcp_sock_proto;
+extern const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto;
/* Shared helpers among cBPF and eBPF. */
void bpf_user_rnd_init_once(void);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4af8b0819a32..4c3e0b0952e6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2775,6 +2775,19 @@ union bpf_attr {
* restricted to raw_tracepoint bpf programs.
* Return
* 0 on success, or a negative error in case of failure.
+ *
+ * int bpf_get_ns_current_pid_tgid(u64 dev, u64 ino, struct bpf_pidns_info *nsdata, u32 size)
+ * Description
+ * Returns 0 on success, values for *pid* and *tgid* as seen from the current
+ * *namespace* will be returned in *nsdata*.
+ *
+ * On failure, the returned value is one of the following:
+ *
+ * **-EINVAL** if dev and inum supplied don't match dev_t and inode number
+ * with nsfs of current task, or if dev conversion to dev_t lost high bits.
+ *
+ * **-ENOENT** if pidns does not exists for the current task.
+ *
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2888,7 +2901,8 @@ union bpf_attr {
FN(sk_storage_delete), \
FN(send_signal), \
FN(tcp_gen_syncookie), \
- FN(skb_output),
+ FN(skb_output), \
+ FN(get_ns_current_pid_tgid),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -3639,4 +3653,8 @@ struct bpf_sockopt {
__s32 retval;
};
+struct bpf_pidns_info {
+ __u32 pid;
+ __u32 tgid;
+};
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 673f5d40a93e..04083942a13a 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2079,6 +2079,7 @@ const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
const struct bpf_func_proto bpf_get_current_comm_proto __weak;
const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
const struct bpf_func_proto bpf_get_local_storage_proto __weak;
+const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto __weak;
const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
{
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 5e28718928ca..5477ad984d7c 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -11,6 +11,8 @@
#include <linux/uidgid.h>
#include <linux/filter.h>
#include <linux/ctype.h>
+#include <linux/pid_namespace.h>
+#include <linux/proc_ns.h>
#include "../../lib/kstrtox.h"
@@ -487,3 +489,46 @@ const struct bpf_func_proto bpf_strtoul_proto = {
.arg4_type = ARG_PTR_TO_LONG,
};
#endif
+
+BPF_CALL_4(bpf_get_ns_current_pid_tgid, u64, dev, u64, ino,
+ struct bpf_pidns_info *, nsdata, u32, size)
+{
+ struct task_struct *task = current;
+ struct pid_namespace *pidns;
+ int err = -EINVAL;
+
+ if (unlikely(size != sizeof(struct bpf_pidns_info)))
+ goto clear;
+
+ if (unlikely((u64)(dev_t)dev != dev))
+ goto clear;
+
+ if (unlikely(!task))
+ goto clear;
+
+ pidns = task_active_pid_ns(task);
+ if (unlikely(!pidns)) {
+ err = -ENOENT;
+ goto clear;
+ }
+
+ if (!ns_match(&pidns->ns, (dev_t)dev, ino))
+ goto clear;
+
+ nsdata->pid = task_pid_nr_ns(task, pidns);
+ nsdata->tgid = task_tgid_nr_ns(task, pidns);
+ return 0;
+clear:
+ memset((void *)nsdata, 0, (size_t) size);
+ return err;
+}
+
+const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto = {
+ .func = bpf_get_ns_current_pid_tgid,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_ANYTHING,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_PTR_TO_UNINIT_MEM,
+ .arg4_type = ARG_CONST_SIZE,
+};
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index c3240898cc44..07f6fa354f15 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -735,6 +735,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
#endif
case BPF_FUNC_send_signal:
return &bpf_send_signal_proto;
+ case BPF_FUNC_get_ns_current_pid_tgid:
+ return &bpf_get_ns_current_pid_tgid_proto;
default:
return NULL;
}
--
2.20.1
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