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

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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>
This commit is contained in:
David Howells 2015-07-10 17:19:58 -04:00 committed by Paul Moore
parent bd1741f4cf
commit c3c188b2c3
1 changed files with 41 additions and 46 deletions
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87
security/selinux/hooks.c
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@ -1709,6 +1709,32 @@ 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,
@ -1725,7 +1751,6 @@ 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;
@ -1736,12 +1761,10 @@ 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)
@ -2715,32 +2738,14 @@ 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);
}
@ -2763,22 +2768,12 @@ 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) {