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linux-next/security
Andy Lutomirski 259e5e6c75 Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs
With this change, calling
  prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)
disables privilege granting operations at execve-time.  For example, a
process will not be able to execute a setuid binary to change their uid
or gid if this bit is set.  The same is true for file capabilities.

Additionally, LSM_UNSAFE_NO_NEW_PRIVS is defined to ensure that
LSMs respect the requested behavior.

To determine if the NO_NEW_PRIVS bit is set, a task may call
  prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0);
It returns 1 if set and 0 if it is not set. If any of the arguments are
non-zero, it will return -1 and set errno to -EINVAL.
(PR_SET_NO_NEW_PRIVS behaves similarly.)

This functionality is desired for the proposed seccomp filter patch
series.  By using PR_SET_NO_NEW_PRIVS, it allows a task to modify the
system call behavior for itself and its child tasks without being
able to impact the behavior of a more privileged task.

Another potential use is making certain privileged operations
unprivileged.  For example, chroot may be considered "safe" if it cannot
affect privileged tasks.

Note, this patch causes execve to fail when PR_SET_NO_NEW_PRIVS is
set and AppArmor is in use.  It is fixed in a subsequent patch.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>

v18: updated change desc
v17: using new define values as per 3.4
Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-04-14 11:13:18 +10:00
..
apparmor Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs 2012-04-14 11:13:18 +10:00
integrity security: fix ima kconfig warning 2012-02-28 11:01:15 +11:00
keys usermodehelper: kill umh_wait, renumber UMH_* constants 2012-03-23 16:58:41 -07:00
selinux Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs 2012-04-14 11:13:18 +10:00
smack lsm_audit: don't specify the audit pre/post callbacks in 'struct common_audit_data' 2012-04-03 09:49:59 -07:00
tomoyo usermodehelper: use UMH_WAIT_PROC consistently 2012-03-23 16:58:41 -07:00
yama Yama: add PR_SET_PTRACER_ANY 2012-02-16 10:25:18 +11:00
capability.c security: create task_free security callback 2012-02-10 09:14:51 +11:00
commoncap.c Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs 2012-04-14 11:13:18 +10:00
device_cgroup.c cgroup: remove cgroup_subsys argument from callbacks 2012-02-02 09:20:22 -08:00
inode.c securityfs: fix object creation races 2012-01-10 10:20:35 -05:00
Kconfig security: Yama LSM 2012-02-10 09:18:52 +11:00
lsm_audit.c lsm_audit: don't specify the audit pre/post callbacks in 'struct common_audit_data' 2012-04-03 09:49:59 -07:00
Makefile security: Yama LSM 2012-02-10 09:18:52 +11:00
min_addr.c mmap_min_addr check CAP_SYS_RAWIO only for write 2010-04-23 08:56:31 +10:00
security.c security: trim security.h 2012-02-14 10:45:42 +11:00