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kexec: factor out kexec_load_permitted

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Both syscalls (kexec and kexec_file) do the same check, let's factor it
out.

Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-2-6a8531a09b9a@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ricardo Ribalda
2023-01-04 15:38:47 +01:00
committed by Andrew Morton
parent 06dcb0138f
commit 7e99f8b69c
4 changed files with 14 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/kexec.h
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@@ -403,7 +403,8 @@ extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
extern struct kimage *kexec_image; extern struct kimage *kexec_image;
extern struct kimage *kexec_crash_image; extern struct kimage *kexec_crash_image;
extern int kexec_load_disabled;
bool kexec_load_permitted(void);
#ifndef kexec_flush_icache_page #ifndef kexec_flush_icache_page
#define kexec_flush_icache_page(page) #define kexec_flush_icache_page(page)

2
kernel/kexec.c
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@@ -193,7 +193,7 @@ static inline int kexec_load_check(unsigned long nr_segments,
int result; int result;
/* We only trust the superuser with rebooting the system. */ /* We only trust the superuser with rebooting the system. */
if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) if (!kexec_load_permitted())
return -EPERM; return -EPERM;
/* Permit LSMs and IMA to fail the kexec */ /* Permit LSMs and IMA to fail the kexec */

11
kernel/kexec_core.c
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@@ -922,7 +922,7 @@ int kimage_load_segment(struct kimage *image,
struct kimage *kexec_image; struct kimage *kexec_image;
struct kimage *kexec_crash_image; struct kimage *kexec_crash_image;
int kexec_load_disabled; static int kexec_load_disabled;
#ifdef CONFIG_SYSCTL #ifdef CONFIG_SYSCTL
static struct ctl_table kexec_core_sysctls[] = { static struct ctl_table kexec_core_sysctls[] = {
{ {
@@ -946,6 +946,15 @@ static int __init kexec_core_sysctl_init(void)
late_initcall(kexec_core_sysctl_init); late_initcall(kexec_core_sysctl_init);
#endif #endif
bool kexec_load_permitted(void)
{
/*
* Only the superuser can use the kexec syscall and if it has not
* been disabled.
*/
return capable(CAP_SYS_BOOT) && !kexec_load_disabled;
}
/* /*
* No panic_cpu check version of crash_kexec(). This function is called * No panic_cpu check version of crash_kexec(). This function is called
* only when panic_cpu holds the current CPU number; this is the only CPU * only when panic_cpu holds the current CPU number; this is the only CPU

2
kernel/kexec_file.c
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@@ -330,7 +330,7 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
struct kimage **dest_image, *image; struct kimage **dest_image, *image;
/* We only trust the superuser with rebooting the system. */ /* We only trust the superuser with rebooting the system. */
if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) if (!kexec_load_permitted())
return -EPERM; return -EPERM;
/* Make sure we have a legal set of flags */ /* Make sure we have a legal set of flags */