6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Borkmann daniel@iogearbox.net
[ 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 --- 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 b051122f62a4f..70fa4ffc3879f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -694,6 +694,11 @@ 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, }; @@ -731,8 +736,6 @@ 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 17a757c78b488..b305b116ce125 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, @@ -566,7 +567,8 @@ 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 bf6c5f685ea22..efb7ff89fe2e2 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5952,7 +5952,8 @@ 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 62cd315984042..e3abf560e405f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8180,16 +8180,6 @@ 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) @@ -8262,16 +8252,6 @@ 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, @@ -8327,8 +8307,6 @@ 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, @@ -8889,9 +8867,11 @@ 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: @@ -8916,17 +8896,6 @@ 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: { err = check_reg_const_str(env, reg, regno); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index cd098846e251c..0b6df2c6ebe08 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1226,7 +1226,8 @@ 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) @@ -1242,7 +1243,8 @@ 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 78a6f746ea0ba..88588dae20267 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6346,7 +6346,8 @@ 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, }; @@ -6357,7 +6358,8 @@ 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, };