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Subject: Re: [REVIEW][PATCH 01/11] sem/security: Pass kern_ipc_perm not
 sem_array into the sem security hooks
To:     "Eric W. Biederman" <ebiederm@xmission.com>,
        Linux Containers <containers@lists.linux-foundation.org>
Cc:     linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        khlebnikov@yandex-team.ru, prakash.sangappa@oracle.com,
        luto@kernel.org, akpm@linux-foundation.org, oleg@redhat.com,
        serge.hallyn@ubuntu.com, esyr@redhat.com, jannh@google.com,
        linux-security-module@vger.kernel.org,
        Pavel Emelyanov <xemul@openvz.org>,
        Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>
References: <87vadmobdw.fsf_-_@xmission.com>
 <20180323191614.32489-1-ebiederm@xmission.com>
From:   Casey Schaufler <casey@schaufler-ca.com>
Message-ID: <bdf6ed62-b75c-1920-d5ce-ea08428d03d0@schaufler-ca.com>
Date:   Fri, 23 Mar 2018 14:46:02 -0700
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On 3/23/2018 12:16 PM, Eric W. Biederman wrote:
> All of the implementations of security hooks that take sem_array only
> access sem_perm the struct kern_ipc_perm member.  This means the
> dependencies of the sem security hooks can be simplified by passing
> the kern_ipc_perm member of sem_array.
>
> Making this change will allow struct sem and struct sem_array
> to become private to ipc/sem.c.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  include/linux/lsm_hooks.h  | 10 +++++-----
>  include/linux/security.h   | 21 ++++++++++-----------
>  ipc/sem.c                  | 19 ++++++++-----------
>  security/security.c        | 10 +++++-----
>  security/selinux/hooks.c   | 28 ++++++++++++++--------------
>  security/smack/smack_lsm.c | 22 +++++++++++-----------
>  6 files changed, 53 insertions(+), 57 deletions(-)
>
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 7161d8e7ee79..e4a94863a88c 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -1592,11 +1592,11 @@ union security_list_options {
>  	int (*shm_shmat)(struct shmid_kernel *shp, char __user *shmaddr,
>  				int shmflg);
>  
> -	int (*sem_alloc_security)(struct sem_array *sma);
> -	void (*sem_free_security)(struct sem_array *sma);
> -	int (*sem_associate)(struct sem_array *sma, int semflg);
> -	int (*sem_semctl)(struct sem_array *sma, int cmd);
> -	int (*sem_semop)(struct sem_array *sma, struct sembuf *sops,
> +	int (*sem_alloc_security)(struct kern_ipc_perm *sma);
> +	void (*sem_free_security)(struct kern_ipc_perm *sma);
> +	int (*sem_associate)(struct kern_ipc_perm *sma, int semflg);
> +	int (*sem_semctl)(struct kern_ipc_perm *sma, int cmd);
> +	int (*sem_semop)(struct kern_ipc_perm *sma, struct sembuf *sops,
>  				unsigned nsops, int alter);
>  
>  	int (*netlink_send)(struct sock *sk, struct sk_buff *skb);
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 73f1ef625d40..fa7adac4b99a 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -36,7 +36,6 @@ struct linux_binprm;
>  struct cred;
>  struct rlimit;
>  struct siginfo;
> -struct sem_array;
>  struct sembuf;
>  struct kern_ipc_perm;
>  struct audit_context;
> @@ -368,11 +367,11 @@ void security_shm_free(struct shmid_kernel *shp);
>  int security_shm_associate(struct shmid_kernel *shp, int shmflg);
>  int security_shm_shmctl(struct shmid_kernel *shp, int cmd);
>  int security_shm_shmat(struct shmid_kernel *shp, char __user *shmaddr, int shmflg);
> -int security_sem_alloc(struct sem_array *sma);
> -void security_sem_free(struct sem_array *sma);
> -int security_sem_associate(struct sem_array *sma, int semflg);
> -int security_sem_semctl(struct sem_array *sma, int cmd);
> -int security_sem_semop(struct sem_array *sma, struct sembuf *sops,
> +int security_sem_alloc(struct kern_ipc_perm *sma);
> +void security_sem_free(struct kern_ipc_perm *sma);
> +int security_sem_associate(struct kern_ipc_perm *sma, int semflg);
> +int security_sem_semctl(struct kern_ipc_perm *sma, int cmd);
> +int security_sem_semop(struct kern_ipc_perm *sma, struct sembuf *sops,
>  			unsigned nsops, int alter);
>  void security_d_instantiate(struct dentry *dentry, struct inode *inode);
>  int security_getprocattr(struct task_struct *p, char *name, char **value);
> @@ -1103,25 +1102,25 @@ static inline int security_shm_shmat(struct shmid_kernel *shp,
>  	return 0;
>  }
>  
> -static inline int security_sem_alloc(struct sem_array *sma)
> +static inline int security_sem_alloc(struct kern_ipc_perm *sma)
>  {
>  	return 0;
>  }
>  
> -static inline void security_sem_free(struct sem_array *sma)
> +static inline void security_sem_free(struct kern_ipc_perm *sma)
>  { }
>  
> -static inline int security_sem_associate(struct sem_array *sma, int semflg)
> +static inline int security_sem_associate(struct kern_ipc_perm *sma, int semflg)
>  {
>  	return 0;
>  }
>  
> -static inline int security_sem_semctl(struct sem_array *sma, int cmd)
> +static inline int security_sem_semctl(struct kern_ipc_perm *sma, int cmd)
>  {
>  	return 0;
>  }
>  
> -static inline int security_sem_semop(struct sem_array *sma,
> +static inline int security_sem_semop(struct kern_ipc_perm *sma,
>  				     struct sembuf *sops, unsigned nsops,
>  				     int alter)
>  {
> diff --git a/ipc/sem.c b/ipc/sem.c
> index a4af04979fd2..01f5c63670ae 100644
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -265,7 +265,7 @@ static void sem_rcu_free(struct rcu_head *head)
>  	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
>  	struct sem_array *sma = container_of(p, struct sem_array, sem_perm);
>  
> -	security_sem_free(sma);
> +	security_sem_free(&sma->sem_perm);
>  	kvfree(sma);
>  }
>  
> @@ -495,7 +495,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
>  	sma->sem_perm.key = key;
>  
>  	sma->sem_perm.security = NULL;
> -	retval = security_sem_alloc(sma);
> +	retval = security_sem_alloc(&sma->sem_perm);
>  	if (retval) {
>  		kvfree(sma);
>  		return retval;
> @@ -535,10 +535,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
>   */
>  static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
>  {
> -	struct sem_array *sma;
> -
> -	sma = container_of(ipcp, struct sem_array, sem_perm);
> -	return security_sem_associate(sma, semflg);
> +	return security_sem_associate(ipcp, semflg);
>  }
>  
>  /*
> @@ -1209,7 +1206,7 @@ static int semctl_stat(struct ipc_namespace *ns, int semid,
>  	if (ipcperms(ns, &sma->sem_perm, S_IRUGO))
>  		goto out_unlock;
>  
> -	err = security_sem_semctl(sma, cmd);
> +	err = security_sem_semctl(&sma->sem_perm, cmd);
>  	if (err)
>  		goto out_unlock;
>  
> @@ -1300,7 +1297,7 @@ static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum,
>  		return -EACCES;
>  	}
>  
> -	err = security_sem_semctl(sma, SETVAL);
> +	err = security_sem_semctl(&sma->sem_perm, SETVAL);
>  	if (err) {
>  		rcu_read_unlock();
>  		return -EACCES;
> @@ -1354,7 +1351,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
>  	if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO))
>  		goto out_rcu_wakeup;
>  
> -	err = security_sem_semctl(sma, cmd);
> +	err = security_sem_semctl(&sma->sem_perm, cmd);
>  	if (err)
>  		goto out_rcu_wakeup;
>  
> @@ -1545,7 +1542,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
>  
>  	sma = container_of(ipcp, struct sem_array, sem_perm);
>  
> -	err = security_sem_semctl(sma, cmd);
> +	err = security_sem_semctl(&sma->sem_perm, cmd);
>  	if (err)
>  		goto out_unlock1;
>  
> @@ -1962,7 +1959,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
>  		goto out_free;
>  	}
>  
> -	error = security_sem_semop(sma, sops, nsops, alter);
> +	error = security_sem_semop(&sma->sem_perm, sops, nsops, alter);
>  	if (error) {
>  		rcu_read_unlock();
>  		goto out_free;
> diff --git a/security/security.c b/security/security.c
> index 1cd8526cb0b7..d3b9aeb6b73b 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1220,27 +1220,27 @@ int security_shm_shmat(struct shmid_kernel *shp, char __user *shmaddr, int shmfl
>  	return call_int_hook(shm_shmat, 0, shp, shmaddr, shmflg);
>  }
>  
> -int security_sem_alloc(struct sem_array *sma)
> +int security_sem_alloc(struct kern_ipc_perm *sma)
>  {
>  	return call_int_hook(sem_alloc_security, 0, sma);
>  }
>  
> -void security_sem_free(struct sem_array *sma)
> +void security_sem_free(struct kern_ipc_perm *sma)
>  {
>  	call_void_hook(sem_free_security, sma);
>  }
>  
> -int security_sem_associate(struct sem_array *sma, int semflg)
> +int security_sem_associate(struct kern_ipc_perm *sma, int semflg)
>  {
>  	return call_int_hook(sem_associate, 0, sma, semflg);
>  }
>  
> -int security_sem_semctl(struct sem_array *sma, int cmd)
> +int security_sem_semctl(struct kern_ipc_perm *sma, int cmd)
>  {
>  	return call_int_hook(sem_semctl, 0, sma, cmd);
>  }
>  
> -int security_sem_semop(struct sem_array *sma, struct sembuf *sops,
> +int security_sem_semop(struct kern_ipc_perm *sma, struct sembuf *sops,
>  			unsigned nsops, int alter)
>  {
>  	return call_int_hook(sem_semop, 0, sma, sops, nsops, alter);
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 8644d864e3c1..cce994e9fc0a 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -5767,53 +5767,53 @@ static int selinux_shm_shmat(struct shmid_kernel *shp,
>  }
>  
>  /* Semaphore security operations */
> -static int selinux_sem_alloc_security(struct sem_array *sma)
> +static int selinux_sem_alloc_security(struct kern_ipc_perm *sma)
>  {
>  	struct ipc_security_struct *isec;
>  	struct common_audit_data ad;
>  	u32 sid = current_sid();
>  	int rc;
>  
> -	rc = ipc_alloc_security(&sma->sem_perm, SECCLASS_SEM);
> +	rc = ipc_alloc_security(sma, SECCLASS_SEM);
>  	if (rc)
>  		return rc;
>  
> -	isec = sma->sem_perm.security;
> +	isec = sma->security;
>  
>  	ad.type = LSM_AUDIT_DATA_IPC;
> -	ad.u.ipc_id = sma->sem_perm.key;
> +	ad.u.ipc_id = sma->key;
>  
>  	rc = avc_has_perm(sid, isec->sid, SECCLASS_SEM,
>  			  SEM__CREATE, &ad);
>  	if (rc) {
> -		ipc_free_security(&sma->sem_perm);
> +		ipc_free_security(sma);
>  		return rc;
>  	}
>  	return 0;
>  }
>  
> -static void selinux_sem_free_security(struct sem_array *sma)
> +static void selinux_sem_free_security(struct kern_ipc_perm *sma)
>  {
> -	ipc_free_security(&sma->sem_perm);
> +	ipc_free_security(sma);
>  }
>  
> -static int selinux_sem_associate(struct sem_array *sma, int semflg)
> +static int selinux_sem_associate(struct kern_ipc_perm *sma, int semflg)
>  {
>  	struct ipc_security_struct *isec;
>  	struct common_audit_data ad;
>  	u32 sid = current_sid();
>  
> -	isec = sma->sem_perm.security;
> +	isec = sma->security;
>  
>  	ad.type = LSM_AUDIT_DATA_IPC;
> -	ad.u.ipc_id = sma->sem_perm.key;
> +	ad.u.ipc_id = sma->key;
>  
>  	return avc_has_perm(sid, isec->sid, SECCLASS_SEM,
>  			    SEM__ASSOCIATE, &ad);
>  }
>  
>  /* Note, at this point, sma is locked down */
> -static int selinux_sem_semctl(struct sem_array *sma, int cmd)
> +static int selinux_sem_semctl(struct kern_ipc_perm *sma, int cmd)
>  {
>  	int err;
>  	u32 perms;
> @@ -5851,11 +5851,11 @@ static int selinux_sem_semctl(struct sem_array *sma, int cmd)
>  		return 0;
>  	}
>  
> -	err = ipc_has_perm(&sma->sem_perm, perms);
> +	err = ipc_has_perm(sma, perms);
>  	return err;
>  }
>  
> -static int selinux_sem_semop(struct sem_array *sma,
> +static int selinux_sem_semop(struct kern_ipc_perm *sma,
>  			     struct sembuf *sops, unsigned nsops, int alter)
>  {
>  	u32 perms;
> @@ -5865,7 +5865,7 @@ static int selinux_sem_semop(struct sem_array *sma,
>  	else
>  		perms = SEM__READ;
>  
> -	return ipc_has_perm(&sma->sem_perm, perms);
> +	return ipc_has_perm(sma, perms);
>  }
>  
>  static int selinux_ipc_permission(struct kern_ipc_perm *ipcp, short flag)
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 03fdecba93bb..0402b8c1aec1 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -3077,9 +3077,9 @@ static int smack_shm_shmat(struct shmid_kernel *shp, char __user *shmaddr,
>   *
>   * Returns a pointer to the smack value
>   */
> -static struct smack_known *smack_of_sem(struct sem_array *sma)
> +static struct smack_known *smack_of_sem(struct kern_ipc_perm *sma)
>  {
> -	return (struct smack_known *)sma->sem_perm.security;
> +	return (struct smack_known *)sma->security;
>  }

This function no longer makes sense and should be removed.

>  
>  /**
> @@ -3088,9 +3088,9 @@ static struct smack_known *smack_of_sem(struct sem_array *sma)
>   *
>   * Returns 0
>   */
> -static int smack_sem_alloc_security(struct sem_array *sma)
> +static int smack_sem_alloc_security(struct kern_ipc_perm *sma)
>  {
> -	struct kern_ipc_perm *isp = &sma->sem_perm;
> +	struct kern_ipc_perm *isp = sma;
>  	struct smack_known *skp = smk_of_current();
>  
>  	isp->security = skp;

A kern_ipc_perm pointer is conventionally named isp in this code.

How about instead:

-static int smack_sem_alloc_security(struct sem_array *sma)
+static int smack_sem_alloc_security(struct kern_ipc_perm *isp)
 {
-	struct kern_ipc_perm *isp = &sma->sem_perm;


> @@ -3103,9 +3103,9 @@ static int smack_sem_alloc_security(struct sem_array *sma)
>   *
>   * Clears the blob pointer
>   */
> -static void smack_sem_free_security(struct sem_array *sma)
> +static void smack_sem_free_security(struct kern_ipc_perm *sma)
>  {
> -	struct kern_ipc_perm *isp = &sma->sem_perm;
> +	struct kern_ipc_perm *isp = sma;

-static void smack_sem_free_security(struct sem_array *sma)
+static void smack_sem_free_security(struct kern_ipc_perm *isp)
 {
-	struct kern_ipc_perm *isp = &sma->sem_perm;

>  
>  	isp->security = NULL;
>  }
> @@ -3117,7 +3117,7 @@ static void smack_sem_free_security(struct sem_array *sma)
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smk_curacc_sem(struct sem_array *sma, int access)
> +static int smk_curacc_sem(struct kern_ipc_perm *sma, int access)


-static int smk_curacc_sem(struct sem_array *sma, int access)
+static int smk_curacc_sem(struct kern_ipc_perm *isp, int access)


>  {
>  	struct smack_known *ssp = smack_of_sem(sma);

	struct smack_known *ssp = smack_of_ipc(isp);

>  	struct smk_audit_info ad;
> @@ -3125,7 +3125,7 @@ static int smk_curacc_sem(struct sem_array *sma, int access)
>  
>  #ifdef CONFIG_AUDIT
>  	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
> -	ad.a.u.ipc_id = sma->sem_perm.id;
> +	ad.a.u.ipc_id = sma->id;

-	ad.a.u.ipc_id = isp->sem_perm.id;
+	ad.a.u.ipc_id = isp->id;

>  #endif
>  	rc = smk_curacc(ssp, access, &ad);
>  	rc = smk_bu_current("sem", ssp, access, rc);
> @@ -3139,7 +3139,7 @@ static int smk_curacc_sem(struct sem_array *sma, int access)
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_sem_associate(struct sem_array *sma, int semflg)
> +static int smack_sem_associate(struct kern_ipc_perm *sma, int semflg)

+static int smack_sem_associate(struct kern_ipc_perm *isp, int semflg)

and related adjustments following.

>  {
>  	int may;
>  
> @@ -3154,7 +3154,7 @@ static int smack_sem_associate(struct sem_array *sma, int semflg)
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_sem_semctl(struct sem_array *sma, int cmd)
> +static int smack_sem_semctl(struct kern_ipc_perm *sma, int cmd)

+static int smack_sem_semctl(struct kern_ipc_perm *isp, int cmd)

and related adjustments following.

>  {
>  	int may;
>  
> @@ -3198,7 +3198,7 @@ static int smack_sem_semctl(struct sem_array *sma, int cmd)
>   *
>   * Returns 0 if access is allowed, error code otherwise
>   */
> -static int smack_sem_semop(struct sem_array *sma, struct sembuf *sops,
> +static int smack_sem_semop(struct kern_ipc_perm *sma, struct sembuf *sops,
>  			   unsigned nsops, int alter)
>  {
>  	return smk_curacc_sem(sma, MAY_READWRITE);

+static int smack_sem_semop(struct kern_ipc_perm *isp, struct sembuf *sops,
 			   unsigned nsops, int alter)
 {
-	return smk_curacc_sem(sma, MAY_READWRITE);
+	return smk_curacc_sem(isp, MAY_READWRITE);