From: thinker.li@gmail.com
To: bpf@vger.kernel.org, ast@kernel.org, martin.lau@linux.dev,
song@kernel.org, kernel-team@meta.com, andrii@kernel.org,
sdf@google.com, yonghong.song@linux.dev
Cc: sinquersw@gmail.com, kuifeng@meta.com,
Kui-Feng Lee <thinker.li@gmail.com>
Subject: [RFC bpf-next v3 3/5] bpf: Prevent BPF programs from access the buffer pointed by user_optval.
Date: Tue, 15 Aug 2023 10:47:10 -0700 [thread overview]
Message-ID: <20230815174712.660956-4-thinker.li@gmail.com> (raw)
In-Reply-To: <20230815174712.660956-1-thinker.li@gmail.com>
From: Kui-Feng Lee <thinker.li@gmail.com>
Since the buffer pointed by ctx->user_optval is in user space, BPF programs
in kernel space should not access it directly. They should use
bpf_copy_from_user() and bpf_copy_to_user() to move data between user and
kernel space.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
---
kernel/bpf/cgroup.c | 16 +++++++++--
kernel/bpf/verifier.c | 66 +++++++++++++++++++++----------------------
2 files changed, 47 insertions(+), 35 deletions(-)
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index b977768a28e5..425094e071ba 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -2494,12 +2494,24 @@ static bool cg_sockopt_is_valid_access(int off, int size,
case offsetof(struct bpf_sockopt, optval):
if (size != sizeof(__u64))
return false;
- info->reg_type = PTR_TO_PACKET;
+ if (prog->aux->sleepable)
+ /* Prohibit access to the memory pointed by optval
+ * in sleepable programs.
+ */
+ info->reg_type = PTR_TO_PACKET | MEM_USER;
+ else
+ info->reg_type = PTR_TO_PACKET;
break;
case offsetof(struct bpf_sockopt, optval_end):
if (size != sizeof(__u64))
return false;
- info->reg_type = PTR_TO_PACKET_END;
+ if (prog->aux->sleepable)
+ /* Prohibit access to the memory pointed by
+ * optval_end in sleepable programs.
+ */
+ info->reg_type = PTR_TO_PACKET_END | MEM_USER;
+ else
+ info->reg_type = PTR_TO_PACKET_END;
break;
case offsetof(struct bpf_sockopt, retval):
if (size != size_default)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 61be432b9420..936a171ea976 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13373,7 +13373,7 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
* dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
*/
bpf_for_each_reg_in_vstate(vstate, state, reg, ({
- if (reg->type == type && reg->id == dst_reg->id)
+ if (base_type(reg->type) == type && reg->id == dst_reg->id)
/* keep the maximum range already checked */
reg->range = max(reg->range, new_range);
}));
@@ -13926,84 +13926,84 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
switch (BPF_OP(insn->code)) {
case BPF_JGT:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
+ if ((base_type(dst_reg->type) == PTR_TO_PACKET &&
+ base_type(src_reg->type) == PTR_TO_PACKET_END) ||
+ (base_type(dst_reg->type) == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' > pkt_end, pkt_meta' > pkt_data */
find_good_pkt_pointers(this_branch, dst_reg,
- dst_reg->type, false);
+ base_type(dst_reg->type), false);
mark_pkt_end(other_branch, insn->dst_reg, true);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
+ } else if ((base_type(dst_reg->type) == PTR_TO_PACKET_END &&
+ base_type(src_reg->type) == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
+ base_type(src_reg->type) == PTR_TO_PACKET_META)) {
/* pkt_end > pkt_data', pkt_data > pkt_meta' */
find_good_pkt_pointers(other_branch, src_reg,
- src_reg->type, true);
+ base_type(src_reg->type), true);
mark_pkt_end(this_branch, insn->src_reg, false);
} else {
return false;
}
break;
case BPF_JLT:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
+ if ((base_type(dst_reg->type) == PTR_TO_PACKET &&
+ base_type(src_reg->type) == PTR_TO_PACKET_END) ||
+ (base_type(dst_reg->type) == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' < pkt_end, pkt_meta' < pkt_data */
find_good_pkt_pointers(other_branch, dst_reg,
- dst_reg->type, true);
+ base_type(dst_reg->type), true);
mark_pkt_end(this_branch, insn->dst_reg, false);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
+ } else if ((base_type(dst_reg->type) == PTR_TO_PACKET_END &&
+ base_type(src_reg->type) == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
+ base_type(src_reg->type) == PTR_TO_PACKET_META)) {
/* pkt_end < pkt_data', pkt_data > pkt_meta' */
find_good_pkt_pointers(this_branch, src_reg,
- src_reg->type, false);
+ base_type(src_reg->type), false);
mark_pkt_end(other_branch, insn->src_reg, true);
} else {
return false;
}
break;
case BPF_JGE:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
+ if ((base_type(dst_reg->type) == PTR_TO_PACKET &&
+ base_type(src_reg->type) == PTR_TO_PACKET_END) ||
+ (base_type(dst_reg->type) == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
find_good_pkt_pointers(this_branch, dst_reg,
- dst_reg->type, true);
+ base_type(dst_reg->type), true);
mark_pkt_end(other_branch, insn->dst_reg, false);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
+ } else if ((base_type(dst_reg->type) == PTR_TO_PACKET_END &&
+ base_type(src_reg->type) == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
+ base_type(src_reg->type) == PTR_TO_PACKET_META)) {
/* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
find_good_pkt_pointers(other_branch, src_reg,
- src_reg->type, false);
+ base_type(src_reg->type), false);
mark_pkt_end(this_branch, insn->src_reg, true);
} else {
return false;
}
break;
case BPF_JLE:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
+ if ((base_type(dst_reg->type) == PTR_TO_PACKET &&
+ base_type(src_reg->type) == PTR_TO_PACKET_END) ||
+ (base_type(dst_reg->type) == PTR_TO_PACKET_META &&
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
/* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
find_good_pkt_pointers(other_branch, dst_reg,
- dst_reg->type, false);
+ base_type(dst_reg->type), false);
mark_pkt_end(this_branch, insn->dst_reg, true);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
+ } else if ((base_type(dst_reg->type) == PTR_TO_PACKET_END &&
+ base_type(src_reg->type) == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
+ base_type(src_reg->type) == PTR_TO_PACKET_META)) {
/* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
find_good_pkt_pointers(this_branch, src_reg,
- src_reg->type, true);
+ base_type(src_reg->type), true);
mark_pkt_end(other_branch, insn->src_reg, false);
} else {
return false;
--
2.34.1
next prev parent reply other threads:[~2023-08-15 17:47 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-15 17:47 [RFC bpf-next v3 0/5] Sleepable BPF programs on cgroup {get,set}sockopt thinker.li
2023-08-15 17:47 ` [RFC bpf-next v3 1/5] bpf: enable sleepable BPF programs attached to cgroup/{get,set}sockopt thinker.li
2023-08-15 20:58 ` Stanislav Fomichev
2023-08-15 21:04 ` Kui-Feng Lee
2023-08-16 0:42 ` kernel test robot
2023-08-15 17:47 ` [RFC bpf-next v3 2/5] libbpf: add sleepable sections for {get,set}sockopt() thinker.li
2023-08-15 17:47 ` thinker.li [this message]
2023-08-17 0:55 ` [RFC bpf-next v3 3/5] bpf: Prevent BPF programs from access the buffer pointed by user_optval Martin KaFai Lau
2023-08-17 18:10 ` Kui-Feng Lee
2023-08-17 1:17 ` Alexei Starovoitov
2023-08-17 18:12 ` Kui-Feng Lee
2023-08-15 17:47 ` [RFC bpf-next v3 4/5] bpf: Add a new dynptr type for CGRUP_SOCKOPT thinker.li
2023-08-16 14:19 ` kernel test robot
2023-08-17 1:25 ` Alexei Starovoitov
2023-08-17 19:00 ` Kui-Feng Lee
2023-08-17 19:43 ` Alexei Starovoitov
2023-08-18 0:14 ` Kui-Feng Lee
2023-08-17 20:41 ` Martin KaFai Lau
2023-08-17 21:37 ` Yonghong Song
2023-08-17 22:56 ` Martin KaFai Lau
2023-08-17 21:46 ` Alexei Starovoitov
2023-08-17 22:45 ` Martin KaFai Lau
2023-08-15 17:47 ` [RFC bpf-next v3 5/5] selftests/bpf: Add test cases for sleepable BPF programs of the CGROUP_SOCKOPT type thinker.li
2023-08-15 20:57 ` Stanislav Fomichev
2023-08-15 23:37 ` Kui-Feng Lee
2023-08-16 0:03 ` Kui-Feng Lee
2023-08-17 1:13 ` Martin KaFai Lau
2023-08-17 18:36 ` Kui-Feng Lee
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