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

Daniel Borkmann says:

====================
pull-request: bpf 2024-04-26

We've added 12 non-merge commits during the last 22 day(s) which contain
a total of 14 files changed, 168 insertions(+), 72 deletions(-).

The main changes are:

1) Fix BPF_PROBE_MEM in verifier and JIT to skip loads from vsyscall page,
   from Puranjay Mohan.

2) Fix a crash in XDP with devmap broadcast redirect when the latter map
   is in process of being torn down, from Toke Høiland-Jørgensen.

3) Fix arm64 and riscv64 BPF JITs to properly clear start time for BPF
   program runtime stats, from Xu Kuohai.

4) Fix a sockmap KCSAN-reported data race in sk_psock_skb_ingress_enqueue,
    from Jason Xing.

5) Fix BPF verifier error message in resolve_pseudo_ldimm64,
   from Anton Protopopov.

6) Fix missing DEBUG_INFO_BTF_MODULES Kconfig menu item,
   from Andrii Nakryiko.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  selftests/bpf: Test PROBE_MEM of VSYSCALL_ADDR on x86-64
  bpf, x86: Fix PROBE_MEM runtime load check
  bpf: verifier: prevent userspace memory access
  xdp: use flags field to disambiguate broadcast redirect
  arm32, bpf: Reimplement sign-extension mov instruction
  riscv, bpf: Fix incorrect runtime stats
  bpf, arm64: Fix incorrect runtime stats
  bpf: Fix a verifier verbose message
  bpf, skmsg: Fix NULL pointer dereference in sk_psock_skb_ingress_enqueue
  MAINTAINERS: bpf: Add Lehui and Puranjay as riscv64 reviewers
  MAINTAINERS: Update email address for Puranjay Mohan
  bpf, kconfig: Fix DEBUG_INFO_BTF_MODULES Kconfig definition
====================

Link: https://lore.kernel.org/r/20240426224248.26197-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 40 insertions, 2 deletions

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 696bc55de8e8..1ea5ce5bb599 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2942,6 +2942,15 @@ bool __weak bpf_jit_supports_arena(void)
 	return false;
 }
 
+u64 __weak bpf_arch_uaddress_limit(void)
+{
+#if defined(CONFIG_64BIT) && defined(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE)
+	return TASK_SIZE;
+#else
+	return 0;
+#endif
+}
+
 /* Return TRUE if the JIT backend satisfies the following two conditions:
  * 1) JIT backend supports atomic_xchg() on pointer-sized words.
  * 2) Under the specific arch, the implementation of xchg() is the same
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 98188379d5c7..cb7ad1f795e1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -18289,8 +18289,7 @@ static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
 			f = fdget(fd);
 			map = __bpf_map_get(f);
 			if (IS_ERR(map)) {
-				verbose(env, "fd %d is not pointing to valid bpf_map\n",
-					insn[0].imm);
+				verbose(env, "fd %d is not pointing to valid bpf_map\n", fd);
 				return PTR_ERR(map);
 			}
 
@@ -19676,6 +19675,36 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 			goto next_insn;
 		}
 
+		/* Make it impossible to de-reference a userspace address */
+		if (BPF_CLASS(insn->code) == BPF_LDX &&
+		    (BPF_MODE(insn->code) == BPF_PROBE_MEM ||
+		     BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) {
+			struct bpf_insn *patch = &insn_buf[0];
+			u64 uaddress_limit = bpf_arch_uaddress_limit();
+
+			if (!uaddress_limit)
+				goto next_insn;
+
+			*patch++ = BPF_MOV64_REG(BPF_REG_AX, insn->src_reg);
+			if (insn->off)
+				*patch++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_AX, insn->off);
+			*patch++ = BPF_ALU64_IMM(BPF_RSH, BPF_REG_AX, 32);
+			*patch++ = BPF_JMP_IMM(BPF_JLE, BPF_REG_AX, uaddress_limit >> 32, 2);
+			*patch++ = *insn;
+			*patch++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
+			*patch++ = BPF_MOV64_IMM(insn->dst_reg, 0);
+
+			cnt = patch - insn_buf;
+			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
+			if (!new_prog)
+				return -ENOMEM;
+
+			delta    += cnt - 1;
+			env->prog = prog = new_prog;
+			insn      = new_prog->insnsi + i + delta;
+			goto next_insn;
+		}
+
 		/* Implement LD_ABS and LD_IND with a rewrite, if supported by the program type. */
 		if (BPF_CLASS(insn->code) == BPF_LD &&
 		    (BPF_MODE(insn->code) == BPF_ABS ||