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:

quoted

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

quoted

+ *		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

quoted

  	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

[...]