• Serge E. Hallyn's avatar
    Implement file posix capabilities · b5376771
    Serge E. Hallyn authored
    Implement file posix capabilities.  This allows programs to be given a
    subset of root's powers regardless of who runs them, without having to use
    setuid and giving the binary all of root's powers.
    
    This version works with Kaigai Kohei's userspace tools, found at
    http://www.kaigai.gr.jp/index.php.  For more information on how to use this
    patch, Chris Friedhoff has posted a nice page at
    http://www.friedhoff.org/fscaps.html.
    
    Changelog:
    	Nov 27:
    	Incorporate fixes from Andrew Morton
    	(security-introduce-file-caps-tweaks and
    	security-introduce-file-caps-warning-fix)
    	Fix Kconfig dependency.
    	Fix change signaling behavior when file caps are not compiled in.
    
    	Nov 13:
    	Integrate comments from Alexey: Remove CONFIG_ ifdef from
    	capability.h, and use %zd for printing a size_t.
    
    	Nov 13:
    	Fix endianness warnings by sparse as suggested by Alexey
    	Dobriyan.
    
    	Nov 09:
    	Address warnings of unused variables at cap_bprm_set_security
    	when file capabilities are disabled, and simultaneously clean
    	up the code a little, by pulling the new code into a helper
    	function.
    
    	Nov 08:
    	For pointers to required userspace tools and how to use
    	them, see http://www.friedhoff.org/fscaps.html.
    
    	Nov 07:
    	Fix the calculation of the highest bit checked in
    	check_cap_sanity().
    
    	Nov 07:
    	Allow file caps to be enabled without CONFIG_SECURITY, since
    	capabilities are the default.
    	Hook cap_task_setscheduler when !CONFIG_SECURITY.
    	Move capable(TASK_KILL) to end of cap_task_kill to reduce
    	audit messages.
    
    	Nov 05:
    	Add secondary calls in selinux/hooks.c to task_setioprio and
    	task_setscheduler so that selinux and capabilities with file
    	cap support can be stacked.
    
    	Sep 05:
    	As Seth Arnold points out, uid checks are out of place
    	for capability code.
    
    	Sep 01:
    	Define task_setscheduler, task_setioprio, cap_task_kill, and
    	task_setnice to make sure a user cannot affect a process in which
    	they called a program with some fscaps.
    
    	One remaining question is the note under task_setscheduler: are we
    	ok with CAP_SYS_NICE being sufficient to confine a process to a
    	cpuset?
    
    	It is a semantic change, as without fsccaps, attach_task doesn't
    	allow CAP_SYS_NICE to override the uid equivalence check.  But since
    	it uses security_task_setscheduler, which elsewhere is used where
    	CAP_SYS_NICE can be used to override the uid equivalence check,
    	fixing it might be tough.
    
    	     task_setscheduler
    		 note: this also controls cpuset:attach_task.  Are we ok with
    		     CAP_SYS_NICE being used to confine to a cpuset?
    	     task_setioprio
    	     task_setnice
    		 sys_setpriority uses this (through set_one_prio) for another
    		 process.  Need same checks as setrlimit
    
    	Aug 21:
    	Updated secureexec implementation to reflect the fact that
    	euid and uid might be the same and nonzero, but the process
    	might still have elevated caps.
    
    	Aug 15:
    	Handle endianness of xattrs.
    	Enforce capability version match between kernel and disk.
    	Enforce that no bits beyond the known max capability are
    	set, else return -EPERM.
    	With this extra processing, it may be worth reconsidering
    	doing all the work at bprm_set_security rather than
    	d_instantiate.
    
    	Aug 10:
    	Always call getxattr at bprm_set_security, rather than
    	caching it at d_instantiate.
    
    [morgan@kernel.org: file-caps clean up for linux/capability.h]
    [bunk@kernel.org: unexport cap_inode_killpriv]
    Signed-off-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
    Cc: Stephen Smalley <sds@tycho.nsa.gov>
    Cc: James Morris <jmorris@namei.org>
    Cc: Chris Wright <chrisw@sous-sol.org>
    Cc: Andrew Morgan <morgan@kernel.org>
    Signed-off-by: default avatarAndrew Morgan <morgan@kernel.org>
    Signed-off-by: default avatarAdrian Bunk <bunk@kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    b5376771
vfs.c 47.6 KB