On Fri, Jul 7, 2023 at 5:44 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote: > On Fri, Jul 7, 2023 at 12:54 PM Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: > > On 7/6/2023 6:43 PM, Paul Moore wrote: > > > On Jun 10, 2023 Roberto Sassu <roberto.sassu@xxxxxxxxxxxxxxx> wrote: > > >> Currently, the LSM infrastructure supports only one LSM providing an xattr > > >> and EVM calculating the HMAC on that xattr, plus other inode metadata. > > >> > > >> Allow all LSMs to provide one or multiple xattrs, by extending the security > > >> blob reservation mechanism. Introduce the new lbs_xattr_count field of the > > >> lsm_blob_sizes structure, so that each LSM can specify how many xattrs it > > >> needs, and the LSM infrastructure knows how many xattr slots it should > > >> allocate. > > >> > > >> Modify the inode_init_security hook definition, by passing the full > > >> xattr array allocated in security_inode_init_security(), and the current > > >> number of xattr slots in that array filled by LSMs. The first parameter > > >> would allow EVM to access and calculate the HMAC on xattrs supplied by > > >> other LSMs, the second to not leave gaps in the xattr array, when an LSM > > >> requested but did not provide xattrs (e.g. if it is not initialized). > > >> > > >> Introduce lsm_get_xattr_slot(), which LSMs can call as many times as the > > >> number specified in the lbs_xattr_count field of the lsm_blob_sizes > > >> structure. During each call, lsm_get_xattr_slot() increments the number of > > >> filled xattrs, so that at the next invocation it returns the next xattr > > >> slot to fill. > > >> > > >> Cleanup security_inode_init_security(). Unify the !initxattrs and > > >> initxattrs case by simply not allocating the new_xattrs array in the > > >> former. Update the documentation to reflect the changes, and fix the > > >> description of the xattr name, as it is not allocated anymore. > > >> > > >> Adapt both SELinux and Smack to use the new definition of the > > >> inode_init_security hook, and to call lsm_get_xattr_slot() to obtain and > > >> fill the reserved slots in the xattr array. > > >> > > >> Move the xattr->name assignment after the xattr->value one, so that it is > > >> done only in case of successful memory allocation. > > >> > > >> Finally, change the default return value of the inode_init_security hook > > >> from zero to -EOPNOTSUPP, so that BPF LSM correctly follows the hook > > >> conventions. > > >> > > >> Reported-by: Nicolas Bouchinet <nicolas.bouchinet@xxxxxxxxxxx> > > >> Link: https://lore.kernel.org/linux-integrity/Y1FTSIo+1x+4X0LS@archlinux/ > > >> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > >> --- > > >> include/linux/lsm_hook_defs.h | 6 +-- > > >> include/linux/lsm_hooks.h | 20 ++++++++++ > > >> security/security.c | 71 +++++++++++++++++++++++------------ > > >> security/selinux/hooks.c | 17 +++++---- > > >> security/smack/smack_lsm.c | 25 ++++++------ > > >> 5 files changed, 92 insertions(+), 47 deletions(-) > > > Two *very* small suggestions below, but I can make those during the > > > merge if you are okay with that Roberto? > > > > > > I'm also going to assume that Casey is okay with the Smack portion of > > > this patchset? It looks fine to me, and considering his ACK on the > > > other Smack patch in this patchset I'm assuming he is okay with this > > > one as well ... ? > > > > Yes, please feel free to add my Acked-by as needed. > > Done. Thanks Casey. I'm merging the full patchset into lsm/next right now. Thanks for all your work on this Roberto, and a thank you for everyone else who helped with reviews, testing, etc. -- paul-moore.com
