From: Stephen Smalley <sds@tycho.nsa.gov>
To: David Howells <dhowells@redhat.com>
Cc: viro@zeniv.linux.org.uk, miklos@szeredi.hu,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org,
SELinux <selinux@tycho.nsa.gov>, Paul Moore <paul@paul-moore.com>
Subject: Re: [PATCH 7/8] SELinux: Create a common helper to determine an inode label
Date: Thu, 18 Jun 2015 11:20:46 -0400 [thread overview]
Message-ID: <5582E1CE.2010301@tycho.nsa.gov> (raw)
In-Reply-To: <17513.1434640431@warthog.procyon.org.uk>
On 06/18/2015 11:13 AM, David Howells wrote:
> Stephen Smalley <sds@tycho.nsa.gov> wrote:
>
>>> + if ((sbsec->flags & SE_SBINITIALIZED) &&
>>> + (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
>>> + *_new_isid = sbsec->mntpoint_sid;
>>> + } else if (tsec->create_sid) {
>>
>> This doesn't quite match the logic in inode_init_security today, see its
>> checking of SBLABEL_MNT.
>
> Fair point. What does SBLABEL_MNT mean precisely? It seems to indicate one
> of an odd mix of behaviours. I presume it means that we *have* to calculate a
> label and can't get one from the underlying fs if it is not set.
It means the filesystem supports per-file labeling and you can use
setxattr(..."security.selinux") and setfscreatecon() for files on it.
You can see whether it is set on a filesystem by looking for the
seclabel option in cat /proc/mounts. If it is not set, then we ignore
tsec->create_sid. It is arguable as to whether it is correct to always
call security_transition_sid() there either, but that's another topic.
>
> Also, in:
>
> sbsec->flags |= SE_SBINITIALIZED;
> if (selinux_is_sblabel_mnt(sb))
> sbsec->flags |= SBLABEL_MNT;
>
> should SE_SBINITIALIZED be set after SBLABEL_MNT? And should there be a
> memory barrier in here somewhere before the setting of SE_SBINITIALIZED?
I believe that's all under sbsec->lock held by the caller, but that code
has changed a lot and been refactored significantly by others.
WARNING: multiple messages have this Message-ID (diff)
From: Stephen Smalley <sds@tycho.nsa.gov>
To: David Howells <dhowells@redhat.com>
Cc: miklos@szeredi.hu, linux-kernel@vger.kernel.org,
linux-unionfs@vger.kernel.org,
linux-security-module@vger.kernel.org, viro@zeniv.linux.org.uk,
SELinux <selinux@tycho.nsa.gov>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 7/8] SELinux: Create a common helper to determine an inode label
Date: Thu, 18 Jun 2015 11:20:46 -0400 [thread overview]
Message-ID: <5582E1CE.2010301@tycho.nsa.gov> (raw)
In-Reply-To: <17513.1434640431@warthog.procyon.org.uk>
On 06/18/2015 11:13 AM, David Howells wrote:
> Stephen Smalley <sds@tycho.nsa.gov> wrote:
>
>>> + if ((sbsec->flags & SE_SBINITIALIZED) &&
>>> + (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
>>> + *_new_isid = sbsec->mntpoint_sid;
>>> + } else if (tsec->create_sid) {
>>
>> This doesn't quite match the logic in inode_init_security today, see its
>> checking of SBLABEL_MNT.
>
> Fair point. What does SBLABEL_MNT mean precisely? It seems to indicate one
> of an odd mix of behaviours. I presume it means that we *have* to calculate a
> label and can't get one from the underlying fs if it is not set.
It means the filesystem supports per-file labeling and you can use
setxattr(..."security.selinux") and setfscreatecon() for files on it.
You can see whether it is set on a filesystem by looking for the
seclabel option in cat /proc/mounts. If it is not set, then we ignore
tsec->create_sid. It is arguable as to whether it is correct to always
call security_transition_sid() there either, but that's another topic.
>
> Also, in:
>
> sbsec->flags |= SE_SBINITIALIZED;
> if (selinux_is_sblabel_mnt(sb))
> sbsec->flags |= SBLABEL_MNT;
>
> should SE_SBINITIALIZED be set after SBLABEL_MNT? And should there be a
> memory barrier in here somewhere before the setting of SE_SBINITIALIZED?
I believe that's all under sbsec->lock held by the caller, but that code
has changed a lot and been refactored significantly by others.
next prev parent reply other threads:[~2015-06-18 15:21 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-18 13:32 [PATCH 0/8] Security: Provide unioned file support David Howells
2015-06-18 13:32 ` [PATCH 1/8] overlay: Call ovl_drop_write() earlier in ovl_dentry_open() David Howells
2015-06-18 13:32 ` [PATCH 2/8] overlayfs: Make f_path always point to the overlay and f_inode to the underlay David Howells
2015-07-20 12:42 ` Konstantin Khlebnikov
2015-07-21 13:28 ` Konstantin Khlebnikov
2015-06-18 13:32 ` [PATCH 3/8] Security: Provide copy-up security hooks for unioned files David Howells
2015-06-18 13:32 ` [PATCH 4/8] Overlayfs: Use copy-up security hooks David Howells
2015-06-18 13:32 ` [PATCH 5/8] SELinux: Stub in copy-up handling David Howells
2015-06-18 14:44 ` Stephen Smalley
2015-06-18 14:44 ` Stephen Smalley
2015-06-18 15:34 ` Casey Schaufler
2015-06-18 16:51 ` David Howells
2015-06-18 16:51 ` David Howells
2015-06-18 13:33 ` [PATCH 6/8] SELinux: Handle opening of a unioned file David Howells
2015-06-18 14:54 ` Stephen Smalley
2015-06-18 14:54 ` Stephen Smalley
2015-06-18 15:04 ` David Howells
2015-06-18 15:04 ` David Howells
2015-06-18 13:33 ` [PATCH 7/8] SELinux: Create a common helper to determine an inode label David Howells
2015-06-18 14:56 ` Stephen Smalley
2015-06-18 14:56 ` Stephen Smalley
2015-06-18 15:13 ` David Howells
2015-06-18 15:13 ` David Howells
2015-06-18 15:20 ` Stephen Smalley [this message]
2015-06-18 15:20 ` Stephen Smalley
2015-06-18 15:32 ` David Howells
2015-06-18 15:32 ` David Howells
2015-06-18 15:47 ` Stephen Smalley
2015-06-18 15:47 ` Stephen Smalley
2015-06-18 15:47 ` Stephen Smalley
2015-06-18 15:47 ` Stephen Smalley
2015-06-18 13:33 ` [PATCH 8/8] SELinux: Check against union label for file operations David Howells
2015-06-19 7:20 ` [PATCH 0/8] Security: Provide unioned file support Al Viro
2015-06-19 7:52 ` Miklos Szeredi
2015-06-19 7:59 ` Al Viro
2015-06-19 8:11 ` Miklos Szeredi
2015-06-19 8:29 ` Al Viro
2015-06-19 8:36 ` Miklos Szeredi
2015-06-19 14:04 ` David Howells
2015-06-19 14:04 ` David Howells
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