On Thu, 2022-11-17 at 09:40 -0800, Casey Schaufler wrote: > On 11/17/2022 9:24 AM, Mimi Zohar wrote: > > On Thu, 2022-11-17 at 09:18 -0800, Casey Schaufler wrote: > >> On 11/17/2022 8:05 AM, Mimi Zohar wrote: > >>> hOn Thu, 2022-11-10 at 10:46 +0100, Roberto Sassu wrote: > >>>> From: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > >>>> > >>>> Currently, security_inode_init_security() 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 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. > >>> Perhaps supporting per LSM multiple xattrs is a nice idea, but EVM > >>> doesn't currently support it. The LSM xattrs are hard coded in > >>> evm_config_default_xattrnames[], based on whether the LSM is > >>> configured. Additional security xattrs may be included in the > >>> security.evm calculation, by extending the list via > >>> security/integrity/evm/evm_xattrs. > >> Smack uses multiple xattrs. All file system objects have a SMACK64 > >> attribute, which is used for access control. A program file may have > >> a SMACK64EXEC attribute, which is the label the program will run with. > >> A library may have a SMACK64MMAP attribute to restrict loading. A > >> directory may have a SMACK64TRANSMUTE attribute, which modifies the > >> new object creation behavior. > >> > >> The point being that it may be more than a "nice idea" to support > >> multiple xattrs. It's not a hypothetical situation. > > And each of these addiitonal Smack xattrs are already defined in > > evm_config_default_xattrnames[]. > > Then I'm confused by the statement that "EVM doesn't currently support it". My mistake. As you pointed out, Smack is defining multiple security xattrs. Mimi
