Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2023-03-23

We've added 8 non-merge commits during the last 13 day(s) which contain
a total of 21 files changed, 238 insertions(+), 161 deletions(-).

The main changes are:

1) Fix verification issues in some BPF programs due to their stack usage
   patterns, from Eduard Zingerman.

2) Fix to add missing overflow checks in xdp_umem_reg and return an error
   in such case, from Kal Conley.

3) Fix and undo poisoning of strlcpy in libbpf given it broke builds for
   libcs which provided the former like uClibc-ng, from Jesus Sanchez-Palencia.

4) Fix insufficient bpf_jit_limit default to avoid users running into hard
   to debug seccomp BPF errors, from Daniel Borkmann.

5) Fix driver return code when they don't support a bpf_xdp_metadata kfunc
   to make it unambiguous from other errors, from Jesper Dangaard Brouer.

6) Two BPF selftest fixes to address compilation errors from recent changes
   in kernel structures, from Alexei Starovoitov.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  xdp: bpf_xdp_metadata use EOPNOTSUPP for no driver support
  bpf: Adjust insufficient default bpf_jit_limit
  xsk: Add missing overflow check in xdp_umem_reg
  selftests/bpf: Fix progs/test_deny_namespace.c issues.
  selftests/bpf: Fix progs/find_vma_fail1.c build error.
  libbpf: Revert poisoning of strlcpy
  selftests/bpf: Tests for uninitialized stack reads
  bpf: Allow reads from uninit stack
====================

Link: https://lore.kernel.org/r/20230323225221.6082-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/uninit_stack.c b/tools/testing/selftests/bpf/progs/uninit_stack.c
new file mode 100644
index 000000000000..8a403470e557
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uninit_stack.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+/* Read an uninitialized value from stack at a fixed offset */
+SEC("socket")
+__naked int read_uninit_stack_fixed_off(void *ctx)
+{
+	asm volatile ("					\
+		r0 = 0;					\
+		/* force stack depth to be 128 */	\
+		*(u64*)(r10 - 128) = r1;		\
+		r1 = *(u8 *)(r10 - 8 );			\
+		r0 += r1;				\
+		r1 = *(u8 *)(r10 - 11);			\
+		r1 = *(u8 *)(r10 - 13);			\
+		r1 = *(u8 *)(r10 - 15);			\
+		r1 = *(u16*)(r10 - 16);			\
+		r1 = *(u32*)(r10 - 32);			\
+		r1 = *(u64*)(r10 - 64);			\
+		/* read from a spill of a wrong size, it is a separate	\
+		 * branch in check_stack_read_fixed_off()		\
+		 */					\
+		*(u32*)(r10 - 72) = r1;			\
+		r1 = *(u64*)(r10 - 72);			\
+		r0 = 0;					\
+		exit;					\
+"
+		      ::: __clobber_all);
+}
+
+/* Read an uninitialized value from stack at a variable offset */
+SEC("socket")
+__naked int read_uninit_stack_var_off(void *ctx)
+{
+	asm volatile ("					\
+		call %[bpf_get_prandom_u32];		\
+		/* force stack depth to be 64 */	\
+		*(u64*)(r10 - 64) = r0;			\
+		r0 = -r0;				\
+		/* give r0 a range [-31, -1] */		\
+		if r0 s<= -32 goto exit_%=;		\
+		if r0 s>= 0 goto exit_%=;		\
+		/* access stack using r0 */		\
+		r1 = r10;				\
+		r1 += r0;				\
+		r2 = *(u8*)(r1 + 0);			\
+exit_%=:	r0 = 0;					\
+		exit;					\
+"
+		      :
+		      : __imm(bpf_get_prandom_u32)
+		      : __clobber_all);
+}
+
+static __noinline void dummy(void) {}
+
+/* Pass a pointer to uninitialized stack memory to a helper.
+ * Passed memory block should be marked as STACK_MISC after helper call.
+ */
+SEC("socket")
+__log_level(7) __msg("fp-104=mmmmmmmm")
+__naked int helper_uninit_to_misc(void *ctx)
+{
+	asm volatile ("					\
+		/* force stack depth to be 128 */	\
+		*(u64*)(r10 - 128) = r1;		\
+		r1 = r10;				\
+		r1 += -128;				\
+		r2 = 32;				\
+		call %[bpf_trace_printk];		\
+		/* Call to dummy() forces print_verifier_state(..., true),	\
+		 * thus showing the stack state, matched by __msg().		\
+		 */					\
+		call %[dummy];				\
+		r0 = 0;					\
+		exit;					\
+"
+		      :
+		      : __imm(bpf_trace_printk),
+			__imm(dummy)
+		      : __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";