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selinux: fix inode_doinit_with_dentry() LABEL_INVALID error handling 

[ Upstream commit 200ea5a229 ]

A previous fix, commit 83370b31a9 ("selinux: fix error initialization
in inode_doinit_with_dentry()"), changed how failures were handled
before a SELinux policy was loaded.  Unfortunately that patch was
potentially problematic for two reasons: it set the isec->initialized
state without holding a lock, and it didn't set the inode's SELinux
label to the "default" for the particular filesystem.  The later can
be a problem if/when a later attempt to revalidate the inode fails
and SELinux reverts to the existing inode label.

This patch should restore the default inode labeling that existed
before the original fix, without affecting the LABEL_INVALID marking
such that revalidation will still be attempted in the future.

Fixes: 83370b31a9 ("selinux: fix error initialization in inode_doinit_with_dentry()")
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Paul Moore 2020-11-03 11:49:38 -05:00 committed by Greg Kroah-Hartman
parent ae54a6d994
commit c807042f2d
1 changed files with 13 additions and 18 deletions
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31
security/selinux/hooks.c
View File

@ -1499,13 +1499,7 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
* inode_doinit with a dentry, before these inodes could
* be used again by userspace.
*/
isec->initialized = LABEL_INVALID;
/*
* There is nothing useful to jump to the "out"
* label, except a needless spin lock/unlock
* cycle.
*/
return 0;
goto out_invalid;
}
rc = inode_doinit_use_xattr(inode, dentry, sbsec->def_sid,
@ -1559,15 +1553,8 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
* inode_doinit() with a dentry, before these inodes
* could be used again by userspace.
*/
if (!dentry) {
isec->initialized = LABEL_INVALID;
/*
* There is nothing useful to jump to the "out"
* label, except a needless spin lock/unlock
* cycle.
*/
return 0;
}
if (!dentry)
goto out_invalid;
rc = selinux_genfs_get_sid(dentry, sclass,
sbsec->flags, &sid);
if (rc) {
@ -1592,11 +1579,10 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
out:
spin_lock(&isec->lock);
if (isec->initialized == LABEL_PENDING) {
if (!sid || rc) {
if (rc) {
isec->initialized = LABEL_INVALID;
goto out_unlock;
}
isec->initialized = LABEL_INITIALIZED;
isec->sid = sid;
}
@ -1604,6 +1590,15 @@ out:
out_unlock:
spin_unlock(&isec->lock);
return rc;
out_invalid:
spin_lock(&isec->lock);
if (isec->initialized == LABEL_PENDING) {
isec->initialized = LABEL_INVALID;
isec->sid = sid;
}
spin_unlock(&isec->lock);
return 0;
}
/* Convert a Linux signal to an access vector. */