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authorJoanne Koong <joannelkoong@gmail.com>2022-05-23 14:07:10 -0700
committerAndrii Nakryiko <andrii@kernel.org>2022-05-23 14:31:28 -0700
commit13bbbfbea7598ea9f8d9c3d73bf053bb57f9c4b2 (patch)
tree418774726bb3e4a88cd5ce4b75f5360e73d90b9f /kernel/bpf
parentbc34dee65a65e9c920c420005b8a43f2a721a458 (diff)
bpf: Add bpf_dynptr_read and bpf_dynptr_write
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> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220523210712.3641569-5-joannelkoong@gmail.com
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/helpers.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index abb08999ff56..8cef3fb0d143 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1417,12 +1417,24 @@ const struct bpf_func_proto bpf_kptr_xchg_proto = {
*/
#define DYNPTR_MAX_SIZE ((1UL << 24) - 1)
#define DYNPTR_TYPE_SHIFT 28
+#define DYNPTR_SIZE_MASK 0xFFFFFF
+#define DYNPTR_RDONLY_BIT BIT(31)
+
+static bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
+{
+ return ptr->size & DYNPTR_RDONLY_BIT;
+}
static void bpf_dynptr_set_type(struct bpf_dynptr_kern *ptr, enum bpf_dynptr_type type)
{
ptr->size |= type << DYNPTR_TYPE_SHIFT;
}
+static u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr)
+{
+ return ptr->size & DYNPTR_SIZE_MASK;
+}
+
int bpf_dynptr_check_size(u32 size)
{
return size > DYNPTR_MAX_SIZE ? -E2BIG : 0;
@@ -1442,6 +1454,16 @@ void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr)
memset(ptr, 0, sizeof(*ptr));
}
+static int bpf_dynptr_check_off_len(struct bpf_dynptr_kern *ptr, u32 offset, u32 len)
+{
+ u32 size = bpf_dynptr_get_size(ptr);
+
+ if (len > size || offset > size - len)
+ return -E2BIG;
+
+ return 0;
+}
+
BPF_CALL_4(bpf_dynptr_from_mem, void *, data, u32, size, u64, flags, struct bpf_dynptr_kern *, ptr)
{
int err;
@@ -1475,6 +1497,58 @@ const struct bpf_func_proto bpf_dynptr_from_mem_proto = {
.arg4_type = ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL | MEM_UNINIT,
};
+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;
@@ -1537,6 +1611,10 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_strncmp_proto;
case BPF_FUNC_dynptr_from_mem:
return &bpf_dynptr_from_mem_proto;
+ case BPF_FUNC_dynptr_read:
+ return &bpf_dynptr_read_proto;
+ case BPF_FUNC_dynptr_write:
+ return &bpf_dynptr_write_proto;
default:
break;
}