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1# SPDX-License-Identifier: GPL-2.0-only
2#
3# Security configuration
4#
5
6menu "Security options"
7
8source "security/keys/Kconfig"
9
10config 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
22config 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
35config SECURITY_WRITABLE_HOOKS
36 depends on SECURITY
37 bool
38 default n
39
40config SECURITYFS
41 bool "Enable the securityfs filesystem"
42 help
43 This will build the securityfs filesystem. It is currently used by
44 various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
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 || X86_PAE) && !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.rst 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/x86/intel_txt.rst 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 imply STRICT_DEVMEM
157 help
158 This option checks for obviously wrong memory regions when
159 copying memory to/from the kernel (via copy_to_user() and
160 copy_from_user() functions) by rejecting memory ranges that
161 are larger than the specified heap object, span multiple
162 separately allocated pages, are not on the process stack,
163 or are part of the kernel text. This kills entire classes
164 of heap overflow exploits and similar kernel memory exposures.
165
166config HARDENED_USERCOPY_FALLBACK
167 bool "Allow usercopy whitelist violations to fallback to object size"
168 depends on HARDENED_USERCOPY
169 default y
170 help
171 This is a temporary option that allows missing usercopy whitelists
172 to be discovered via a WARN() to the kernel log, instead of
173 rejecting the copy, falling back to non-whitelisted hardened
174 usercopy that checks the slab allocation size instead of the
175 whitelist size. This option will be removed once it seems like
176 all missing usercopy whitelists have been identified and fixed.
177 Booting with "slab_common.usercopy_fallback=Y/N" can change
178 this setting.
179
180config HARDENED_USERCOPY_PAGESPAN
181 bool "Refuse to copy allocations that span multiple pages"
182 depends on HARDENED_USERCOPY
183 depends on EXPERT
184 help
185 When a multi-page allocation is done without __GFP_COMP,
186 hardened usercopy will reject attempts to copy it. There are,
187 however, several cases of this in the kernel that have not all
188 been removed. This config is intended to be used only while
189 trying to find such users.
190
191config FORTIFY_SOURCE
192 bool "Harden common str/mem functions against buffer overflows"
193 depends on ARCH_HAS_FORTIFY_SOURCE
194 help
195 Detect overflows of buffers in common string and memory functions
196 where the compiler can determine and validate the buffer sizes.
197
198config STATIC_USERMODEHELPER
199 bool "Force all usermode helper calls through a single binary"
200 help
201 By default, the kernel can call many different userspace
202 binary programs through the "usermode helper" kernel
203 interface. Some of these binaries are statically defined
204 either in the kernel code itself, or as a kernel configuration
205 option. However, some of these are dynamically created at
206 runtime, or can be modified after the kernel has started up.
207 To provide an additional layer of security, route all of these
208 calls through a single executable that can not have its name
209 changed.
210
211 Note, it is up to this single binary to then call the relevant
212 "real" usermode helper binary, based on the first argument
213 passed to it. If desired, this program can filter and pick
214 and choose what real programs are called.
215
216 If you wish for all usermode helper programs are to be
217 disabled, choose this option and then set
218 STATIC_USERMODEHELPER_PATH to an empty string.
219
220config STATIC_USERMODEHELPER_PATH
221 string "Path to the static usermode helper binary"
222 depends on STATIC_USERMODEHELPER
223 default "/sbin/usermode-helper"
224 help
225 The binary called by the kernel when any usermode helper
226 program is wish to be run. The "real" application's name will
227 be in the first argument passed to this program on the command
228 line.
229
230 If you wish for all usermode helper programs to be disabled,
231 specify an empty string here (i.e. "").
232
233source "security/selinux/Kconfig"
234source "security/smack/Kconfig"
235source "security/tomoyo/Kconfig"
236source "security/apparmor/Kconfig"
237source "security/loadpin/Kconfig"
238source "security/yama/Kconfig"
239source "security/safesetid/Kconfig"
240source "security/lockdown/Kconfig"
241
242source "security/integrity/Kconfig"
243
244choice
245 prompt "First legacy 'major LSM' to be initialized"
246 default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
247 default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
248 default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
249 default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
250 default DEFAULT_SECURITY_DAC
251
252 help
253 This choice is there only for converting CONFIG_DEFAULT_SECURITY
254 in old kernel configs to CONFIG_LSM in new kernel configs. Don't
255 change this choice unless you are creating a fresh kernel config,
256 for this choice will be ignored after CONFIG_LSM has been set.
257
258 Selects the legacy "major security module" that will be
259 initialized first. Overridden by non-default CONFIG_LSM.
260
261 config DEFAULT_SECURITY_SELINUX
262 bool "SELinux" if SECURITY_SELINUX=y
263
264 config DEFAULT_SECURITY_SMACK
265 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
266
267 config DEFAULT_SECURITY_TOMOYO
268 bool "TOMOYO" if SECURITY_TOMOYO=y
269
270 config DEFAULT_SECURITY_APPARMOR
271 bool "AppArmor" if SECURITY_APPARMOR=y
272
273 config DEFAULT_SECURITY_DAC
274 bool "Unix Discretionary Access Controls"
275
276endchoice
277
278config LSM
279 string "Ordered list of enabled LSMs"
280 default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK
281 default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR
282 default "lockdown,yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
283 default "lockdown,yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC
284 default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
285 help
286 A comma-separated list of LSMs, in initialization order.
287 Any LSMs left off this list will be ignored. This can be
288 controlled at boot with the "lsm=" parameter.
289
290 If unsure, leave this as the default.
291
292source "security/Kconfig.hardening"
293
294endmenu
295
1# SPDX-License-Identifier: GPL-2.0-only
2#
3# Security configuration
4#
5
6menu "Security options"
7
8source "security/keys/Kconfig"
9
10config 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
22config 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
35config 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
43config 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
52config 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
61config 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
74config 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
83config 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
113config 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
130config HARDENED_USERCOPY
131 bool "Harden memory copies between kernel and userspace"
132 imply STRICT_DEVMEM
133 help
134 This option checks for obviously wrong memory regions when
135 copying memory to/from the kernel (via copy_to_user() and
136 copy_from_user() functions) by rejecting memory ranges that
137 are larger than the specified heap object, span multiple
138 separately allocated pages, are not on the process stack,
139 or are part of the kernel text. This prevents entire classes
140 of heap overflow exploits and similar kernel memory exposures.
141
142config FORTIFY_SOURCE
143 bool "Harden common str/mem functions against buffer overflows"
144 depends on ARCH_HAS_FORTIFY_SOURCE
145 # https://bugs.llvm.org/show_bug.cgi?id=41459
146 depends on !CC_IS_CLANG || CLANG_VERSION >= 120001
147 # https://github.com/llvm/llvm-project/issues/53645
148 depends on !CC_IS_CLANG || !X86_32
149 help
150 Detect overflows of buffers in common string and memory functions
151 where the compiler can determine and validate the buffer sizes.
152
153config STATIC_USERMODEHELPER
154 bool "Force all usermode helper calls through a single binary"
155 help
156 By default, the kernel can call many different userspace
157 binary programs through the "usermode helper" kernel
158 interface. Some of these binaries are statically defined
159 either in the kernel code itself, or as a kernel configuration
160 option. However, some of these are dynamically created at
161 runtime, or can be modified after the kernel has started up.
162 To provide an additional layer of security, route all of these
163 calls through a single executable that can not have its name
164 changed.
165
166 Note, it is up to this single binary to then call the relevant
167 "real" usermode helper binary, based on the first argument
168 passed to it. If desired, this program can filter and pick
169 and choose what real programs are called.
170
171 If you wish for all usermode helper programs are to be
172 disabled, choose this option and then set
173 STATIC_USERMODEHELPER_PATH to an empty string.
174
175config STATIC_USERMODEHELPER_PATH
176 string "Path to the static usermode helper binary"
177 depends on STATIC_USERMODEHELPER
178 default "/sbin/usermode-helper"
179 help
180 The binary called by the kernel when any usermode helper
181 program is wish to be run. The "real" application's name will
182 be in the first argument passed to this program on the command
183 line.
184
185 If you wish for all usermode helper programs to be disabled,
186 specify an empty string here (i.e. "").
187
188source "security/selinux/Kconfig"
189source "security/smack/Kconfig"
190source "security/tomoyo/Kconfig"
191source "security/apparmor/Kconfig"
192source "security/loadpin/Kconfig"
193source "security/yama/Kconfig"
194source "security/safesetid/Kconfig"
195source "security/lockdown/Kconfig"
196source "security/landlock/Kconfig"
197
198source "security/integrity/Kconfig"
199
200choice
201 prompt "First legacy 'major LSM' to be initialized"
202 default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
203 default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
204 default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
205 default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
206 default DEFAULT_SECURITY_DAC
207
208 help
209 This choice is there only for converting CONFIG_DEFAULT_SECURITY
210 in old kernel configs to CONFIG_LSM in new kernel configs. Don't
211 change this choice unless you are creating a fresh kernel config,
212 for this choice will be ignored after CONFIG_LSM has been set.
213
214 Selects the legacy "major security module" that will be
215 initialized first. Overridden by non-default CONFIG_LSM.
216
217 config DEFAULT_SECURITY_SELINUX
218 bool "SELinux" if SECURITY_SELINUX=y
219
220 config DEFAULT_SECURITY_SMACK
221 bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
222
223 config DEFAULT_SECURITY_TOMOYO
224 bool "TOMOYO" if SECURITY_TOMOYO=y
225
226 config DEFAULT_SECURITY_APPARMOR
227 bool "AppArmor" if SECURITY_APPARMOR=y
228
229 config DEFAULT_SECURITY_DAC
230 bool "Unix Discretionary Access Controls"
231
232endchoice
233
234config LSM
235 string "Ordered list of enabled LSMs"
236 default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
237 default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
238 default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
239 default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
240 default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
241 help
242 A comma-separated list of LSMs, in initialization order.
243 Any LSMs left off this list, except for those with order
244 LSM_ORDER_FIRST and LSM_ORDER_LAST, which are always enabled
245 if selected in the kernel configuration, will be ignored.
246 This can be controlled at boot with the "lsm=" parameter.
247
248 If unsure, leave this as the default.
249
250source "security/Kconfig.hardening"
251
252endmenu
253