x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 225 insertions, 0 deletions

diff --git a/net/netlabel/netlabel_mgmt.h b/net/netlabel/netlabel_mgmt.h
new file mode 100644
index 000000000..db20dfbbd
--- /dev/null
+++ b/net/netlabel/netlabel_mgmt.h
@@ -0,0 +1,225 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * NetLabel Management Support
+ *
+ * This file defines the management functions for the NetLabel system.  The
+ * NetLabel system manages static and dynamic label mappings for network
+ * protocols such as CIPSO and RIPSO.
+ *
+ * Author: Paul Moore <paul@paul-moore.com>
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ */
+
+#ifndef _NETLABEL_MGMT_H
+#define _NETLABEL_MGMT_H
+
+#include <net/netlabel.h>
+#include <linux/atomic.h>
+
+/*
+ * The following NetLabel payloads are supported by the management interface.
+ *
+ * o ADD:
+ *   Sent by an application to add a domain mapping to the NetLabel system.
+ *
+ *   Required attributes:
+ *
+ *     NLBL_MGMT_A_DOMAIN
+ *     NLBL_MGMT_A_PROTOCOL
+ *
+ *   If IPv4 is specified the following attributes are required:
+ *
+ *     NLBL_MGMT_A_IPV4ADDR
+ *     NLBL_MGMT_A_IPV4MASK
+ *
+ *   If IPv6 is specified the following attributes are required:
+ *
+ *     NLBL_MGMT_A_IPV6ADDR
+ *     NLBL_MGMT_A_IPV6MASK
+ *
+ *   If using NETLBL_NLTYPE_CIPSOV4 the following attributes are required:
+ *
+ *     NLBL_MGMT_A_CV4DOI
+ *
+ *   If using NETLBL_NLTYPE_UNLABELED no other attributes are required,
+ *   however the following attribute may optionally be sent:
+ *
+ *     NLBL_MGMT_A_FAMILY
+ *
+ * o REMOVE:
+ *   Sent by an application to remove a domain mapping from the NetLabel
+ *   system.
+ *
+ *   Required attributes:
+ *
+ *     NLBL_MGMT_A_DOMAIN
+ *
+ * o LISTALL:
+ *   This message can be sent either from an application or by the kernel in
+ *   response to an application generated LISTALL message.  When sent by an
+ *   application there is no payload and the NLM_F_DUMP flag should be set.
+ *   The kernel should respond with a series of the following messages.
+ *
+ *   Required attributes:
+ *
+ *     NLBL_MGMT_A_DOMAIN
+ *     NLBL_MGMT_A_FAMILY
+ *
+ *   If the IP address selectors are not used the following attribute is
+ *   required:
+ *
+ *     NLBL_MGMT_A_PROTOCOL
+ *
+ *   If the IP address selectors are used then the following attritbute is
+ *   required:
+ *
+ *     NLBL_MGMT_A_SELECTORLIST
+ *
+ *   If the mapping is using the NETLBL_NLTYPE_CIPSOV4 type then the following
+ *   attributes are required:
+ *
+ *     NLBL_MGMT_A_CV4DOI
+ *
+ *   If the mapping is using the NETLBL_NLTYPE_UNLABELED type no other
+ *   attributes are required.
+ *
+ * o ADDDEF:
+ *   Sent by an application to set the default domain mapping for the NetLabel
+ *   system.
+ *
+ *   Required attributes:
+ *
+ *     NLBL_MGMT_A_PROTOCOL
+ *
+ *   If using NETLBL_NLTYPE_CIPSOV4 the following attributes are required:
+ *
+ *     NLBL_MGMT_A_CV4DOI
+ *
+ *   If using NETLBL_NLTYPE_UNLABELED no other attributes are required,
+ *   however the following attribute may optionally be sent:
+ *
+ *     NLBL_MGMT_A_FAMILY
+ *
+ * o REMOVEDEF:
+ *   Sent by an application to remove the default domain mapping from the
+ *   NetLabel system, there is no payload.
+ *
+ * o LISTDEF:
+ *   This message can be sent either from an application or by the kernel in
+ *   response to an application generated LISTDEF message.  When sent by an
+ *   application there may be an optional payload.
+ *
+ *     NLBL_MGMT_A_FAMILY
+ *
+ *   On success the kernel should send a response using the following format:
+ *
+ *   If the IP address selectors are not used the following attributes are
+ *   required:
+ *
+ *     NLBL_MGMT_A_PROTOCOL
+ *     NLBL_MGMT_A_FAMILY
+ *
+ *   If the IP address selectors are used then the following attritbute is
+ *   required:
+ *
+ *     NLBL_MGMT_A_SELECTORLIST
+ *
+ *   If the mapping is using the NETLBL_NLTYPE_CIPSOV4 type then the following
+ *   attributes are required:
+ *
+ *     NLBL_MGMT_A_CV4DOI
+ *
+ *   If the mapping is using the NETLBL_NLTYPE_UNLABELED type no other
+ *   attributes are required.
+ *
+ * o PROTOCOLS:
+ *   Sent by an application to request a list of configured NetLabel protocols
+ *   in the kernel.  When sent by an application there is no payload and the
+ *   NLM_F_DUMP flag should be set.  The kernel should respond with a series of
+ *   the following messages.
+ *
+ *   Required attributes:
+ *
+ *     NLBL_MGMT_A_PROTOCOL
+ *
+ * o VERSION:
+ *   Sent by an application to request the NetLabel version.  When sent by an
+ *   application there is no payload.  This message type is also used by the
+ *   kernel to respond to an VERSION request.
+ *
+ *   Required attributes:
+ *
+ *     NLBL_MGMT_A_VERSION
+ *
+ */
+
+/* NetLabel Management commands */
+enum {
+	NLBL_MGMT_C_UNSPEC,
+	NLBL_MGMT_C_ADD,
+	NLBL_MGMT_C_REMOVE,
+	NLBL_MGMT_C_LISTALL,
+	NLBL_MGMT_C_ADDDEF,
+	NLBL_MGMT_C_REMOVEDEF,
+	NLBL_MGMT_C_LISTDEF,
+	NLBL_MGMT_C_PROTOCOLS,
+	NLBL_MGMT_C_VERSION,
+	__NLBL_MGMT_C_MAX,
+};
+
+/* NetLabel Management attributes */
+enum {
+	NLBL_MGMT_A_UNSPEC,
+	NLBL_MGMT_A_DOMAIN,
+	/* (NLA_NUL_STRING)
+	 * the NULL terminated LSM domain string */
+	NLBL_MGMT_A_PROTOCOL,
+	/* (NLA_U32)
+	 * the NetLabel protocol type (defined by NETLBL_NLTYPE_*) */
+	NLBL_MGMT_A_VERSION,
+	/* (NLA_U32)
+	 * the NetLabel protocol version number (defined by
+	 * NETLBL_PROTO_VERSION) */
+	NLBL_MGMT_A_CV4DOI,
+	/* (NLA_U32)
+	 * the CIPSOv4 DOI value */
+	NLBL_MGMT_A_IPV6ADDR,
+	/* (NLA_BINARY, struct in6_addr)
+	 * an IPv6 address */
+	NLBL_MGMT_A_IPV6MASK,
+	/* (NLA_BINARY, struct in6_addr)
+	 * an IPv6 address mask */
+	NLBL_MGMT_A_IPV4ADDR,
+	/* (NLA_BINARY, struct in_addr)
+	 * an IPv4 address */
+	NLBL_MGMT_A_IPV4MASK,
+	/* (NLA_BINARY, struct in_addr)
+	 * and IPv4 address mask */
+	NLBL_MGMT_A_ADDRSELECTOR,
+	/* (NLA_NESTED)
+	 * an IP address selector, must contain an address, mask, and protocol
+	 * attribute plus any protocol specific attributes */
+	NLBL_MGMT_A_SELECTORLIST,
+	/* (NLA_NESTED)
+	 * the selector list, there must be at least one
+	 * NLBL_MGMT_A_ADDRSELECTOR attribute */
+	NLBL_MGMT_A_FAMILY,
+	/* (NLA_U16)
+	 * The address family */
+	NLBL_MGMT_A_CLPDOI,
+	/* (NLA_U32)
+	 * the CALIPSO DOI value */
+	__NLBL_MGMT_A_MAX,
+};
+#define NLBL_MGMT_A_MAX (__NLBL_MGMT_A_MAX - 1)
+
+/* NetLabel protocol functions */
+int netlbl_mgmt_genl_init(void);
+
+/* NetLabel configured protocol reference counter */
+extern atomic_t netlabel_mgmt_protocount;
+
+#endif