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authorDavid Howells <dhowells@redhat.com>2019-08-20 02:17:59 +0200
committerJames Morris <jmorris@namei.org>2019-08-20 06:54:16 +0200
commit9d1f8be5cf42b497a3bddf1d523f2bb142e9318c (patch)
treefc926ba08f6b2b69c2b9341de2a16d2870b25bda /kernel
parentlockdown: Lock down tracing and perf kprobes when in confidentiality mode (diff)
downloadlinux-9d1f8be5cf42b497a3bddf1d523f2bb142e9318c.tar.xz
linux-9d1f8be5cf42b497a3bddf1d523f2bb142e9318c.zip
bpf: Restrict bpf when kernel lockdown is in confidentiality mode
bpf_read() and bpf_read_str() could potentially be abused to (eg) allow private keys in kernel memory to be leaked. Disable them if the kernel has been locked down in confidentiality mode. Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: netdev@vger.kernel.org cc: Chun-Yi Lee <jlee@suse.com> cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/bpf_trace.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 1c9a4745e596..33a954c367f3 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -139,8 +139,13 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
{
int ret;
+ ret = security_locked_down(LOCKDOWN_BPF_READ);
+ if (ret < 0)
+ goto out;
+
ret = probe_kernel_read(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
+out:
memset(dst, 0, size);
return ret;
@@ -566,6 +571,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
{
int ret;
+ ret = security_locked_down(LOCKDOWN_BPF_READ);
+ if (ret < 0)
+ goto out;
+
/*
* The strncpy_from_unsafe() call will likely not fill the entire
* buffer, but that's okay in this circumstance as we're probing
@@ -577,6 +586,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
*/
ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
+out:
memset(dst, 0, size);
return ret;