From: Levi Zim rsworktech@outlook.com
This patch add a helper function bpf_copy_from_user_dynptr:
bpf_copy_from_user_dynptr(const struct bpf_dynptr *dst, u32 offset, u32 size, const void *user_ptr, u64 flags)
It is useful for reading variable-length data from kernel memory into dynptr.
Signed-off-by: Levi Zim rsworktech@outlook.com --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 17 +++++++++++++++++ kernel/bpf/helpers.c | 42 ++++++++++++++++++++++++++++++++++++++++++ kernel/trace/bpf_trace.c | 2 ++ 4 files changed, 62 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 9d5ae8b4b7d82c4523bf0ab041d4b76bf134a106..d0412eaf63d69c0e437575c77008548edc692335 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3357,6 +3357,7 @@ extern const struct bpf_func_proto bpf_get_retval_proto; extern const struct bpf_func_proto bpf_user_ringbuf_drain_proto; extern const struct bpf_func_proto bpf_cgrp_storage_get_proto; extern const struct bpf_func_proto bpf_cgrp_storage_delete_proto; +extern const struct bpf_func_proto bpf_copy_from_user_dynptr_proto;
const struct bpf_func_proto *tracing_prog_func_proto( enum bpf_func_id func_id, const struct bpf_prog *prog); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index d7d7a9ddd5dca07ba89d81ba77101a704af3163b..f92cf809b50bc393d54eb0e8de2e1ce2a39e95d0 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5835,6 +5835,22 @@ union bpf_attr { * support this helper, or if *flags* is not 0. * * Or other negative errors on failure reading user space memory. + * + * long bpf_copy_from_user_dynptr(const struct bpf_dynptr *dst, u32 offset, u32 size, const void *user_ptr, u64 flags) + * Description + * Read *size* bytes from user space address *user_ptr* and store + * the data in *dst* starting from *offset*. + * This is a wrapper of **copy_from_user**\ (). + * *flags* is currently unused. + * Return + * 0 on success. + * + * **-E2BIG** if *offset* + *len* exceeds the length of *src*'s data + * + * **-EINVAL** if *src* is an invalid dynptr or doesn't support this + * support this helper, or if *flags* is not 0. + * + * Or other negative errors on failure reading user space memory. */ #define ___BPF_FUNC_MAPPER(FN, ctx...) \ FN(unspec, 0, ##ctx) \ @@ -6051,6 +6067,7 @@ union bpf_attr { FN(cgrp_storage_delete, 211, ##ctx) \ FN(probe_read_kernel_dynptr, 212, ##ctx) \ FN(probe_read_user_dynptr, 213, ##ctx) \ + FN(copy_from_user_dynptr, 214, ##ctx) \ /* */
/* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index ac563d09082e7c721999d7de035aabc000206a29..d756c80596315bd07fe6e71885b61efc8cb2ef4f 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -676,6 +676,48 @@ const struct bpf_func_proto bpf_copy_from_user_proto = { .arg3_type = ARG_ANYTHING, };
+BPF_CALL_5(bpf_copy_from_user_dynptr, const struct bpf_dynptr_kern *, dst, + u32, offset, u32, size, const void __user *, user_ptr, u32, flags) +{ + enum bpf_dynptr_type type; + int err; + + if (!dst->data || __bpf_dynptr_is_rdonly(dst)) + return -EINVAL; + + err = bpf_dynptr_check_off_len(dst, offset, size); + if (err) + return err; + + type = bpf_dynptr_get_type(dst); + + switch (type) { + case BPF_DYNPTR_TYPE_LOCAL: + case BPF_DYNPTR_TYPE_RINGBUF: + if (flags) + return -EINVAL; + return ____bpf_copy_from_user(dst->data + dst->offset + offset, size, user_ptr); + case BPF_DYNPTR_TYPE_SKB: + case BPF_DYNPTR_TYPE_XDP: + return -EINVAL; + default: + WARN_ONCE(true, "%s: unknown dynptr type %d\n", __func__, type); + return -EFAULT; + } +} + +const struct bpf_func_proto bpf_copy_from_user_dynptr_proto = { + .func = bpf_copy_from_user_dynptr, + .gpl_only = false, + .might_sleep = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_ANYTHING, + .arg4_type = ARG_ANYTHING, + .arg5_type = ARG_ANYTHING, +}; + BPF_CALL_5(bpf_copy_from_user_task, void *, dst, u32, size, const void __user *, user_ptr, struct task_struct *, tsk, u64, flags) { diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d9f704c1342773c74b2414be4adfc8271d6d364d..424931925fe3b02db083bc19cc64e19918b40c5a 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1598,6 +1598,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_copy_from_user_proto; case BPF_FUNC_copy_from_user_task: return &bpf_copy_from_user_task_proto; + case BPF_FUNC_copy_from_user_dynptr: + return &bpf_copy_from_user_dynptr_proto; case BPF_FUNC_snprintf_btf: return &bpf_snprintf_btf_proto; case BPF_FUNC_per_cpu_ptr: