Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2021-05-11

The following pull-request contains BPF updates for your *net* tree.

We've added 13 non-merge commits during the last 8 day(s) which contain
a total of 21 files changed, 817 insertions(+), 382 deletions(-).

The main changes are:

1) Fix multiple ringbuf bugs in particular to prevent writable mmap of
   read-only pages, from Andrii Nakryiko & Thadeu Lima de Souza Cascardo.

2) Fix verifier alu32 known-const subregister bound tracking for bitwise
   operations and/or/xor, from Daniel Borkmann.

3) Reject trampoline attachment for functions with variable arguments,
   and also add a deny list of other forbidden functions, from Jiri Olsa.

4) Fix nested bpf_bprintf_prepare() calls used by various helpers by
   switching to per-CPU buffers, from Florent Revest.

5) Fix kernel compilation with BTF debug info on ppc64 due to pahole
   missing TCP-CC functions like cubictcp_init, from Martin KaFai Lau.

6) Add a kconfig entry to provide an option to disallow unprivileged
   BPF by default, from Daniel Borkmann.

7) Fix libbpf compilation for older libelf when GELF_ST_VISIBILITY()
   macro is not available, from Arnaldo Carvalho de Melo.

8) Migrate test_tc_redirect to test_progs framework as prep work
   for upcoming skb_change_head() fix & selftest, from Jussi Maki.

9) Fix a libbpf segfault in add_dummy_ksym_var() if BTF is not
   present, from Ian Rogers.

10) Fix tx_only micro-benchmark in xdpsock BPF sample with proper frame
    size, from Magnus Karlsson.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 5 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 14edf84cc571..d4a78e08f6d8 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -225,7 +225,27 @@ static int bpf_stats_handler(struct ctl_table *table, int write,
 	mutex_unlock(&bpf_stats_enabled_mutex);
 	return ret;
 }
-#endif
+
+static int bpf_unpriv_handler(struct ctl_table *table, int write,
+			      void *buffer, size_t *lenp, loff_t *ppos)
+{
+	int ret, unpriv_enable = *(int *)table->data;
+	bool locked_state = unpriv_enable == 1;
+	struct ctl_table tmp = *table;
+
+	if (write && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	tmp.data = &unpriv_enable;
+	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
+	if (write && !ret) {
+		if (locked_state && unpriv_enable != 1)
+			return -EPERM;
+		*(int *)table->data = unpriv_enable;
+	}
+	return ret;
+}
+#endif /* CONFIG_BPF_SYSCALL && CONFIG_SYSCTL */
 
 /*
  * /proc/sys support
@@ -2600,10 +2620,9 @@ static struct ctl_table kern_table[] = {
 		.data		= &sysctl_unprivileged_bpf_disabled,
 		.maxlen		= sizeof(sysctl_unprivileged_bpf_disabled),
 		.mode		= 0644,
-		/* only handle a transition from default "0" to "1" */
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ONE,
-		.extra2		= SYSCTL_ONE,
+		.proc_handler	= bpf_unpriv_handler,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= &two,
 	},
 	{
 		.procname	= "bpf_stats_enabled",