Re: [PATCH v2 3/3] kexec: Introduce paramters load_limit_reboot and load_limit_panic
On 08/12/2022 13:38, Ricardo Ribalda wrote: > Add two parameter to specify how many times a kexec kernel can be loaded. > > The sysadmin can set different limits for kexec panic and kexec reboot > kernels. > > The value can be modified at runtime via sysfs, but only with a value > smaller than the current one (except -1). > > Signed-off-by: Ricardo Ribalda > --- Thanks for your patches Ricardo! Small nit in the subject: s/paramters/parameters. Just observed that after Joel's review anyway, so kudos to him heh Cheers, Guilherme ___ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
Re: [PATCH v2 3/3] kexec: Introduce paramters load_limit_reboot and load_limit_panic
Hi Ricardo,
On Thu, Dec 08, 2022 at 05:38:02PM +0100, Ricardo Ribalda wrote:
> Add two parameter to specify how many times a kexec kernel can be loaded.
>
> The sysadmin can set different limits for kexec panic and kexec reboot
> kernels.
>
> The value can be modified at runtime via sysfs, but only with a value
> smaller than the current one (except -1).
>
> Signed-off-by: Ricardo Ribalda
> ---
> Documentation/admin-guide/kernel-parameters.txt | 14
> include/linux/kexec.h | 2 +-
> kernel/kexec.c | 2 +-
> kernel/kexec_core.c | 91
> -
> kernel/kexec_file.c | 2 +-
> 5 files changed, 106 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 42af9ca0127e..2b37d6a20747 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2374,6 +2374,20 @@
> for Movable pages. "nn[KMGTPE]", "nn%", and "mirror"
> are exclusive, so you cannot specify multiple forms.
>
> + kexec_core.load_limit_reboot=
> + kexec_core.load_limit_panic=
> + [KNL]
> + This parameter specifies a limit to the number of times
> + a kexec kernel can be loaded.
> + Format:
> + -1 = Unlimited.
> + int = Number of times kexec can be called.
> +
> + During runtime, this parameter can be modified with a
> + value smaller than the current one (but not -1).
> +
> + Default: -1
> +
> kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
> Format: [,poll interval]
> The controller # is the number of the ehci usb debug
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e9e1ab5e8006..3d7d10f7187a 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -407,7 +407,7 @@ extern int kimage_crash_copy_vmcoreinfo(struct kimage
> *image);
> extern struct kimage *kexec_image;
> extern struct kimage *kexec_crash_image;
>
> -bool kexec_load_permited(void);
> +bool kexec_load_permited(bool crash_image);
>
> #ifndef kexec_flush_icache_page
> #define kexec_flush_icache_page(page)
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index d83fc9093aff..2b0856e83fe1 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -193,7 +193,7 @@ static inline int kexec_load_check(unsigned long
> nr_segments,
> int result;
>
> /* We only trust the superuser with rebooting the system. */
> - if (!kexec_load_permited())
> + if (!kexec_load_permited(flags & KEXEC_ON_CRASH))
nit: permitted.
> return -EPERM;
>
> /* Permit LSMs and IMA to fail the kexec */
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 18bd90ca9c99..7f9d5288b24b 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -952,13 +952,100 @@ static int __init kexec_core_sysctl_init(void)
> late_initcall(kexec_core_sysctl_init);
> #endif
>
> -bool kexec_load_permited(void)
> +struct kexec_load_limit {
> + /* Mutex protects the limit count. */
> + struct mutex mutex;
> + int limit;
Can you not just use atomic ops for limit, and get rid of the mutex?
That will simplify the code as well.
> +};
> +
> +struct kexec_load_limit load_limit_reboot = {
> + .mutex = __MUTEX_INITIALIZER(load_limit_reboot.mutex),
> + .limit = -1,
> +};
> +
> +struct kexec_load_limit load_limit_panic = {
> + .mutex = __MUTEX_INITIALIZER(load_limit_panic.mutex),
> + .limit = -1,
> +};
> +
> +static int param_get_limit(char *buffer, const struct kernel_param *kp)
> {
> + int ret;
> + struct kexec_load_limit *limit = kp->arg;
> +
> + mutex_lock(>mutex);
> + ret = scnprintf(buffer, PAGE_SIZE, "%i\n", limit->limit);
> + mutex_unlock(>mutex);
> +
> + return ret;
> +}
> +
> +static int param_set_limit(const char *buffer, const struct kernel_param *kp)
> +{
> + int ret;
> + struct kexec_load_limit *limit = kp->arg;
> + int new_val;
> +
> + ret = kstrtoint(buffer, 0, _val);
> + if (ret)
> + return ret;
> +
> + new_val = max(-1, new_val);
> +
> + mutex_lock(>mutex);
> +
> + if (new_val == -1 && limit->limit != -1) {
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + if (limit->limit != -1 && new_val > limit->limit) {
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + limit->limit = new_val;
> +
> +done:
> + mutex_unlock(>mutex);
> +
> + return ret;
> +}
> +
> +static const struct kernel_param_ops load_limit_ops = {
> + .get = param_get_limit,
> + .set = param_set_limit,
>
[PATCH 2/2] kexec: Remove unnecessary arch_kexec_kernel_image_load()
From: Bjorn Helgaas
arch_kexec_kernel_image_load() only calls kexec_image_load_default(), and
there are no arch-specific implementations.
Remove the unnecessary arch_kexec_kernel_image_load() and make
kexec_image_load_default() static .
No functional change intended.
Signed-off-by: Bjorn Helgaas
kexec: make static
Signed-off-by: Bjorn Helgaas
---
include/linux/kexec.h | 6 --
kernel/kexec_file.c | 6 +++---
2 files changed, 3 insertions(+), 9 deletions(-)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index c08d5d52223a..8844e7debfa4 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -190,7 +190,6 @@ int kexec_purgatory_get_set_symbol(struct kimage *image,
const char *name,
void *buf, unsigned int size,
bool get_value);
void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name);
-void *kexec_image_load_default(struct kimage *image);
#ifndef arch_kexec_kernel_image_probe
static inline int
@@ -207,11 +206,6 @@ static inline int
arch_kimage_file_post_load_cleanup(struct kimage *image)
}
#endif
-static inline void *arch_kexec_kernel_image_load(struct kimage *image)
-{
- return kexec_image_load_default(image);
-}
-
#ifdef CONFIG_KEXEC_SIG
#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len);
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index dd5983010b7b..39ddf09ab573 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -65,7 +65,7 @@ int kexec_image_probe_default(struct kimage *image, void *buf,
return ret;
}
-void *kexec_image_load_default(struct kimage *image)
+static void *kexec_image_load_default(struct kimage *image)
{
if (!image->fops || !image->fops->load)
return ERR_PTR(-ENOEXEC);
@@ -249,8 +249,8 @@ kimage_file_prepare_segments(struct kimage *image, int
kernel_fd, int initrd_fd,
/* IMA needs to pass the measurement list to the next kernel. */
ima_add_kexec_buffer(image);
- /* Call arch image load handlers */
- ldata = arch_kexec_kernel_image_load(image);
+ /* Call image load handler */
+ ldata = kexec_image_load_default(image);
if (IS_ERR(ldata)) {
ret = PTR_ERR(ldata);
--
2.25.1
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[PATCH 0/2] kexec: Remove unnecessary arch hook
From: Bjorn Helgaas There are no arch-specific things in arch_kexec_kernel_image_load(), so remove it and just use the generic version. Bjorn Helgaas (2): x86/kexec: Remove unnecessary arch_kexec_kernel_image_load() kexec: Remove unnecessary arch_kexec_kernel_image_load() arch/x86/include/asm/kexec.h | 3 --- arch/x86/kernel/machine_kexec_64.c | 11 --- include/linux/kexec.h | 8 kernel/kexec_file.c| 6 +++--- 4 files changed, 3 insertions(+), 25 deletions(-) -- 2.25.1 ___ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
[PATCH 1/2] x86/kexec: Remove unnecessary arch_kexec_kernel_image_load()
From: Bjorn Helgaas
The x86 implementation of arch_kexec_kernel_image_load() is functionally
identical to the generic arch_kexec_kernel_image_load().
Remove it and use the generic arch_kexec_kernel_image_load(). No
functional change intended.
Signed-off-by: Bjorn Helgaas
---
arch/x86/include/asm/kexec.h | 3 ---
arch/x86/kernel/machine_kexec_64.c | 11 ---
include/linux/kexec.h | 2 --
3 files changed, 16 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index a3760ca796aa..5b77bbc28f96 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -200,9 +200,6 @@ int arch_kexec_apply_relocations_add(struct purgatory_info
*pi,
const Elf_Shdr *symtab);
#define arch_kexec_apply_relocations_add arch_kexec_apply_relocations_add
-void *arch_kexec_kernel_image_load(struct kimage *image);
-#define arch_kexec_kernel_image_load arch_kexec_kernel_image_load
-
int arch_kimage_file_post_load_cleanup(struct kimage *image);
#define arch_kimage_file_post_load_cleanup arch_kimage_file_post_load_cleanup
#endif
diff --git a/arch/x86/kernel/machine_kexec_64.c
b/arch/x86/kernel/machine_kexec_64.c
index 0611fd83858e..1a3e2c05a8a5 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -374,17 +374,6 @@ void machine_kexec(struct kimage *image)
/* arch-dependent functionality related to kexec file-based syscall */
#ifdef CONFIG_KEXEC_FILE
-void *arch_kexec_kernel_image_load(struct kimage *image)
-{
- if (!image->fops || !image->fops->load)
- return ERR_PTR(-ENOEXEC);
-
- return image->fops->load(image, image->kernel_buf,
-image->kernel_buf_len, image->initrd_buf,
-image->initrd_buf_len, image->cmdline_buf,
-image->cmdline_buf_len);
-}
-
/*
* Apply purgatory relocations.
*
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 5dd4343c1bbe..c08d5d52223a 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -207,12 +207,10 @@ static inline int
arch_kimage_file_post_load_cleanup(struct kimage *image)
}
#endif
-#ifndef arch_kexec_kernel_image_load
static inline void *arch_kexec_kernel_image_load(struct kimage *image)
{
return kexec_image_load_default(image);
}
-#endif
#ifdef CONFIG_KEXEC_SIG
#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
--
2.25.1
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