Re: [PATCH v9 2/8] IMA: add support to measure buffer data hash

[Tushar Sugandhi]

<snip>

> > >   void process_buffer_measurement(struct inode *inode, const void 
> > > *buf, int size,
> > >                   const char *eventname, enum ima_hooks func,
> > > -                int pcr, const char *func_data);
> > > +                int pcr, const char *func_data,
> > > +                bool measure_buf_hash);
> >
> > Please abbreviate the boolean name to "hash".   The test would then be
> > "if (hash == true)" or "if (hash)".
> Will do.

<snip>

> > > - * process_buffer_measurement - Measure the buffer to ima log.
> > > + * process_buffer_measurement - Measure the buffer or the buffer 
> > > data hash
> > >    * @inode: inode associated with the object being measured (NULL 
> > > for KEY_CHECK)
> > >    * @buf: pointer to the buffer that needs to be added to the log.
> > >    * @size: size of buffer(in bytes).
> > > @@ -787,12 +787,23 @@ int ima_post_load_data(char *buf, loff_t size,
> > >    * @func: IMA hook
> > >    * @pcr: pcr to extend the measurement
> > >    * @func_data: private data specific to @func, can be NULL.
> > > + * @measure_buf_hash: measure buffer hash
> >
> > ^@hash: measure buffer data hash
> Agreed. Will fix.
<snip>
> > >   void process_buffer_measurement(struct inode *inode, const void 
> > > *buf, int size,
> > >                   const char *eventname, enum ima_hooks func,
> > > -                int pcr, const char *func_data)
> > > +                int pcr, const char *func_data,
> > > +                bool measure_buf_hash)
> > >   {
> > >       int ret = 0;
> > >       const char *audit_cause = "ENOMEM";
> > > @@ -807,6 +818,8 @@ void process_buffer_measurement(struct inode 
> > > *inode, const void *buf, int size,
> > >           struct ima_digest_data hdr;
> > >           char digest[IMA_MAX_DIGEST_SIZE];
> > >       } hash = {};
> > > +    char buf_hash[IMA_MAX_DIGEST_SIZE];
> > > +    int buf_hash_len = hash_digest_size[ima_hash_algo];
> > >       int violation = 0;
> > >       int action = 0;
> > >       u32 secid;
> > > @@ -849,13 +862,27 @@ void process_buffer_measurement(struct inode 
> > > *inode, const void *buf, int size,
> > >           goto out;
> > >       }
> > > +    if (measure_buf_hash) {
> >
> > ^ if (hash) {
> Yes.
> > > +        memcpy(buf_hash, hash.hdr.digest, buf_hash_len);
> > > +
> > > +        ret = ima_calc_buffer_hash(buf_hash, buf_hash_len,
> > > +                       iint.ima_hash);
> > > +        if (ret < 0) {
> > > +            audit_cause = "measure_buf_hash_error";


Hi Mimi,
There already exist a local struct variable named "hash" in p_b_m().
I was thinking of using "buf_hash", but that one is taken too.
Maybe I should use "buf_hash" for the input bool, and rename the
existing "buf_hash" local variable to "digest_hash"?
Does it sound ok?

Thanks,
Tushar


<snip>