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IB/core: uverbs copy to struct or zero helper

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Add a helper to zero fill fields before copying data to
UVERBS_ATTR_STRUCT.

As UVERBS_ATTR_STRUCT can be used as an extensible struct, we want to make
sure that if the user supplies us with a struct that has new fields that
we are not aware of, we return them zeroed to the user.

This helper should be used when using UVERBS_ATTR_STRUCT for an extendable
data structure and there is a need to make sure that extended members of
the struct, that the kernel doesn't handle, are returned zeroed to the
user. This is needed due to the fact that UVERBS_ATTR_STRUCT allows
non-zero values for members after 'last' member.

Signed-off-by: Michael Guralnik <michaelgur@mellanox.com>
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Michael Guralnik 2018-12-09 11:58:04 +02:00 committed by Jason Gunthorpe
parent f55c3ec42a
commit 2e8039c656
2 changed files with 19 additions and 0 deletions
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11
drivers/infiniband/core/uverbs_ioctl.c
View File

@ -751,3 +751,14 @@ int _uverbs_get_const(s64 *to, const struct uverbs_attr_bundle *attrs_bundle,
return 0;
}
EXPORT_SYMBOL(_uverbs_get_const);
int uverbs_copy_to_struct_or_zero(const struct uverbs_attr_bundle *bundle,
size_t idx, const void *from, size_t size)
{
const struct uverbs_attr *attr = uverbs_attr_get(bundle, idx);
if (clear_user(u64_to_user_ptr(attr->ptr_attr.data),
attr->ptr_attr.len))
return -EFAULT;
return uverbs_copy_to(bundle, idx, from, size);
}

8
include/rdma/uverbs_ioctl.h
View File

@ -871,6 +871,8 @@ static inline __malloc void *uverbs_zalloc(struct uverbs_attr_bundle *bundle,
int _uverbs_get_const(s64 *to, const struct uverbs_attr_bundle *attrs_bundle,
size_t idx, s64 lower_bound, u64 upper_bound,
s64 *def_val);
int uverbs_copy_to_struct_or_zero(const struct uverbs_attr_bundle *bundle,
size_t idx, const void *from, size_t size);
#else
static inline int
uverbs_get_flags64(u64 *to, const struct uverbs_attr_bundle *attrs_bundle,
@ -906,6 +908,12 @@ _uverbs_get_const(s64 *to, const struct uverbs_attr_bundle *attrs_bundle,
{
return -EINVAL;
}
static inline int
uverbs_copy_to_struct_or_zero(const struct uverbs_attr_bundle *bundle,
size_t idx, const void *from, size_t size)
{
return -EINVAL;
}
#endif
#define uverbs_get_const(_to, _attrs_bundle, _idx) \