Message-ID: <80cd2fea-c9a8-4f26-acbb-e0ecb34e4e40@schaufler-ca.com>
Date:   Sat, 24 Mar 2018 17:05:01 -0700
From:   Casey Schaufler <casey@...aufler-ca.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Linux Containers <containers@...ts.linux-foundation.org>
Cc:     esyr@...hat.com, jannh@...gle.com, khlebnikov@...dex-team.ru,
        linux-api@...r.kernel.org, serge.hallyn@...ntu.com,
        linux-kernel@...r.kernel.org, prakash.sangappa@...cle.com,
        linux-security-module@...r.kernel.org, luto@...nel.org,
        oleg@...hat.com, akpm@...ux-foundation.org,
        Nagarathnam Muthusamy <nagarathnam.muthusamy@...cle.com>,
        Pavel Emelyanov <xemul@...nvz.org>,
        Paul Moore <paul@...l-moore.com>,
        Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [REVIEW][PATCH 13/11] ipc/smack: Tidy up from the change in type
 of the ipc security hooks

On 3/23/2018 10:42 PM, Eric W. Biederman wrote:
> Rename the variables shp, sma, msq to isp. As that is how the code already
> refers to those variables.

Thanks. It's important to keep the code readable.

> Collapse smack_of_shm, smack_of_sem, and smack_of_msq into smack_of_ipc,
> as the three functions had become completely identical.

Thanks. Completely reasonable and correct.

> Collapse smack_shm_alloc_security, smack_sem_alloc_security and
> smack_msg_queue_alloc_security into smack_ipc_alloc_security as the
> three functions had become identical.
>
> Collapse smack_shm_free_security, smack_sem_free_security and
> smack_msg_queue_free_security into smack_ipc_free_security as the three
> functions had become identical.

This is reasonable but unprecedented. Nowhere else is the
same function used to supply multiple LSM hooks. Does anyone
out there see a reason not to do this?

> Requested-by: Casey Schaufler <casey@...aufler-ca.com>
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> ---
>  security/smack/smack_lsm.c | 197 +++++++++++++--------------------------------
>  1 file changed, 58 insertions(+), 139 deletions(-)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index d960c2ea8d79..0735b8db158b 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -2945,25 +2945,24 @@ static void smack_msg_msg_free_security(struct msg_msg *msg)
>  }
>  
>  /**
> - * smack_of_shm - the smack pointer for the shm
> - * @shp: the object
> + * smack_of_ipc - the smack pointer for the ipc
> + * @isp: the object
>   *
>   * Returns a pointer to the smack value
>   */
> -static struct smack_known *smack_of_shm(struct kern_ipc_perm *shp)
> +static struct smack_known *smack_of_ipc(struct kern_ipc_perm *isp)
>  {
> -	return (struct smack_known *)shp->security;
> +	return (struct smack_known *)isp->security;
>  }
>  
>  /**
> - * smack_shm_alloc_security - Set the security blob for shm
> - * @shp: the object
> + * smack_ipc_alloc_security - Set the security blob for ipc
> + * @isp: the object
>   *
>   * Returns 0
>   */
> -static int smack_shm_alloc_security(struct kern_ipc_perm *shp)
> +static int smack_ipc_alloc_security(struct kern_ipc_perm *isp)
>  {
> -	struct kern_ipc_perm *isp = shp;
>  	struct smack_known *skp = smk_of_current();
>  
>  	isp->security = skp;
> @@ -2971,34 +2970,32 @@ static int smack_shm_alloc_security(struct kern_ipc_perm *shp)
>  }
>  
>  /**
> - * smack_shm_free_security - Clear the security blob for shm
> - * @shp: the object
> + * smack_ipc_free_security - Clear the security blob for ipc
> + * @isp: the object
>   *
>   * Clears the blob pointer
>   */
> -static void smack_shm_free_security(struct kern_ipc_perm *shp)
> +static void smack_ipc_free_security(struct kern_ipc_perm *isp)
>  {
> -	struct kern_ipc_perm *isp = shp;
> -
>  	isp->security = NULL;
>  }
>  
>  /**
>   * smk_curacc_shm : check if current has access on shm
> - * @shp : the object
> + * @isp : the object
>   * @access : access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smk_curacc_shm(struct kern_ipc_perm *shp, int access)
> +static int smk_curacc_shm(struct kern_ipc_perm *isp, int access)
>  {
> -	struct smack_known *ssp = smack_of_shm(shp);
> +	struct smack_known *ssp = smack_of_ipc(isp);
>  	struct smk_audit_info ad;
>  	int rc;
>  
>  #ifdef CONFIG_AUDIT
>  	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
> -	ad.a.u.ipc_id = shp->id;
> +	ad.a.u.ipc_id = isp->id;
>  #endif
>  	rc = smk_curacc(ssp, access, &ad);
>  	rc = smk_bu_current("shm", ssp, access, rc);
> @@ -3007,27 +3004,27 @@ static int smk_curacc_shm(struct kern_ipc_perm *shp, int access)
>  
>  /**
>   * smack_shm_associate - Smack access check for shm
> - * @shp: the object
> + * @isp: the object
>   * @shmflg: access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_shm_associate(struct kern_ipc_perm *shp, int shmflg)
> +static int smack_shm_associate(struct kern_ipc_perm *isp, int shmflg)
>  {
>  	int may;
>  
>  	may = smack_flags_to_may(shmflg);
> -	return smk_curacc_shm(shp, may);
> +	return smk_curacc_shm(isp, may);
>  }
>  
>  /**
>   * smack_shm_shmctl - Smack access check for shm
> - * @shp: the object
> + * @isp: the object
>   * @cmd: what it wants to do
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_shm_shmctl(struct kern_ipc_perm *shp, int cmd)
> +static int smack_shm_shmctl(struct kern_ipc_perm *isp, int cmd)
>  {
>  	int may;
>  
> @@ -3051,81 +3048,42 @@ static int smack_shm_shmctl(struct kern_ipc_perm *shp, int cmd)
>  	default:
>  		return -EINVAL;
>  	}
> -	return smk_curacc_shm(shp, may);
> +	return smk_curacc_shm(isp, may);
>  }
>  
>  /**
>   * smack_shm_shmat - Smack access for shmat
> - * @shp: the object
> + * @isp: the object
>   * @shmaddr: unused
>   * @shmflg: access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_shm_shmat(struct kern_ipc_perm *shp, char __user *shmaddr,
> +static int smack_shm_shmat(struct kern_ipc_perm *ipc, char __user *shmaddr,
>  			   int shmflg)
>  {
>  	int may;
>  
>  	may = smack_flags_to_may(shmflg);
> -	return smk_curacc_shm(shp, may);
> -}
> -
> -/**
> - * smack_of_sem - the smack pointer for the sem
> - * @sma: the object
> - *
> - * Returns a pointer to the smack value
> - */
> -static struct smack_known *smack_of_sem(struct kern_ipc_perm *sma)
> -{
> -	return (struct smack_known *)sma->security;
> -}
> -
> -/**
> - * smack_sem_alloc_security - Set the security blob for sem
> - * @sma: the object
> - *
> - * Returns 0
> - */
> -static int smack_sem_alloc_security(struct kern_ipc_perm *sma)
> -{
> -	struct kern_ipc_perm *isp = sma;
> -	struct smack_known *skp = smk_of_current();
> -
> -	isp->security = skp;
> -	return 0;
> -}
> -
> -/**
> - * smack_sem_free_security - Clear the security blob for sem
> - * @sma: the object
> - *
> - * Clears the blob pointer
> - */
> -static void smack_sem_free_security(struct kern_ipc_perm *sma)
> -{
> -	struct kern_ipc_perm *isp = sma;
> -
> -	isp->security = NULL;
> +	return smk_curacc_shm(ipc, may);
>  }
>  
>  /**
>   * smk_curacc_sem : check if current has access on sem
> - * @sma : the object
> + * @isp : the object
>   * @access : access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smk_curacc_sem(struct kern_ipc_perm *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;
>  	int rc;
>  
>  #ifdef CONFIG_AUDIT
>  	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
> -	ad.a.u.ipc_id = sma->id;
> +	ad.a.u.ipc_id = isp->id;
>  #endif
>  	rc = smk_curacc(ssp, access, &ad);
>  	rc = smk_bu_current("sem", ssp, access, rc);
> @@ -3134,27 +3092,27 @@ static int smk_curacc_sem(struct kern_ipc_perm *sma, int access)
>  
>  /**
>   * smack_sem_associate - Smack access check for sem
> - * @sma: the object
> + * @isp: the object
>   * @semflg: access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_sem_associate(struct kern_ipc_perm *sma, int semflg)
> +static int smack_sem_associate(struct kern_ipc_perm *isp, int semflg)
>  {
>  	int may;
>  
>  	may = smack_flags_to_may(semflg);
> -	return smk_curacc_sem(sma, may);
> +	return smk_curacc_sem(isp, may);
>  }
>  
>  /**
>   * smack_sem_shmctl - Smack access check for sem
> - * @sma: the object
> + * @isp: the object
>   * @cmd: what it wants to do
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_sem_semctl(struct kern_ipc_perm *sma, int cmd)
> +static int smack_sem_semctl(struct kern_ipc_perm *isp, int cmd)
>  {
>  	int may;
>  
> @@ -3184,12 +3142,12 @@ static int smack_sem_semctl(struct kern_ipc_perm *sma, int cmd)
>  		return -EINVAL;
>  	}
>  
> -	return smk_curacc_sem(sma, may);
> +	return smk_curacc_sem(isp, may);
>  }
>  
>  /**
>   * smack_sem_semop - Smack checks of semaphore operations
> - * @sma: the object
> + * @isp: the object
>   * @sops: unused
>   * @nsops: unused
>   * @alter: unused
> @@ -3198,67 +3156,28 @@ static int smack_sem_semctl(struct kern_ipc_perm *sma, int cmd)
>   *
>   * Returns 0 if access is allowed, error code otherwise
>   */
> -static int smack_sem_semop(struct kern_ipc_perm *sma, struct sembuf *sops,
> +static int smack_sem_semop(struct kern_ipc_perm *isp, struct sembuf *sops,
>  			   unsigned nsops, int alter)
>  {
> -	return smk_curacc_sem(sma, MAY_READWRITE);
> -}
> -
> -/**
> - * smack_msg_alloc_security - Set the security blob for msg
> - * @msq: the object
> - *
> - * Returns 0
> - */
> -static int smack_msg_queue_alloc_security(struct kern_ipc_perm *msq)
> -{
> -	struct kern_ipc_perm *kisp = msq;
> -	struct smack_known *skp = smk_of_current();
> -
> -	kisp->security = skp;
> -	return 0;
> -}
> -
> -/**
> - * smack_msg_free_security - Clear the security blob for msg
> - * @msq: the object
> - *
> - * Clears the blob pointer
> - */
> -static void smack_msg_queue_free_security(struct kern_ipc_perm *msq)
> -{
> -	struct kern_ipc_perm *kisp = msq;
> -
> -	kisp->security = NULL;
> -}
> -
> -/**
> - * smack_of_msq - the smack pointer for the msq
> - * @msq: the object
> - *
> - * Returns a pointer to the smack label entry
> - */
> -static struct smack_known *smack_of_msq(struct kern_ipc_perm *msq)
> -{
> -	return (struct smack_known *)msq->security;
> +	return smk_curacc_sem(isp, MAY_READWRITE);
>  }
>  
>  /**
>   * smk_curacc_msq : helper to check if current has access on msq
> - * @msq : the msq
> + * @isp : the msq
>   * @access : access requested
>   *
>   * return 0 if current has access, error otherwise
>   */
> -static int smk_curacc_msq(struct kern_ipc_perm *msq, int access)
> +static int smk_curacc_msq(struct kern_ipc_perm *isp, int access)
>  {
> -	struct smack_known *msp = smack_of_msq(msq);
> +	struct smack_known *msp = smack_of_ipc(isp);
>  	struct smk_audit_info ad;
>  	int rc;
>  
>  #ifdef CONFIG_AUDIT
>  	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_IPC);
> -	ad.a.u.ipc_id = msq->id;
> +	ad.a.u.ipc_id = isp->id;
>  #endif
>  	rc = smk_curacc(msp, access, &ad);
>  	rc = smk_bu_current("msq", msp, access, rc);
> @@ -3267,27 +3186,27 @@ static int smk_curacc_msq(struct kern_ipc_perm *msq, int access)
>  
>  /**
>   * smack_msg_queue_associate - Smack access check for msg_queue
> - * @msq: the object
> + * @isp: the object
>   * @msqflg: access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_msg_queue_associate(struct kern_ipc_perm *msq, int msqflg)
> +static int smack_msg_queue_associate(struct kern_ipc_perm *isp, int msqflg)
>  {
>  	int may;
>  
>  	may = smack_flags_to_may(msqflg);
> -	return smk_curacc_msq(msq, may);
> +	return smk_curacc_msq(isp, may);
>  }
>  
>  /**
>   * smack_msg_queue_msgctl - Smack access check for msg_queue
> - * @msq: the object
> + * @isp: the object
>   * @cmd: what it wants to do
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_msg_queue_msgctl(struct kern_ipc_perm *msq, int cmd)
> +static int smack_msg_queue_msgctl(struct kern_ipc_perm *isp, int cmd)
>  {
>  	int may;
>  
> @@ -3310,29 +3229,29 @@ static int smack_msg_queue_msgctl(struct kern_ipc_perm *msq, int cmd)
>  		return -EINVAL;
>  	}
>  
> -	return smk_curacc_msq(msq, may);
> +	return smk_curacc_msq(isp, may);
>  }
>  
>  /**
>   * smack_msg_queue_msgsnd - Smack access check for msg_queue
> - * @msq: the object
> + * @isp: the object
>   * @msg: unused
>   * @msqflg: access requested
>   *
>   * Returns 0 if current has the requested access, error code otherwise
>   */
> -static int smack_msg_queue_msgsnd(struct kern_ipc_perm *msq, struct msg_msg *msg,
> +static int smack_msg_queue_msgsnd(struct kern_ipc_perm *isp, struct msg_msg *msg,
>  				  int msqflg)
>  {
>  	int may;
>  
>  	may = smack_flags_to_may(msqflg);
> -	return smk_curacc_msq(msq, may);
> +	return smk_curacc_msq(isp, may);
>  }
>  
>  /**
>   * smack_msg_queue_msgsnd - Smack access check for msg_queue
> - * @msq: the object
> + * @isp: the object
>   * @msg: unused
>   * @target: unused
>   * @type: unused
> @@ -3340,10 +3259,10 @@ static int smack_msg_queue_msgsnd(struct kern_ipc_perm *msq, struct msg_msg *msg
>   *
>   * Returns 0 if current has read and write access, error code otherwise
>   */
> -static int smack_msg_queue_msgrcv(struct kern_ipc_perm *msq, struct msg_msg *msg,
> +static int smack_msg_queue_msgrcv(struct kern_ipc_perm *isp, struct msg_msg *msg,
>  			struct task_struct *target, long type, int mode)
>  {
> -	return smk_curacc_msq(msq, MAY_READWRITE);
> +	return smk_curacc_msq(isp, MAY_READWRITE);
>  }
>  
>  /**
> @@ -4756,21 +4675,21 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
>  	LSM_HOOK_INIT(msg_msg_alloc_security, smack_msg_msg_alloc_security),
>  	LSM_HOOK_INIT(msg_msg_free_security, smack_msg_msg_free_security),
>  
> -	LSM_HOOK_INIT(msg_queue_alloc_security, smack_msg_queue_alloc_security),
> -	LSM_HOOK_INIT(msg_queue_free_security, smack_msg_queue_free_security),
> +	LSM_HOOK_INIT(msg_queue_alloc_security, smack_ipc_alloc_security),
> +	LSM_HOOK_INIT(msg_queue_free_security, smack_ipc_free_security),
>  	LSM_HOOK_INIT(msg_queue_associate, smack_msg_queue_associate),
>  	LSM_HOOK_INIT(msg_queue_msgctl, smack_msg_queue_msgctl),
>  	LSM_HOOK_INIT(msg_queue_msgsnd, smack_msg_queue_msgsnd),
>  	LSM_HOOK_INIT(msg_queue_msgrcv, smack_msg_queue_msgrcv),
>  
> -	LSM_HOOK_INIT(shm_alloc_security, smack_shm_alloc_security),
> -	LSM_HOOK_INIT(shm_free_security, smack_shm_free_security),
> +	LSM_HOOK_INIT(shm_alloc_security, smack_ipc_alloc_security),
> +	LSM_HOOK_INIT(shm_free_security, smack_ipc_free_security),
>  	LSM_HOOK_INIT(shm_associate, smack_shm_associate),
>  	LSM_HOOK_INIT(shm_shmctl, smack_shm_shmctl),
>  	LSM_HOOK_INIT(shm_shmat, smack_shm_shmat),
>  
> -	LSM_HOOK_INIT(sem_alloc_security, smack_sem_alloc_security),
> -	LSM_HOOK_INIT(sem_free_security, smack_sem_free_security),
> +	LSM_HOOK_INIT(sem_alloc_security, smack_ipc_alloc_security),
> +	LSM_HOOK_INIT(sem_free_security, smack_ipc_free_security),
>  	LSM_HOOK_INIT(sem_associate, smack_sem_associate),
>  	LSM_HOOK_INIT(sem_semctl, smack_sem_semctl),
>  	LSM_HOOK_INIT(sem_semop, smack_sem_semop),

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