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 v2 2/6] bpf: Prevent BPF programs from access the buffer pointed by user_optval.
Date: Thu, 10 Aug 2023 21:31:23 -0700 [thread overview]
Message-ID: <20230811043127.1318152-3-thinker.li@gmail.com> (raw)
In-Reply-To: <20230811043127.1318152-1-thinker.li@gmail.com>
From: Kui-Feng Lee <kuifeng@meta.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 <kuifeng@meta.com>
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 59489d9619a3..5bf3115b265c 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -2509,12 +2509,24 @@ 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 fbc0096693e7..ca27be76207a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13364,7 +13364,7 @@ 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);
}));
@@ -13917,84 +13917,84 @@ 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:[~2023-08-11 4:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-11 4:31 [RFC bpf-next v2 0/6] Sleepable BPF programs on cgroup {get,set}sockopt thinker.li
2023-08-11 4:31 ` [RFC bpf-next v2 1/6] bpf: enable sleepable BPF programs attached to cgroup/{get,set}sockopt thinker.li
2023-08-11 23:01 ` Stanislav Fomichev
2023-08-11 23:17 ` Kui-Feng Lee
2023-08-11 23:22 ` Kui-Feng Lee
2023-08-11 4:31 ` thinker.li [this message]
2023-08-11 6:27 ` [RFC bpf-next v2 2/6] bpf: Prevent BPF programs from access the buffer pointed by user_optval Yonghong Song
2023-08-11 16:01 ` Kui-Feng Lee
2023-08-11 4:31 ` [RFC bpf-next v2 3/6] bpf: rename bpf_copy_to_user() thinker.li
2023-08-11 4:31 ` [RFC bpf-next v2 4/6] bpf: Provide bpf_copy_from_user() and bpf_copy_to_user() thinker.li
2023-08-11 23:05 ` Stanislav Fomichev
2023-08-11 23:27 ` Kui-Feng Lee
2023-08-11 23:31 ` Kui-Feng Lee
2023-08-14 17:07 ` Stanislav Fomichev
2023-08-14 19:20 ` Kui-Feng Lee
2023-08-14 20:16 ` Stanislav Fomichev
2023-08-11 4:31 ` [RFC bpf-next v2 5/6] bpf: Add a new dynptr type for CGRUP_SOCKOPT thinker.li
2023-08-14 5:03 ` kernel test robot
2023-08-11 4:31 ` [RFC bpf-next v2 6/6] bpf: Add test cases for sleepable BPF programs of the CGROUP_SOCKOPT type thinker.li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230811043127.1318152-3-thinker.li@gmail.com \
--to=thinker.li@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=kernel-team@meta.com \
--cc=kuifeng@meta.com \
--cc=martin.lau@linux.dev \
--cc=sdf@google.com \
--cc=sinquersw@gmail.com \
--cc=song@kernel.org \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.