Re: [PATCH v3 4/4] added LSM hook to call ima_buffer_check

[Mimi Zohar <zohar@linux.ibm.com>]

On Mon, 2019-04-29 at 14:47 -0700, Prakhar Srivastava wrote:
> From: Prakhar Srivastava <prsriva02@gmail.com>
> 
> added LSM hook to call ima_buffer_check

Casey just responded, "I can imagine an LSM that cares about the
command line, but I don't have interest in it for any work I have in
progress."  Unless one of the other LSM maintainers is interested,
let's leave it as an IMA only hook.

Mimi

> 
> Signed-off-by: Prakhar Srivastava <prsriva02@gmail.com>
> ---
>  include/linux/lsm_hooks.h | 3 +++
>  include/linux/security.h  | 3 +++
>  kernel/kexec_internal.h   | 4 +++-
>  security/security.c       | 6 ++++++
>  4 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index a240a3fc5fc4..f18562c1eb24 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -1672,6 +1672,8 @@ union security_list_options {
>  	int (*inode_setsecctx)(struct dentry *dentry, void *ctx, u32 ctxlen);
>  	int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen);
>  
> +	int (*buffer_check)(const void *buff, int size, const char *eventname);
> +
>  #ifdef CONFIG_SECURITY_NETWORK
>  	int (*unix_stream_connect)(struct sock *sock, struct sock *other,
>  					struct sock *newsk);
> @@ -1945,6 +1947,7 @@ struct security_hook_heads {
>  	struct hlist_head inode_notifysecctx;
>  	struct hlist_head inode_setsecctx;
>  	struct hlist_head inode_getsecctx;
> +	struct hlist_head buffer_check;
>  #ifdef CONFIG_SECURITY_NETWORK
>  	struct hlist_head unix_stream_connect;
>  	struct hlist_head unix_may_send;
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 49f2685324b0..8dece6da0dda 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -388,6 +388,7 @@ void security_inode_invalidate_secctx(struct inode *inode);
>  int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
>  int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
>  int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
> +void security_buffer_measure(const void *buff, int size, char *eventname);
>  #else /* CONFIG_SECURITY */
>  
>  static inline int call_lsm_notifier(enum lsm_event event, void *data)
> @@ -1188,6 +1189,8 @@ static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32
>  {
>  	return -EOPNOTSUPP;
>  }
> +static inline void security_buffer_measure(const void *buff, int size, char *eventname)
> +{ }
>  #endif	/* CONFIG_SECURITY */
>  
>  #ifdef CONFIG_SECURITY_NETWORK
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index 48aaf2ac0d0d..9f967fbb5aa0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -12,7 +12,9 @@ int kimage_load_segment(struct kimage *image, struct kexec_segment *segment);
>  void kimage_terminate(struct kimage *image);
>  int kimage_is_destination_range(struct kimage *image,
>  				unsigned long start, unsigned long end);
> -
> +int kexec_cmdline_prepend_img_name(char **outbuf, int kernel_fd,
> +				const char *cmdline_ptr,
> +				unsigned long cmdline_len);
>  extern struct mutex kexec_mutex;
>  
>  #ifdef CONFIG_KEXEC_FILE
> diff --git a/security/security.c b/security/security.c
> index 23cbb1a295a3..2b575a40470e 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -754,6 +754,12 @@ int security_bprm_check(struct linux_binprm *bprm)
>  	return ima_bprm_check(bprm);
>  }
>  
> +void security_buffer_measure(const void *buff, int size, char *eventname)
> +{
> +	call_void_hook(buffer_check, buff, size, eventname);
> +	return ima_buffer_check(buff, size, eventname);
> +}
> +
>  void security_bprm_committing_creds(struct linux_binprm *bprm)
>  {
>  	call_void_hook(bprm_committing_creds, bprm);