| Message ID | 20220428211059.4065379-5-joannelkoong@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | Dynamic pointers | expand |
On Thu, Apr 28, 2022 at 2:12 PM Joanne Koong <joannelkoong@gmail.com> wrote: > > This patch adds two helper functions, bpf_dynptr_read and > bpf_dynptr_write: > > long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset); > > long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len); > > The dynptr passed into these functions must be valid dynptrs that have > been initialized. > > Signed-off-by: Joanne Koong <joannelkoong@gmail.com> > --- > include/linux/bpf.h | 16 ++++++++++ > include/uapi/linux/bpf.h | 19 ++++++++++++ > kernel/bpf/helpers.c | 56 ++++++++++++++++++++++++++++++++++ > tools/include/uapi/linux/bpf.h | 19 ++++++++++++ > 4 files changed, 110 insertions(+) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 10efbec99e93..b276dbf942dd 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -2387,6 +2387,12 @@ enum bpf_dynptr_type { > #define DYNPTR_SIZE_MASK 0xFFFFFF > #define DYNPTR_TYPE_SHIFT 28 > #define DYNPTR_TYPE_MASK 0x7 > +#define DYNPTR_RDONLY_BIT BIT(31) > + > +static inline bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr) > +{ > + return ptr->size & DYNPTR_RDONLY_BIT; > +} > > static inline enum bpf_dynptr_type bpf_dynptr_get_type(struct bpf_dynptr_kern *ptr) > { > @@ -2408,6 +2414,16 @@ static inline int bpf_dynptr_check_size(u32 size) > return size > DYNPTR_MAX_SIZE ? -E2BIG : 0; > } > > +static inline int bpf_dynptr_check_off_len(struct bpf_dynptr_kern *ptr, u32 offset, u32 len) > +{ > + u32 capacity = bpf_dynptr_get_size(ptr) - ptr->offset; didn't you specify that size excludes offset, so size is a capacity? + /* Size represents the number of usable bytes in the dynptr. + * If for example the offset is at 200 for a malloc dynptr with + * allocation size 256, the number of usable bytes is 56. > + > + if (len > capacity || offset > capacity - len) > + return -EINVAL; > + > + return 0; > +} > + > void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data, enum bpf_dynptr_type type, > u32 offset, u32 size); > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 679f960d2514..2d539930b7b2 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -5209,6 +5209,23 @@ union bpf_attr { > * 'bpf_ringbuf_discard'. > * Return > * Nothing. Always succeeds. > + * > + * long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset) > + * Description > + * Read *len* bytes from *src* into *dst*, starting from *offset* > + * into *src*. > + * Return > + * 0 on success, -EINVAL if *offset* + *len* exceeds the length this sounds more like E2BIG ? > + * of *src*'s data or if *src* is an invalid dynptr. > + * [...]
On Fri, May 6, 2022 at 4:48 PM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Thu, Apr 28, 2022 at 2:12 PM Joanne Koong <joannelkoong@gmail.com> wrote: > > > > This patch adds two helper functions, bpf_dynptr_read and > > bpf_dynptr_write: > > > > long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset); > > > > long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len); > > > > The dynptr passed into these functions must be valid dynptrs that have > > been initialized. > > > > Signed-off-by: Joanne Koong <joannelkoong@gmail.com> > > --- > > include/linux/bpf.h | 16 ++++++++++ > > include/uapi/linux/bpf.h | 19 ++++++++++++ > > kernel/bpf/helpers.c | 56 ++++++++++++++++++++++++++++++++++ > > tools/include/uapi/linux/bpf.h | 19 ++++++++++++ > > 4 files changed, 110 insertions(+) > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index 10efbec99e93..b276dbf942dd 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -2387,6 +2387,12 @@ enum bpf_dynptr_type { > > #define DYNPTR_SIZE_MASK 0xFFFFFF > > #define DYNPTR_TYPE_SHIFT 28 > > #define DYNPTR_TYPE_MASK 0x7 > > +#define DYNPTR_RDONLY_BIT BIT(31) > > + > > +static inline bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr) > > +{ > > + return ptr->size & DYNPTR_RDONLY_BIT; > > +} > > > > static inline enum bpf_dynptr_type bpf_dynptr_get_type(struct bpf_dynptr_kern *ptr) > > { > > @@ -2408,6 +2414,16 @@ static inline int bpf_dynptr_check_size(u32 size) > > return size > DYNPTR_MAX_SIZE ? -E2BIG : 0; > > } > > > > +static inline int bpf_dynptr_check_off_len(struct bpf_dynptr_kern *ptr, u32 offset, u32 len) > > +{ > > + u32 capacity = bpf_dynptr_get_size(ptr) - ptr->offset; > > didn't you specify that size excludes offset, so size is a capacity? Yes, bpf_dynptr_get_size(ptr) is the capacity. I will fix this for v4 > > + /* Size represents the number of usable bytes in the dynptr. > + * If for example the offset is at 200 for a malloc dynptr with > + * allocation size 256, the number of usable bytes is 56. > > > + > > + if (len > capacity || offset > capacity - len) > > + return -EINVAL; > > + > > + return 0; > > +} > > + > > void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data, enum bpf_dynptr_type type, > > u32 offset, u32 size); > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index 679f960d2514..2d539930b7b2 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -5209,6 +5209,23 @@ union bpf_attr { > > * 'bpf_ringbuf_discard'. > > * Return > > * Nothing. Always succeeds. > > + * > > + * long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset) > > + * Description > > + * Read *len* bytes from *src* into *dst*, starting from *offset* > > + * into *src*. > > + * Return > > + * 0 on success, -EINVAL if *offset* + *len* exceeds the length > > this sounds more like E2BIG ? I'll change this to -E2BIG here and in bpf_dynptr_write > > > + * of *src*'s data or if *src* is an invalid dynptr. > > + * > > [...]
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 10efbec99e93..b276dbf942dd 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2387,6 +2387,12 @@ enum bpf_dynptr_type { #define DYNPTR_SIZE_MASK 0xFFFFFF #define DYNPTR_TYPE_SHIFT 28 #define DYNPTR_TYPE_MASK 0x7 +#define DYNPTR_RDONLY_BIT BIT(31) + +static inline bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr) +{ + return ptr->size & DYNPTR_RDONLY_BIT; +} static inline enum bpf_dynptr_type bpf_dynptr_get_type(struct bpf_dynptr_kern *ptr) { @@ -2408,6 +2414,16 @@ static inline int bpf_dynptr_check_size(u32 size) return size > DYNPTR_MAX_SIZE ? -E2BIG : 0; } +static inline int bpf_dynptr_check_off_len(struct bpf_dynptr_kern *ptr, u32 offset, u32 len) +{ + u32 capacity = bpf_dynptr_get_size(ptr) - ptr->offset; + + if (len > capacity || offset > capacity - len) + return -EINVAL; + + return 0; +} + void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data, enum bpf_dynptr_type type, u32 offset, u32 size); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 679f960d2514..2d539930b7b2 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5209,6 +5209,23 @@ union bpf_attr { * 'bpf_ringbuf_discard'. * Return * Nothing. Always succeeds. + * + * long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset) + * Description + * Read *len* bytes from *src* into *dst*, starting from *offset* + * into *src*. + * Return + * 0 on success, -EINVAL if *offset* + *len* exceeds the length + * of *src*'s data or if *src* is an invalid dynptr. + * + * long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len) + * Description + * Write *len* bytes from *src* into *dst*, starting from *offset* + * into *dst*. + * Return + * 0 on success, -EINVAL if *offset* + *len* exceeds the length + * of *dst*'s data or if *dst* is an invalid dynptr or if *dst* + * is a read-only dynptr. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5411,6 +5428,8 @@ union bpf_attr { FN(ringbuf_reserve_dynptr), \ FN(ringbuf_submit_dynptr), \ FN(ringbuf_discard_dynptr), \ + FN(dynptr_read), \ + FN(dynptr_write), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 2d6f2e28b580..7206b9e5322f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1467,6 +1467,58 @@ const struct bpf_func_proto bpf_dynptr_put_proto = { .arg1_type = ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_MALLOC | OBJ_RELEASE, }; +BPF_CALL_4(bpf_dynptr_read, void *, dst, u32, len, struct bpf_dynptr_kern *, src, u32, offset) +{ + int err; + + if (!src->data) + return -EINVAL; + + err = bpf_dynptr_check_off_len(src, offset, len); + if (err) + return err; + + memcpy(dst, src->data + src->offset + offset, len); + + return 0; +} + +const struct bpf_func_proto bpf_dynptr_read_proto = { + .func = bpf_dynptr_read, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_UNINIT_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_PTR_TO_DYNPTR, + .arg4_type = ARG_ANYTHING, +}; + +BPF_CALL_4(bpf_dynptr_write, struct bpf_dynptr_kern *, dst, u32, offset, void *, src, u32, len) +{ + int err; + + if (!dst->data || bpf_dynptr_is_rdonly(dst)) + return -EINVAL; + + err = bpf_dynptr_check_off_len(dst, offset, len); + if (err) + return err; + + memcpy(dst->data + dst->offset + offset, src, len); + + return 0; +} + +const struct bpf_func_proto bpf_dynptr_write_proto = { + .func = bpf_dynptr_write, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_DYNPTR, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_PTR_TO_MEM | MEM_RDONLY, + .arg4_type = ARG_CONST_SIZE_OR_ZERO, +}; + const struct bpf_func_proto bpf_get_current_task_proto __weak; const struct bpf_func_proto bpf_get_current_task_btf_proto __weak; const struct bpf_func_proto bpf_probe_read_user_proto __weak; @@ -1529,6 +1581,10 @@ bpf_base_func_proto(enum bpf_func_id func_id) return &bpf_dynptr_alloc_proto; case BPF_FUNC_dynptr_put: return &bpf_dynptr_put_proto; + case BPF_FUNC_dynptr_read: + return &bpf_dynptr_read_proto; + case BPF_FUNC_dynptr_write: + return &bpf_dynptr_write_proto; default: break; } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 679f960d2514..2d539930b7b2 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5209,6 +5209,23 @@ union bpf_attr { * 'bpf_ringbuf_discard'. * Return * Nothing. Always succeeds. + * + * long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset) + * Description + * Read *len* bytes from *src* into *dst*, starting from *offset* + * into *src*. + * Return + * 0 on success, -EINVAL if *offset* + *len* exceeds the length + * of *src*'s data or if *src* is an invalid dynptr. + * + * long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len) + * Description + * Write *len* bytes from *src* into *dst*, starting from *offset* + * into *dst*. + * Return + * 0 on success, -EINVAL if *offset* + *len* exceeds the length + * of *dst*'s data or if *dst* is an invalid dynptr or if *dst* + * is a read-only dynptr. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5411,6 +5428,8 @@ union bpf_attr { FN(ringbuf_reserve_dynptr), \ FN(ringbuf_submit_dynptr), \ FN(ringbuf_discard_dynptr), \ + FN(dynptr_read), \ + FN(dynptr_write), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper
This patch adds two helper functions, bpf_dynptr_read and bpf_dynptr_write: long bpf_dynptr_read(void *dst, u32 len, struct bpf_dynptr *src, u32 offset); long bpf_dynptr_write(struct bpf_dynptr *dst, u32 offset, void *src, u32 len); The dynptr passed into these functions must be valid dynptrs that have been initialized. Signed-off-by: Joanne Koong <joannelkoong@gmail.com> --- include/linux/bpf.h | 16 ++++++++++ include/uapi/linux/bpf.h | 19 ++++++++++++ kernel/bpf/helpers.c | 56 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 19 ++++++++++++ 4 files changed, 110 insertions(+)