Merge branch 'bpf-lsm: Extend interoperability with IMA'

Roberto Sassu says:

====================
Extend the interoperability with IMA, to give wider flexibility for the
implementation of integrity-focused LSMs based on eBPF.

Patch 1 fixes some style issues.

Patches 2-6 give the ability to eBPF-based LSMs to take advantage of the
measurement capability of IMA without needing to setup a policy in IMA
(those LSMs might implement the policy capability themselves).

Patches 7-9 allow eBPF-based LSMs to evaluate files read by the kernel.

Changelog

v2:
- Add better description to patch 1 (suggested by Shuah)
- Recalculate digest if it is not fresh (when IMA_COLLECTED flag not set)
- Move declaration of bpf_ima_file_hash() at the end (suggested by
  Yonghong)
- Add tests to check if the digest has been recalculated
- Add deny test for bpf_kernel_read_file()
- Add description to tests

v1:
- Modify ima_file_hash() only and allow the usage of the function with the
  modified behavior by eBPF-based LSMs through the new function
  bpf_ima_file_hash() (suggested by Mimi)
- Make bpf_lsm_kernel_read_file() sleepable so that bpf_ima_inode_hash()
  and bpf_ima_file_hash() can be called inside the implementation of
  eBPF-based LSMs for this hook
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index e9978a916c3e..99fab54ae9c0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5119,6 +5119,16 @@ union bpf_attr {
  *		0 on success.
  *		**-EINVAL** for invalid input
  *		**-EOPNOTSUPP** for unsupported protocol
+ *
+ * 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.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5314,6 +5324,7 @@ union bpf_attr {
 	FN(xdp_store_bytes),		\
 	FN(copy_from_user_task),	\
 	FN(skb_set_tstamp),		\
+	FN(ima_file_hash),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper