linux-kernel - Re: [PATCH security-next v3 05/29] LSM: Convert from initcall to struct lsm

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Message-ID: <7aff4c37-6e43-1417-bb11-b819e1d583a6@canonical.com>
Date:   Mon, 1 Oct 2018 14:08:28 -0700
From:   John Johansen <john.johansen@...onical.com>
To:     Kees Cook <keescook@...omium.org>, James Morris <jmorris@...ei.org>
Cc:     "Serge E. Hallyn" <serge@...lyn.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Paul Moore <paul@...l-moore.com>,
        linux-security-module@...r.kernel.org,
        Casey Schaufler <casey@...aufler-ca.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        "Schaufler, Casey" <casey.schaufler@...el.com>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH security-next v3 05/29] LSM: Convert from initcall to
 struct lsm_info

On 09/24/2018 05:18 PM, Kees Cook wrote:
> In preparation for doing more interesting LSM init probing, this converts
> the existing initcall system into an explicit call into a function pointer
> from a section-collected struct lsm_info array.
> 
> Cc: James Morris <jmorris@...ei.org>
> Cc: "Serge E. Hallyn" <serge@...lyn.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Cc: Paul Moore <paul@...l-moore.com>
> Cc: linux-security-module@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>


Reviewed-by: John Johansen <john.johansen@...onical.com>

> ---
>  include/linux/init.h      |  2 --
>  include/linux/lsm_hooks.h | 12 ++++++++++++
>  include/linux/module.h    |  1 -
>  security/integrity/iint.c |  1 +
>  security/security.c       | 14 +++++---------
>  5 files changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/init.h b/include/linux/init.h
> index 77636539e77c..9c2aba1dbabf 100644
> --- a/include/linux/init.h
> +++ b/include/linux/init.h
> @@ -133,7 +133,6 @@ static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
>  #endif
>  
>  extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
> -extern initcall_entry_t __start_lsm_info[], __end_lsm_info[];
>  
>  /* Used for contructor calls. */
>  typedef void (*ctor_fn_t)(void);
> @@ -236,7 +235,6 @@ extern bool initcall_debug;
>  	static exitcall_t __exitcall_##fn __exit_call = fn
>  
>  #define console_initcall(fn)	___define_initcall(fn,, .con_initcall)
> -#define security_initcall(fn)	___define_initcall(fn,, .lsm_info)
>  
>  struct obs_kernel_param {
>  	const char *str;
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 97a020c616ad..ad04761e5587 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -2039,6 +2039,18 @@ extern char *lsm_names;
>  extern void security_add_hooks(struct security_hook_list *hooks, int count,
>  				char *lsm);
>  
> +struct lsm_info {
> +	int (*init)(void);
> +};
> +
> +extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
> +
> +#define security_initcall(lsm)						\
> +	static struct lsm_info __lsm_##lsm				\
> +		__used __section(.lsm_info.init)			\
> +		__aligned(sizeof(unsigned long))			\
> +		= { .init = lsm, }
> +
>  #ifdef CONFIG_SECURITY_SELINUX_DISABLE
>  /*
>   * Assuring the safety of deleting a security module is up to
> diff --git a/include/linux/module.h b/include/linux/module.h
> index f807f15bebbe..264979283756 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -123,7 +123,6 @@ extern void cleanup_module(void);
>  #define late_initcall_sync(fn)		module_init(fn)
>  
>  #define console_initcall(fn)		module_init(fn)
> -#define security_initcall(fn)		module_init(fn)
>  
>  /* Each module must use one module_init(). */
>  #define module_init(initfn)					\
> diff --git a/security/integrity/iint.c b/security/integrity/iint.c
> index 5a6810041e5c..70d21b566955 100644
> --- a/security/integrity/iint.c
> +++ b/security/integrity/iint.c
> @@ -22,6 +22,7 @@
>  #include <linux/file.h>
>  #include <linux/uaccess.h>
>  #include <linux/security.h>
> +#include <linux/lsm_hooks.h>
>  #include "integrity.h"
>  
>  static struct rb_root integrity_iint_tree = RB_ROOT;
> diff --git a/security/security.c b/security/security.c
> index 41a5da2c7faf..e74f46fba591 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -43,16 +43,12 @@ char *lsm_names;
>  static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
>  	CONFIG_DEFAULT_SECURITY;
>  
> -static void __init do_security_initcalls(void)
> +static void __init major_lsm_init(void)
>  {
> -	initcall_t call;
> -	initcall_entry_t *ce;
> +	struct lsm_info *lsm;
>  
> -	ce = __start_lsm_info;
> -	while (ce < __end_lsm_info) {
> -		call = initcall_from_entry(ce);
> -		call();
> -		ce++;
> +	for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
> +		lsm->init();
>  	}
>  }
>  
> @@ -82,7 +78,7 @@ int __init security_init(void)
>  	/*
>  	 * Load all the remaining security modules.
>  	 */
> -	do_security_initcalls();
> +	major_lsm_init();
>  
>  	return 0;
>  }
>