One of the choices of security options proposes to select default security
CONFIG_DEFAULT_SECURITY
User can select traditional Unix DAC or one of LSMs.
Suppose CONFIG_DEFAULT_SECURITY_DAC=y selected.
I wonder how it affects LSM policy decisions?
Lets take file permissions
file fs/namei.c, kernel 4.8
__inode_permission ---> do_inode_permission --> generic_permission :
/*
* Do the basic permission checks.
*/
ret = acl_permission_check(inode, mask);
if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
return 0;
do_inode_permission(inode, mask);
if (retval)
return retval;
...
retval = devcgroup_inode_permission(inode, mask);
if (retval)
return retval;
return security_inode_permission(inode, mask);
from reading the code we see that first file ACL is consulted, then unix UID/GID then
capabilties and finally security_inode_permissions, i.e LSM
So the questioned config option seems obsolete ?
Wheher LSM always consulted last ?
Am I write ? Perhaps I miss another code path?
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