Re: [PATCH v20 05/23] net: Prepare UDS for security module stacking

On Wed, Aug 26, 2020 at 11:07 AM Casey Schaufler <casey(a)schaufler-ca.com&gt; wrote: > Change the data used in UDS SO_PEERSEC processing from a > secid to a more general struct lsmblob. Update the > security_socket_getpeersec_dgram() interface to use the > lsmblob. There is a small amount of scaffolding code > that will come out when the security_secid_to_secctx() > code is brought in line with the lsmblob. > > Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; > --- > include/linux/security.h | 7 +++++-- > include/net/af_unix.h | 2 +- > include/net/scm.h | 8 +++++--- > net/ipv4/ip_sockglue.c | 8 +++++--- > net/unix/af_unix.c | 6 +++--- > security/security.c | 18 +++++++++++++++--- > 6 files changed, 34 insertions(+), 15 deletions(-) ... > diff --git a/include/net/af_unix.h b/include/net/af_unix.h > index f42fdddecd41..a86da0cb5ec1 100644 > --- a/include/net/af_unix.h > +++ b/include/net/af_unix.h > @@ -36,7 +36,7 @@ struct unix_skb_parms { > kgid_t gid; > struct scm_fp_list *fp; /* Passed files */ > #ifdef CONFIG_SECURITY_NETWORK > - u32 secid; /* Security ID */ > + struct lsmblob lsmblob; /* Security LSM data */ As mentioned in a previous revision, I remain concerned that this is going to become a problem due to the size limit on unix_skb_parms. I would need to redo the math to be certain, but if I recall correctly this would limit us to five LSMs assuming both that we don't need to grow the per-LSM size of lsmblob *and* the netdev folks don't decide to add more fields to the unix_skb_parms. I lost track of that earlier discussion so I'm not sure where it ended up, but if there is a viable alternative it might be a good idea to pursue it.