diff mbox series

[v1,bpf-next,2/5] bpf: Add bpf_dynptr_is_null and bpf_dynptr_is_rdonly

Message ID 20230409033431.3992432-3-joannelkoong@gmail.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Dynptr convenience helpers | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 55 this patch: 57
netdev/cc_maintainers warning 8 maintainers not CCed: song@kernel.org sdf@google.com haoluo@google.com yhs@fb.com john.fastabend@gmail.com kpsingh@kernel.org jolsa@kernel.org martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 59 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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Commit Message

Joanne Koong April 9, 2023, 3:34 a.m. UTC 
bpf_dynptr_is_null returns true if the dynptr is null / invalid
(determined by whether ptr->data is NULL), else false if
the dynptr is a valid dynptr.

bpf_dynptr_is_rdonly returns true if the dynptr is read-only,
else false if the dynptr is read-writable.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
 kernel/bpf/helpers.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

Comments

Andrii Nakryiko April 12, 2023, 9:50 p.m. UTC | #1 
On Sat, Apr 8, 2023 at 8:34 PM Joanne Koong <joannelkoong@gmail.com> wrote:
>
> bpf_dynptr_is_null returns true if the dynptr is null / invalid
> (determined by whether ptr->data is NULL), else false if
> the dynptr is a valid dynptr.
>
> bpf_dynptr_is_rdonly returns true if the dynptr is read-only,
> else false if the dynptr is read-writable.
>
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> ---
>  kernel/bpf/helpers.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 51b4c4b5dbed..e4e84e92a4c6 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -1423,7 +1423,7 @@ static const struct bpf_func_proto bpf_kptr_xchg_proto = {
>  #define DYNPTR_SIZE_MASK       0xFFFFFF
>  #define DYNPTR_RDONLY_BIT      BIT(31)
>
> -static bool bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
> +static bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
>  {
>         return ptr->size & DYNPTR_RDONLY_BIT;
>  }
> @@ -1570,7 +1570,7 @@ BPF_CALL_5(bpf_dynptr_write, const struct bpf_dynptr_kern *, dst, u32, offset, v
>         enum bpf_dynptr_type type;
>         int err;
>
> -       if (!dst->data || bpf_dynptr_is_rdonly(dst))
> +       if (!dst->data || __bpf_dynptr_is_rdonly(dst))
>                 return -EINVAL;
>
>         err = bpf_dynptr_check_off_len(dst, offset, len);
> @@ -1626,7 +1626,7 @@ BPF_CALL_3(bpf_dynptr_data, const struct bpf_dynptr_kern *, ptr, u32, offset, u3
>         if (err)
>                 return 0;
>
> -       if (bpf_dynptr_is_rdonly(ptr))
> +       if (__bpf_dynptr_is_rdonly(ptr))
>                 return 0;
>
>         type = bpf_dynptr_get_type(ptr);
> @@ -2254,7 +2254,7 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
>  __bpf_kfunc void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr_kern *ptr, u32 offset,
>                                         void *buffer, u32 buffer__szk)
>  {
> -       if (!ptr->data || bpf_dynptr_is_rdonly(ptr))
> +       if (!ptr->data || __bpf_dynptr_is_rdonly(ptr))

seems like all the uses of __bpf_dynptr_is_rdonly check !ptr->data
explicitly, so maybe move that ptr->data check inside and simplify all
the callers?

Regardless, looks good:

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>                 return NULL;
>
>         /* bpf_dynptr_slice_rdwr is the same logic as bpf_dynptr_slice.
> @@ -2322,6 +2322,19 @@ __bpf_kfunc int bpf_dynptr_trim(struct bpf_dynptr_kern *ptr, u32 len)
>         return bpf_dynptr_adjust(ptr, 0, len);
>  }
>
> +__bpf_kfunc bool bpf_dynptr_is_null(struct bpf_dynptr_kern *ptr)
> +{
> +       return !ptr->data;
> +}
> +
> +__bpf_kfunc bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
> +{
> +       if (!ptr->data)
> +               return false;
> +
> +       return __bpf_dynptr_is_rdonly(ptr);
> +}
> +
>  __bpf_kfunc void *bpf_cast_to_kern_ctx(void *obj)
>  {
>         return obj;
> @@ -2396,6 +2409,8 @@ BTF_ID_FLAGS(func, bpf_iter_num_next, KF_ITER_NEXT | KF_RET_NULL)
>  BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY)
>  BTF_ID_FLAGS(func, bpf_dynptr_trim)
>  BTF_ID_FLAGS(func, bpf_dynptr_advance)
> +BTF_ID_FLAGS(func, bpf_dynptr_is_null)
> +BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
>  BTF_SET8_END(common_btf_ids)
>
>  static const struct btf_kfunc_id_set common_kfunc_set = {
> --
> 2.34.1
>
Joanne Koong April 20, 2023, 6:45 a.m. UTC | #2 
On Wed, Apr 12, 2023 at 2:50 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Sat, Apr 8, 2023 at 8:34 PM Joanne Koong <joannelkoong@gmail.com> wrote:
> >
> > bpf_dynptr_is_null returns true if the dynptr is null / invalid
> > (determined by whether ptr->data is NULL), else false if
> > the dynptr is a valid dynptr.
> >
> > bpf_dynptr_is_rdonly returns true if the dynptr is read-only,
> > else false if the dynptr is read-writable.
> >
> > Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> > ---
> >  kernel/bpf/helpers.c | 23 +++++++++++++++++++----
> >  1 file changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> > index 51b4c4b5dbed..e4e84e92a4c6 100644
> > --- a/kernel/bpf/helpers.c
> > +++ b/kernel/bpf/helpers.c
> > @@ -1423,7 +1423,7 @@ static const struct bpf_func_proto bpf_kptr_xchg_proto = {
> >  #define DYNPTR_SIZE_MASK       0xFFFFFF
> >  #define DYNPTR_RDONLY_BIT      BIT(31)
> >
> > -static bool bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
> > +static bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
> >  {
> >         return ptr->size & DYNPTR_RDONLY_BIT;
> >  }
> > @@ -1570,7 +1570,7 @@ BPF_CALL_5(bpf_dynptr_write, const struct bpf_dynptr_kern *, dst, u32, offset, v
> >         enum bpf_dynptr_type type;
> >         int err;
> >
> > -       if (!dst->data || bpf_dynptr_is_rdonly(dst))
> > +       if (!dst->data || __bpf_dynptr_is_rdonly(dst))
> >                 return -EINVAL;
> >
> >         err = bpf_dynptr_check_off_len(dst, offset, len);
> > @@ -1626,7 +1626,7 @@ BPF_CALL_3(bpf_dynptr_data, const struct bpf_dynptr_kern *, ptr, u32, offset, u3
> >         if (err)
> >                 return 0;
> >
> > -       if (bpf_dynptr_is_rdonly(ptr))
> > +       if (__bpf_dynptr_is_rdonly(ptr))
> >                 return 0;
> >
> >         type = bpf_dynptr_get_type(ptr);
> > @@ -2254,7 +2254,7 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
> >  __bpf_kfunc void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr_kern *ptr, u32 offset,
> >                                         void *buffer, u32 buffer__szk)
> >  {
> > -       if (!ptr->data || bpf_dynptr_is_rdonly(ptr))
> > +       if (!ptr->data || __bpf_dynptr_is_rdonly(ptr))
>
> seems like all the uses of __bpf_dynptr_is_rdonly check !ptr->data
> explicitly, so maybe move that ptr->data check inside and simplify all
> the callers?

i think combining it gets confusing in the case where ptr->data is
null, as to how the invoked places interpret the return value. I think
having the check spelled out more explicitly in the invoked places (eg
bpf_dynptr_write, bpf_dynptr_data, ...) makes it more clear as well
where the check for null is happening. for v2 I will leave this as is,
but also happy to change it if you prefer the two be combined

>
> Regardless, looks good:
>
> Acked-by: Andrii Nakryiko <andrii@kernel.org>
>
> >                 return NULL;
> >
> >         /* bpf_dynptr_slice_rdwr is the same logic as bpf_dynptr_slice.
> > @@ -2322,6 +2322,19 @@ __bpf_kfunc int bpf_dynptr_trim(struct bpf_dynptr_kern *ptr, u32 len)
> >         return bpf_dynptr_adjust(ptr, 0, len);
> >  }
> >
> > +__bpf_kfunc bool bpf_dynptr_is_null(struct bpf_dynptr_kern *ptr)
> > +{
> > +       return !ptr->data;
> > +}
> > +
> > +__bpf_kfunc bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
> > +{
> > +       if (!ptr->data)
> > +               return false;
> > +
> > +       return __bpf_dynptr_is_rdonly(ptr);
> > +}
> > +
> >  __bpf_kfunc void *bpf_cast_to_kern_ctx(void *obj)
> >  {
> >         return obj;
> > @@ -2396,6 +2409,8 @@ BTF_ID_FLAGS(func, bpf_iter_num_next, KF_ITER_NEXT | KF_RET_NULL)
> >  BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY)
> >  BTF_ID_FLAGS(func, bpf_dynptr_trim)
> >  BTF_ID_FLAGS(func, bpf_dynptr_advance)
> > +BTF_ID_FLAGS(func, bpf_dynptr_is_null)
> > +BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
> >  BTF_SET8_END(common_btf_ids)
> >
> >  static const struct btf_kfunc_id_set common_kfunc_set = {
> > --
> > 2.34.1
> >
diff mbox series

Patch

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 51b4c4b5dbed..e4e84e92a4c6 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1423,7 +1423,7 @@  static const struct bpf_func_proto bpf_kptr_xchg_proto = {
 #define DYNPTR_SIZE_MASK	0xFFFFFF
 #define DYNPTR_RDONLY_BIT	BIT(31)
 
-static bool bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
+static bool __bpf_dynptr_is_rdonly(const struct bpf_dynptr_kern *ptr)
 {
 	return ptr->size & DYNPTR_RDONLY_BIT;
 }
@@ -1570,7 +1570,7 @@  BPF_CALL_5(bpf_dynptr_write, const struct bpf_dynptr_kern *, dst, u32, offset, v
 	enum bpf_dynptr_type type;
 	int err;
 
-	if (!dst->data || bpf_dynptr_is_rdonly(dst))
+	if (!dst->data || __bpf_dynptr_is_rdonly(dst))
 		return -EINVAL;
 
 	err = bpf_dynptr_check_off_len(dst, offset, len);
@@ -1626,7 +1626,7 @@  BPF_CALL_3(bpf_dynptr_data, const struct bpf_dynptr_kern *, ptr, u32, offset, u3
 	if (err)
 		return 0;
 
-	if (bpf_dynptr_is_rdonly(ptr))
+	if (__bpf_dynptr_is_rdonly(ptr))
 		return 0;
 
 	type = bpf_dynptr_get_type(ptr);
@@ -2254,7 +2254,7 @@  __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
 __bpf_kfunc void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr_kern *ptr, u32 offset,
 					void *buffer, u32 buffer__szk)
 {
-	if (!ptr->data || bpf_dynptr_is_rdonly(ptr))
+	if (!ptr->data || __bpf_dynptr_is_rdonly(ptr))
 		return NULL;
 
 	/* bpf_dynptr_slice_rdwr is the same logic as bpf_dynptr_slice.
@@ -2322,6 +2322,19 @@  __bpf_kfunc int bpf_dynptr_trim(struct bpf_dynptr_kern *ptr, u32 len)
 	return bpf_dynptr_adjust(ptr, 0, len);
 }
 
+__bpf_kfunc bool bpf_dynptr_is_null(struct bpf_dynptr_kern *ptr)
+{
+	return !ptr->data;
+}
+
+__bpf_kfunc bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
+{
+	if (!ptr->data)
+		return false;
+
+	return __bpf_dynptr_is_rdonly(ptr);
+}
+
 __bpf_kfunc void *bpf_cast_to_kern_ctx(void *obj)
 {
 	return obj;
@@ -2396,6 +2409,8 @@  BTF_ID_FLAGS(func, bpf_iter_num_next, KF_ITER_NEXT | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY)
 BTF_ID_FLAGS(func, bpf_dynptr_trim)
 BTF_ID_FLAGS(func, bpf_dynptr_advance)
+BTF_ID_FLAGS(func, bpf_dynptr_is_null)
+BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
 BTF_SET8_END(common_btf_ids)
 
 static const struct btf_kfunc_id_set common_kfunc_set = {