Ophestra
1a8840bebc
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This enables loading syscall filter policies from external cross-platform config files. This also removes a significant amount of C code. Signed-off-by: Ophestra <cat@gensokyo.uk>
231 lines
7.5 KiB
Go
231 lines
7.5 KiB
Go
package seccomp
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/* flatpak commit 4c3bf179e2e4a2a298cd1db1d045adaf3f564532 */
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import "C"
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import (
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. "syscall"
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)
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type FilterPreset int
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const (
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// PresetExt are project-specific extensions.
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PresetExt FilterPreset = 1 << iota
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// PresetDenyNS denies namespace setup syscalls.
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PresetDenyNS
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// PresetDenyTTY denies faking input.
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PresetDenyTTY
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// PresetDenyDevel denies development-related syscalls.
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PresetDenyDevel
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// PresetLinux32 sets PER_LINUX32.
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PresetLinux32
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)
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func preparePreset(fd int, presets FilterPreset, flags PrepareFlag) error {
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allowedPersonality := PER_LINUX
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if presets&PresetLinux32 != 0 {
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allowedPersonality = PER_LINUX32
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}
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presetDevelFinal := presetDevel(ScmpDatum(allowedPersonality))
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l := len(presetCommon)
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if presets&PresetDenyNS != 0 {
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l += len(presetNamespace)
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}
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if presets&PresetDenyTTY != 0 {
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l += len(presetTTY)
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}
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if presets&PresetDenyDevel != 0 {
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l += len(presetDevelFinal)
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}
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if flags&AllowMultiarch == 0 {
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l += len(presetEmu)
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}
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if presets&PresetExt != 0 {
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l += len(presetCommonExt)
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if presets&PresetDenyNS != 0 {
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l += len(presetNamespaceExt)
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}
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if flags&AllowMultiarch == 0 {
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l += len(presetEmuExt)
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}
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}
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rules := make([]NativeRule, 0, l)
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rules = append(rules, presetCommon...)
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if presets&PresetDenyNS != 0 {
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rules = append(rules, presetNamespace...)
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}
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if presets&PresetDenyTTY != 0 {
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rules = append(rules, presetTTY...)
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}
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if presets&PresetDenyDevel != 0 {
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rules = append(rules, presetDevelFinal...)
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}
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if flags&AllowMultiarch == 0 {
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rules = append(rules, presetEmu...)
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}
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if presets&PresetExt != 0 {
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rules = append(rules, presetCommonExt...)
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if presets&PresetDenyNS != 0 {
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rules = append(rules, presetNamespaceExt...)
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}
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if flags&AllowMultiarch == 0 {
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rules = append(rules, presetEmuExt...)
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}
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}
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return Prepare(fd, rules, flags)
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}
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var (
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presetCommon = []NativeRule{
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/* Block dmesg */
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{C.int(SYS_SYSLOG), C.int(EPERM), nil},
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/* Useless old syscall */
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{C.int(SYS_USELIB), C.int(EPERM), nil},
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/* Don't allow disabling accounting */
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{C.int(SYS_ACCT), C.int(EPERM), nil},
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/* Don't allow reading current quota use */
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{C.int(SYS_QUOTACTL), C.int(EPERM), nil},
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/* Don't allow access to the kernel keyring */
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{C.int(SYS_ADD_KEY), C.int(EPERM), nil},
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{C.int(SYS_KEYCTL), C.int(EPERM), nil},
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{C.int(SYS_REQUEST_KEY), C.int(EPERM), nil},
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/* Scary VM/NUMA ops */
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{C.int(SYS_MOVE_PAGES), C.int(EPERM), nil},
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{C.int(SYS_MBIND), C.int(EPERM), nil},
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{C.int(SYS_GET_MEMPOLICY), C.int(EPERM), nil},
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{C.int(SYS_SET_MEMPOLICY), C.int(EPERM), nil},
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{C.int(SYS_MIGRATE_PAGES), C.int(EPERM), nil},
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}
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/* hakurei: project-specific extensions */
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presetCommonExt = []NativeRule{
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/* system calls for changing the system clock */
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{C.int(SYS_ADJTIMEX), C.int(EPERM), nil},
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{C.int(SYS_CLOCK_ADJTIME), C.int(EPERM), nil},
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{C.int(SYS_CLOCK_ADJTIME64), C.int(EPERM), nil},
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{C.int(SYS_CLOCK_SETTIME), C.int(EPERM), nil},
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{C.int(SYS_CLOCK_SETTIME64), C.int(EPERM), nil},
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{C.int(SYS_SETTIMEOFDAY), C.int(EPERM), nil},
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/* loading and unloading of kernel modules */
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{C.int(SYS_DELETE_MODULE), C.int(EPERM), nil},
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{C.int(SYS_FINIT_MODULE), C.int(EPERM), nil},
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{C.int(SYS_INIT_MODULE), C.int(EPERM), nil},
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/* system calls for rebooting and reboot preparation */
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{C.int(SYS_KEXEC_FILE_LOAD), C.int(EPERM), nil},
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{C.int(SYS_KEXEC_LOAD), C.int(EPERM), nil},
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{C.int(SYS_REBOOT), C.int(EPERM), nil},
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/* system calls for enabling/disabling swap devices */
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{C.int(SYS_SWAPOFF), C.int(EPERM), nil},
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{C.int(SYS_SWAPON), C.int(EPERM), nil},
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}
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presetNamespace = []NativeRule{
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/* Don't allow subnamespace setups: */
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{C.int(SYS_UNSHARE), C.int(EPERM), nil},
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{C.int(SYS_SETNS), C.int(EPERM), nil},
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{C.int(SYS_MOUNT), C.int(EPERM), nil},
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{C.int(SYS_UMOUNT), C.int(EPERM), nil},
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{C.int(SYS_UMOUNT2), C.int(EPERM), nil},
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{C.int(SYS_PIVOT_ROOT), C.int(EPERM), nil},
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{C.int(SYS_CHROOT), C.int(EPERM), nil},
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{C.int(SYS_CLONE), C.int(EPERM),
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&ScmpArgCmp{cloneArg, SCMP_CMP_MASKED_EQ, CLONE_NEWUSER, CLONE_NEWUSER}},
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/* seccomp can't look into clone3()'s struct clone_args to check whether
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* the flags are OK, so we have no choice but to block clone3().
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* Return ENOSYS so user-space will fall back to clone().
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* (CVE-2021-41133; see also https://github.com/moby/moby/commit/9f6b562d)
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*/
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{C.int(SYS_CLONE3), C.int(ENOSYS), nil},
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/* New mount manipulation APIs can also change our VFS. There's no
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* legitimate reason to do these in the sandbox, so block all of them
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* rather than thinking about which ones might be dangerous.
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* (CVE-2021-41133) */
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{C.int(SYS_OPEN_TREE), C.int(ENOSYS), nil},
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{C.int(SYS_MOVE_MOUNT), C.int(ENOSYS), nil},
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{C.int(SYS_FSOPEN), C.int(ENOSYS), nil},
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{C.int(SYS_FSCONFIG), C.int(ENOSYS), nil},
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{C.int(SYS_FSMOUNT), C.int(ENOSYS), nil},
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{C.int(SYS_FSPICK), C.int(ENOSYS), nil},
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{C.int(SYS_MOUNT_SETATTR), C.int(ENOSYS), nil},
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}
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/* hakurei: project-specific extensions */
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presetNamespaceExt = []NativeRule{
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/* changing file ownership */
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{C.int(SYS_CHOWN), C.int(EPERM), nil},
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{C.int(SYS_CHOWN32), C.int(EPERM), nil},
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{C.int(SYS_FCHOWN), C.int(EPERM), nil},
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{C.int(SYS_FCHOWN32), C.int(EPERM), nil},
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{C.int(SYS_FCHOWNAT), C.int(EPERM), nil},
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{C.int(SYS_LCHOWN), C.int(EPERM), nil},
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{C.int(SYS_LCHOWN32), C.int(EPERM), nil},
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/* system calls for changing user ID and group ID credentials */
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{C.int(SYS_SETGID), C.int(EPERM), nil},
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{C.int(SYS_SETGID32), C.int(EPERM), nil},
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{C.int(SYS_SETGROUPS), C.int(EPERM), nil},
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{C.int(SYS_SETGROUPS32), C.int(EPERM), nil},
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{C.int(SYS_SETREGID), C.int(EPERM), nil},
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{C.int(SYS_SETREGID32), C.int(EPERM), nil},
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{C.int(SYS_SETRESGID), C.int(EPERM), nil},
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{C.int(SYS_SETRESGID32), C.int(EPERM), nil},
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{C.int(SYS_SETRESUID), C.int(EPERM), nil},
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{C.int(SYS_SETRESUID32), C.int(EPERM), nil},
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{C.int(SYS_SETREUID), C.int(EPERM), nil},
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{C.int(SYS_SETREUID32), C.int(EPERM), nil},
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{C.int(SYS_SETUID), C.int(EPERM), nil},
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{C.int(SYS_SETUID32), C.int(EPERM), nil},
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}
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presetTTY = []NativeRule{
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/* Don't allow faking input to the controlling tty (CVE-2017-5226) */
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{C.int(SYS_IOCTL), C.int(EPERM),
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&ScmpArgCmp{1, SCMP_CMP_MASKED_EQ, 0xFFFFFFFF, TIOCSTI}},
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/* In the unlikely event that the controlling tty is a Linux virtual
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* console (/dev/tty2 or similar), copy/paste operations have an effect
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* similar to TIOCSTI (CVE-2023-28100) */
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{C.int(SYS_IOCTL), C.int(EPERM),
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&ScmpArgCmp{1, SCMP_CMP_MASKED_EQ, 0xFFFFFFFF, TIOCLINUX}},
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}
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presetEmu = []NativeRule{
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/* modify_ldt is a historic source of interesting information leaks,
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* so it's disabled as a hardening measure.
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* However, it is required to run old 16-bit applications
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* as well as some Wine patches, so it's allowed in multiarch. */
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{C.int(SYS_MODIFY_LDT), C.int(EPERM), nil},
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}
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/* hakurei: project-specific extensions */
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presetEmuExt = []NativeRule{
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{C.int(SYS_SUBPAGE_PROT), C.int(ENOSYS), nil},
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{C.int(SYS_SWITCH_ENDIAN), C.int(ENOSYS), nil},
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{C.int(SYS_VM86), C.int(ENOSYS), nil},
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{C.int(SYS_VM86OLD), C.int(ENOSYS), nil},
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}
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)
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func presetDevel(allowedPersonality ScmpDatum) []NativeRule {
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return []NativeRule{
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/* Profiling operations; we expect these to be done by tools from outside
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* the sandbox. In particular perf has been the source of many CVEs. */
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{C.int(SYS_PERF_EVENT_OPEN), C.int(EPERM), nil},
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/* Don't allow you to switch to bsd emulation or whatnot */
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{C.int(SYS_PERSONALITY), C.int(EPERM),
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&ScmpArgCmp{0, SCMP_CMP_NE, allowedPersonality, 0}},
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{C.int(SYS_PTRACE), C.int(EPERM), nil},
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}
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}
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