RE: [PATCH v2 3/6] bpf-lsm: Introduce new helper bpf_ima_file_hash()

From: Yonghong Song [mailto:yhs@fb.com] Sent: Tuesday, February 15, 2022 6:03 PM On 2/15/22 4:40 AM, Roberto Sassu wrote:

...

ima_file_hash() has been modified to calculate the measurement of a file on demand, if it has not been already performed by IMA. For compatibility reasons, ima_inode_hash() remains unchanged.

Keep the same approach in eBPF and introduce the new helper bpf_ima_file_hash() to take advantage of the modified behavior of ima_file_hash().

Signed-off-by: Roberto Sassu roberto.sassu@huawei.com

include/uapi/linux/bpf.h | 11 +++++++++++ kernel/bpf/bpf_lsm.c | 20 ++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 11 +++++++++++ 3 files changed, 42 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b0383d371b9a..ba33d5718d6b 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4648,6 +4648,16 @@ union bpf_attr {

• **-EOPNOTSUP** if IMA is disabled or **-EINVAL** if
  

• invalid arguments are passed.
  

• • long bpf_ima_file_hash(struct file *file, void *dst, u32 size)
• • Description

• • Returns a calculated IMA hash of the *file*.
    

• • If the hash is larger than *size*, then only *size*
    

• • bytes will be copied to *dst*
    

• • Return

• • The **hash_algo** is returned on success,
    

• • **-EOPNOTSUP** if the hash calculation failed or **-EINVAL**
    

if

...

• • invalid arguments are passed.
    

• • struct socket *bpf_sock_from_file(struct file *file)
  • Description

  • If the given file represents a socket, returns the associated
    

@@ -5182,6 +5192,7 @@ union bpf_attr { FN(bprm_opts_set), \ FN(ktime_get_coarse_ns), \ FN(ima_inode_hash), \

• FN(ima_file_hash), \

Please put the above FN(ima_file_hash) to the end of the list. Otherwise, we have a backward compatability issue.

Hi Yonghong

sure, will do.

Thanks

Roberto

HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Li Peng, Zhong Ronghua

...

FN(sock_from_file), \ FN(check_mtu), \ FN(for_each_map_elem), \ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 9e4ecc990647..e8d27af5bbcc 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c

[...]