On 12/17/21 12:49, Christophe Leroy wrote:
> Hi Kees,
>
> Le 17/10/2021 à 14:38, Christophe Leroy a écrit :
>> execute_location() and execute_user_location() intent
>> to copy do_nothing() text and execute it at a new location.
>> However, at the time being it doesn't copy do_nothing() function
>> but do_nothing() function descriptor which still points to the
>> original text. So at the end it still executes do_nothing() at
>> its original location allthough using a copied function descriptor.
>>
>> So, fix that by really copying do_nothing() text and build a new
>> function descriptor by copying do_nothing() function descriptor and
>> updating the target address with the new location.
>>
>> Also fix the displayed addresses by dereferencing do_nothing()
>> function descriptor.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
>
> Do you have any comment to this patch and to patch 12 ?
>
> If not, is it ok to get your acked-by ?
Hi Christophe,
I think this whole series is a nice cleanup and harmonization
of how function descriptors are used.
At least for the PA-RISC parts you may add:
Acked-by: Helge Deller <deller@xxxxxx>
Thanks!
Helge
>
>> ---
>> drivers/misc/lkdtm/perms.c | 37 ++++++++++++++++++++++++++++---------
>> 1 file changed, 28 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
>> index 035fcca441f0..1cf24c4a79e9 100644
>> --- a/drivers/misc/lkdtm/perms.c
>> +++ b/drivers/misc/lkdtm/perms.c
>> @@ -44,19 +44,34 @@ static noinline void do_overwritten(void)
>> return;
>> }
>>
>> +static void *setup_function_descriptor(func_desc_t *fdesc, void *dst)
>> +{
>> + if (!have_function_descriptors())
>> + return dst;
>> +
>> + memcpy(fdesc, do_nothing, sizeof(*fdesc));
>> + fdesc->addr = (unsigned long)dst;
>> + barrier();
>> +
>> + return fdesc;
>> +}
>> +
>> static noinline void execute_location(void *dst, bool write)
>> {
>> - void (*func)(void) = dst;
>> + void (*func)(void);
>> + func_desc_t fdesc;
>> + void *do_nothing_text = dereference_function_descriptor(do_nothing);
>>
>> - pr_info("attempting ok execution at %px\n", do_nothing);
>> + pr_info("attempting ok execution at %px\n", do_nothing_text);
>> do_nothing();
>>
>> if (write == CODE_WRITE) {
>> - memcpy(dst, do_nothing, EXEC_SIZE);
>> + memcpy(dst, do_nothing_text, EXEC_SIZE);
>> flush_icache_range((unsigned long)dst,
>> (unsigned long)dst + EXEC_SIZE);
>> }
>> - pr_info("attempting bad execution at %px\n", func);
>> + pr_info("attempting bad execution at %px\n", dst);
>> + func = setup_function_descriptor(&fdesc, dst);
>> func();
>> pr_err("FAIL: func returned\n");
>> }
>> @@ -66,16 +81,19 @@ static void execute_user_location(void *dst)
>> int copied;
>>
>> /* Intentionally crossing kernel/user memory boundary. */
>> - void (*func)(void) = dst;
>> + void (*func)(void);
>> + func_desc_t fdesc;
>> + void *do_nothing_text = dereference_function_descriptor(do_nothing);
>>
>> - pr_info("attempting ok execution at %px\n", do_nothing);
>> + pr_info("attempting ok execution at %px\n", do_nothing_text);
>> do_nothing();
>>
>> - copied = access_process_vm(current, (unsigned long)dst, do_nothing,
>> + copied = access_process_vm(current, (unsigned long)dst, do_nothing_text,
>> EXEC_SIZE, FOLL_WRITE);
>> if (copied < EXEC_SIZE)
>> return;
>> - pr_info("attempting bad execution at %px\n", func);
>> + pr_info("attempting bad execution at %px\n", dst);
>> + func = setup_function_descriptor(&fdesc, dst);
>> func();
>> pr_err("FAIL: func returned\n");
>> }
>> @@ -153,7 +171,8 @@ void lkdtm_EXEC_VMALLOC(void)
>>
>> void lkdtm_EXEC_RODATA(void)
>> {
>> - execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS);
>> + execute_location(dereference_function_descriptor(lkdtm_rodata_do_nothing),
>> + CODE_AS_IS);
>> }
>>
>> void lkdtm_EXEC_USERSPACE(void)
|