[RFC][PATCH 1/2] smack: Retrieve transmuting information in smack_inode_getsecurity()

[Munehisa Kamata]

Hi Casey, Roberto

On Thu, 2023-05-11 17:12:50 +0000, Casey Schaufler wrote:
>
> On 5/8/2023 10:02 AM, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu at huawei.com>
> >
> > Enhance smack_inode_getsecurity() to retrieve the value for
> > SMACK64TRANSMUTE from the inode security blob, similarly to SMACK64.
> >
> > This helps to display accurate values in the situation where the security
> > labels come from mount options and not from xattrs.
> >
> > Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
> 
> Looks good. I have added to smack next.

Do you have any objections to backporting these patches to -stable? If not,
I'll ask it in the stable list along with another overlayfs-related fix
387ef964460f ("Smack:- Use overlay inode label in smack_inode_copy_up()").


Thanks,
Munehisa

> 
> > ---
> >  security/smack/smack_lsm.c | 22 ++++++++++++++++++----
> >  1 file changed, 18 insertions(+), 4 deletions(-)
> >
> > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> > index 7a3e9ab137d..c7e37ed2799 100644
> > --- a/security/smack/smack_lsm.c
> > +++ b/security/smack/smack_lsm.c
> > @@ -1463,10 +1463,19 @@ static int smack_inode_getsecurity(struct mnt_idmap *idmap,
> >  	struct super_block *sbp;
> >  	struct inode *ip = inode;
> >  	struct smack_known *isp;
> > +	struct inode_smack *ispp;
> > +	size_t label_len;
> > +	char *label = NULL;
> >  
> > -	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0)
> > +	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
> >  		isp = smk_of_inode(inode);
> > -	else {
> > +	} else if (strcmp(name, XATTR_SMACK_TRANSMUTE) == 0) {
> > +		ispp = smack_inode(inode);
> > +		if (ispp->smk_flags & SMK_INODE_TRANSMUTE)
> > +			label = TRANS_TRUE;
> > +		else
> > +			label = "";
> > +	} else {
> >  		/*
> >  		 * The rest of the Smack xattrs are only on sockets.
> >  		 */
> > @@ -1488,13 +1497,18 @@ static int smack_inode_getsecurity(struct mnt_idmap *idmap,
> >  			return -EOPNOTSUPP;
> >  	}
> >  
> > +	if (!label)
> > +		label = isp->smk_known;
> > +
> > +	label_len = strlen(label);
> > +
> >  	if (alloc) {
> > -		*buffer = kstrdup(isp->smk_known, GFP_KERNEL);
> > +		*buffer = kstrdup(label, GFP_KERNEL);
> >  		if (*buffer == NULL)
> >  			return -ENOMEM;
> >  	}
> >  
> > -	return strlen(isp->smk_known);
> > +	return label_len;
> >  }
> >  
> >  
>