This is a note to let you know that I've just added the patch titled
bpf: Restrict bpf_sys_bpf to CAP_PERFMON
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-restrict-bpf_sys_bpf-to-cap_perfmon.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ced0af0a708c1851905310ca658e59fd7d7f6bec
Author: YiFei Zhu <zhuyifei@xxxxxxxxxx>
Date: Tue Aug 16 20:55:16 2022 +0000
bpf: Restrict bpf_sys_bpf to CAP_PERFMON
[ Upstream commit 14b20b784f59bdd95f6f1cfb112c9818bcec4d84 ]
The verifier cannot perform sufficient validation of any pointers passed
into bpf_attr and treats them as integers rather than pointers. The helper
will then read from arbitrary pointers passed into it. Restrict the helper
to CAP_PERFMON since the security model in BPF of arbitrary kernel read is
CAP_BPF + CAP_PERFMON.
Fixes: af2ac3e13e45 ("bpf: Prepare bpf syscall to be used from kernel and user space.")
Signed-off-by: YiFei Zhu <zhuyifei@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220816205517.682470-1-zhuyifei@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 48e02a725563f..99ce46f518893 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -4785,7 +4785,7 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_sys_bpf:
- return &bpf_sys_bpf_proto;
+ return !perfmon_capable() ? NULL : &bpf_sys_bpf_proto;
case BPF_FUNC_btf_find_by_name_kind:
return &bpf_btf_find_by_name_kind_proto;
case BPF_FUNC_sys_close:
