SELinux: Create a common helper to determine an inode label [ver #3]

PATCH In review David Howells 4 participants 7 messages Jun 18, 2015 – Jun 22, 2015

Subsystems (2)

VFS SELinux security module

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David Howells

author

2015-06-18 18:25 UTC #0 lore raw

PATCH 1/1 SELinux: Create a common helper to determine an inode label [ver #3]

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.

Signed-off-by David Howells <[email protected]>

---

security/selinux/hooks.c +41 ~~-46~~

index ffa5a642629a..ec30e599fb46 100644
@@ -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->d_parent), 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) {

Stephen Smalley

Acked-by on v1 1/1

2015-06-18 18:27 UTC #1 lore raw

Quoted 8 lines · David Howells

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()

Quoted 5 lines

This will change the behaviour of the functions slightly, bringing them all into line.
Suggested-by Stephen Smalley <[email protected]>
Signed-off-by David Howells <[email protected]>

Acked-by Stephen Smalley <[email protected]>

Quoted 132 lines

---

security/selinux/hooks.c +41 ~~-46~~

index ffa5a642629a..ec30e599fb46 100644
@@ -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->d_parent), 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) {

Paul Moore

maintainer

2015-06-18 20:35 UTC #2 lore raw

In reply to David Howells

Quoted 7 lines · David Howells

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()

Quoted 5 lines

This will change the behaviour of the functions slightly, bringing them all into line.
Suggested-by Stephen Smalley <[email protected]>
Signed-off-by David Howells <[email protected]>

This patch looks fine to me and I think there is an advantage to merging this regardless of what happens with the "unioning" work so I'm inclined to queue this up now unless you would prefer to resubmit with the union patches?

Quoted 130 lines

---

security/selinux/hooks.c +41 ~~-46~~

index ffa5a642629a..ec30e599fb46 100644
@@ -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->d_parent), 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) {

Signature · 2 lines

paul moore
www.paul-moore.com

David Howells

author

2015-06-22 09:41 UTC #3 lore raw

Quoted 3 lines · Paul Moore

This patch looks fine to me and I think there is an advantage to merging this regardless of what happens with the "unioning" work so I'm inclined to queue this up now unless you would prefer to resubmit with the union patches?

If you could queue it up now, that'd be great!

David

Dominick Grift

2015-06-22 12:14 UTC #4 lore raw

libselinux equivalent of restorecon -F

Please excuse my ignorance, and please bear with me for a moment:

I would consider lsetfilecon() functionality roughly the same to that of "restorecon" (in a sense at least).

Which libselinux interface would be provide roughly the same functionality to that of "restorecon -F" (in a sense at least) ?

Is that what selinux_lsetfilecon_default() is for?

Thanks

Signature · 4 lines

02DFF788
4D30 903A 1CF3 B756 FB48  1514 3148 83A2 02DF F788
http://keys.gnupg.net/pks/lookup?op=vindex&search=0x314883A202DFF788
Dominick Grift

Stephen Smalley

2015-06-22 12:49 UTC #5 lore raw

Re: libselinux equivalent of restorecon -F

Quoted 7 lines · Dominick Grift

Please excuse my ignorance, and please bear with me for a moment:
I would consider lsetfilecon() functionality roughly the same to that of "restorecon" (in a sense at least).
Which libselinux interface would be provide roughly the same functionality to that of "restorecon -F" (in a sense at least) ?
Is that what selinux_lsetfilecon_default() is for?

Yes, that's probably the closest equivalent in upstream libselinux. However, in Android libselinux [1], we have a selinux_android_restorecon() function that fully replicates restorecon functionality. We should likely take a version of that to upstream libselinux. Interface is:
#define SELINUX_ANDROID_RESTORECON_NOCHANGE 1

#define SELINUX_ANDROID_RESTORECON_VERBOSE  2
#define SELINUX_ANDROID_RESTORECON_RECURSE  4
#define SELINUX_ANDROID_RESTORECON_FORCE    8

#define SELINUX_ANDROID_RESTORECON_DATADATA 16
extern int selinux_android_restorecon(const char *file, unsigned int flags);

[1] https://android.googlesource.com/platform/external/libselinux

Paul Moore

maintainer

2015-06-22 21:48 UTC #6 lore raw

In reply to David Howells

Quoted 7 lines · David Howells

Quoted 3 lines · Paul Moore
This patch looks fine to me and I think there is an advantage to merging this regardless of what happens with the "unioning" work so I'm inclined to queue this up now unless you would prefer to resubmit with the union patches?
If you could queue it up now, that'd be great!

All set. As soon as the merge window closes I'll push it to the selinux#next branch.

Signature · 4 lines

paul moore
www.paul-moore.com
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