From: Daniel Borkmann daniel@iogearbox.net

stable inclusion from stable-v6.6.54 commit a2c8dc7e21803257e762b0bf067fd13e9c995da0 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAW1S1 CVE: CVE-2024-49861

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 32556ce93bc45c730829083cb60f95a2728ea48b ]

Lonial found an issue that despite user- and BPF-side frozen BPF map (like in case of .rodata), it was still possible to write into it from a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT} as arguments.

In check_func_arg() when the argument is as mentioned, the meta->raw_mode is never set. Later, check_helper_mem_access(), under the case of PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the subsequent call to check_map_access_type() and given the BPF map is read-only it succeeds.

The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT when results are written into them as opposed to read out of them. The latter indicates that it's okay to pass a pointer to uninitialized memory as the memory is written to anyway.

However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM just with additional alignment requirement. So it is better to just get rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the fixed size memory types. For this, add MEM_ALIGNED to additionally ensure alignment given these helpers write directly into the args via *<ptr> = val. The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).

MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated argument types, since in !MEM_FIXED_SIZE cases the verifier does not know the buffer size a priori and therefore cannot blindly write *<ptr> = val.

Fixes: 57c3bb725a3d ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types") Reported-by: Lonial Con kongln9170@gmail.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Andrii Nakryiko andrii@kernel.org Acked-by: Shung-Hsi Yu shung-hsi.yu@suse.com Link: https://lore.kernel.org/r/20240913191754.13290-3-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Xiaomeng Zhang zhangxiaomeng13@huawei.com --- include/linux/bpf.h | 7 +++++-- kernel/bpf/helpers.c | 6 ++++-- kernel/bpf/syscall.c | 3 ++- kernel/bpf/verifier.c | 41 +++++----------------------------------- kernel/trace/bpf_trace.c | 6 ++++-- net/core/filter.c | 6 ++++-- 6 files changed, 24 insertions(+), 45 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h index d8a53afe7127..69b3e3c9b7c6 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -685,6 +685,11 @@ enum bpf_type_flag { /* DYNPTR points to xdp_buff */ DYNPTR_TYPE_XDP = BIT(16 + BPF_BASE_TYPE_BITS),

+ /* Memory must be aligned on some architectures, used in combination with + * MEM_FIXED_SIZE. + */ + MEM_ALIGNED = BIT(17 + BPF_BASE_TYPE_BITS), + __BPF_TYPE_FLAG_MAX, __BPF_TYPE_LAST_FLAG = __BPF_TYPE_FLAG_MAX - 1, }; @@ -721,8 +726,6 @@ enum bpf_arg_type { ARG_ANYTHING, /* any (initialized) argument is ok */ ARG_PTR_TO_SPIN_LOCK, /* pointer to bpf_spin_lock */ ARG_PTR_TO_SOCK_COMMON, /* pointer to sock_common */ - ARG_PTR_TO_INT, /* pointer to int */ - ARG_PTR_TO_LONG, /* pointer to long */ ARG_PTR_TO_SOCKET, /* pointer to bpf_sock (fullsock) */ ARG_PTR_TO_BTF_ID, /* pointer to in-kernel struct */ ARG_PTR_TO_RINGBUF_MEM, /* pointer to dynamically reserved ringbuf memory */ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index cadf65818c8c..68cb3f6c7842 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -538,7 +538,8 @@ const struct bpf_func_proto bpf_strtol_proto = { .arg1_type = ARG_PTR_TO_MEM | MEM_RDONLY, .arg2_type = ARG_CONST_SIZE, .arg3_type = ARG_ANYTHING, - .arg4_type = ARG_PTR_TO_LONG, + .arg4_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg4_size = sizeof(s64), };

BPF_CALL_4(bpf_strtoul, const char *, buf, size_t, buf_len, u64, flags, @@ -567,7 +568,8 @@ const struct bpf_func_proto bpf_strtoul_proto = { .arg1_type = ARG_PTR_TO_MEM | MEM_RDONLY, .arg2_type = ARG_CONST_SIZE, .arg3_type = ARG_ANYTHING, - .arg4_type = ARG_PTR_TO_LONG, + .arg4_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg4_size = sizeof(u64), };

BPF_CALL_3(bpf_strncmp, const char *, s1, u32, s1_sz, const char *, s2) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 650297142186..00a5ffa85d6c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5713,7 +5713,8 @@ static const struct bpf_func_proto bpf_kallsyms_lookup_name_proto = { .arg1_type = ARG_PTR_TO_MEM, .arg2_type = ARG_CONST_SIZE_OR_ZERO, .arg3_type = ARG_ANYTHING, - .arg4_type = ARG_PTR_TO_LONG, + .arg4_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg4_size = sizeof(u64), };

static const struct bpf_func_proto * diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 28f91feb7851..d327fb41355b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8086,16 +8086,6 @@ static bool arg_type_is_dynptr(enum bpf_arg_type type) return base_type(type) == ARG_PTR_TO_DYNPTR; }

-static int int_ptr_type_to_size(enum bpf_arg_type type) -{ - if (type == ARG_PTR_TO_INT) - return sizeof(u32); - else if (type == ARG_PTR_TO_LONG) - return sizeof(u64); - - return -EINVAL; -} - static int resolve_map_arg_type(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_arg_type *arg_type) @@ -8168,16 +8158,6 @@ static const struct bpf_reg_types mem_types = { }, };

-static const struct bpf_reg_types int_ptr_types = { - .types = { - PTR_TO_STACK, - PTR_TO_PACKET, - PTR_TO_PACKET_META, - PTR_TO_MAP_KEY, - PTR_TO_MAP_VALUE, - }, -}; - static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE, @@ -8232,8 +8212,6 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types, [ARG_PTR_TO_MEM] = &mem_types, [ARG_PTR_TO_RINGBUF_MEM] = &ringbuf_mem_types, - [ARG_PTR_TO_INT] = &int_ptr_types, - [ARG_PTR_TO_LONG] = &int_ptr_types, [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, [ARG_PTR_TO_FUNC] = &func_ptr_types, [ARG_PTR_TO_STACK] = &stack_ptr_types, @@ -8740,9 +8718,11 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, */ meta->raw_mode = arg_type & MEM_UNINIT; if (arg_type & MEM_FIXED_SIZE) { - err = check_helper_mem_access(env, regno, - fn->arg_size[arg], false, - meta); + err = check_helper_mem_access(env, regno, fn->arg_size[arg], false, meta); + if (err) + return err; + if (arg_type & MEM_ALIGNED) + err = check_ptr_alignment(env, reg, 0, fn->arg_size[arg], true); } break; case ARG_CONST_SIZE: @@ -8767,17 +8747,6 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, if (err) return err; break; - case ARG_PTR_TO_INT: - case ARG_PTR_TO_LONG: - { - int size = int_ptr_type_to_size(arg_type); - - err = check_helper_mem_access(env, regno, size, false, meta); - if (err) - return err; - err = check_ptr_alignment(env, reg, 0, size, true); - break; - } case ARG_PTR_TO_CONST_STR: { struct bpf_map *map = reg->map_ptr; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 91255fe5512b..fe40b41e1c97 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1220,7 +1220,8 @@ static const struct bpf_func_proto bpf_get_func_arg_proto = { .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_ANYTHING, - .arg3_type = ARG_PTR_TO_LONG, + .arg3_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg3_size = sizeof(u64), };

BPF_CALL_2(get_func_ret, void *, ctx, u64 *, value) @@ -1236,7 +1237,8 @@ static const struct bpf_func_proto bpf_get_func_ret_proto = { .func = get_func_ret, .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, - .arg2_type = ARG_PTR_TO_LONG, + .arg2_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg2_size = sizeof(u64), };

BPF_CALL_1(get_func_arg_cnt, void *, ctx) diff --git a/net/core/filter.c b/net/core/filter.c index e28a76b4c094..5b27f9d4a36d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6376,7 +6376,8 @@ static const struct bpf_func_proto bpf_skb_check_mtu_proto = { .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_ANYTHING, - .arg3_type = ARG_PTR_TO_INT, + .arg3_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg3_size = sizeof(u32), .arg4_type = ARG_ANYTHING, .arg5_type = ARG_ANYTHING, }; @@ -6387,7 +6388,8 @@ static const struct bpf_func_proto bpf_xdp_check_mtu_proto = { .ret_type = RET_INTEGER, .arg1_type = ARG_PTR_TO_CTX, .arg2_type = ARG_ANYTHING, - .arg3_type = ARG_PTR_TO_INT, + .arg3_type = ARG_PTR_TO_FIXED_SIZE_MEM | MEM_UNINIT | MEM_ALIGNED, + .arg3_size = sizeof(u32), .arg4_type = ARG_ANYTHING, .arg5_type = ARG_ANYTHING, };