在 2020年09月10日 16:49, HAGIO KAZUHITO(萩尾 一仁) 写道:
> -----Original Message-----
>> Kernel commit fe557319aa06c23cffc9346000f119547e0f289a renamed
>> probe_kernel_{read,write} to copy_{from,to}_kernel_nofault.
>>
>> Additionally, commit 0493cb086353e786be56010780a0b7025b5db34c
>> unexported probe_kernel_write(), so writing kernel memory is
>> no longer possible from a module.
>>
>> I have renamed the functions in source, but I'm also adding wrappers to
>> allow building the module with older kernel versions.
>>
>> Without this patch, build with kernel 5.8 and later fails:
>>
>> kbuild/default/crash.c: In function 'crash_write':
>> kbuild/default/crash.c:189:12: error: implicit declaration of function 'probe_kernel_write'; did you mean
>> 'kernel_write'? [-Werror=implicit-function-declaration]
>> 189 | if (probe_kernel_write(vaddr, buffer, count)) {
>> | ^~~~~~~~~~~~~~~~~~
>> | kernel_write
>> kbuild/default/crash.c: In function 'crash_read':
>> kbuild/default/crash.c:225:13: error: implicit declaration of function 'probe_kernel_read'; did you mean
>> 'kernel_read'? [-Werror=implicit-function-declaration]
>> 225 | if (probe_kernel_read(buffer, vaddr, count)) {
>> | ^~~~~~~~~~~~~~~~~
>> | kernel_read
>>
>> Signed-off-by: Petr Tesarik <ptesarik@xxxxxxxx>
>
> Thank you for catching this, the patch looks good to me.
>
> Acked-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
>
> additionally, I think we should update the version number of this module.
> I'll add this change when applying, is it ok? Lianbo, Bhupesh.
>
That should be good.
For this patch:
Acked-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> -#define CRASH_VERSION "1.4"
> +#define CRASH_VERSION "1.5"
>
> Anyway, please wait for another ack.
>
> Thanks,
> Kazu
>
>>
>> ---
>> memory_driver/crash.c | 27 +++++++++++++++++++++++++--
>> 1 file changed, 25 insertions(+), 2 deletions(-)
>>
>> --- a/memory_driver/crash.c
>> +++ b/memory_driver/crash.c
>> @@ -25,6 +25,7 @@
>> *****************************************************************************/
>>
>> #include <linux/module.h>
>> +#include <linux/version.h>
>> #include <linux/types.h>
>> #include <linux/miscdevice.h>
>> #include <linux/init.h>
>> @@ -37,6 +38,22 @@
>>
>> extern int page_is_ram(unsigned long);
>>
>> +#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 8, 0)
>> +
>> +#define CAN_WRITE_KERNEL 1
>> +
>> +static inline long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
>> +{
>> + return probe_kernel_read(dst, src, size);
>> +}
>> +
>> +static inline long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
>> +{
>> + return probe_kernel_write(dst, src, size);
>> +}
>> +
>> +#endif
>> +
>> #ifdef CONFIG_S390
>> /*
>> * For swapped prefix pages get bounce buffer using xlate_dev_mem_ptr()
>> @@ -160,6 +177,8 @@ crash_llseek(struct file * file, loff_t
>> }
>> }
>>
>> +#ifdef CAN_WRITE_KERNEL
>> +
>> static ssize_t
>> crash_write(struct file *file, const char *buf, size_t count, loff_t *poff)
>> {
>> @@ -186,7 +205,7 @@ crash_write(struct file *file, const cha
>> return -EFAULT;
>> }
>>
>> - if (probe_kernel_write(vaddr, buffer, count)) {
>> + if (copy_to_kernel_nofault(vaddr, buffer, count)) {
>> unmap_virtual(page);
>> return -EFAULT;
>> }
>> @@ -197,6 +216,8 @@ crash_write(struct file *file, const cha
>> return written;
>> }
>>
>> +#endif
>> +
>> /*
>> * Determine the page address for an address offset value,
>> * get a virtual address for it, and copy it out.
>> @@ -222,7 +243,7 @@ crash_read(struct file *file, char *buf,
>> * Use bounce buffer to bypass the CONFIG_HARDENED_USERCOPY
>> * kernel text restriction.
>> */
>> - if (probe_kernel_read(buffer, vaddr, count)) {
>> + if (copy_from_kernel_nofault(buffer, vaddr, count)) {
>> unmap_virtual(page);
>> return -EFAULT;
>> }
>> @@ -294,7 +315,9 @@ static struct file_operations crash_fops
>> .owner = THIS_MODULE,
>> .llseek = crash_llseek,
>> .read = crash_read,
>> +#ifdef CAN_WRITE_KERNEL
>> .write = crash_write,
>> +#endif
>> .unlocked_ioctl = crash_ioctl,
>> .open = crash_open,
>> .release = crash_release,
>
--
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