On 5/31/2018 9:11 AM, Tejun Heo wrote: > On Thu, May 31, 2018 at 09:04:25AM -0700, Casey Schaufler wrote: >> On 5/31/2018 8:39 AM, Tejun Heo wrote: >>> (cc'ing more security folks and copying whole body) >>> >>> So, I'm sure the patch fixes the memory leak but API wise it looks >>> super confusing. Can security folks chime in here? Is this the right >>> fix? >> security_inode_getsecctx() provides a security context. Technically, >> this is a data blob, although both provider provide a null terminated >> string. security_inode_getsecurity(), on the other hand, provides a >> string to match an attribute name. The former releases the security >> context with security_release_secctx(), where the later releases the >> string with kfree(). >> >> When the Smack hook smack_inode_getsecctx() was added in 2009 >> for use by labeled NFS the alloc value passed to >> smack_inode_getsecurity() was set incorrectly. This wasn't a >> major issue, since labeled NFS is a fringe case. When kernfs >> started using the hook, it became the issue you discovered. >> >> The reason that we have all this confusion is that SELinux >> generates security contexts as needed, while Smack keeps them >> around all the time. Releasing an SELinux context frees memory, >> while releasing a Smack context is a null operation. > Any chance this detail can be hidden behind security api? This looks > pretty error-prone, no? It *is* hidden behind the security API. The problem is strictly within the Smack code, where the implementer of smack_inode_getsecctx() made an error. > > Thanks. > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
