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b507808ebc
Patch series "mm: In-kernel support for memory-deny-write-execute (MDWE)", v2. The background to this is that systemd has a configuration option called MemoryDenyWriteExecute [2], implemented as a SECCOMP BPF filter. Its aim is to prevent a user task from inadvertently creating an executable mapping that is (or was) writeable. Since such BPF filter is stateless, it cannot detect mappings that were previously writeable but subsequently changed to read-only. Therefore the filter simply rejects any mprotect(PROT_EXEC). The side-effect is that on arm64 with BTI support (Branch Target Identification), the dynamic loader cannot change an ELF section from PROT_EXEC to PROT_EXEC|PROT_BTI using mprotect(). For libraries, it can resort to unmapping and re-mapping but for the main executable it does not have a file descriptor. The original bug report in the Red Hat bugzilla - [3] - and subsequent glibc workaround for libraries - [4]. This series adds in-kernel support for this feature as a prctl PR_SET_MDWE, that is inherited on fork(). The prctl denies PROT_WRITE | PROT_EXEC mappings. Like the systemd BPF filter it also denies adding PROT_EXEC to mappings. However unlike the BPF filter it only denies it if the mapping didn't previous have PROT_EXEC. This allows to PROT_EXEC -> PROT_EXEC | PROT_BTI with mprotect(), which is a problem with the BPF filter. This patch (of 2): The aim of such policy is to prevent a user task from creating an executable mapping that is also writeable. An example of mmap() returning -EACCESS if the policy is enabled: mmap(0, size, PROT_READ | PROT_WRITE | PROT_EXEC, flags, 0, 0); Similarly, mprotect() would return -EACCESS below: addr = mmap(0, size, PROT_READ | PROT_EXEC, flags, 0, 0); mprotect(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC); The BPF filter that systemd MDWE uses is stateless, and disallows mprotect() with PROT_EXEC completely. This new prctl allows PROT_EXEC to be enabled if it was already PROT_EXEC, which allows the following case: addr = mmap(0, size, PROT_READ | PROT_EXEC, flags, 0, 0); mprotect(addr, size, PROT_READ | PROT_EXEC | PROT_BTI); where PROT_BTI enables branch tracking identification on arm64. Link: https://lkml.kernel.org/r/20230119160344.54358-1-joey.gouly@arm.com Link: https://lkml.kernel.org/r/20230119160344.54358-2-joey.gouly@arm.com Signed-off-by: Joey Gouly <joey.gouly@arm.com> Co-developed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Jeremy Linton <jeremy.linton@arm.com> Cc: Kees Cook <keescook@chromium.org> Cc: Lennart Poettering <lennart@poettering.net> Cc: Mark Brown <broonie@kernel.org> Cc: nd <nd@arm.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Szabolcs Nagy <szabolcs.nagy@arm.com> Cc: Topi Miettinen <toiwoton@gmail.com> Cc: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
293 lines
9.9 KiB
C
293 lines
9.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _LINUX_PRCTL_H
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#define _LINUX_PRCTL_H
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#include <linux/types.h>
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/* Values to pass as first argument to prctl() */
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#define PR_SET_PDEATHSIG 1 /* Second arg is a signal */
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#define PR_GET_PDEATHSIG 2 /* Second arg is a ptr to return the signal */
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/* Get/set current->mm->dumpable */
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#define PR_GET_DUMPABLE 3
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#define PR_SET_DUMPABLE 4
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/* Get/set unaligned access control bits (if meaningful) */
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#define PR_GET_UNALIGN 5
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#define PR_SET_UNALIGN 6
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# define PR_UNALIGN_NOPRINT 1 /* silently fix up unaligned user accesses */
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# define PR_UNALIGN_SIGBUS 2 /* generate SIGBUS on unaligned user access */
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/* Get/set whether or not to drop capabilities on setuid() away from
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* uid 0 (as per security/commoncap.c) */
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#define PR_GET_KEEPCAPS 7
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#define PR_SET_KEEPCAPS 8
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/* Get/set floating-point emulation control bits (if meaningful) */
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#define PR_GET_FPEMU 9
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#define PR_SET_FPEMU 10
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# define PR_FPEMU_NOPRINT 1 /* silently emulate fp operations accesses */
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# define PR_FPEMU_SIGFPE 2 /* don't emulate fp operations, send SIGFPE instead */
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/* Get/set floating-point exception mode (if meaningful) */
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#define PR_GET_FPEXC 11
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#define PR_SET_FPEXC 12
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# define PR_FP_EXC_SW_ENABLE 0x80 /* Use FPEXC for FP exception enables */
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# define PR_FP_EXC_DIV 0x010000 /* floating point divide by zero */
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# define PR_FP_EXC_OVF 0x020000 /* floating point overflow */
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# define PR_FP_EXC_UND 0x040000 /* floating point underflow */
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# define PR_FP_EXC_RES 0x080000 /* floating point inexact result */
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# define PR_FP_EXC_INV 0x100000 /* floating point invalid operation */
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# define PR_FP_EXC_DISABLED 0 /* FP exceptions disabled */
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# define PR_FP_EXC_NONRECOV 1 /* async non-recoverable exc. mode */
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# define PR_FP_EXC_ASYNC 2 /* async recoverable exception mode */
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# define PR_FP_EXC_PRECISE 3 /* precise exception mode */
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/* Get/set whether we use statistical process timing or accurate timestamp
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* based process timing */
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#define PR_GET_TIMING 13
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#define PR_SET_TIMING 14
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# define PR_TIMING_STATISTICAL 0 /* Normal, traditional,
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statistical process timing */
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# define PR_TIMING_TIMESTAMP 1 /* Accurate timestamp based
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process timing */
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#define PR_SET_NAME 15 /* Set process name */
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#define PR_GET_NAME 16 /* Get process name */
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/* Get/set process endian */
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#define PR_GET_ENDIAN 19
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#define PR_SET_ENDIAN 20
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# define PR_ENDIAN_BIG 0
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# define PR_ENDIAN_LITTLE 1 /* True little endian mode */
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# define PR_ENDIAN_PPC_LITTLE 2 /* "PowerPC" pseudo little endian */
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/* Get/set process seccomp mode */
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#define PR_GET_SECCOMP 21
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#define PR_SET_SECCOMP 22
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/* Get/set the capability bounding set (as per security/commoncap.c) */
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#define PR_CAPBSET_READ 23
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#define PR_CAPBSET_DROP 24
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/* Get/set the process' ability to use the timestamp counter instruction */
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#define PR_GET_TSC 25
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#define PR_SET_TSC 26
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# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
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# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
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/* Get/set securebits (as per security/commoncap.c) */
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#define PR_GET_SECUREBITS 27
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#define PR_SET_SECUREBITS 28
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/*
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* Get/set the timerslack as used by poll/select/nanosleep
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* A value of 0 means "use default"
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*/
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#define PR_SET_TIMERSLACK 29
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#define PR_GET_TIMERSLACK 30
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#define PR_TASK_PERF_EVENTS_DISABLE 31
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#define PR_TASK_PERF_EVENTS_ENABLE 32
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/*
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* Set early/late kill mode for hwpoison memory corruption.
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* This influences when the process gets killed on a memory corruption.
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*/
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#define PR_MCE_KILL 33
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# define PR_MCE_KILL_CLEAR 0
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# define PR_MCE_KILL_SET 1
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# define PR_MCE_KILL_LATE 0
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# define PR_MCE_KILL_EARLY 1
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# define PR_MCE_KILL_DEFAULT 2
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#define PR_MCE_KILL_GET 34
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/*
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* Tune up process memory map specifics.
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*/
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#define PR_SET_MM 35
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# define PR_SET_MM_START_CODE 1
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# define PR_SET_MM_END_CODE 2
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# define PR_SET_MM_START_DATA 3
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# define PR_SET_MM_END_DATA 4
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# define PR_SET_MM_START_STACK 5
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# define PR_SET_MM_START_BRK 6
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# define PR_SET_MM_BRK 7
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# define PR_SET_MM_ARG_START 8
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# define PR_SET_MM_ARG_END 9
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# define PR_SET_MM_ENV_START 10
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# define PR_SET_MM_ENV_END 11
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# define PR_SET_MM_AUXV 12
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# define PR_SET_MM_EXE_FILE 13
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# define PR_SET_MM_MAP 14
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# define PR_SET_MM_MAP_SIZE 15
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/*
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* This structure provides new memory descriptor
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* map which mostly modifies /proc/pid/stat[m]
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* output for a task. This mostly done in a
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* sake of checkpoint/restore functionality.
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*/
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struct prctl_mm_map {
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__u64 start_code; /* code section bounds */
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__u64 end_code;
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__u64 start_data; /* data section bounds */
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__u64 end_data;
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__u64 start_brk; /* heap for brk() syscall */
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__u64 brk;
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__u64 start_stack; /* stack starts at */
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__u64 arg_start; /* command line arguments bounds */
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__u64 arg_end;
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__u64 env_start; /* environment variables bounds */
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__u64 env_end;
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__u64 *auxv; /* auxiliary vector */
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__u32 auxv_size; /* vector size */
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__u32 exe_fd; /* /proc/$pid/exe link file */
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};
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/*
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* Set specific pid that is allowed to ptrace the current task.
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* A value of 0 mean "no process".
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*/
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#define PR_SET_PTRACER 0x59616d61
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# define PR_SET_PTRACER_ANY ((unsigned long)-1)
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#define PR_SET_CHILD_SUBREAPER 36
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#define PR_GET_CHILD_SUBREAPER 37
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/*
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* If no_new_privs is set, then operations that grant new privileges (i.e.
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* execve) will either fail or not grant them. This affects suid/sgid,
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* file capabilities, and LSMs.
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*
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* Operations that merely manipulate or drop existing privileges (setresuid,
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* capset, etc.) will still work. Drop those privileges if you want them gone.
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*
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* Changing LSM security domain is considered a new privilege. So, for example,
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* asking selinux for a specific new context (e.g. with runcon) will result
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* in execve returning -EPERM.
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*
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* See Documentation/userspace-api/no_new_privs.rst for more details.
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*/
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#define PR_SET_NO_NEW_PRIVS 38
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#define PR_GET_NO_NEW_PRIVS 39
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#define PR_GET_TID_ADDRESS 40
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#define PR_SET_THP_DISABLE 41
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#define PR_GET_THP_DISABLE 42
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/*
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* No longer implemented, but left here to ensure the numbers stay reserved:
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*/
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#define PR_MPX_ENABLE_MANAGEMENT 43
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#define PR_MPX_DISABLE_MANAGEMENT 44
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#define PR_SET_FP_MODE 45
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#define PR_GET_FP_MODE 46
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# define PR_FP_MODE_FR (1 << 0) /* 64b FP registers */
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# define PR_FP_MODE_FRE (1 << 1) /* 32b compatibility */
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/* Control the ambient capability set */
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#define PR_CAP_AMBIENT 47
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# define PR_CAP_AMBIENT_IS_SET 1
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# define PR_CAP_AMBIENT_RAISE 2
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# define PR_CAP_AMBIENT_LOWER 3
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# define PR_CAP_AMBIENT_CLEAR_ALL 4
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/* arm64 Scalable Vector Extension controls */
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/* Flag values must be kept in sync with ptrace NT_ARM_SVE interface */
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#define PR_SVE_SET_VL 50 /* set task vector length */
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# define PR_SVE_SET_VL_ONEXEC (1 << 18) /* defer effect until exec */
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#define PR_SVE_GET_VL 51 /* get task vector length */
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/* Bits common to PR_SVE_SET_VL and PR_SVE_GET_VL */
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# define PR_SVE_VL_LEN_MASK 0xffff
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# define PR_SVE_VL_INHERIT (1 << 17) /* inherit across exec */
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/* Per task speculation control */
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#define PR_GET_SPECULATION_CTRL 52
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#define PR_SET_SPECULATION_CTRL 53
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/* Speculation control variants */
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# define PR_SPEC_STORE_BYPASS 0
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# define PR_SPEC_INDIRECT_BRANCH 1
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# define PR_SPEC_L1D_FLUSH 2
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/* Return and control values for PR_SET/GET_SPECULATION_CTRL */
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# define PR_SPEC_NOT_AFFECTED 0
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# define PR_SPEC_PRCTL (1UL << 0)
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# define PR_SPEC_ENABLE (1UL << 1)
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# define PR_SPEC_DISABLE (1UL << 2)
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# define PR_SPEC_FORCE_DISABLE (1UL << 3)
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# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
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/* Reset arm64 pointer authentication keys */
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#define PR_PAC_RESET_KEYS 54
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# define PR_PAC_APIAKEY (1UL << 0)
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# define PR_PAC_APIBKEY (1UL << 1)
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# define PR_PAC_APDAKEY (1UL << 2)
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# define PR_PAC_APDBKEY (1UL << 3)
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# define PR_PAC_APGAKEY (1UL << 4)
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/* Tagged user address controls for arm64 */
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#define PR_SET_TAGGED_ADDR_CTRL 55
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#define PR_GET_TAGGED_ADDR_CTRL 56
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# define PR_TAGGED_ADDR_ENABLE (1UL << 0)
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/* MTE tag check fault modes */
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# define PR_MTE_TCF_NONE 0UL
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# define PR_MTE_TCF_SYNC (1UL << 1)
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# define PR_MTE_TCF_ASYNC (1UL << 2)
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# define PR_MTE_TCF_MASK (PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC)
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/* MTE tag inclusion mask */
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# define PR_MTE_TAG_SHIFT 3
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# define PR_MTE_TAG_MASK (0xffffUL << PR_MTE_TAG_SHIFT)
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/* Unused; kept only for source compatibility */
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# define PR_MTE_TCF_SHIFT 1
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/* Control reclaim behavior when allocating memory */
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#define PR_SET_IO_FLUSHER 57
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#define PR_GET_IO_FLUSHER 58
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/* Dispatch syscalls to a userspace handler */
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#define PR_SET_SYSCALL_USER_DISPATCH 59
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# define PR_SYS_DISPATCH_OFF 0
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# define PR_SYS_DISPATCH_ON 1
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/* The control values for the user space selector when dispatch is enabled */
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# define SYSCALL_DISPATCH_FILTER_ALLOW 0
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# define SYSCALL_DISPATCH_FILTER_BLOCK 1
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/* Set/get enabled arm64 pointer authentication keys */
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#define PR_PAC_SET_ENABLED_KEYS 60
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#define PR_PAC_GET_ENABLED_KEYS 61
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/* Request the scheduler to share a core */
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#define PR_SCHED_CORE 62
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# define PR_SCHED_CORE_GET 0
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# define PR_SCHED_CORE_CREATE 1 /* create unique core_sched cookie */
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# define PR_SCHED_CORE_SHARE_TO 2 /* push core_sched cookie to pid */
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# define PR_SCHED_CORE_SHARE_FROM 3 /* pull core_sched cookie to pid */
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# define PR_SCHED_CORE_MAX 4
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# define PR_SCHED_CORE_SCOPE_THREAD 0
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# define PR_SCHED_CORE_SCOPE_THREAD_GROUP 1
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# define PR_SCHED_CORE_SCOPE_PROCESS_GROUP 2
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/* arm64 Scalable Matrix Extension controls */
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/* Flag values must be in sync with SVE versions */
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#define PR_SME_SET_VL 63 /* set task vector length */
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# define PR_SME_SET_VL_ONEXEC (1 << 18) /* defer effect until exec */
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#define PR_SME_GET_VL 64 /* get task vector length */
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/* Bits common to PR_SME_SET_VL and PR_SME_GET_VL */
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# define PR_SME_VL_LEN_MASK 0xffff
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# define PR_SME_VL_INHERIT (1 << 17) /* inherit across exec */
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/* Memory deny write / execute */
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#define PR_SET_MDWE 65
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# define PR_MDWE_REFUSE_EXEC_GAIN 1
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#define PR_GET_MDWE 66
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#define PR_SET_VMA 0x53564d41
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# define PR_SET_VMA_ANON_NAME 0
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#endif /* _LINUX_PRCTL_H */
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