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Date: Tue, 13 Aug 2019 11:47:45 -0700
From: Carlos Neira <cneirabustos@...il.com>
To: netdev@...r.kernel.org
Cc: yhs@...com, ebiederm@...ssion.com, brouer@...hat.com,
cneirabustos@...il.com, bpf@...r.kernel.org
Subject: [PATCH bpf-next V9 1/3] bpf: new helper to obtain namespace data from current task
From: Carlos <cneirabustos@...il.com>
New bpf helper bpf_get_current_pidns_info.
This helper obtains the active namespace from current and returns
pid, tgid, device and namespace id as seen from that namespace,
allowing to instrument a process inside a container.
Signed-off-by: Carlos Neira <cneirabustos@...il.com>
---
fs/internal.h | 2 --
fs/namei.c | 1 -
include/linux/bpf.h | 1 +
include/linux/namei.h | 4 +++
include/uapi/linux/bpf.h | 31 ++++++++++++++++++++++-
kernel/bpf/core.c | 1 +
kernel/bpf/helpers.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
kernel/trace/bpf_trace.c | 2 ++
8 files changed, 102 insertions(+), 4 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index 315fcd8d237c..6647e15dd419 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -59,8 +59,6 @@ extern int finish_clean_context(struct fs_context *fc);
/*
* namei.c
*/
-extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
- struct path *path, struct path *root);
extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
diff --git a/fs/namei.c b/fs/namei.c
index 209c51a5226c..a89fc72a4a10 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -19,7 +19,6 @@
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/slab.h>
-#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/fsnotify.h>
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f9a506147c8a..e4adf5e05afd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1050,6 +1050,7 @@ 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_current_pidns_info_proto;
/* Shared helpers among cBPF and eBPF. */
void bpf_user_rnd_init_once(void);
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 9138b4471dbf..b45c8b6f7cb4 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -6,6 +6,7 @@
#include <linux/path.h>
#include <linux/fcntl.h>
#include <linux/errno.h>
+#include <linux/fs.h>
enum { MAX_NESTED_LINKS = 8 };
@@ -97,6 +98,9 @@ extern void unlock_rename(struct dentry *, struct dentry *);
extern void nd_jump_link(struct path *path);
+extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
+ struct path *path, struct path *root);
+
static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
{
((char *) name)[min(len, maxlen)] = '\0';
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4393bd4b2419..db241857ec15 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2741,6 +2741,28 @@ union bpf_attr {
* **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
*
* **-EPROTONOSUPPORT** IP packet version is not 4 or 6
+ *
+ * int bpf_get_current_pidns_info(struct bpf_pidns_info *pidns, u32 size_of_pidns)
+ * Description
+ * Copies into *pidns* pid, namespace id and tgid as seen by the
+ * current namespace and also device from /proc/self/ns/pid.
+ * *size_of_pidns* must be the size of *pidns*
+ *
+ * This helper is used when pid filtering is needed inside a
+ * container as bpf_get_current_tgid() helper returns always the
+ * pid id as seen by the root namespace.
+ * Return
+ * 0 on success
+ *
+ * **-EINVAL** if *size_of_pidns* is not valid or unable to get ns, pid
+ * or tgid of the current task.
+ *
+ * **-ECHILD** if /proc/self/ns/pid does not exists.
+ *
+ * **-ENOTDIR** if /proc/self/ns does not exists.
+ *
+ * **-ENOMEM** if allocation fails.
+ *
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2853,7 +2875,8 @@ union bpf_attr {
FN(sk_storage_get), \
FN(sk_storage_delete), \
FN(send_signal), \
- FN(tcp_gen_syncookie),
+ FN(tcp_gen_syncookie), \
+ FN(get_current_pidns_info),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -3604,4 +3627,10 @@ struct bpf_sockopt {
__s32 retval;
};
+struct bpf_pidns_info {
+ __u32 dev;
+ __u32 nsid;
+ __u32 tgid;
+ __u32 pid;
+};
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 8191a7db2777..3159f2a0188c 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2038,6 +2038,7 @@ 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_current_pidns_info __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..41fbf1f28a48 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -11,6 +11,12 @@
#include <linux/uidgid.h>
#include <linux/filter.h>
#include <linux/ctype.h>
+#include <linux/pid_namespace.h>
+#include <linux/major.h>
+#include <linux/stat.h>
+#include <linux/namei.h>
+#include <linux/version.h>
+
#include "../../lib/kstrtox.h"
@@ -312,6 +318,64 @@ void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
preempt_enable();
}
+BPF_CALL_2(bpf_get_current_pidns_info, struct bpf_pidns_info *, pidns_info, u32,
+ size)
+{
+ const char *pidns_path = "/proc/self/ns/pid";
+ struct pid_namespace *pidns = NULL;
+ struct filename *tmp = NULL;
+ struct inode *inode;
+ struct path kp;
+ pid_t tgid = 0;
+ pid_t pid = 0;
+ int ret;
+ int len;
+
+ if (unlikely(size != sizeof(struct bpf_pidns_info)))
+ return -EINVAL;
+ pidns = task_active_pid_ns(current);
+ if (unlikely(!pidns))
+ goto clear;
+ pidns_info->nsid = pidns->ns.inum;
+ pid = task_pid_nr_ns(current, pidns);
+ if (unlikely(!pid))
+ goto clear;
+ tgid = task_tgid_nr_ns(current, pidns);
+ if (unlikely(!tgid))
+ goto clear;
+ pidns_info->tgid = (u32) tgid;
+ pidns_info->pid = (u32) pid;
+ tmp = kmem_cache_alloc(names_cachep, GFP_ATOMIC);
+ if (unlikely(!tmp)) {
+ memset((void *)pidns_info, 0, (size_t) size);
+ return -ENOMEM;
+ }
+ len = strlen(pidns_path) + 1;
+ memcpy((char *)tmp->name, pidns_path, len);
+ tmp->uptr = NULL;
+ tmp->aname = NULL;
+ tmp->refcnt = 1;
+ ret = filename_lookup(AT_FDCWD, tmp, 0, &kp, NULL);
+ if (ret) {
+ memset((void *)pidns_info, 0, (size_t) size);
+ return ret;
+ }
+ inode = d_backing_inode(kp.dentry);
+ pidns_info->dev = inode->i_sb->s_dev;
+ return 0;
+clear:
+ memset((void *)pidns_info, 0, (size_t) size);
+ return -EINVAL;
+}
+
+const struct bpf_func_proto bpf_get_current_pidns_info_proto = {
+ .func = bpf_get_current_pidns_info,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_UNINIT_MEM,
+ .arg2_type = ARG_CONST_SIZE,
+};
+
#ifdef CONFIG_CGROUPS
BPF_CALL_0(bpf_get_current_cgroup_id)
{
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ca1255d14576..5e1dc22765a5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -709,6 +709,8 @@ 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_current_pidns_info:
+ return &bpf_get_current_pidns_info_proto;
default:
return NULL;
}
--
2.11.0
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