Re: [PATCH] security/selinux: fix /proc/sys/ labeling

[Lucian Adrian Grijincu]

On Tue, Feb 1, 2011 at 5:02 PM, Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
> Is this patch really from Eric or just derived from an earlier patch by him?


No, sorry for the confusion.
I seem to have triggered a git send-email bug.

>> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
>
> And did Eric truly sign off on this patch or just on an earlier one?


Just the earlier one. I added his sign-off because of this paragraph
in SubmittingPatches:
| The Signed-off-by: tag indicates that the signer was involved in the
| development of the patch, or that he/she was in the patch's delivery path.

>
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index e276eb4..7c5dfb1 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -1317,9 +1311,9 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
>>
>> Â Â Â Â Â Â Â if ((sbsec->flags & SE_SBPROC) && !S_ISLNK(inode->i_mode)) {
>> Â Â Â Â Â Â Â Â Â Â Â struct proc_inode *proci = PROC_I(inode);
>> - Â Â Â Â Â Â Â Â Â Â if (proci->pde) {
>> + Â Â Â Â Â Â Â Â Â Â if (opt_dentry && (proci->pde || proci->sysctl)) {
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â isec->sclass = inode_mode_to_security_class(inode->i_mode);
>> - Â Â Â Â Â Â Â Â Â Â Â Â Â Â rc = selinux_proc_get_sid(proci->pde,
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â rc = selinux_proc_get_sid(opt_dentry,
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â isec->sclass,
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â &sid);
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â if (rc)
>
> It would be nice if we could eliminate the last remaining piece of proc
> internal knowledge from this code - why do we need the proci->pde ||
> proci->sysctl test here? ÂWhat changes without it?


Without we label all nodes in /proc/ through selinux_proc_get_sid.

/proc/1/limits should not get it's sid from here, but from
security_task_to_inode -> selinux_task_to_inode.

Without the check we send "/1/limits" to selinux_proc_get_sid, which
strips off "/1" leaving "/limits". This will be labeled with "proc_t"
IIRC.


-- 
Â.
..: Lucian
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