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. Suggested-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Paul Moore <pmoore@redhat.com>
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@ -1709,6 +1709,32 @@ out:
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return rc;
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}
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/*
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* Determine the label for an inode that might be unioned.
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*/
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static int selinux_determine_inode_label(const struct inode *dir,
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const struct qstr *name,
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u16 tclass,
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u32 *_new_isid)
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{
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const struct superblock_security_struct *sbsec = dir->i_sb->s_security;
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const struct inode_security_struct *dsec = dir->i_security;
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const struct task_security_struct *tsec = current_security();
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if ((sbsec->flags & SE_SBINITIALIZED) &&
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(sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
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*_new_isid = sbsec->mntpoint_sid;
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} else if ((sbsec->flags & SBLABEL_MNT) &&
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tsec->create_sid) {
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*_new_isid = tsec->create_sid;
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} else {
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return security_transition_sid(tsec->sid, dsec->sid, tclass,
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name, _new_isid);
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}
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return 0;
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}
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/* Check whether a task can create a file. */
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static int may_create(struct inode *dir,
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struct dentry *dentry,
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@ -1725,7 +1751,6 @@ static int may_create(struct inode *dir,
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sbsec = dir->i_sb->s_security;
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sid = tsec->sid;
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newsid = tsec->create_sid;
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ad.type = LSM_AUDIT_DATA_DENTRY;
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ad.u.dentry = dentry;
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@ -1736,12 +1761,10 @@ static int may_create(struct inode *dir,
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if (rc)
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return rc;
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if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
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rc = security_transition_sid(sid, dsec->sid, tclass,
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&dentry->d_name, &newsid);
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if (rc)
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return rc;
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}
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rc = selinux_determine_inode_label(dir, &dentry->d_name, tclass,
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&newsid);
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if (rc)
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return rc;
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rc = avc_has_perm(sid, newsid, tclass, FILE__CREATE, &ad);
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if (rc)
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@ -2715,32 +2738,14 @@ static int selinux_dentry_init_security(struct dentry *dentry, int mode,
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struct qstr *name, void **ctx,
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u32 *ctxlen)
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{
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const struct cred *cred = current_cred();
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struct task_security_struct *tsec;
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struct inode_security_struct *dsec;
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struct superblock_security_struct *sbsec;
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struct inode *dir = d_backing_inode(dentry->d_parent);
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u32 newsid;
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int rc;
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tsec = cred->security;
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dsec = dir->i_security;
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sbsec = dir->i_sb->s_security;
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if (tsec->create_sid && sbsec->behavior != SECURITY_FS_USE_MNTPOINT) {
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newsid = tsec->create_sid;
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} else {
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rc = security_transition_sid(tsec->sid, dsec->sid,
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inode_mode_to_security_class(mode),
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name,
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&newsid);
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if (rc) {
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printk(KERN_WARNING
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"%s: security_transition_sid failed, rc=%d\n",
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__func__, -rc);
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return rc;
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}
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}
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rc = selinux_determine_inode_label(d_inode(dentry->d_parent), name,
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inode_mode_to_security_class(mode),
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&newsid);
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if (rc)
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return rc;
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return security_sid_to_context(newsid, (char **)ctx, ctxlen);
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}
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@ -2763,22 +2768,12 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
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sid = tsec->sid;
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newsid = tsec->create_sid;
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if ((sbsec->flags & SE_SBINITIALIZED) &&
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(sbsec->behavior == SECURITY_FS_USE_MNTPOINT))
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newsid = sbsec->mntpoint_sid;
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else if (!newsid || !(sbsec->flags & SBLABEL_MNT)) {
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rc = security_transition_sid(sid, dsec->sid,
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inode_mode_to_security_class(inode->i_mode),
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qstr, &newsid);
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if (rc) {
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printk(KERN_WARNING "%s: "
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"security_transition_sid failed, rc=%d (dev=%s "
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"ino=%ld)\n",
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__func__,
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-rc, inode->i_sb->s_id, inode->i_ino);
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return rc;
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}
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}
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rc = selinux_determine_inode_label(
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dir, qstr,
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inode_mode_to_security_class(inode->i_mode),
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&newsid);
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if (rc)
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return rc;
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/* Possibly defer initialization to selinux_complete_init. */
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if (sbsec->flags & SE_SBINITIALIZED) {
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