mirror of
https://github.com/torvalds/linux.git
synced 2024-11-10 22:21:40 +00:00
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>
61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef LINUX_PID_SYSCTL_H
|
|
#define LINUX_PID_SYSCTL_H
|
|
|
|
#include <linux/pid_namespace.h>
|
|
|
|
#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
|
|
static inline void initialize_memfd_noexec_scope(struct pid_namespace *ns)
|
|
{
|
|
ns->memfd_noexec_scope =
|
|
task_active_pid_ns(current)->memfd_noexec_scope;
|
|
}
|
|
|
|
static int pid_mfd_noexec_dointvec_minmax(struct ctl_table *table,
|
|
int write, void *buf, size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct pid_namespace *ns = task_active_pid_ns(current);
|
|
struct ctl_table table_copy;
|
|
|
|
if (write && !ns_capable(ns->user_ns, CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
table_copy = *table;
|
|
if (ns != &init_pid_ns)
|
|
table_copy.data = &ns->memfd_noexec_scope;
|
|
|
|
/*
|
|
* set minimum to current value, the effect is only bigger
|
|
* value is accepted.
|
|
*/
|
|
if (*(int *)table_copy.data > *(int *)table_copy.extra1)
|
|
table_copy.extra1 = table_copy.data;
|
|
|
|
return proc_dointvec_minmax(&table_copy, write, buf, lenp, ppos);
|
|
}
|
|
|
|
static struct ctl_table pid_ns_ctl_table_vm[] = {
|
|
{
|
|
.procname = "memfd_noexec",
|
|
.data = &init_pid_ns.memfd_noexec_scope,
|
|
.maxlen = sizeof(init_pid_ns.memfd_noexec_scope),
|
|
.mode = 0644,
|
|
.proc_handler = pid_mfd_noexec_dointvec_minmax,
|
|
.extra1 = SYSCTL_ZERO,
|
|
.extra2 = SYSCTL_TWO,
|
|
},
|
|
{ }
|
|
};
|
|
static struct ctl_path vm_path[] = { { .procname = "vm", }, { } };
|
|
static inline void register_pid_ns_sysctl_table_vm(void)
|
|
{
|
|
register_sysctl_paths(vm_path, pid_ns_ctl_table_vm);
|
|
}
|
|
#else
|
|
static inline void initialize_memfd_noexec_scope(struct pid_namespace *ns) {}
|
|
static inline void set_memfd_noexec_scope(struct pid_namespace *ns) {}
|
|
static inline void register_pid_ns_sysctl_table_vm(void) {}
|
|
#endif
|
|
|
|
#endif /* LINUX_PID_SYSCTL_H */
|