Capability Inheritance Algorithm

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Capability Inheritance Algorithm

Capability Inheritance Algorithm was implemented in full as specified in the Chapter 4 (Subsection 4.2.9). The inheritance algorithm (function linsec_compute_creds, linsec_exec.c) is invoked in two occasions:

when a new executable is loaded by a process, to reflect the executable file's privileges (eg. when exec is called by an userspace program to run some other program), and
when a process changes its ownership, to reflect privileges of the new owner (eg. when setuid function is called by a suid binary).

Therefore, a call to linsec_compute_creds is placed in compute_creds (fs/exec.c) function invoked from do_execve (fs/exec.c) and also in linsec_do_suid (kernel/linsec_suid.c) invoked from the family of sys_setXuid (kernel/sys.c) functions. linsec_do_suid also handles manipulation of linsec_usr (Section 5.5).