xref: /openbmc/linux/security/Kconfig (revision ba61bb17)
1#
2# Security configuration
3#
4
5menu "Security options"
6
7source security/keys/Kconfig
8
9config SECURITY_DMESG_RESTRICT
10	bool "Restrict unprivileged access to the kernel syslog"
11	default n
12	help
13	  This enforces restrictions on unprivileged users reading the kernel
14	  syslog via dmesg(8).
15
16	  If this option is not selected, no restrictions will be enforced
17	  unless the dmesg_restrict sysctl is explicitly set to (1).
18
19	  If you are unsure how to answer this question, answer N.
20
21config SECURITY
22	bool "Enable different security models"
23	depends on SYSFS
24	depends on MULTIUSER
25	help
26	  This allows you to choose different security modules to be
27	  configured into your kernel.
28
29	  If this option is not selected, the default Linux security
30	  model will be used.
31
32	  If you are unsure how to answer this question, answer N.
33
34config SECURITY_WRITABLE_HOOKS
35	depends on SECURITY
36	bool
37	default n
38
39config SECURITYFS
40	bool "Enable the securityfs filesystem"
41	help
42	  This will build the securityfs filesystem.  It is currently used by
43	  the TPM bios character driver and IMA, an integrity provider.  It is
44	  not used by SELinux or SMACK.
45
46	  If you are unsure how to answer this question, answer N.
47
48config SECURITY_NETWORK
49	bool "Socket and Networking Security Hooks"
50	depends on SECURITY
51	help
52	  This enables the socket and networking security hooks.
53	  If enabled, a security module can use these hooks to
54	  implement socket and networking access controls.
55	  If you are unsure how to answer this question, answer N.
56
57config PAGE_TABLE_ISOLATION
58	bool "Remove the kernel mapping in user mode"
59	default y
60	depends on X86_64 && !UML
61	help
62	  This feature reduces the number of hardware side channels by
63	  ensuring that the majority of kernel addresses are not mapped
64	  into userspace.
65
66	  See Documentation/x86/pti.txt for more details.
67
68config SECURITY_INFINIBAND
69	bool "Infiniband Security Hooks"
70	depends on SECURITY && INFINIBAND
71	help
72	  This enables the Infiniband security hooks.
73	  If enabled, a security module can use these hooks to
74	  implement Infiniband access controls.
75	  If you are unsure how to answer this question, answer N.
76
77config SECURITY_NETWORK_XFRM
78	bool "XFRM (IPSec) Networking Security Hooks"
79	depends on XFRM && SECURITY_NETWORK
80	help
81	  This enables the XFRM (IPSec) networking security hooks.
82	  If enabled, a security module can use these hooks to
83	  implement per-packet access controls based on labels
84	  derived from IPSec policy.  Non-IPSec communications are
85	  designated as unlabelled, and only sockets authorized
86	  to communicate unlabelled data can send without using
87	  IPSec.
88	  If you are unsure how to answer this question, answer N.
89
90config SECURITY_PATH
91	bool "Security hooks for pathname based access control"
92	depends on SECURITY
93	help
94	  This enables the security hooks for pathname based access control.
95	  If enabled, a security module can use these hooks to
96	  implement pathname based access controls.
97	  If you are unsure how to answer this question, answer N.
98
99config INTEL_TXT
100	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
101	depends on HAVE_INTEL_TXT
102	help
103	  This option enables support for booting the kernel with the
104	  Trusted Boot (tboot) module. This will utilize
105	  Intel(R) Trusted Execution Technology to perform a measured launch
106	  of the kernel. If the system does not support Intel(R) TXT, this
107	  will have no effect.
108
109	  Intel TXT will provide higher assurance of system configuration and
110	  initial state as well as data reset protection.  This is used to
111	  create a robust initial kernel measurement and verification, which
112	  helps to ensure that kernel security mechanisms are functioning
113	  correctly. This level of protection requires a root of trust outside
114	  of the kernel itself.
115
116	  Intel TXT also helps solve real end user concerns about having
117	  confidence that their hardware is running the VMM or kernel that
118	  it was configured with, especially since they may be responsible for
119	  providing such assurances to VMs and services running on it.
120
121	  See <http://www.intel.com/technology/security/> for more information
122	  about Intel(R) TXT.
123	  See <http://tboot.sourceforge.net> for more information about tboot.
124	  See Documentation/intel_txt.txt for a description of how to enable
125	  Intel TXT support in a kernel boot.
126
127	  If you are unsure as to whether this is required, answer N.
128
129config LSM_MMAP_MIN_ADDR
130	int "Low address space for LSM to protect from user allocation"
131	depends on SECURITY && SECURITY_SELINUX
132	default 32768 if ARM || (ARM64 && COMPAT)
133	default 65536
134	help
135	  This is the portion of low virtual memory which should be protected
136	  from userspace allocation.  Keeping a user from writing to low pages
137	  can help reduce the impact of kernel NULL pointer bugs.
138
139	  For most ia64, ppc64 and x86 users with lots of address space
140	  a value of 65536 is reasonable and should cause no problems.
141	  On arm and other archs it should not be higher than 32768.
142	  Programs which use vm86 functionality or have some need to map
143	  this low address space will need the permission specific to the
144	  systems running LSM.
145
146config HAVE_HARDENED_USERCOPY_ALLOCATOR
147	bool
148	help
149	  The heap allocator implements __check_heap_object() for
150	  validating memory ranges against heap object sizes in
151	  support of CONFIG_HARDENED_USERCOPY.
152
153config HARDENED_USERCOPY
154	bool "Harden memory copies between kernel and userspace"
155	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
156	select BUG
157	imply STRICT_DEVMEM
158	help
159	  This option checks for obviously wrong memory regions when
160	  copying memory to/from the kernel (via copy_to_user() and
161	  copy_from_user() functions) by rejecting memory ranges that
162	  are larger than the specified heap object, span multiple
163	  separately allocated pages, are not on the process stack,
164	  or are part of the kernel text. This kills entire classes
165	  of heap overflow exploits and similar kernel memory exposures.
166
167config HARDENED_USERCOPY_FALLBACK
168	bool "Allow usercopy whitelist violations to fallback to object size"
169	depends on HARDENED_USERCOPY
170	default y
171	help
172	  This is a temporary option that allows missing usercopy whitelists
173	  to be discovered via a WARN() to the kernel log, instead of
174	  rejecting the copy, falling back to non-whitelisted hardened
175	  usercopy that checks the slab allocation size instead of the
176	  whitelist size. This option will be removed once it seems like
177	  all missing usercopy whitelists have been identified and fixed.
178	  Booting with "slab_common.usercopy_fallback=Y/N" can change
179	  this setting.
180
181config HARDENED_USERCOPY_PAGESPAN
182	bool "Refuse to copy allocations that span multiple pages"
183	depends on HARDENED_USERCOPY
184	depends on EXPERT
185	help
186	  When a multi-page allocation is done without __GFP_COMP,
187	  hardened usercopy will reject attempts to copy it. There are,
188	  however, several cases of this in the kernel that have not all
189	  been removed. This config is intended to be used only while
190	  trying to find such users.
191
192config FORTIFY_SOURCE
193	bool "Harden common str/mem functions against buffer overflows"
194	depends on ARCH_HAS_FORTIFY_SOURCE
195	help
196	  Detect overflows of buffers in common string and memory functions
197	  where the compiler can determine and validate the buffer sizes.
198
199config STATIC_USERMODEHELPER
200	bool "Force all usermode helper calls through a single binary"
201	help
202	  By default, the kernel can call many different userspace
203	  binary programs through the "usermode helper" kernel
204	  interface.  Some of these binaries are statically defined
205	  either in the kernel code itself, or as a kernel configuration
206	  option.  However, some of these are dynamically created at
207	  runtime, or can be modified after the kernel has started up.
208	  To provide an additional layer of security, route all of these
209	  calls through a single executable that can not have its name
210	  changed.
211
212	  Note, it is up to this single binary to then call the relevant
213	  "real" usermode helper binary, based on the first argument
214	  passed to it.  If desired, this program can filter and pick
215	  and choose what real programs are called.
216
217	  If you wish for all usermode helper programs are to be
218	  disabled, choose this option and then set
219	  STATIC_USERMODEHELPER_PATH to an empty string.
220
221config STATIC_USERMODEHELPER_PATH
222	string "Path to the static usermode helper binary"
223	depends on STATIC_USERMODEHELPER
224	default "/sbin/usermode-helper"
225	help
226	  The binary called by the kernel when any usermode helper
227	  program is wish to be run.  The "real" application's name will
228	  be in the first argument passed to this program on the command
229	  line.
230
231	  If you wish for all usermode helper programs to be disabled,
232	  specify an empty string here (i.e. "").
233
234source security/selinux/Kconfig
235source security/smack/Kconfig
236source security/tomoyo/Kconfig
237source security/apparmor/Kconfig
238source security/loadpin/Kconfig
239source security/yama/Kconfig
240
241source security/integrity/Kconfig
242
243choice
244	prompt "Default security module"
245	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
246	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
247	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
248	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
249	default DEFAULT_SECURITY_DAC
250
251	help
252	  Select the security module that will be used by default if the
253	  kernel parameter security= is not specified.
254
255	config DEFAULT_SECURITY_SELINUX
256		bool "SELinux" if SECURITY_SELINUX=y
257
258	config DEFAULT_SECURITY_SMACK
259		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
260
261	config DEFAULT_SECURITY_TOMOYO
262		bool "TOMOYO" if SECURITY_TOMOYO=y
263
264	config DEFAULT_SECURITY_APPARMOR
265		bool "AppArmor" if SECURITY_APPARMOR=y
266
267	config DEFAULT_SECURITY_DAC
268		bool "Unix Discretionary Access Controls"
269
270endchoice
271
272config DEFAULT_SECURITY
273	string
274	default "selinux" if DEFAULT_SECURITY_SELINUX
275	default "smack" if DEFAULT_SECURITY_SMACK
276	default "tomoyo" if DEFAULT_SECURITY_TOMOYO
277	default "apparmor" if DEFAULT_SECURITY_APPARMOR
278	default "" if DEFAULT_SECURITY_DAC
279
280endmenu
281
282