Re: [PATCH 0/7 v21] LSM: Multiple concurrent LSMs

[Casey Schaufler <casey@schaufler-ca.com>]

On 4/10/2015 4:24 AM, Tetsuo Handa wrote:
> This patchset seems to be blocked for waiting for an ACK from AppArmor
> people. John, can you give us ACK?
>
> Apart from ACK from John, I wrote a cleanup patch (shown below) which
> we might want to append to this patchset, though we anyway need to
> refresh this patchset with commit 58bc19542455 in linux-next.git included.

I'm good with all of this except #7. I'll incorporate it in the next
version.

> ----------------------------------------
> >From 49f753bb197ed2dda9c7958b5acf9d5458d102ef Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Date: Fri, 10 Apr 2015 13:57:45 +0900
> Subject: [PATCH] Cleanups for LSM: Multiple concurrent LSMs
>
> (1) Move definition of SECURITY_NAME_MAX from include/linux/security.h and
>     include/linux/lsm_hooks.h to security/security.c.
>
> (2) Drop "#ifdef CONFIG_SECURITY" from include/linux/lsm_hooks.h because
>     all files which include this file depend on CONFIG_SECURITY=y.
>
> (3) Drop comment of removed "union security_list_options"->name member.
>
> (4) Drop cap_netlink_send() which always returns 0.
>
> (5) Simplify security_add_hooks(), and move it from security/security.c
>     to include/linux/lsm_hooks.h as an inline function.
>
> (6) Move prototype of yama_add_hooks() and capability_add_hooks() from
>     include/linux/security.h to include/linux/lsm_hooks.h, and mark them
>     as __init functions.
>
> (7) Move security_delete_hooks() from security/security.c to
>     security/selinux/hooks.c.

I don't like this bit as it moves understanding of the module
list mechanism into a security module.

>
> (8) Update comment of prototype of commoncap functions.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
>  include/linux/lsm_hooks.h | 33 +++++++++++++++------------------
>  include/linux/security.h  | 17 ++---------------
>  security/commoncap.c      |  7 +------
>  security/security.c       | 28 +++-------------------------
>  security/selinux/hooks.c  |  8 ++++++++
>  security/yama/yama_lsm.c  |  2 +-
>  6 files changed, 30 insertions(+), 65 deletions(-)
>
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index c86aaf0..3b805de 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -25,19 +25,10 @@
>  #define __LINUX_LSM_HOOKS_H
>  
>  #include <linux/security.h>
> -
> -/* Maximum number of letters for an LSM name string */
> -#define SECURITY_NAME_MAX	10
> -
> -#ifdef CONFIG_SECURITY
> +#include <linux/init.h>
> +#include <linux/rculist.h>
>  
>  /**
> - * Security module identifier.
> - *
> - * @name:
> - *	A string that acts as a unique identifier for the LSM with max number
> - *	of characters = SECURITY_NAME_MAX.
> - *
>   * Security hooks for program execution operations.
>   *
>   * @bprm_set_creds:
> @@ -1859,14 +1850,20 @@ struct security_hook_list {
>  
>  extern struct security_hook_heads security_hook_heads;
>  
> +static inline void security_add_hooks(struct security_hook_list *hooks,
> +				      int count)
> +{
> +	int i;
> +
> +	for (i = 0; i < count; i++)
> +		list_add_tail_rcu(&hooks[i].list, hooks[i].head);
> +}
> +
>  /* prototypes */
> -extern int security_module_enable(const char *module);
> -extern void security_add_hooks(struct security_hook_list *hooks, int count);
> -#ifdef CONFIG_SECURITY_SELINUX_DISABLE
> -extern void security_delete_hooks(struct security_hook_list *hooks, int count);
> +extern int __init security_module_enable(const char *module);
> +extern void __init capability_add_hooks(void);
> +#ifdef CONFIG_SECURITY_YAMA_STACKED
> +void __init yama_add_hooks(void);
>  #endif
>  
> -#endif /* CONFIG_SECURITY */
> -
>  #endif /* ! __LINUX_LSM_HOOKS_H */
> -
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 04e2a3e..337105f 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -55,9 +55,6 @@ struct xattr;
>  struct xfrm_sec_ctx;
>  struct mm_struct;
>  
> -/* Maximum number of letters for an LSM name string */
> -#define SECURITY_NAME_MAX	10
> -
>  /* If capable should audit the security request */
>  #define SECURITY_CAP_NOAUDIT 0
>  #define SECURITY_CAP_AUDIT 1
> @@ -70,10 +67,7 @@ struct audit_krule;
>  struct user_namespace;
>  struct timezone;
>  
> -/*
> - * These functions are in security/capability.c and are used
> - * as the default capabilities functions
> - */
> +/* These functions are in security/commoncap.c */
>  extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
>  		       int cap, int audit);
>  extern int cap_settime(const struct timespec *ts, const struct timezone *tz);
> @@ -101,7 +95,6 @@ extern int cap_task_setscheduler(struct task_struct *p);
>  extern int cap_task_setioprio(struct task_struct *p, int ioprio);
>  extern int cap_task_setnice(struct task_struct *p, int nice);
>  extern int cap_vm_enough_memory(struct mm_struct *mm, long pages);
> -extern void capability_add_hooks(void);
>  
>  struct msghdr;
>  struct sk_buff;
> @@ -116,8 +109,6 @@ struct xfrm_state;
>  struct xfrm_user_sec_ctx;
>  struct seq_file;
>  
> -extern int cap_netlink_send(struct sock *sk, struct sk_buff *skb);
> -
>  #ifdef CONFIG_MMU
>  extern unsigned long mmap_min_addr;
>  extern unsigned long dac_mmap_min_addr;
> @@ -1078,7 +1069,7 @@ static inline int security_setprocattr(struct task_struct *p, char *name, void *
>  
>  static inline int security_netlink_send(struct sock *sk, struct sk_buff *skb)
>  {
> -	return cap_netlink_send(sk, skb);
> +	return 0;
>  }
>  
>  static inline int security_ismaclabel(const char *name)
> @@ -1653,9 +1644,5 @@ static inline void free_secdata(void *secdata)
>  { }
>  #endif /* CONFIG_SECURITY */
>  
> -#ifdef CONFIG_SECURITY_YAMA_STACKED
> -void yama_add_hooks(void);
> -#endif
> -
>  #endif /* ! __LINUX_SECURITY_H */
>  
> diff --git a/security/commoncap.c b/security/commoncap.c
> index b7f341f..fe76865 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -53,11 +53,6 @@ static void warn_setuid_and_fcaps_mixed(const char *fname)
>  	}
>  }
>  
> -int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
> -{
> -	return 0;
> -}
> -
>  /**
>   * cap_capable - Determine whether a task has a particular effective capability
>   * @cred: The credentials to use
> @@ -1005,7 +1000,7 @@ struct security_hook_list capability_hooks[] = {
>  	LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
>  };
>  
> -void capability_add_hooks(void)
> +void __init capability_add_hooks(void)
>  {
>  	security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
>  }
> diff --git a/security/security.c b/security/security.c
> index be10ea4..e9d7171 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -29,6 +29,9 @@
>  
>  #define MAX_LSM_EVM_XATTR	2
>  
> +/* Maximum number of letters for an LSM name string */
> +#define SECURITY_NAME_MAX	10
> +
>  /* Boot-time LSM user choice */
>  static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
>  	CONFIG_DEFAULT_SECURITY;
> @@ -1888,28 +1891,3 @@ struct security_hook_heads security_hook_heads = {
>  		LIST_HEAD_INIT(security_hook_heads.audit_rule_free),
>  #endif /* CONFIG_AUDIT */
>  };
> -
> -void security_add_hooks(struct security_hook_list *hooks, int count)
> -{
> -	struct security_hook_list *shp;
> -	int i;
> -
> -	for (i = 0; i < count; i++) {
> -		INIT_LIST_HEAD(&hooks[i].list);
> -		shp = list_last_entry(hooks[i].head,
> -					struct security_hook_list, list);
> -		list_add_rcu(&hooks[i].list, &shp->list);
> -	}
> -}
> -
> -#ifdef CONFIG_SECURITY_SELINUX_DISABLE
> -
> -void security_delete_hooks(struct security_hook_list *hooks, int count)
> -{
> -	int i;
> -
> -	for (i = 0; i < count; i++)
> -		list_del_rcu(&hooks[i].list);
> -}
> -
> -#endif /* CONFIG_SECURITY_SELINUX_DISABLE */
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 3fd8610..cea78f2 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6161,6 +6161,14 @@ static void selinux_nf_ip_exit(void)
>  #ifdef CONFIG_SECURITY_SELINUX_DISABLE
>  static int selinux_disabled;
>  
> +static void security_delete_hooks(struct security_hook_list *hooks, int count)
> +{
> +	int i;
> +
> +	for (i = 0; i < count; i++)
> +		list_del_rcu(&hooks[i].list);
> +}
> +
>  int selinux_disable(void)
>  {
>  	if (ss_initialized) {
> diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
> index a6b876d..9ed3250 100644
> --- a/security/yama/yama_lsm.c
> +++ b/security/yama/yama_lsm.c
> @@ -353,7 +353,7 @@ static struct security_hook_list yama_hooks[] = {
>  	LSM_HOOK_INIT(task_free, yama_task_free),
>  };
>  
> -void yama_add_hooks(void)
> +void __init yama_add_hooks(void)
>  {
>  	security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks));
>  }