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-rw-r--r--arch/x86/kernel/kprobes/core.c1062
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diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
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+++ b/arch/x86/kernel/kprobes/core.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Kernel Probes (KProbes)
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ *
+ * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
+ * Probes initial implementation ( includes contributions from
+ * Rusty Russell).
+ * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
+ * interface to access function arguments.
+ * 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ * <prasanna@in.ibm.com> adapted for x86_64 from i386.
+ * 2005-Mar Roland McGrath <roland@redhat.com>
+ * Fixed to handle %rip-relative addressing mode correctly.
+ * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
+ * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ * <prasanna@in.ibm.com> added function-return probes.
+ * 2005-May Rusty Lynch <rusty.lynch@intel.com>
+ * Added function return probes functionality
+ * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
+ * kprobe-booster and kretprobe-booster for i386.
+ * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
+ * and kretprobe-booster for x86-64
+ * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
+ * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
+ * unified x86 kprobes code.
+ */
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/hardirq.h>
+#include <linux/preempt.h>
+#include <linux/sched/debug.h>
+#include <linux/perf_event.h>
+#include <linux/extable.h>
+#include <linux/kdebug.h>
+#include <linux/kallsyms.h>
+#include <linux/kgdb.h>
+#include <linux/ftrace.h>
+#include <linux/kasan.h>
+#include <linux/moduleloader.h>
+#include <linux/objtool.h>
+#include <linux/vmalloc.h>
+#include <linux/pgtable.h>
+#include <linux/set_memory.h>
+#include <linux/cfi.h>
+
+#include <asm/text-patching.h>
+#include <asm/cacheflush.h>
+#include <asm/desc.h>
+#include <linux/uaccess.h>
+#include <asm/alternative.h>
+#include <asm/insn.h>
+#include <asm/debugreg.h>
+#include <asm/ibt.h>
+
+#include "common.h"
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
+ (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
+ (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
+ (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
+ (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
+ << (row % 32))
+ /*
+ * Undefined/reserved opcodes, conditional jump, Opcode Extension
+ * Groups, and some special opcodes can not boost.
+ * This is non-const and volatile to keep gcc from statically
+ * optimizing it out, as variable_test_bit makes gcc think only
+ * *(unsigned long*) is used.
+ */
+static volatile u32 twobyte_is_boostable[256 / 32] = {
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ /* ---------------------------------------------- */
+ W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */
+ W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 10 */
+ W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */
+ W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
+ W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
+ W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */
+ W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */
+ W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
+ W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */
+ W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+ W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */
+ W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */
+ W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
+ W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */
+ W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */
+ W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */
+ /* ----------------------------------------------- */
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+};
+#undef W
+
+struct kretprobe_blackpoint kretprobe_blacklist[] = {
+ {"__switch_to", }, /* This function switches only current task, but
+ doesn't switch kernel stack.*/
+ {NULL, NULL} /* Terminator */
+};
+
+const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
+
+static nokprobe_inline void
+__synthesize_relative_insn(void *dest, void *from, void *to, u8 op)
+{
+ struct __arch_relative_insn {
+ u8 op;
+ s32 raddr;
+ } __packed *insn;
+
+ insn = (struct __arch_relative_insn *)dest;
+ insn->raddr = (s32)((long)(to) - ((long)(from) + 5));
+ insn->op = op;
+}
+
+/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
+void synthesize_reljump(void *dest, void *from, void *to)
+{
+ __synthesize_relative_insn(dest, from, to, JMP32_INSN_OPCODE);
+}
+NOKPROBE_SYMBOL(synthesize_reljump);
+
+/* Insert a call instruction at address 'from', which calls address 'to'.*/
+void synthesize_relcall(void *dest, void *from, void *to)
+{
+ __synthesize_relative_insn(dest, from, to, CALL_INSN_OPCODE);
+}
+NOKPROBE_SYMBOL(synthesize_relcall);
+
+/*
+ * Returns non-zero if INSN is boostable.
+ * RIP relative instructions are adjusted at copying time in 64 bits mode
+ */
+int can_boost(struct insn *insn, void *addr)
+{
+ kprobe_opcode_t opcode;
+ insn_byte_t prefix;
+ int i;
+
+ if (search_exception_tables((unsigned long)addr))
+ return 0; /* Page fault may occur on this address. */
+
+ /* 2nd-byte opcode */
+ if (insn->opcode.nbytes == 2)
+ return test_bit(insn->opcode.bytes[1],
+ (unsigned long *)twobyte_is_boostable);
+
+ if (insn->opcode.nbytes != 1)
+ return 0;
+
+ for_each_insn_prefix(insn, i, prefix) {
+ insn_attr_t attr;
+
+ attr = inat_get_opcode_attribute(prefix);
+ /* Can't boost Address-size override prefix and CS override prefix */
+ if (prefix == 0x2e || inat_is_address_size_prefix(attr))
+ return 0;
+ }
+
+ opcode = insn->opcode.bytes[0];
+
+ switch (opcode) {
+ case 0x62: /* bound */
+ case 0x70 ... 0x7f: /* Conditional jumps */
+ case 0x9a: /* Call far */
+ case 0xc0 ... 0xc1: /* Grp2 */
+ case 0xcc ... 0xce: /* software exceptions */
+ case 0xd0 ... 0xd3: /* Grp2 */
+ case 0xd6: /* (UD) */
+ case 0xd8 ... 0xdf: /* ESC */
+ case 0xe0 ... 0xe3: /* LOOP*, JCXZ */
+ case 0xe8 ... 0xe9: /* near Call, JMP */
+ case 0xeb: /* Short JMP */
+ case 0xf0 ... 0xf4: /* LOCK/REP, HLT */
+ case 0xf6 ... 0xf7: /* Grp3 */
+ case 0xfe: /* Grp4 */
+ /* ... are not boostable */
+ return 0;
+ case 0xff: /* Grp5 */
+ /* Only indirect jmp is boostable */
+ return X86_MODRM_REG(insn->modrm.bytes[0]) == 4;
+ default:
+ return 1;
+ }
+}
+
+static unsigned long
+__recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
+{
+ struct kprobe *kp;
+ bool faddr;
+
+ kp = get_kprobe((void *)addr);
+ faddr = ftrace_location(addr) == addr;
+ /*
+ * Use the current code if it is not modified by Kprobe
+ * and it cannot be modified by ftrace.
+ */
+ if (!kp && !faddr)
+ return addr;
+
+ /*
+ * Basically, kp->ainsn.insn has an original instruction.
+ * However, RIP-relative instruction can not do single-stepping
+ * at different place, __copy_instruction() tweaks the displacement of
+ * that instruction. In that case, we can't recover the instruction
+ * from the kp->ainsn.insn.
+ *
+ * On the other hand, in case on normal Kprobe, kp->opcode has a copy
+ * of the first byte of the probed instruction, which is overwritten
+ * by int3. And the instruction at kp->addr is not modified by kprobes
+ * except for the first byte, we can recover the original instruction
+ * from it and kp->opcode.
+ *
+ * In case of Kprobes using ftrace, we do not have a copy of
+ * the original instruction. In fact, the ftrace location might
+ * be modified at anytime and even could be in an inconsistent state.
+ * Fortunately, we know that the original code is the ideal 5-byte
+ * long NOP.
+ */
+ if (copy_from_kernel_nofault(buf, (void *)addr,
+ MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+ return 0UL;
+
+ if (faddr)
+ memcpy(buf, x86_nops[5], 5);
+ else
+ buf[0] = kp->opcode;
+ return (unsigned long)buf;
+}
+
+/*
+ * Recover the probed instruction at addr for further analysis.
+ * Caller must lock kprobes by kprobe_mutex, or disable preemption
+ * for preventing to release referencing kprobes.
+ * Returns zero if the instruction can not get recovered (or access failed).
+ */
+unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
+{
+ unsigned long __addr;
+
+ __addr = __recover_optprobed_insn(buf, addr);
+ if (__addr != addr)
+ return __addr;
+
+ return __recover_probed_insn(buf, addr);
+}
+
+/* Check if paddr is at an instruction boundary */
+static int can_probe(unsigned long paddr)
+{
+ unsigned long addr, __addr, offset = 0;
+ struct insn insn;
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+ if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
+ return 0;
+
+ /* Decode instructions */
+ addr = paddr - offset;
+ while (addr < paddr) {
+ int ret;
+
+ /*
+ * Check if the instruction has been modified by another
+ * kprobe, in which case we replace the breakpoint by the
+ * original instruction in our buffer.
+ * Also, jump optimization will change the breakpoint to
+ * relative-jump. Since the relative-jump itself is
+ * normally used, we just go through if there is no kprobe.
+ */
+ __addr = recover_probed_instruction(buf, addr);
+ if (!__addr)
+ return 0;
+
+ ret = insn_decode_kernel(&insn, (void *)__addr);
+ if (ret < 0)
+ return 0;
+
+#ifdef CONFIG_KGDB
+ /*
+ * If there is a dynamically installed kgdb sw breakpoint,
+ * this function should not be probed.
+ */
+ if (insn.opcode.bytes[0] == INT3_INSN_OPCODE &&
+ kgdb_has_hit_break(addr))
+ return 0;
+#endif
+ addr += insn.length;
+ }
+ if (IS_ENABLED(CONFIG_CFI_CLANG)) {
+ /*
+ * The compiler generates the following instruction sequence
+ * for indirect call checks and cfi.c decodes this;
+ *
+ *  movl -<id>, %r10d ; 6 bytes
+ * addl -4(%reg), %r10d ; 4 bytes
+ * je .Ltmp1 ; 2 bytes
+ * ud2 ; <- regs->ip
+ * .Ltmp1:
+ *
+ * Also, these movl and addl are used for showing expected
+ * type. So those must not be touched.
+ */
+ __addr = recover_probed_instruction(buf, addr);
+ if (!__addr)
+ return 0;
+
+ if (insn_decode_kernel(&insn, (void *)__addr) < 0)
+ return 0;
+
+ if (insn.opcode.value == 0xBA)
+ offset = 12;
+ else if (insn.opcode.value == 0x3)
+ offset = 6;
+ else
+ goto out;
+
+ /* This movl/addl is used for decoding CFI. */
+ if (is_cfi_trap(addr + offset))
+ return 0;
+ }
+
+out:
+ return (addr == paddr);
+}
+
+/* If x86 supports IBT (ENDBR) it must be skipped. */
+kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset,
+ bool *on_func_entry)
+{
+ if (is_endbr(*(u32 *)addr)) {
+ *on_func_entry = !offset || offset == 4;
+ if (*on_func_entry)
+ offset = 4;
+
+ } else {
+ *on_func_entry = !offset;
+ }
+
+ return (kprobe_opcode_t *)(addr + offset);
+}
+
+/*
+ * Copy an instruction with recovering modified instruction by kprobes
+ * and adjust the displacement if the instruction uses the %rip-relative
+ * addressing mode. Note that since @real will be the final place of copied
+ * instruction, displacement must be adjust by @real, not @dest.
+ * This returns the length of copied instruction, or 0 if it has an error.
+ */
+int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
+{
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+ unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src);
+ int ret;
+
+ if (!recovered_insn || !insn)
+ return 0;
+
+ /* This can access kernel text if given address is not recovered */
+ if (copy_from_kernel_nofault(dest, (void *)recovered_insn,
+ MAX_INSN_SIZE))
+ return 0;
+
+ ret = insn_decode_kernel(insn, dest);
+ if (ret < 0)
+ return 0;
+
+ /* We can not probe force emulate prefixed instruction */
+ if (insn_has_emulate_prefix(insn))
+ return 0;
+
+ /* Another subsystem puts a breakpoint, failed to recover */
+ if (insn->opcode.bytes[0] == INT3_INSN_OPCODE)
+ return 0;
+
+ /* We should not singlestep on the exception masking instructions */
+ if (insn_masking_exception(insn))
+ return 0;
+
+#ifdef CONFIG_X86_64
+ /* Only x86_64 has RIP relative instructions */
+ if (insn_rip_relative(insn)) {
+ s64 newdisp;
+ u8 *disp;
+ /*
+ * The copied instruction uses the %rip-relative addressing
+ * mode. Adjust the displacement for the difference between
+ * the original location of this instruction and the location
+ * of the copy that will actually be run. The tricky bit here
+ * is making sure that the sign extension happens correctly in
+ * this calculation, since we need a signed 32-bit result to
+ * be sign-extended to 64 bits when it's added to the %rip
+ * value and yield the same 64-bit result that the sign-
+ * extension of the original signed 32-bit displacement would
+ * have given.
+ */
+ newdisp = (u8 *) src + (s64) insn->displacement.value
+ - (u8 *) real;
+ if ((s64) (s32) newdisp != newdisp) {
+ pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp);
+ return 0;
+ }
+ disp = (u8 *) dest + insn_offset_displacement(insn);
+ *(s32 *) disp = (s32) newdisp;
+ }
+#endif
+ return insn->length;
+}
+
+/* Prepare reljump or int3 right after instruction */
+static int prepare_singlestep(kprobe_opcode_t *buf, struct kprobe *p,
+ struct insn *insn)
+{
+ int len = insn->length;
+
+ if (!IS_ENABLED(CONFIG_PREEMPTION) &&
+ !p->post_handler && can_boost(insn, p->addr) &&
+ MAX_INSN_SIZE - len >= JMP32_INSN_SIZE) {
+ /*
+ * These instructions can be executed directly if it
+ * jumps back to correct address.
+ */
+ synthesize_reljump(buf + len, p->ainsn.insn + len,
+ p->addr + insn->length);
+ len += JMP32_INSN_SIZE;
+ p->ainsn.boostable = 1;
+ } else {
+ /* Otherwise, put an int3 for trapping singlestep */
+ if (MAX_INSN_SIZE - len < INT3_INSN_SIZE)
+ return -ENOSPC;
+
+ buf[len] = INT3_INSN_OPCODE;
+ len += INT3_INSN_SIZE;
+ }
+
+ return len;
+}
+
+/* Make page to RO mode when allocate it */
+void *alloc_insn_page(void)
+{
+ void *page;
+
+ page = module_alloc(PAGE_SIZE);
+ if (!page)
+ return NULL;
+
+ /*
+ * TODO: Once additional kernel code protection mechanisms are set, ensure
+ * that the page was not maliciously altered and it is still zeroed.
+ */
+ set_memory_rox((unsigned long)page, 1);
+
+ return page;
+}
+
+/* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */
+
+static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs)
+{
+ switch (p->ainsn.opcode) {
+ case 0xfa: /* cli */
+ regs->flags &= ~(X86_EFLAGS_IF);
+ break;
+ case 0xfb: /* sti */
+ regs->flags |= X86_EFLAGS_IF;
+ break;
+ case 0x9c: /* pushf */
+ int3_emulate_push(regs, regs->flags);
+ break;
+ case 0x9d: /* popf */
+ regs->flags = int3_emulate_pop(regs);
+ break;
+ }
+ regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+}
+NOKPROBE_SYMBOL(kprobe_emulate_ifmodifiers);
+
+static void kprobe_emulate_ret(struct kprobe *p, struct pt_regs *regs)
+{
+ int3_emulate_ret(regs);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_ret);
+
+static void kprobe_emulate_call(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long func = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+
+ func += p->ainsn.rel32;
+ int3_emulate_call(regs, func);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_call);
+
+static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+
+ ip += p->ainsn.rel32;
+ int3_emulate_jmp(regs, ip);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_jmp);
+
+static void kprobe_emulate_jcc(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+
+ int3_emulate_jcc(regs, p->ainsn.jcc.type, ip, p->ainsn.rel32);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_jcc);
+
+static void kprobe_emulate_loop(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+ bool match;
+
+ if (p->ainsn.loop.type != 3) { /* LOOP* */
+ if (p->ainsn.loop.asize == 32)
+ match = ((*(u32 *)&regs->cx)--) != 0;
+#ifdef CONFIG_X86_64
+ else if (p->ainsn.loop.asize == 64)
+ match = ((*(u64 *)&regs->cx)--) != 0;
+#endif
+ else
+ match = ((*(u16 *)&regs->cx)--) != 0;
+ } else { /* JCXZ */
+ if (p->ainsn.loop.asize == 32)
+ match = *(u32 *)(&regs->cx) == 0;
+#ifdef CONFIG_X86_64
+ else if (p->ainsn.loop.asize == 64)
+ match = *(u64 *)(&regs->cx) == 0;
+#endif
+ else
+ match = *(u16 *)(&regs->cx) == 0;
+ }
+
+ if (p->ainsn.loop.type == 0) /* LOOPNE */
+ match = match && !(regs->flags & X86_EFLAGS_ZF);
+ else if (p->ainsn.loop.type == 1) /* LOOPE */
+ match = match && (regs->flags & X86_EFLAGS_ZF);
+
+ if (match)
+ ip += p->ainsn.rel32;
+ int3_emulate_jmp(regs, ip);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_loop);
+
+static const int addrmode_regoffs[] = {
+ offsetof(struct pt_regs, ax),
+ offsetof(struct pt_regs, cx),
+ offsetof(struct pt_regs, dx),
+ offsetof(struct pt_regs, bx),
+ offsetof(struct pt_regs, sp),
+ offsetof(struct pt_regs, bp),
+ offsetof(struct pt_regs, si),
+ offsetof(struct pt_regs, di),
+#ifdef CONFIG_X86_64
+ offsetof(struct pt_regs, r8),
+ offsetof(struct pt_regs, r9),
+ offsetof(struct pt_regs, r10),
+ offsetof(struct pt_regs, r11),
+ offsetof(struct pt_regs, r12),
+ offsetof(struct pt_regs, r13),
+ offsetof(struct pt_regs, r14),
+ offsetof(struct pt_regs, r15),
+#endif
+};
+
+static void kprobe_emulate_call_indirect(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg];
+
+ int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + p->ainsn.size);
+ int3_emulate_jmp(regs, regs_get_register(regs, offs));
+}
+NOKPROBE_SYMBOL(kprobe_emulate_call_indirect);
+
+static void kprobe_emulate_jmp_indirect(struct kprobe *p, struct pt_regs *regs)
+{
+ unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg];
+
+ int3_emulate_jmp(regs, regs_get_register(regs, offs));
+}
+NOKPROBE_SYMBOL(kprobe_emulate_jmp_indirect);
+
+static int prepare_emulation(struct kprobe *p, struct insn *insn)
+{
+ insn_byte_t opcode = insn->opcode.bytes[0];
+
+ switch (opcode) {
+ case 0xfa: /* cli */
+ case 0xfb: /* sti */
+ case 0x9c: /* pushfl */
+ case 0x9d: /* popf/popfd */
+ /*
+ * IF modifiers must be emulated since it will enable interrupt while
+ * int3 single stepping.
+ */
+ p->ainsn.emulate_op = kprobe_emulate_ifmodifiers;
+ p->ainsn.opcode = opcode;
+ break;
+ case 0xc2: /* ret/lret */
+ case 0xc3:
+ case 0xca:
+ case 0xcb:
+ p->ainsn.emulate_op = kprobe_emulate_ret;
+ break;
+ case 0x9a: /* far call absolute -- segment is not supported */
+ case 0xea: /* far jmp absolute -- segment is not supported */
+ case 0xcc: /* int3 */
+ case 0xcf: /* iret -- in-kernel IRET is not supported */
+ return -EOPNOTSUPP;
+ break;
+ case 0xe8: /* near call relative */
+ p->ainsn.emulate_op = kprobe_emulate_call;
+ if (insn->immediate.nbytes == 2)
+ p->ainsn.rel32 = *(s16 *)&insn->immediate.value;
+ else
+ p->ainsn.rel32 = *(s32 *)&insn->immediate.value;
+ break;
+ case 0xeb: /* short jump relative */
+ case 0xe9: /* near jump relative */
+ p->ainsn.emulate_op = kprobe_emulate_jmp;
+ if (insn->immediate.nbytes == 1)
+ p->ainsn.rel32 = *(s8 *)&insn->immediate.value;
+ else if (insn->immediate.nbytes == 2)
+ p->ainsn.rel32 = *(s16 *)&insn->immediate.value;
+ else
+ p->ainsn.rel32 = *(s32 *)&insn->immediate.value;
+ break;
+ case 0x70 ... 0x7f:
+ /* 1 byte conditional jump */
+ p->ainsn.emulate_op = kprobe_emulate_jcc;
+ p->ainsn.jcc.type = opcode & 0xf;
+ p->ainsn.rel32 = insn->immediate.value;
+ break;
+ case 0x0f:
+ opcode = insn->opcode.bytes[1];
+ if ((opcode & 0xf0) == 0x80) {
+ /* 2 bytes Conditional Jump */
+ p->ainsn.emulate_op = kprobe_emulate_jcc;
+ p->ainsn.jcc.type = opcode & 0xf;
+ if (insn->immediate.nbytes == 2)
+ p->ainsn.rel32 = *(s16 *)&insn->immediate.value;
+ else
+ p->ainsn.rel32 = *(s32 *)&insn->immediate.value;
+ } else if (opcode == 0x01 &&
+ X86_MODRM_REG(insn->modrm.bytes[0]) == 0 &&
+ X86_MODRM_MOD(insn->modrm.bytes[0]) == 3) {
+ /* VM extensions - not supported */
+ return -EOPNOTSUPP;
+ }
+ break;
+ case 0xe0: /* Loop NZ */
+ case 0xe1: /* Loop */
+ case 0xe2: /* Loop */
+ case 0xe3: /* J*CXZ */
+ p->ainsn.emulate_op = kprobe_emulate_loop;
+ p->ainsn.loop.type = opcode & 0x3;
+ p->ainsn.loop.asize = insn->addr_bytes * 8;
+ p->ainsn.rel32 = *(s8 *)&insn->immediate.value;
+ break;
+ case 0xff:
+ /*
+ * Since the 0xff is an extended group opcode, the instruction
+ * is determined by the MOD/RM byte.
+ */
+ opcode = insn->modrm.bytes[0];
+ switch (X86_MODRM_REG(opcode)) {
+ case 0b010: /* FF /2, call near, absolute indirect */
+ p->ainsn.emulate_op = kprobe_emulate_call_indirect;
+ break;
+ case 0b100: /* FF /4, jmp near, absolute indirect */
+ p->ainsn.emulate_op = kprobe_emulate_jmp_indirect;
+ break;
+ case 0b011: /* FF /3, call far, absolute indirect */
+ case 0b101: /* FF /5, jmp far, absolute indirect */
+ return -EOPNOTSUPP;
+ }
+
+ if (!p->ainsn.emulate_op)
+ break;
+
+ if (insn->addr_bytes != sizeof(unsigned long))
+ return -EOPNOTSUPP; /* Don't support different size */
+ if (X86_MODRM_MOD(opcode) != 3)
+ return -EOPNOTSUPP; /* TODO: support memory addressing */
+
+ p->ainsn.indirect.reg = X86_MODRM_RM(opcode);
+#ifdef CONFIG_X86_64
+ if (X86_REX_B(insn->rex_prefix.value))
+ p->ainsn.indirect.reg += 8;
+#endif
+ break;
+ default:
+ break;
+ }
+ p->ainsn.size = insn->length;
+
+ return 0;
+}
+
+static int arch_copy_kprobe(struct kprobe *p)
+{
+ struct insn insn;
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+ int ret, len;
+
+ /* Copy an instruction with recovering if other optprobe modifies it.*/
+ len = __copy_instruction(buf, p->addr, p->ainsn.insn, &insn);
+ if (!len)
+ return -EINVAL;
+
+ /* Analyze the opcode and setup emulate functions */
+ ret = prepare_emulation(p, &insn);
+ if (ret < 0)
+ return ret;
+
+ /* Add int3 for single-step or booster jmp */
+ len = prepare_singlestep(buf, p, &insn);
+ if (len < 0)
+ return len;
+
+ /* Also, displacement change doesn't affect the first byte */
+ p->opcode = buf[0];
+
+ p->ainsn.tp_len = len;
+ perf_event_text_poke(p->ainsn.insn, NULL, 0, buf, len);
+
+ /* OK, write back the instruction(s) into ROX insn buffer */
+ text_poke(p->ainsn.insn, buf, len);
+
+ return 0;
+}
+
+int arch_prepare_kprobe(struct kprobe *p)
+{
+ int ret;
+
+ if (alternatives_text_reserved(p->addr, p->addr))
+ return -EINVAL;
+
+ if (!can_probe((unsigned long)p->addr))
+ return -EILSEQ;
+
+ memset(&p->ainsn, 0, sizeof(p->ainsn));
+
+ /* insn: must be on special executable page on x86. */
+ p->ainsn.insn = get_insn_slot();
+ if (!p->ainsn.insn)
+ return -ENOMEM;
+
+ ret = arch_copy_kprobe(p);
+ if (ret) {
+ free_insn_slot(p->ainsn.insn, 0);
+ p->ainsn.insn = NULL;
+ }
+
+ return ret;
+}
+
+void arch_arm_kprobe(struct kprobe *p)
+{
+ u8 int3 = INT3_INSN_OPCODE;
+
+ text_poke(p->addr, &int3, 1);
+ text_poke_sync();
+ perf_event_text_poke(p->addr, &p->opcode, 1, &int3, 1);
+}
+
+void arch_disarm_kprobe(struct kprobe *p)
+{
+ u8 int3 = INT3_INSN_OPCODE;
+
+ perf_event_text_poke(p->addr, &int3, 1, &p->opcode, 1);
+ text_poke(p->addr, &p->opcode, 1);
+ text_poke_sync();
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+ if (p->ainsn.insn) {
+ /* Record the perf event before freeing the slot */
+ perf_event_text_poke(p->ainsn.insn, p->ainsn.insn,
+ p->ainsn.tp_len, NULL, 0);
+ free_insn_slot(p->ainsn.insn, p->ainsn.boostable);
+ p->ainsn.insn = NULL;
+ }
+}
+
+static nokprobe_inline void
+save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+ kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags;
+ kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags;
+}
+
+static nokprobe_inline void
+restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+ kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags;
+ kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags;
+}
+
+static nokprobe_inline void
+set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ __this_cpu_write(current_kprobe, p);
+ kcb->kprobe_saved_flags = kcb->kprobe_old_flags
+ = (regs->flags & X86_EFLAGS_IF);
+}
+
+static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ /* Restore back the original saved kprobes variables and continue. */
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ /* This will restore both kcb and current_kprobe */
+ restore_previous_kprobe(kcb);
+ } else {
+ /*
+ * Always update the kcb status because
+ * reset_curent_kprobe() doesn't update kcb.
+ */
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ if (cur->post_handler)
+ cur->post_handler(cur, regs, 0);
+ reset_current_kprobe();
+ }
+}
+NOKPROBE_SYMBOL(kprobe_post_process);
+
+static void setup_singlestep(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb, int reenter)
+{
+ if (setup_detour_execution(p, regs, reenter))
+ return;
+
+#if !defined(CONFIG_PREEMPTION)
+ if (p->ainsn.boostable) {
+ /* Boost up -- we can execute copied instructions directly */
+ if (!reenter)
+ reset_current_kprobe();
+ /*
+ * Reentering boosted probe doesn't reset current_kprobe,
+ * nor set current_kprobe, because it doesn't use single
+ * stepping.
+ */
+ regs->ip = (unsigned long)p->ainsn.insn;
+ return;
+ }
+#endif
+ if (reenter) {
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_REENTER;
+ } else
+ kcb->kprobe_status = KPROBE_HIT_SS;
+
+ if (p->ainsn.emulate_op) {
+ p->ainsn.emulate_op(p, regs);
+ kprobe_post_process(p, regs, kcb);
+ return;
+ }
+
+ /* Disable interrupt, and set ip register on trampoline */
+ regs->flags &= ~X86_EFLAGS_IF;
+ regs->ip = (unsigned long)p->ainsn.insn;
+}
+NOKPROBE_SYMBOL(setup_singlestep);
+
+/*
+ * Called after single-stepping. p->addr is the address of the
+ * instruction whose first byte has been replaced by the "int3"
+ * instruction. To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction. The address of this
+ * copy is p->ainsn.insn. We also doesn't use trap, but "int3" again
+ * right after the copied instruction.
+ * Different from the trap single-step, "int3" single-step can not
+ * handle the instruction which changes the ip register, e.g. jmp,
+ * call, conditional jmp, and the instructions which changes the IF
+ * flags because interrupt must be disabled around the single-stepping.
+ * Such instructions are software emulated, but others are single-stepped
+ * using "int3".
+ *
+ * When the 2nd "int3" handled, the regs->ip and regs->flags needs to
+ * be adjusted, so that we can resume execution on correct code.
+ */
+static void resume_singlestep(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ unsigned long copy_ip = (unsigned long)p->ainsn.insn;
+ unsigned long orig_ip = (unsigned long)p->addr;
+
+ /* Restore saved interrupt flag and ip register */
+ regs->flags |= kcb->kprobe_saved_flags;
+ /* Note that regs->ip is executed int3 so must be a step back */
+ regs->ip += (orig_ip - copy_ip) - INT3_INSN_SIZE;
+}
+NOKPROBE_SYMBOL(resume_singlestep);
+
+/*
+ * We have reentered the kprobe_handler(), since another probe was hit while
+ * within the handler. We save the original kprobes variables and just single
+ * step on the instruction of the new probe without calling any user handlers.
+ */
+static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ switch (kcb->kprobe_status) {
+ case KPROBE_HIT_SSDONE:
+ case KPROBE_HIT_ACTIVE:
+ case KPROBE_HIT_SS:
+ kprobes_inc_nmissed_count(p);
+ setup_singlestep(p, regs, kcb, 1);
+ break;
+ case KPROBE_REENTER:
+ /* A probe has been hit in the codepath leading up to, or just
+ * after, single-stepping of a probed instruction. This entire
+ * codepath should strictly reside in .kprobes.text section.
+ * Raise a BUG or we'll continue in an endless reentering loop
+ * and eventually a stack overflow.
+ */
+ pr_err("Unrecoverable kprobe detected.\n");
+ dump_kprobe(p);
+ BUG();
+ default:
+ /* impossible cases */
+ WARN_ON(1);
+ return 0;
+ }
+
+ return 1;
+}
+NOKPROBE_SYMBOL(reenter_kprobe);
+
+static nokprobe_inline int kprobe_is_ss(struct kprobe_ctlblk *kcb)
+{
+ return (kcb->kprobe_status == KPROBE_HIT_SS ||
+ kcb->kprobe_status == KPROBE_REENTER);
+}
+
+/*
+ * Interrupts are disabled on entry as trap3 is an interrupt gate and they
+ * remain disabled throughout this function.
+ */
+int kprobe_int3_handler(struct pt_regs *regs)
+{
+ kprobe_opcode_t *addr;
+ struct kprobe *p;
+ struct kprobe_ctlblk *kcb;
+
+ if (user_mode(regs))
+ return 0;
+
+ addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
+ /*
+ * We don't want to be preempted for the entire duration of kprobe
+ * processing. Since int3 and debug trap disables irqs and we clear
+ * IF while singlestepping, it must be no preemptible.
+ */
+
+ kcb = get_kprobe_ctlblk();
+ p = get_kprobe(addr);
+
+ if (p) {
+ if (kprobe_running()) {
+ if (reenter_kprobe(p, regs, kcb))
+ return 1;
+ } else {
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+ /*
+ * If we have no pre-handler or it returned 0, we
+ * continue with normal processing. If we have a
+ * pre-handler and it returned non-zero, that means
+ * user handler setup registers to exit to another
+ * instruction, we must skip the single stepping.
+ */
+ if (!p->pre_handler || !p->pre_handler(p, regs))
+ setup_singlestep(p, regs, kcb, 0);
+ else
+ reset_current_kprobe();
+ return 1;
+ }
+ } else if (kprobe_is_ss(kcb)) {
+ p = kprobe_running();
+ if ((unsigned long)p->ainsn.insn < regs->ip &&
+ (unsigned long)p->ainsn.insn + MAX_INSN_SIZE > regs->ip) {
+ /* Most provably this is the second int3 for singlestep */
+ resume_singlestep(p, regs, kcb);
+ kprobe_post_process(p, regs, kcb);
+ return 1;
+ }
+ } /* else: not a kprobe fault; let the kernel handle it */
+
+ return 0;
+}
+NOKPROBE_SYMBOL(kprobe_int3_handler);
+
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) {
+ /* This must happen on single-stepping */
+ WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS &&
+ kcb->kprobe_status != KPROBE_REENTER);
+ /*
+ * We are here because the instruction being single
+ * stepped caused a page fault. We reset the current
+ * kprobe and the ip points back to the probe address
+ * and allow the page fault handler to continue as a
+ * normal page fault.
+ */
+ regs->ip = (unsigned long)cur->addr;
+
+ /*
+ * If the IF flag was set before the kprobe hit,
+ * don't touch it:
+ */
+ regs->flags |= kcb->kprobe_old_flags;
+
+ if (kcb->kprobe_status == KPROBE_REENTER)
+ restore_previous_kprobe(kcb);
+ else
+ reset_current_kprobe();
+ }
+
+ return 0;
+}
+NOKPROBE_SYMBOL(kprobe_fault_handler);
+
+int __init arch_populate_kprobe_blacklist(void)
+{
+ return kprobe_add_area_blacklist((unsigned long)__entry_text_start,
+ (unsigned long)__entry_text_end);
+}
+
+int __init arch_init_kprobes(void)
+{
+ return 0;
+}
+
+int arch_trampoline_kprobe(struct kprobe *p)
+{
+ return 0;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-19 23:31:08 +0000