SELinux: Create a common helper to determine an inode label [ver #2]
diff mbox

Message ID 1509.1434645664@warthog.procyon.org.uk
State New
Headers show

Commit Message

David Howells June 18, 2015, 4:41 p.m. UTC
SELinux: Create a common helper to determine an inode label

Create a common helper function to determine the label for a new inode.
This is then used by:

	- may_create()
	- selinux_dentry_init_security()
	- selinux_inode_init_security()

This will change the behaviour of the functions slightly, bringing them all
into line.

Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: David Howells <dhowells@redhat.com>
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Comments

Stephen Smalley June 18, 2015, 5:08 p.m. UTC | #1
On 06/18/2015 12:41 PM, David Howells wrote:
> SELinux: Create a common helper to determine an inode label
> 
> Create a common helper function to determine the label for a new inode.
> This is then used by:
> 
> 	- may_create()
> 	- selinux_dentry_init_security()
> 	- selinux_inode_init_security()
> 
> This will change the behaviour of the functions slightly, bringing them all
> into line.
> 
> Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index ffa5a642629a..902113d71acd 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -1684,6 +1684,32 @@ out:
>  	return rc;
>  }
>  
> +/*
> + * Determine the label for an inode that might be unioned.
> + */
> +static int selinux_determine_inode_label(const struct inode *dir,
> +					 const struct qstr *name,
> +					 u16 tclass,
> +					 u32 *_new_isid)
> +{
> +	const struct superblock_security_struct *sbsec = dir->i_sb->s_security;
> +	const struct inode_security_struct *dsec = dir->i_security;
> +	const struct task_security_struct *tsec = current_security();
> +
> +	if ((sbsec->flags & SE_SBINITIALIZED) &&
> +	    (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
> +		*_new_isid = sbsec->mntpoint_sid;
> +	} else if ((sbsec->flags & SBLABEL_MNT) &&
> +		   tsec->create_sid) {
> +		*_new_isid = tsec->create_sid;
> +	} else {
> +		return security_transition_sid(tsec->sid, dsec->sid, tclass,
> +					       name, _new_isid);
> +	}
> +
> +	return 0;
> +}
> +
>  /* Check whether a task can create a file. */
>  static int may_create(struct inode *dir,
>  		      struct dentry *dentry,
> @@ -1700,7 +1726,6 @@ static int may_create(struct inode *dir,
>  	sbsec = dir->i_sb->s_security;
>  
>  	sid = tsec->sid;
> -	newsid = tsec->create_sid;
>  
>  	ad.type = LSM_AUDIT_DATA_DENTRY;
>  	ad.u.dentry = dentry;
> @@ -1711,12 +1736,10 @@ static int may_create(struct inode *dir,
>  	if (rc)
>  		return rc;
>  
> -	if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
> -		rc = security_transition_sid(sid, dsec->sid, tclass,
> -					     &dentry->d_name, &newsid);
> -		if (rc)
> -			return rc;
> -	}
> +	rc = selinux_determine_inode_label(dir, &dentry->d_name, tclass,
> +					   &newsid);
> +	if (rc)
> +		return rc;
>  
>  	rc = avc_has_perm(sid, newsid, tclass, FILE__CREATE, &ad);
>  	if (rc)
> @@ -2723,32 +2746,14 @@ static int selinux_dentry_init_security(struct dentry *dentry, int mode,
>  					struct qstr *name, void **ctx,
>  					u32 *ctxlen)
>  {
> -	const struct cred *cred = current_cred();
> -	struct task_security_struct *tsec;
> -	struct inode_security_struct *dsec;
> -	struct superblock_security_struct *sbsec;
> -	struct inode *dir = d_backing_inode(dentry->d_parent);
>  	u32 newsid;
>  	int rc;
>  
> -	tsec = cred->security;
> -	dsec = dir->i_security;
> -	sbsec = dir->i_sb->s_security;
> -
> -	if (tsec->create_sid && sbsec->behavior != SECURITY_FS_USE_MNTPOINT) {
> -		newsid = tsec->create_sid;
> -	} else {
> -		rc = security_transition_sid(tsec->sid, dsec->sid,
> -					     inode_mode_to_security_class(mode),
> -					     name,
> -					     &newsid);
> -		if (rc) {
> -			printk(KERN_WARNING
> -				"%s: security_transition_sid failed, rc=%d\n",
> -			       __func__, -rc);
> -			return rc;
> -		}
> -	}
> +	rc = selinux_determine_inode_label(d_inode(dentry), name,

We want d_inode(dentry->d_parent) here.

> +					   inode_mode_to_security_class(mode),
> +					   &newsid);
> +	if (rc)
> +		return rc;
>  
>  	return security_sid_to_context(newsid, (char **)ctx, ctxlen);
>  }
> @@ -2771,22 +2776,12 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
>  	sid = tsec->sid;
>  	newsid = tsec->create_sid;
>  
> -	if ((sbsec->flags & SE_SBINITIALIZED) &&
> -	    (sbsec->behavior == SECURITY_FS_USE_MNTPOINT))
> -		newsid = sbsec->mntpoint_sid;
> -	else if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
> -		rc = security_transition_sid(sid, dsec->sid,
> -					     inode_mode_to_security_class(inode->i_mode),
> -					     qstr, &newsid);
> -		if (rc) {
> -			printk(KERN_WARNING "%s:  "
> -			       "security_transition_sid failed, rc=%d (dev=%s "
> -			       "ino=%ld)\n",
> -			       __func__,
> -			       -rc, inode->i_sb->s_id, inode->i_ino);
> -			return rc;
> -		}
> -	}
> +	rc = selinux_determine_inode_label(
> +		dir, qstr,
> +		inode_mode_to_security_class(inode->i_mode),
> +		&newsid);
> +	if (rc)
> +		return rc;
>  
>  	/* Possibly defer initialization to selinux_complete_init. */
>  	if (sbsec->flags & SE_SBINITIALIZED) {
> 
> 

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Stephen Smalley June 18, 2015, 5:31 p.m. UTC | #2
On 06/18/2015 01:08 PM, Stephen Smalley wrote:
> On 06/18/2015 12:41 PM, David Howells wrote:
>> SELinux: Create a common helper to determine an inode label
>>
>> Create a common helper function to determine the label for a new inode.
>> This is then used by:
>>
>> 	- may_create()
>> 	- selinux_dentry_init_security()
>> 	- selinux_inode_init_security()
>>
>> This will change the behaviour of the functions slightly, bringing them all
>> into line.
>>
>> Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
>> Signed-off-by: David Howells <dhowells@redhat.com>
>> ---
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index ffa5a642629a..902113d71acd 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -1684,6 +1684,32 @@ out:
>>  	return rc;
>>  }
>>  
>> +/*
>> + * Determine the label for an inode that might be unioned.
>> + */
>> +static int selinux_determine_inode_label(const struct inode *dir,
>> +					 const struct qstr *name,
>> +					 u16 tclass,
>> +					 u32 *_new_isid)
>> +{
>> +	const struct superblock_security_struct *sbsec = dir->i_sb->s_security;
>> +	const struct inode_security_struct *dsec = dir->i_security;
>> +	const struct task_security_struct *tsec = current_security();
>> +
>> +	if ((sbsec->flags & SE_SBINITIALIZED) &&
>> +	    (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
>> +		*_new_isid = sbsec->mntpoint_sid;
>> +	} else if ((sbsec->flags & SBLABEL_MNT) &&
>> +		   tsec->create_sid) {
>> +		*_new_isid = tsec->create_sid;
>> +	} else {
>> +		return security_transition_sid(tsec->sid, dsec->sid, tclass,
>> +					       name, _new_isid);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>  /* Check whether a task can create a file. */
>>  static int may_create(struct inode *dir,
>>  		      struct dentry *dentry,
>> @@ -1700,7 +1726,6 @@ static int may_create(struct inode *dir,
>>  	sbsec = dir->i_sb->s_security;
>>  
>>  	sid = tsec->sid;
>> -	newsid = tsec->create_sid;
>>  
>>  	ad.type = LSM_AUDIT_DATA_DENTRY;
>>  	ad.u.dentry = dentry;
>> @@ -1711,12 +1736,10 @@ static int may_create(struct inode *dir,
>>  	if (rc)
>>  		return rc;
>>  
>> -	if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
>> -		rc = security_transition_sid(sid, dsec->sid, tclass,
>> -					     &dentry->d_name, &newsid);
>> -		if (rc)
>> -			return rc;
>> -	}
>> +	rc = selinux_determine_inode_label(dir, &dentry->d_name, tclass,
>> +					   &newsid);
>> +	if (rc)
>> +		return rc;
>>  
>>  	rc = avc_has_perm(sid, newsid, tclass, FILE__CREATE, &ad);
>>  	if (rc)
>> @@ -2723,32 +2746,14 @@ static int selinux_dentry_init_security(struct dentry *dentry, int mode,
>>  					struct qstr *name, void **ctx,
>>  					u32 *ctxlen)
>>  {
>> -	const struct cred *cred = current_cred();
>> -	struct task_security_struct *tsec;
>> -	struct inode_security_struct *dsec;
>> -	struct superblock_security_struct *sbsec;
>> -	struct inode *dir = d_backing_inode(dentry->d_parent);
>>  	u32 newsid;
>>  	int rc;
>>  
>> -	tsec = cred->security;
>> -	dsec = dir->i_security;
>> -	sbsec = dir->i_sb->s_security;
>> -
>> -	if (tsec->create_sid && sbsec->behavior != SECURITY_FS_USE_MNTPOINT) {
>> -		newsid = tsec->create_sid;
>> -	} else {
>> -		rc = security_transition_sid(tsec->sid, dsec->sid,
>> -					     inode_mode_to_security_class(mode),
>> -					     name,
>> -					     &newsid);
>> -		if (rc) {
>> -			printk(KERN_WARNING
>> -				"%s: security_transition_sid failed, rc=%d\n",
>> -			       __func__, -rc);
>> -			return rc;
>> -		}
>> -	}
>> +	rc = selinux_determine_inode_label(d_inode(dentry), name,
> 
> We want d_inode(dentry->d_parent) here.

Not sure why the caller didn't just pass in the dir inode in the first
place.

> 
>> +					   inode_mode_to_security_class(mode),
>> +					   &newsid);
>> +	if (rc)
>> +		return rc;
>>  
>>  	return security_sid_to_context(newsid, (char **)ctx, ctxlen);
>>  }
>> @@ -2771,22 +2776,12 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
>>  	sid = tsec->sid;
>>  	newsid = tsec->create_sid;
>>  
>> -	if ((sbsec->flags & SE_SBINITIALIZED) &&
>> -	    (sbsec->behavior == SECURITY_FS_USE_MNTPOINT))
>> -		newsid = sbsec->mntpoint_sid;
>> -	else if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
>> -		rc = security_transition_sid(sid, dsec->sid,
>> -					     inode_mode_to_security_class(inode->i_mode),
>> -					     qstr, &newsid);
>> -		if (rc) {
>> -			printk(KERN_WARNING "%s:  "
>> -			       "security_transition_sid failed, rc=%d (dev=%s "
>> -			       "ino=%ld)\n",
>> -			       __func__,
>> -			       -rc, inode->i_sb->s_id, inode->i_ino);
>> -			return rc;
>> -		}
>> -	}
>> +	rc = selinux_determine_inode_label(
>> +		dir, qstr,
>> +		inode_mode_to_security_class(inode->i_mode),
>> +		&newsid);
>> +	if (rc)
>> +		return rc;
>>  
>>  	/* Possibly defer initialization to selinux_complete_init. */
>>  	if (sbsec->flags & SE_SBINITIALIZED) {
>>
>>
> 

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David Howells June 18, 2015, 6:22 p.m. UTC | #3
Stephen Smalley <sds@tycho.nsa.gov> wrote:

> > +	rc = selinux_determine_inode_label(d_inode(dentry), name,
> 
> We want d_inode(dentry->d_parent) here.

Aargh.  I forgot to commit it.

David
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David Howells June 18, 2015, 6:23 p.m. UTC | #4
Stephen Smalley <sds@tycho.nsa.gov> wrote:

> >> +	rc = selinux_determine_inode_label(d_inode(dentry), name,
> > 
> > We want d_inode(dentry->d_parent) here.
> 
> Not sure why the caller didn't just pass in the dir inode in the first
> place.

Might be something in one of the other LSMs?

David
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Patch
diff mbox

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ffa5a642629a..902113d71acd 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1684,6 +1684,32 @@  out:
 	return rc;
 }
 
+/*
+ * Determine the label for an inode that might be unioned.
+ */
+static int selinux_determine_inode_label(const struct inode *dir,
+					 const struct qstr *name,
+					 u16 tclass,
+					 u32 *_new_isid)
+{
+	const struct superblock_security_struct *sbsec = dir->i_sb->s_security;
+	const struct inode_security_struct *dsec = dir->i_security;
+	const struct task_security_struct *tsec = current_security();
+
+	if ((sbsec->flags & SE_SBINITIALIZED) &&
+	    (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
+		*_new_isid = sbsec->mntpoint_sid;
+	} else if ((sbsec->flags & SBLABEL_MNT) &&
+		   tsec->create_sid) {
+		*_new_isid = tsec->create_sid;
+	} else {
+		return security_transition_sid(tsec->sid, dsec->sid, tclass,
+					       name, _new_isid);
+	}
+
+	return 0;
+}
+
 /* Check whether a task can create a file. */
 static int may_create(struct inode *dir,
 		      struct dentry *dentry,
@@ -1700,7 +1726,6 @@  static int may_create(struct inode *dir,
 	sbsec = dir->i_sb->s_security;
 
 	sid = tsec->sid;
-	newsid = tsec->create_sid;
 
 	ad.type = LSM_AUDIT_DATA_DENTRY;
 	ad.u.dentry = dentry;
@@ -1711,12 +1736,10 @@  static int may_create(struct inode *dir,
 	if (rc)
 		return rc;
 
-	if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
-		rc = security_transition_sid(sid, dsec->sid, tclass,
-					     &dentry->d_name, &newsid);
-		if (rc)
-			return rc;
-	}
+	rc = selinux_determine_inode_label(dir, &dentry->d_name, tclass,
+					   &newsid);
+	if (rc)
+		return rc;
 
 	rc = avc_has_perm(sid, newsid, tclass, FILE__CREATE, &ad);
 	if (rc)
@@ -2723,32 +2746,14 @@  static int selinux_dentry_init_security(struct dentry *dentry, int mode,
 					struct qstr *name, void **ctx,
 					u32 *ctxlen)
 {
-	const struct cred *cred = current_cred();
-	struct task_security_struct *tsec;
-	struct inode_security_struct *dsec;
-	struct superblock_security_struct *sbsec;
-	struct inode *dir = d_backing_inode(dentry->d_parent);
 	u32 newsid;
 	int rc;
 
-	tsec = cred->security;
-	dsec = dir->i_security;
-	sbsec = dir->i_sb->s_security;
-
-	if (tsec->create_sid && sbsec->behavior != SECURITY_FS_USE_MNTPOINT) {
-		newsid = tsec->create_sid;
-	} else {
-		rc = security_transition_sid(tsec->sid, dsec->sid,
-					     inode_mode_to_security_class(mode),
-					     name,
-					     &newsid);
-		if (rc) {
-			printk(KERN_WARNING
-				"%s: security_transition_sid failed, rc=%d\n",
-			       __func__, -rc);
-			return rc;
-		}
-	}
+	rc = selinux_determine_inode_label(d_inode(dentry), name,
+					   inode_mode_to_security_class(mode),
+					   &newsid);
+	if (rc)
+		return rc;
 
 	return security_sid_to_context(newsid, (char **)ctx, ctxlen);
 }
@@ -2771,22 +2776,12 @@  static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 	sid = tsec->sid;
 	newsid = tsec->create_sid;
 
-	if ((sbsec->flags & SE_SBINITIALIZED) &&
-	    (sbsec->behavior == SECURITY_FS_USE_MNTPOINT))
-		newsid = sbsec->mntpoint_sid;
-	else if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
-		rc = security_transition_sid(sid, dsec->sid,
-					     inode_mode_to_security_class(inode->i_mode),
-					     qstr, &newsid);
-		if (rc) {
-			printk(KERN_WARNING "%s:  "
-			       "security_transition_sid failed, rc=%d (dev=%s "
-			       "ino=%ld)\n",
-			       __func__,
-			       -rc, inode->i_sb->s_id, inode->i_ino);
-			return rc;
-		}
-	}
+	rc = selinux_determine_inode_label(
+		dir, qstr,
+		inode_mode_to_security_class(inode->i_mode),
+		&newsid);
+	if (rc)
+		return rc;
 
 	/* Possibly defer initialization to selinux_complete_init. */
 	if (sbsec->flags & SE_SBINITIALIZED) {