From: Daniel Borkmann <daniel@iogearbox.net>
To: ast@kernel.org
Cc: netdev@vger.kernel.org, Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH bpf-next 6/9] bpf: restrict access to core bpf sysctls
Date: Sat, 20 Jan 2018 01:24:34 +0100 [thread overview]
Message-ID: <20180120002437.3528-7-daniel@iogearbox.net> (raw)
In-Reply-To: <20180120002437.3528-1-daniel@iogearbox.net>
Given BPF reaches far beyond just networking these days, it was
never intended to allow setting and in some cases reading those
knobs out of a user namespace root running without CAP_SYS_ADMIN,
thus tighten such access.
Also the bpf_jit_enable = 2 debugging mode should only be allowed
if kptr_restrict is not set since it otherwise can leak addresses
to the kernel log. Dump a note to the kernel log that this is for
debugging JITs only when enabled.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
---
net/core/sysctl_net_core.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 43 insertions(+), 3 deletions(-)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 6d39b4c..f2d0462 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -251,6 +251,46 @@ static int proc_do_rss_key(struct ctl_table *table, int write,
return proc_dostring(&fake_table, write, buffer, lenp, ppos);
}
+#ifdef CONFIG_BPF_JIT
+static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret, jit_enable = *(int *)table->data;
+ struct ctl_table tmp = *table;
+
+ if (write && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ tmp.data = &jit_enable;
+ ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
+ if (write && !ret) {
+ if (jit_enable < 2 ||
+ (jit_enable == 2 && bpf_dump_raw_ok())) {
+ *(int *)table->data = jit_enable;
+ if (jit_enable == 2)
+ pr_warn("bpf_jit_enable = 2 was set! NEVER use this in production, only for JIT debugging!\n");
+ } else {
+ ret = -EPERM;
+ }
+ }
+ return ret;
+}
+
+# ifdef CONFIG_HAVE_EBPF_JIT
+static int
+proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+}
+# endif
+#endif
+
static struct ctl_table net_core_table[] = {
#ifdef CONFIG_NET
{
@@ -326,7 +366,7 @@ static struct ctl_table net_core_table[] = {
.data = &bpf_jit_enable,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax_bpf_enable,
# ifdef CONFIG_BPF_JIT_ALWAYS_ON
.extra1 = &one,
.extra2 = &one,
@@ -341,7 +381,7 @@ static struct ctl_table net_core_table[] = {
.data = &bpf_jit_harden,
.maxlen = sizeof(int),
.mode = 0600,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax_bpf_restricted,
.extra1 = &zero,
.extra2 = &two,
},
@@ -350,7 +390,7 @@ static struct ctl_table net_core_table[] = {
.data = &bpf_jit_kallsyms,
.maxlen = sizeof(int),
.mode = 0600,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_dointvec_minmax_bpf_restricted,
.extra1 = &zero,
.extra2 = &one,
},
--
2.9.5
next prev parent reply other threads:[~2018-01-20 0:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-20 0:24 [PATCH bpf-next 0/9] BPF misc improvements Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 1/9] bpf, verifier: detect misconfigured mem,size argument pair Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 2/9] bpf: add csum_diff helper to xdp as well Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 3/9] bpf: add couple of test cases for signed extended imms Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 4/9] bpf: add couple of test cases for div/mod by zero Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 5/9] bpf: get rid of pure_initcall dependency to enable jits Daniel Borkmann
2018-01-20 0:24 ` Daniel Borkmann [this message]
2018-01-20 0:24 ` [PATCH bpf-next 7/9] bpf, x86: small optimization in alu ops with imm Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 8/9] bpf: add upper complexity limit to verifier log Daniel Borkmann
2018-01-20 0:24 ` [PATCH bpf-next 9/9] bpf: move event_output to const_size_or_zero for xdp/skb as well Daniel Borkmann
2018-01-20 2:54 ` [PATCH bpf-next 0/9] BPF misc improvements Alexei Starovoitov
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