Hi Daniel, Sorry for the late reply. I was in PTO last few days. On Fri, Aug 28, 2020 at 11:56:37PM +0200, Daniel Borkmann wrote: > On 8/26/20 3:19 PM, Hangbin Liu wrote: > > Add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL which could be > > used when we want to allow NULL pointer for map parameter. The bpf helper > > need to take care and check if the map is NULL when use this type. > > > > Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx> > > --- > > > > v9: merge the patch from [1] in to this series. > > v1-v8: no this patch > > > > [1] https://lore.kernel.org/bpf/20200715070001.2048207-1-liuhangbin@xxxxxxxxx/ > > --- > > include/linux/bpf.h | 2 ++ > > kernel/bpf/verifier.c | 23 ++++++++++++++++------- > > 2 files changed, 18 insertions(+), 7 deletions(-) > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index a6131d95e31e..cb40a1281ea2 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -276,6 +276,7 @@ enum bpf_arg_type { > > ARG_PTR_TO_ALLOC_MEM, /* pointer to dynamically allocated memory */ > > ARG_PTR_TO_ALLOC_MEM_OR_NULL, /* pointer to dynamically allocated memory or NULL */ > > ARG_CONST_ALLOC_SIZE_OR_ZERO, /* number of allocated bytes requested */ > > + ARG_CONST_MAP_PTR_OR_NULL, /* const argument used as pointer to bpf_map or NULL */ > > }; > > /* type of values returned from helper functions */ > > @@ -369,6 +370,7 @@ enum bpf_reg_type { > > PTR_TO_RDONLY_BUF_OR_NULL, /* reg points to a readonly buffer or NULL */ > > PTR_TO_RDWR_BUF, /* reg points to a read/write buffer */ > > PTR_TO_RDWR_BUF_OR_NULL, /* reg points to a read/write buffer or NULL */ > > + CONST_PTR_TO_MAP_OR_NULL, /* reg points to struct bpf_map or NULL */ > > Why is this needed & where do you assign it? Also, if we were to use CONST_PTR_TO_MAP_OR_NULL > then it's missing few things like rejection of arithmetic in adjust_ptr_min_max_vals(), handling > in pruning logic etc. > > Either way, given no helper currently returns CONST_PTR_TO_MAP_OR_NULL, the ARG_CONST_MAP_PTR_OR_NULL > one should be sufficient, so I'd suggest to remove the CONST_PTR_TO_MAP_OR_NULL bits. Sorry, I misunderstand the bpf_reg_type when added it. Thanks for the comment. I will remove it. > > - } else if (arg_type == ARG_CONST_MAP_PTR) { > > + } else if (arg_type == ARG_CONST_MAP_PTR || > > + arg_type == ARG_CONST_MAP_PTR_OR_NULL) { > > expected_type = CONST_PTR_TO_MAP; > > - if (type != expected_type) > > + if (register_is_null(reg) && > > + arg_type == ARG_CONST_MAP_PTR_OR_NULL) > > + /* final test in check_stack_boundary() */; > > Where is that test in the code? Copy-paste leftover comment? Yeah... I will remove it. Thanks Hangbin
