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105ff5339f
The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to set
executable bit at creation time (memfd_create).
When MFD_NOEXEC_SEAL is set, memfd is created without executable bit
(mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to be
executable (mode: 0777) after creation.
when MFD_EXEC flag is set, memfd is created with executable bit
(mode:0777), this is the same as the old behavior of memfd_create.
The new pid namespaced sysctl vm.memfd_noexec has 3 values:
0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
MFD_EXEC was set.
1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
MFD_NOEXEC_SEAL was set.
2: memfd_create() without MFD_NOEXEC_SEAL will be rejected.
The sysctl allows finer control of memfd_create for old-software that
doesn't set the executable bit, for example, a container with
vm.memfd_noexec=1 means the old-software will create non-executable memfd
by default. Also, the value of memfd_noexec is passed to child namespace
at creation time. For example, if the init namespace has
vm.memfd_noexec=2, all its children namespaces will be created with 2.
[akpm@linux-foundation.org: add stub functions to fix build]
[akpm@linux-foundation.org: remove unneeded register_pid_ns_ctl_table_vm() stub, per Jeff]
[akpm@linux-foundation.org: s/pr_warn_ratelimited/pr_warn_once/, per review]
[akpm@linux-foundation.org: fix CONFIG_SYSCTL=n warning]
Link: https://lkml.kernel.org/r/20221215001205.51969-4-jeffxu@google.com
Signed-off-by: Jeff Xu <jeffxu@google.com>
Co-developed-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
39 lines
1.4 KiB
C
39 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_MEMFD_H
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#define _UAPI_LINUX_MEMFD_H
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#include <asm-generic/hugetlb_encode.h>
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/* flags for memfd_create(2) (unsigned int) */
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#define MFD_CLOEXEC 0x0001U
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#define MFD_ALLOW_SEALING 0x0002U
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#define MFD_HUGETLB 0x0004U
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/* not executable and sealed to prevent changing to executable. */
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#define MFD_NOEXEC_SEAL 0x0008U
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/* executable */
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#define MFD_EXEC 0x0010U
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/*
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* Huge page size encoding when MFD_HUGETLB is specified, and a huge page
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* size other than the default is desired. See hugetlb_encode.h.
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* All known huge page size encodings are provided here. It is the
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* responsibility of the application to know which sizes are supported on
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* the running system. See mmap(2) man page for details.
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*/
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#define MFD_HUGE_SHIFT HUGETLB_FLAG_ENCODE_SHIFT
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#define MFD_HUGE_MASK HUGETLB_FLAG_ENCODE_MASK
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#define MFD_HUGE_64KB HUGETLB_FLAG_ENCODE_64KB
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#define MFD_HUGE_512KB HUGETLB_FLAG_ENCODE_512KB
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#define MFD_HUGE_1MB HUGETLB_FLAG_ENCODE_1MB
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#define MFD_HUGE_2MB HUGETLB_FLAG_ENCODE_2MB
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#define MFD_HUGE_8MB HUGETLB_FLAG_ENCODE_8MB
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#define MFD_HUGE_16MB HUGETLB_FLAG_ENCODE_16MB
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#define MFD_HUGE_32MB HUGETLB_FLAG_ENCODE_32MB
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#define MFD_HUGE_256MB HUGETLB_FLAG_ENCODE_256MB
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#define MFD_HUGE_512MB HUGETLB_FLAG_ENCODE_512MB
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#define MFD_HUGE_1GB HUGETLB_FLAG_ENCODE_1GB
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#define MFD_HUGE_2GB HUGETLB_FLAG_ENCODE_2GB
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#define MFD_HUGE_16GB HUGETLB_FLAG_ENCODE_16GB
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#endif /* _UAPI_LINUX_MEMFD_H */
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