seccomp: Move config option SECCOMP to arch/Kconfig

In order to make adding configurable features into seccomp easier,
it's better to have the options at one single location, considering
especially that the bulk of seccomp code is arch-independent. An quick
look also show that many SECCOMP descriptions are outdated; they talk
about /proc rather than prctl.

As a result of moving the config option and keeping it default on,
architectures arm, arm64, csky, riscv, sh, and xtensa did not have SECCOMP
on by default prior to this and SECCOMP will be default in this change.

Architectures microblaze, mips, powerpc, s390, sh, and sparc have an
outdated depend on PROC_FS and this dependency is removed in this change.

Suggested-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/lkml/CAG48ez1YWz9cnp08UZgeieYRhHdqh-ch7aNwc4JRBnGyrmgfMg@mail.gmail.com/
Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu>
[kees: added HAVE_ARCH_SECCOMP help text, tweaked wording]
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/9ede6ef35c847e58d61e476c6a39540520066613.1600951211.git.yifeifz2@illinois.edu

diff --git a/arch/Kconfig b/arch/Kconfig
index af14a56..21a3675 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -444,10 +444,23 @@ config ARCH_WANT_OLD_COMPAT_IPC
        select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
        bool
 
+config HAVE_ARCH_SECCOMP
+       bool
+       help
+         An arch should select this symbol to support seccomp mode 1 (the fixed
+         syscall policy), and must provide an overrides for __NR_seccomp_sigreturn,
+         and compat syscalls if the asm-generic/seccomp.h defaults need adjustment:
+         - __NR_seccomp_read_32
+         - __NR_seccomp_write_32
+         - __NR_seccomp_exit_32
+         - __NR_seccomp_sigreturn_32
+
 config HAVE_ARCH_SECCOMP_FILTER
        bool
+       select HAVE_ARCH_SECCOMP
        help
          An arch should select this symbol if it provides all of these things:
+         - all the requirements for HAVE_ARCH_SECCOMP
          - syscall_get_arch()
          - syscall_get_arguments()
          - syscall_rollback()
@@ -458,6 +471,23 @@ config HAVE_ARCH_SECCOMP_FILTER
            results in the system call being skipped immediately.
          - seccomp syscall wired up
 
+config SECCOMP
+       prompt "Enable seccomp to safely execute untrusted bytecode"
+       def_bool y
+       depends on HAVE_ARCH_SECCOMP
+       help
+         This kernel feature is useful for number crunching applications
+         that may need to handle untrusted bytecode during their
+         execution. By using pipes or other transports made available
+         to the process as file descriptors supporting the read/write
+         syscalls, it's possible to isolate those applications in their
+         own address space using seccomp. Once seccomp is enabled via
+         prctl(PR_SET_SECCOMP) or the seccomp() syscall, it cannot be
+         disabled and the task is only allowed to execute a few safe
+         syscalls defined by each seccomp mode.
+
+         If unsure, say Y.
+
 config SECCOMP_FILTER
        def_bool y
        depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e00d94b..e26c19a 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -67,6 +67,7 @@ config ARM
        select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
        select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
        select HAVE_ARCH_MMAP_RND_BITS if MMU
+       select HAVE_ARCH_SECCOMP
        select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT
        select HAVE_ARCH_THREAD_STRUCT_WHITELIST
        select HAVE_ARCH_TRACEHOOK
@@ -1617,20 +1618,6 @@ config UACCESS_WITH_MEMCPY
          However, if the CPU data cache is using a write-allocate mode,
          this option is unlikely to provide any performance gain.
 
-config SECCOMP
-       bool
-       prompt "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
 config PARAVIRT
        bool "Enable paravirtualization code"
        help

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d23283..98c4e34 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1033,19 +1033,6 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 config CC_HAVE_SHADOW_CALL_STACK
        def_bool $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18)
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
 config PARAVIRT
        bool "Enable paravirtualization code"
        help

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 3d5afb5..7f424c8 100644 (file)
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -309,16 +309,3 @@ endmenu
 source "arch/csky/Kconfig.platforms"
 
 source "kernel/Kconfig.hz"
-
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.

diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index d262ac0..37bd6a5 100644 (file)
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -26,6 +26,7 @@ config MICROBLAZE
        select GENERIC_SCHED_CLOCK
        select HAVE_ARCH_HASH
        select HAVE_ARCH_KGDB
+       select HAVE_ARCH_SECCOMP
        select HAVE_DEBUG_KMEMLEAK
        select HAVE_DMA_CONTIGUOUS
        select HAVE_DYNAMIC_FTRACE
@@ -120,23 +121,6 @@ config CMDLINE_FORCE
          Set this to have arguments from the default kernel command string
          override those passed by the boot loader.
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       depends on PROC_FS
-       default y
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via /proc/<pid>/seccomp, it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y. Only embedded should say N here.
-
 endmenu
 
 menu "Kernel features"

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c95fa3a..5f88a8f 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -3004,23 +3004,6 @@ config PHYSICAL_START
          specified in the "crashkernel=YM@XM" command line boot parameter
          passed to the panic-ed kernel).
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       depends on PROC_FS
-       default y
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via /proc/<pid>/seccomp, it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y. Only embedded should say N here.
-
 config MIPS_O32_FP64_SUPPORT
        bool "Support for O32 binaries using 64-bit FP" if !CPU_MIPSR6
        depends on 32BIT || MIPS32_O32

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 3b0f53d..cd4afe1 100644 (file)
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -378,19 +378,3 @@ endmenu
 
 
 source "drivers/parisc/Kconfig"
-
-config SECCOMP
-       def_bool y
-       prompt "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y. Only embedded should say N here.

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1f48bbf..136fe86 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -934,23 +934,6 @@ config ARCH_WANTS_FREEZER_CONTROL
 
 source "kernel/power/Kconfig"
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       depends on PROC_FS
-       default y
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via /proc/<pid>/seccomp, it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y. Only embedded should say N here.
-
 config PPC_MEM_KEYS
        prompt "PowerPC Memory Protection Keys"
        def_bool y

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index df18372..c456b55 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -333,19 +333,6 @@ menu "Kernel features"
 
 source "kernel/Kconfig.hz"
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
 config RISCV_SBI_V01
        bool "SBI v0.1 support"
        default y

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3d86e12..7f7b40e 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -791,23 +791,6 @@ config CRASH_DUMP
 
 endmenu
 
-config SECCOMP
-       def_bool y
-       prompt "Enable seccomp to safely compute untrusted bytecode"
-       depends on PROC_FS
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via /proc/<pid>/seccomp, it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y.
-
 config CCW
        def_bool y
 

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index d209271..1827815 100644 (file)
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -600,22 +600,6 @@ config PHYSICAL_START
          where the fail safe kernel needs to run at a different address
          than the panic-ed kernel.
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       depends on PROC_FS
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl, it cannot be disabled and the task is only
-         allowed to execute a few safe syscalls defined by each seccomp
-         mode.
-
-         If unsure, say N.
-
 config SMP
        bool "Symmetric multi-processing support"
        depends on SYS_SUPPORTS_SMP

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index efeff2c..d62ce83 100644 (file)
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -23,6 +23,7 @@ config SPARC
        select HAVE_OPROFILE
        select HAVE_ARCH_KGDB if !SMP || SPARC64
        select HAVE_ARCH_TRACEHOOK
+       select HAVE_ARCH_SECCOMP if SPARC64
        select HAVE_EXIT_THREAD
        select HAVE_PCI
        select SYSCTL_EXCEPTION_TRACE
@@ -226,23 +227,6 @@ config EARLYFB
        help
          Say Y here to enable a faster early framebuffer boot console.
 
-config SECCOMP
-       bool "Enable seccomp to safely compute untrusted bytecode"
-       depends on SPARC64 && PROC_FS
-       default y
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via /proc/<pid>/seccomp, it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y. Only embedded should say N here.
-
 config HOTPLUG_CPU
        bool "Support for hot-pluggable CPUs"
        depends on SPARC64 && SMP

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index eb51fec..d49f471 100644 (file)
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -173,22 +173,6 @@ config PGTABLE_LEVELS
        default 3 if 3_LEVEL_PGTABLES
        default 2
 
-config SECCOMP
-       def_bool y
-       prompt "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y.
-
 config UML_TIME_TRAVEL_SUPPORT
        bool
        prompt "Support time-travel mode (e.g. for test execution)"

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7101ac6..1ab2286 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1968,22 +1968,6 @@ config EFI_MIXED
 
           If unsure, say N.
 
-config SECCOMP
-       def_bool y
-       prompt "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
-         If unsure, say Y. Only embedded should say N here.
-
 source "kernel/Kconfig.hz"
 
 config KEXEC

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index e997e01..d8a29dc 100644 (file)
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -217,20 +217,6 @@ config HOTPLUG_CPU
 
          Say N if you want to disable CPU hotplug.
 
-config SECCOMP
-       bool
-       prompt "Enable seccomp to safely compute untrusted bytecode"
-       help
-         This kernel feature is useful for number crunching applications
-         that may need to compute untrusted bytecode during their
-         execution. By using pipes or other transports made available to
-         the process as file descriptors supporting the read/write
-         syscalls, it's possible to isolate those applications in
-         their own address space using seccomp. Once seccomp is
-         enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
-         and the task is only allowed to execute a few safe syscalls
-         defined by each seccomp mode.
-
 config FAST_SYSCALL_XTENSA
        bool "Enable fast atomic syscalls"
        default n