Re: [PATCH bpf-next 1/3] ima: Implement ima_inode_hash

From: KP Singh <kpsingh@chromium.org>
To: Yonghong Song <yhs@fb.com>
Cc: James Morris <jmorris@namei.org>,
	open list <linux-kernel@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>,
	Linux Security Module list 
	<linux-security-module@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Florent Revest <revest@chromium.org>,
	Brendan Jackman <jackmanb@chromium.org>,
	Mimi Zohar <zohar@linux.ibm.com>
Subject: Re: [PATCH bpf-next 1/3] ima: Implement ima_inode_hash
Date: Sat, 21 Nov 2020 01:08:40 +0100	[thread overview]
Message-ID: <CACYkzJ7Oi8wXf=9a-e=fFHJirRbD=u47z+3+M2cRTCy_1fwtgw@mail.gmail.com> (raw)
In-Reply-To: <deea0ee7-85f4-1f3a-9737-1dba98aa8278@fb.com>

[...]

> >
> > diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
> > index c5bc947a70ad..add7fcb32dcd 100755
> > --- a/scripts/bpf_helpers_doc.py
> > +++ b/scripts/bpf_helpers_doc.py
> > @@ -478,6 +478,7 @@ class PrinterHelpers(Printer):
> >               'struct tcp_request_sock',
> >               'struct udp6_sock',
> >               'struct task_struct',
> > +            'struct inode',
>
> This change (bpf_helpers_doc.py) belongs to patch #2.

Indeed, I missed it during a rebase. Thanks!

>
> >               'struct path',
> >               'struct btf_ptr',
> >       }
> > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> > index 2d1af8899cab..1dd2123b5b43 100644
> > --- a/security/integrity/ima/ima_main.c
> > +++ b/security/integrity/ima/ima_main.c
> > @@ -501,37 +501,17 @@ int ima_file_check(struct file *file, int mask)
> >   }
> >   EXPORT_SYMBOL_GPL(ima_file_check);
> >
> > -/**
> > - * ima_file_hash - return the stored measurement if a file has been hashed and
> > - * is in the iint cache.
> > - * @file: pointer to the file
> > - * @buf: buffer in which to store the hash
> > - * @buf_size: length of the buffer
> > - *
> > - * On success, return the hash algorithm (as defined in the enum hash_algo).
> > - * If buf is not NULL, this function also outputs the hash into buf.
> > - * If the hash is larger than buf_size, then only buf_size bytes will be copied.
> > - * It generally just makes sense to pass a buffer capable of holding the largest
> > - * possible hash: IMA_MAX_DIGEST_SIZE.
> > - * The file hash returned is based on the entire file, including the appended
> > - * signature.
> > - *
> > - * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP.
> > - * If the parameters are incorrect, return -EINVAL.
> > - */
> > -int ima_file_hash(struct file *file, char *buf, size_t buf_size)
> > +static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size)
> >   {
> > -     struct inode *inode;
> >       struct integrity_iint_cache *iint;
> >       int hash_algo;
> >
> > -     if (!file)
> > +     if (!inode)
> >               return -EINVAL;
>
> Based on original code, for ima_file_hash(), inode cannot be NULL,
> so I prefer to remove this change here and add !inode test in
> ima_inode_hash.

Makes sense. Thanks!

>
>
> >

[...]

> > + * If the parameters are incorrect, return -EINVAL.
> > + */
> > +int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size)
> > +{
>
> Add
>         if (!inode)
>                 return -EINVAL;

Done.

>
>
> > +     return __ima_inode_hash(inode, buf, buf_size);
> > +}
> > +EXPORT_SYMBOL_GPL(ima_inode_hash);
> > +
> >   /**
> >    * ima_post_create_tmpfile - mark newly created tmpfile as new
> >    * @file : newly created tmpfile
> >