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 <s...@tycho.nsa.gov>
Signed-off-by: David Howells <dhowe...@redhat.com>
---
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ffa5a642629a..ec30e599fb46 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->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) {
--
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