[PATCH v6 1/5] security: create file_truncate hook from path_truncate hook

[Paul Moore]

On Thu, Sep 8, 2022 at 3:58 PM Günther Noack <gnoack3000 at gmail.com> wrote:
>
> Like path_truncate, the file_truncate hook also restricts file
> truncation, but is called in the cases where truncation is attempted
> on an already-opened file.
>
> This is required in a subsequent commit to handle ftruncate()
> operations differently to truncate() operations.
>
> Signed-off-by: Günther Noack <gnoack3000 at gmail.com>
> ---
>  fs/namei.c                    |  6 +++---
>  fs/open.c                     |  4 ++--
>  include/linux/lsm_hook_defs.h |  1 +
>  include/linux/security.h      |  6 ++++++
>  security/apparmor/lsm.c       |  6 ++++++
>  security/security.c           |  5 +++++
>  security/tomoyo/tomoyo.c      | 13 +++++++++++++
>  7 files changed, 36 insertions(+), 5 deletions(-)

We need to get John and Tetsuo's ACKs on this patch, but in addition
to that I have two small comments (below).

> diff --git a/fs/namei.c b/fs/namei.c
> index 53b4bc094db2..52105873d1f8 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -53,8 +53,8 @@
>   * The new code replaces the old recursive symlink resolution with
>   * an iterative one (in case of non-nested symlink chains).  It does
>   * this with calls to <fs>_follow_link().
> - * As a side effect, dir_namei(), _namei() and follow_link() are now
> - * replaced with a single function lookup_dentry() that can handle all
> + * As a side effect, dir_namei(), _namei() and follow_link() are now
> + * replaced with a single function lookup_dentry() that can handle all

Since this patch(set) is likely to go in via the Landlock tree, it is
very important to keep changes outside of security/landlock to a bare
minimum of what is required both to reduce merge conflicts and
highlight the significant changes.  This change doesn't appear
necessary ... and I'm having a hard time spotting the difference in
the lines.

> diff --git a/fs/open.c b/fs/open.c
> index 8a813fa5ca56..0831433e493a 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -1271,7 +1271,7 @@ struct file *filp_open(const char *filename, int flags, umode_t mode)
>  {
>         struct filename *name = getname_kernel(filename);
>         struct file *file = ERR_CAST(name);
> -
> +

See my comment above about unnecessary changes.

-- 
paul-moore.com