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Commit 746bf6d6 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Linus Torvalds
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capabilities: add a securebit to disable PR_CAP_AMBIENT_RAISE 



Per Andrew Morgan's request, add a securebit to allow admins to disable
PR_CAP_AMBIENT_RAISE.  This securebit will prevent processes from adding
capabilities to their ambient set.

For simplicity, this disables PR_CAP_AMBIENT_RAISE entirely rather than
just disabling setting previously cleared bits.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Acked-by: default avatarAndrew G. Morgan <morgan@kernel.org>
Acked-by: default avatarSerge Hallyn <serge.hallyn@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Aaron Jones <aaronmdjones@gmail.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Andrew G. Morgan <morgan@kernel.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Austin S Hemmelgarn <ahferroin7@gmail.com>
Cc: Markku Savela <msa@moth.iki.fi>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: James Morris <james.l.morris@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 32ae976e

include/uapi/linux/securebits.h

+10 −1
Original line number Diff line number Diff line
@@ -43,9 +43,18 @@ 
#define SECBIT_KEEP_CAPS	(issecure_mask(SECURE_KEEP_CAPS))

#define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED))



/* When set, a process cannot add new capabilities to its ambient set. */

#define SECURE_NO_CAP_AMBIENT_RAISE		6

#define SECURE_NO_CAP_AMBIENT_RAISE_LOCKED	7  /* make bit-6 immutable */



#define SECBIT_NO_CAP_AMBIENT_RAISE (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE))

#define SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED \

			(issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE_LOCKED))



#define SECURE_ALL_BITS		(issecure_mask(SECURE_NOROOT) | \

				 issecure_mask(SECURE_NO_SETUID_FIXUP) | \

				 issecure_mask(SECURE_KEEP_CAPS))

				 issecure_mask(SECURE_KEEP_CAPS) | \

				 issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE))

#define SECURE_ALL_LOCKS	(SECURE_ALL_BITS << 1)



#endif /* _UAPI_LINUX_SECUREBITS_H */

security/commoncap.c

+2 −1
Original line number Diff line number Diff line
@@ -993,7 +993,8 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, 
			if (arg2 == PR_CAP_AMBIENT_RAISE &&

			    (!cap_raised(current_cred()->cap_permitted, arg3) ||

			     !cap_raised(current_cred()->cap_inheritable,

					 arg3)))

					 arg3) ||

			     issecure(SECURE_NO_CAP_AMBIENT_RAISE)))

				return -EPERM;



			new = prepare_creds();