From: Jeff Xu <jeffxu@chromium.org>
Add vm.mfd_noexec. When the value is 1 (enabled),
memfd_create syscall will created non-executable memfd.
The default value is 0 (disabled), admin can change the
setting from 0 => 1, however 1 => 0 is not allowed,
unless reboot.
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
---
include/linux/mm.h | 4 ++++
kernel/sysctl.c | 9 +++++++++
mm/memfd.c | 27 +++++++++++++++++++++++++++
3 files changed, 40 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7898e29bcfb5..1c66cf4aca11 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -203,6 +203,10 @@ extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
extern unsigned long sysctl_overcommit_kbytes;
+extern int sysctl_mfd_noexec_scope;
+extern int mfd_noexec_dointvec_minmax(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos);
+
int overcommit_ratio_handler(struct ctl_table *, int, void *, size_t *,
loff_t *);
int overcommit_kbytes_handler(struct ctl_table *, int, void *, size_t *,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b233714a1c78..54510da007ff 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2362,6 +2362,15 @@ static struct ctl_table vm_table[] = {
.mode = 0644,
.proc_handler = mmap_min_addr_handler,
},
+ {
+ .procname = "mfd_noexec",
+ .data = &sysctl_mfd_noexec_scope,
+ .maxlen = sizeof(sysctl_mfd_noexec_scope),
+ .mode = 0644,
+ .proc_handler = mfd_noexec_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
#endif
#ifdef CONFIG_NUMA
{
diff --git a/mm/memfd.c b/mm/memfd.c
index b841514eb0fd..c6ccb8481ed2 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -20,6 +20,11 @@
#include <linux/memfd.h>
#include <uapi/linux/memfd.h>
+#define MFD_NOEXEC_SCOPE_DISABLED 0
+#define MFD_NOEXEC_SCOPE_ENABLED 1
+
+int sysctl_mfd_noexec_scope __read_mostly = MFD_NOEXEC_SCOPE_DISABLED;
+
/*
* We need a tag: a new tag would expand every xa_node by 8 bytes,
* so reuse a tag which we firmly believe is never set or cleared on tmpfs
@@ -275,6 +280,10 @@ SYSCALL_DEFINE2(memfd_create,
char *name;
long len;
+ if (sysctl_mfd_noexec_scope == MFD_NOEXEC_SCOPE_ENABLED) {
+ flags |= MFD_NOEXEC;
+ }
+
if (!(flags & MFD_HUGETLB)) {
if (flags & ~(unsigned int)MFD_ALL_FLAGS)
return -EINVAL;
@@ -351,3 +360,21 @@ SYSCALL_DEFINE2(memfd_create,
kfree(name);
return error;
}
+
+#ifdef CONFIG_SYSCTL
+int mfd_noexec_dointvec_minmax(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table table_copy;
+
+ if (write && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Lock the max value if it ever gets set. */
+ table_copy = *table;
+ if (*(int *)table_copy.data == *(int *)table_copy.extra2)
+ table_copy.extra1 = table_copy.extra2;
+
+ return proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);
+}
+#endif
--
2.37.1.559.g78731f0fdb-googHi,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on 9e2f40233670c70c25e0681cb66d50d1e2742829]
url: https://github.com/intel-lab-lkp/linux/commits/jeffxu-google-com/mm-memfd-MFD_NOEXEC-for-memfd_create/20220806-062430
base: 9e2f40233670c70c25e0681cb66d50d1e2742829
config: openrisc-randconfig-r004-20220805 (https://download.01.org/0day-ci/archive/20220814/202208140205.5zR1h5VB-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/e71897c778df5381c6d1ca858ae096a557a08a2a
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review jeffxu-google-com/mm-memfd-MFD_NOEXEC-for-memfd_create/20220806-062430
git checkout e71897c778df5381c6d1ca858ae096a557a08a2a
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=openrisc SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
>> or1k-linux-ld: kernel/sysctl.o:(.data+0x440): undefined reference to `sysctl_mfd_noexec_scope'
>> or1k-linux-ld: kernel/sysctl.o:(.data+0x450): undefined reference to `mfd_noexec_dointvec_minmax'
--
0-DAY CI Kernel Test Service
https://01.org/lkp
Hi,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on 9e2f40233670c70c25e0681cb66d50d1e2742829]
url: https://github.com/intel-lab-lkp/linux/commits/jeffxu-google-com/mm-memfd-MFD_NOEXEC-for-memfd_create/20220806-062430
base: 9e2f40233670c70c25e0681cb66d50d1e2742829
config: csky-allnoconfig (https://download.01.org/0day-ci/archive/20220814/202208140256.CLDuIPhh-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/e71897c778df5381c6d1ca858ae096a557a08a2a
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review jeffxu-google-com/mm-memfd-MFD_NOEXEC-for-memfd_create/20220806-062430
git checkout e71897c778df5381c6d1ca858ae096a557a08a2a
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=csky SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
>> csky-linux-ld: kernel/sysctl.o:(.data+0x398): undefined reference to `sysctl_mfd_noexec_scope'
>> csky-linux-ld: kernel/sysctl.o:(.data+0x3a8): undefined reference to `mfd_noexec_dointvec_minmax'
--
0-DAY CI Kernel Test Service
https://01.org/lkp
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