net: core: Two Helper function about socket information

From: Chenbo Feng <[email protected]>

Introduce two eBpf helper function to get the socket cookie and socket uid for each packet. The helper function is useful when the *sk field inside sk_buff is not empty. These helper functions can be used on socket and uid based traffic monitoring programs.

Change since V7:
* change the user namespace of uid helper function to sock_net(sk)->user_ns

Change since V6:
* change the user namespace of uid helper function back to init_user_ns since in some situation, for example, pinned bpf object, the current user namespace is not always applicable.

Change since V5:
* Delete unnecessary blank lines in sample program.
* Refine the variable orders in get_uid helper function.

Change since V4:
* Using current user namespace to get uid instead of using init_ns.
* Add compiling setup of example program in to Makefile.
* Change the name style of the example program binaries.

Change since V3:
* Fixed some typos and incorrect comments in sample program
* replaced raw insns with BPF_STX_XADD and add it to libbpf.h
* Use a temp dir as mount point instead and added a check for the user input string.
* Make the get uid helper function returns the user namespace uid instead of kuid.
* Return a overflowuid instead of 0 when no uid information is found.

Change since V2:
* Add a sample program to demostrate the usage of the helper function.
* Moved the helper function proto invoking place.
* Add function header into tools/include
* Apply sk_to_full_sk() before getting uid.

Change since V1:
* Removed the unnecessary declarations and export command
* resolved conflict with master branch.
* Examine if the socket is a full socket before getting the uid.

Chenbo Feng (3):
Add a helper function to get socket cookie in eBPF Add a eBPF helper function to retrieve socket uid
A Sample of using socket cookie and uid for traffic monitoring

Chenbo Feng (3):
Add a helper function to get socket cookie in eBPF Add a eBPF helper function to retrieve socket uid
A Sample of using socket cookie and uid for traffic monitoring

 include/linux/sock_diag.h                    |   1 +
 include/uapi/linux/bpf.h                     |  16 +-
 net/core/filter.c                            |  39 +++++
 net/core/sock_diag.c                         |   2 +-
 samples/bpf/Makefile                         |   3 +
 samples/bpf/cookie_uid_helper_example.c      | 217 +++++++++++++++++++++++++++
 samples/bpf/libbpf.h                         |  10 ++
 samples/bpf/run_cookie_uid_helper_example.sh |  14 ++
 tools/include/uapi/linux/bpf.h               |   4 +-
 9 files changed, 303 insertions(+), 3 deletions(-)
 create mode 100644 samples/bpf/cookie_uid_helper_example.c
 create mode 100755 samples/bpf/run_cookie_uid_helper_example.sh

2.7.4