xref: /openbmc/linux/security/Kconfig (revision c23f28975abc2eb02cecc8bc1f2c95473a59ed2e)
1 # SPDX-License-Identifier: GPL-2.0-only
2 #
3 # Security configuration
4 #
5 
6 menu "Security options"
7 
8 source "security/keys/Kconfig"
9 
10 config SECURITY_DMESG_RESTRICT
11 	bool "Restrict unprivileged access to the kernel syslog"
12 	default n
13 	help
14 	  This enforces restrictions on unprivileged users reading the kernel
15 	  syslog via dmesg(8).
16 
17 	  If this option is not selected, no restrictions will be enforced
18 	  unless the dmesg_restrict sysctl is explicitly set to (1).
19 
20 	  If you are unsure how to answer this question, answer N.
21 
22 config SECURITY
23 	bool "Enable different security models"
24 	depends on SYSFS
25 	depends on MULTIUSER
26 	help
27 	  This allows you to choose different security modules to be
28 	  configured into your kernel.
29 
30 	  If this option is not selected, the default Linux security
31 	  model will be used.
32 
33 	  If you are unsure how to answer this question, answer N.
34 
35 config SECURITYFS
36 	bool "Enable the securityfs filesystem"
37 	help
38 	  This will build the securityfs filesystem.  It is currently used by
39 	  various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
40 
41 	  If you are unsure how to answer this question, answer N.
42 
43 config SECURITY_NETWORK
44 	bool "Socket and Networking Security Hooks"
45 	depends on SECURITY
46 	help
47 	  This enables the socket and networking security hooks.
48 	  If enabled, a security module can use these hooks to
49 	  implement socket and networking access controls.
50 	  If you are unsure how to answer this question, answer N.
51 
52 config SECURITY_INFINIBAND
53 	bool "Infiniband Security Hooks"
54 	depends on SECURITY && INFINIBAND
55 	help
56 	  This enables the Infiniband security hooks.
57 	  If enabled, a security module can use these hooks to
58 	  implement Infiniband access controls.
59 	  If you are unsure how to answer this question, answer N.
60 
61 config SECURITY_NETWORK_XFRM
62 	bool "XFRM (IPSec) Networking Security Hooks"
63 	depends on XFRM && SECURITY_NETWORK
64 	help
65 	  This enables the XFRM (IPSec) networking security hooks.
66 	  If enabled, a security module can use these hooks to
67 	  implement per-packet access controls based on labels
68 	  derived from IPSec policy.  Non-IPSec communications are
69 	  designated as unlabelled, and only sockets authorized
70 	  to communicate unlabelled data can send without using
71 	  IPSec.
72 	  If you are unsure how to answer this question, answer N.
73 
74 config SECURITY_PATH
75 	bool "Security hooks for pathname based access control"
76 	depends on SECURITY
77 	help
78 	  This enables the security hooks for pathname based access control.
79 	  If enabled, a security module can use these hooks to
80 	  implement pathname based access controls.
81 	  If you are unsure how to answer this question, answer N.
82 
83 config INTEL_TXT
84 	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
85 	depends on HAVE_INTEL_TXT
86 	help
87 	  This option enables support for booting the kernel with the
88 	  Trusted Boot (tboot) module. This will utilize
89 	  Intel(R) Trusted Execution Technology to perform a measured launch
90 	  of the kernel. If the system does not support Intel(R) TXT, this
91 	  will have no effect.
92 
93 	  Intel TXT will provide higher assurance of system configuration and
94 	  initial state as well as data reset protection.  This is used to
95 	  create a robust initial kernel measurement and verification, which
96 	  helps to ensure that kernel security mechanisms are functioning
97 	  correctly. This level of protection requires a root of trust outside
98 	  of the kernel itself.
99 
100 	  Intel TXT also helps solve real end user concerns about having
101 	  confidence that their hardware is running the VMM or kernel that
102 	  it was configured with, especially since they may be responsible for
103 	  providing such assurances to VMs and services running on it.
104 
105 	  See <https://www.intel.com/technology/security/> for more information
106 	  about Intel(R) TXT.
107 	  See <http://tboot.sourceforge.net> for more information about tboot.
108 	  See Documentation/arch/x86/intel_txt.rst for a description of how to enable
109 	  Intel TXT support in a kernel boot.
110 
111 	  If you are unsure as to whether this is required, answer N.
112 
113 config LSM_MMAP_MIN_ADDR
114 	int "Low address space for LSM to protect from user allocation"
115 	depends on SECURITY && SECURITY_SELINUX
116 	default 32768 if ARM || (ARM64 && COMPAT)
117 	default 65536
118 	help
119 	  This is the portion of low virtual memory which should be protected
120 	  from userspace allocation.  Keeping a user from writing to low pages
121 	  can help reduce the impact of kernel NULL pointer bugs.
122 
123 	  For most ia64, ppc64 and x86 users with lots of address space
124 	  a value of 65536 is reasonable and should cause no problems.
125 	  On arm and other archs it should not be higher than 32768.
126 	  Programs which use vm86 functionality or have some need to map
127 	  this low address space will need the permission specific to the
128 	  systems running LSM.
129 
130 config HAVE_HARDENED_USERCOPY_ALLOCATOR
131 	bool
132 	help
133 	  The heap allocator implements __check_heap_object() for
134 	  validating memory ranges against heap object sizes in
135 	  support of CONFIG_HARDENED_USERCOPY.
136 
137 config HARDENED_USERCOPY
138 	bool "Harden memory copies between kernel and userspace"
139 	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
140 	imply STRICT_DEVMEM
141 	help
142 	  This option checks for obviously wrong memory regions when
143 	  copying memory to/from the kernel (via copy_to_user() and
144 	  copy_from_user() functions) by rejecting memory ranges that
145 	  are larger than the specified heap object, span multiple
146 	  separately allocated pages, are not on the process stack,
147 	  or are part of the kernel text. This prevents entire classes
148 	  of heap overflow exploits and similar kernel memory exposures.
149 
150 config FORTIFY_SOURCE
151 	bool "Harden common str/mem functions against buffer overflows"
152 	depends on ARCH_HAS_FORTIFY_SOURCE
153 	# https://bugs.llvm.org/show_bug.cgi?id=41459
154 	depends on !CC_IS_CLANG || CLANG_VERSION >= 120001
155 	# https://github.com/llvm/llvm-project/issues/53645
156 	depends on !CC_IS_CLANG || !X86_32
157 	help
158 	  Detect overflows of buffers in common string and memory functions
159 	  where the compiler can determine and validate the buffer sizes.
160 
161 config STATIC_USERMODEHELPER
162 	bool "Force all usermode helper calls through a single binary"
163 	help
164 	  By default, the kernel can call many different userspace
165 	  binary programs through the "usermode helper" kernel
166 	  interface.  Some of these binaries are statically defined
167 	  either in the kernel code itself, or as a kernel configuration
168 	  option.  However, some of these are dynamically created at
169 	  runtime, or can be modified after the kernel has started up.
170 	  To provide an additional layer of security, route all of these
171 	  calls through a single executable that can not have its name
172 	  changed.
173 
174 	  Note, it is up to this single binary to then call the relevant
175 	  "real" usermode helper binary, based on the first argument
176 	  passed to it.  If desired, this program can filter and pick
177 	  and choose what real programs are called.
178 
179 	  If you wish for all usermode helper programs are to be
180 	  disabled, choose this option and then set
181 	  STATIC_USERMODEHELPER_PATH to an empty string.
182 
183 config STATIC_USERMODEHELPER_PATH
184 	string "Path to the static usermode helper binary"
185 	depends on STATIC_USERMODEHELPER
186 	default "/sbin/usermode-helper"
187 	help
188 	  The binary called by the kernel when any usermode helper
189 	  program is wish to be run.  The "real" application's name will
190 	  be in the first argument passed to this program on the command
191 	  line.
192 
193 	  If you wish for all usermode helper programs to be disabled,
194 	  specify an empty string here (i.e. "").
195 
196 source "security/selinux/Kconfig"
197 source "security/smack/Kconfig"
198 source "security/tomoyo/Kconfig"
199 source "security/apparmor/Kconfig"
200 source "security/loadpin/Kconfig"
201 source "security/yama/Kconfig"
202 source "security/safesetid/Kconfig"
203 source "security/lockdown/Kconfig"
204 source "security/landlock/Kconfig"
205 
206 source "security/integrity/Kconfig"
207 
208 choice
209 	prompt "First legacy 'major LSM' to be initialized"
210 	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
211 	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
212 	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
213 	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
214 	default DEFAULT_SECURITY_DAC
215 
216 	help
217 	  This choice is there only for converting CONFIG_DEFAULT_SECURITY
218 	  in old kernel configs to CONFIG_LSM in new kernel configs. Don't
219 	  change this choice unless you are creating a fresh kernel config,
220 	  for this choice will be ignored after CONFIG_LSM has been set.
221 
222 	  Selects the legacy "major security module" that will be
223 	  initialized first. Overridden by non-default CONFIG_LSM.
224 
225 	config DEFAULT_SECURITY_SELINUX
226 		bool "SELinux" if SECURITY_SELINUX=y
227 
228 	config DEFAULT_SECURITY_SMACK
229 		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
230 
231 	config DEFAULT_SECURITY_TOMOYO
232 		bool "TOMOYO" if SECURITY_TOMOYO=y
233 
234 	config DEFAULT_SECURITY_APPARMOR
235 		bool "AppArmor" if SECURITY_APPARMOR=y
236 
237 	config DEFAULT_SECURITY_DAC
238 		bool "Unix Discretionary Access Controls"
239 
240 endchoice
241 
242 config LSM
243 	string "Ordered list of enabled LSMs"
244 	default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
245 	default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
246 	default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
247 	default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
248 	default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
249 	help
250 	  A comma-separated list of LSMs, in initialization order.
251 	  Any LSMs left off this list, except for those with order
252 	  LSM_ORDER_FIRST and LSM_ORDER_LAST, which are always enabled
253 	  if selected in the kernel configuration, will be ignored.
254 	  This can be controlled at boot with the "lsm=" parameter.
255 
256 	  If unsure, leave this as the default.
257 
258 source "security/Kconfig.hardening"
259 
260 endmenu
261 
262