Re: [PATCH 3/4] integrity: IMA as an integrity service provider

Mimi Zohar
2008-11-21T01:42:54Z

On Thu, 2008-11-20 at 13:15 -0500, Christoph Hellwig wrote:
> Ok, after the API is sorted out I had a quick looks at this patch.
>
> The first very odd thing is the data strucutures:
>
> > +struct ima_args_data {
> > + const char *filename;
> > + struct file *file;
> > + struct path *path;
> > + struct dentry *dentry;
> > + struct inode *inode;
> > + enum lim_hooks function;
> > + u32 osid;
> > + int mask;
> > +};
>
> You can always get from a file to a path, from a path to a dentry,
> from a dentry to and inode and from a path to some defintion of a
> filename. So a lot of things here seems very redundant.
>
> When looking at how it's used it's acually even worse. AFAICS the
> code would be a lot cleaner if you'd just kill struct ima_args_data
> and the odd pass arguments as void pointers obsfucations and just
> pass the file/path + mask directly to the lower level functions.
>
> That's also help killing things like ima_store_measurement which
> do entirely different things depending on idata->type.

hm, looking into it.

> > +static int skip_measurement(struct inode *inode, int mask)
> > +{
> > + if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
> > + return 1; /* can't measure */
> > +
> > + if (special_file(inode->i_mode) || S_ISLNK(inode->i_mode))
> > + return 1; /* don't measure */
> > +
> > + if (S_ISREG(inode->i_mode))
> > + return 0; /* measure */
> > + return 1; /* don't measure */
> > +}
>
> This could just be an
>
> if (!S_ISREG(inode->i_mode))
>
> in the caller..

Done.

> > +static int update_file_hash(struct file *f, struct path *path,
> > + struct hash_desc *desc)
>
> Please split this into a update_file_hash that always operates on a
> struct file, and a wrapper around it that creates the struct file
> for the cases that needs it.

Ok.

> > +void ima_fixup_argsdata(struct ima_args_data *data, struct file *file,
> > + struct path *path, int mask, int function)
> > +{
> > + struct dentry *dentry = NULL;
> > +
> > + data->file = file;
> > + data->path = path;
> > + data->mask = mask;
> > + data->function = function;
> > +
> > + if (file)
> > + data->dentry = dentry = file->f_dentry;
> > +
> > + if (path) {
> > + if (!dentry)
> > + data->dentry = dentry = path->dentry;
> > + }
> > + if (dentry)
> > + data->inode = dentry->d_inode;
> > +
> > + return;
> > +}
>
> You have two different callers for this, either file NULL or path NULL
> but never neither or both. So just do the setup in the callers and do
> the right thing there. (and please kill the inode member, it's entirely
> superflous)
>
> > +static void ima_file_free(struct file *file)
> > +{
> > + struct inode *inode = NULL;
> > + struct ima_iint_cache *iint;
> > +
> > + if (!file->f_dentry) /* can be NULL */
> > + return;
>
> No, it can't.
>
> > +
> > + inode = file->f_dentry->d_inode;
> > + if (S_ISDIR(inode->i_mode))
> > + return;
> > + if ((file->f_mode & FMODE_WRITE) &&
> > + (atomic_read(&inode->i_writecount) == 1)) {
>
> > + * Returns 0 on success, -ENOMEM on failure
> > + */
> > +static int ima_inode_alloc_integrity(struct inode *inode)
> > +{
> > + return ima_iint_insert(inode);
> > +}
> > +
> > +/**
> > + * ima_inode_free_integrity - free the integrity structure
> > + * @inode: the inode structure
> > + */
> > +static void ima_inode_free_integrity(struct inode *inode)
> > +{
> > + ima_iint_delete(inode);
> > +}
>
> Why these wrappers?

You're right. I'll remove these routines and assign
ima_iint_insert()/delete() directly in ima_integrity_ops.

> > + /* The file name is only a hint. */
> > + dentry = path->dentry;
> > + data->filename = (!dentry->d_name.name) ? (char *)dentry->d_iname :
> > + (char *)dentry->d_name.name;
>
> d_iname is the internal storage for d_name, always use d_name only.

ok

>
> > + if (!file || !file->f_dentry)
> > + return rc;
>
> Can't happen.

Will remove test.

> > +#define audit_type(type) AUDIT_ ##type
> > +#define lsm_type(type) LSM_ ##type
>
> Just spelling out the constants would be a lot more readable..

ok

Mimi