kprobes: Prohibit probing on .entry.text code

.entry.text is a code area which is used for interrupt/syscall
entries, which includes many sensitive code.
Thus, it is better to prohibit probing on all of such code
instead of a part of that.
Since some symbols are already registered on kprobe blacklist,
this also removes them from the blacklist.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jonathan Lebon <jlebon@redhat.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/20140417081658.26341.57354.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>

5 files changed, 17 insertions, 58 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index a2a4f4697889..0ca5bf1697bb 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -315,10 +315,6 @@ ENTRY(ret_from_kernel_thread)
 ENDPROC(ret_from_kernel_thread)
 
 /*
- * Interrupt exit functions should be protected against kprobes
- */
-        .pushsection .kprobes.text, "ax"
-/*
  * Return to user mode is not as complex as all this looks,
  * but we want the default path for a system call return to
  * go as quickly as possible which is why some of this is
@@ -372,10 +368,6 @@ need_resched:
 END(resume_kernel)
 #endif
         CFI_ENDPROC
-/*
- * End of kprobes section
- */
-        .popsection
 
 /* SYSENTER_RETURN points to after the "sysenter" instruction in
    the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */
@@ -495,10 +487,6 @@ sysexit_audit:
         PTGS_TO_GS_EX
 ENDPROC(ia32_sysenter_target)
 
-/*
- * syscall stub including irq exit should be protected against kprobes
- */
-        .pushsection .kprobes.text, "ax"
         # system call handler stub
 ENTRY(system_call)
         RING0_INT_FRAME                 # can't unwind into user space anyway
@@ -691,10 +679,6 @@ syscall_badsys:
         jmp resume_userspace
 END(syscall_badsys)
         CFI_ENDPROC
-/*
- * End of kprobes section
- */
-        .popsection
 
 .macro FIXUP_ESPFIX_STACK
 /*
@@ -781,10 +765,6 @@ common_interrupt:
 ENDPROC(common_interrupt)
         CFI_ENDPROC
 
-/*
- *  Irq entries should be protected against kprobes
- */
-        .pushsection .kprobes.text, "ax"
 #define BUILD_INTERRUPT3(name, nr, fn)  \
 ENTRY(name)                             \
         RING0_INT_FRAME;                \
@@ -961,10 +941,6 @@ ENTRY(spurious_interrupt_bug)
         jmp error_code
         CFI_ENDPROC
 END(spurious_interrupt_bug)
-/*
- * End of kprobes section
- */
-        .popsection
 
 #ifdef CONFIG_XEN
 /* Xen doesn't set %esp to be precisely what the normal sysenter
@@ -1239,11 +1215,6 @@ return_to_handler:
         jmp *%ecx
 #endif
 
-/*
- * Some functions should be protected against kprobes
- */
-        .pushsection .kprobes.text, "ax"
-
 #ifdef CONFIG_TRACING
 ENTRY(trace_page_fault)
         RING0_EC_FRAME
@@ -1453,7 +1424,3 @@ ENTRY(async_page_fault)
 END(async_page_fault)
 #endif
 
-/*
- * End of kprobes section
- */
-        .popsection
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1e96c3628bf2..43bb38951660 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -487,8 +487,6 @@ ENDPROC(native_usergs_sysret64)
         TRACE_IRQS_OFF
         .endm
 
-/* save complete stack frame */
-        .pushsection .kprobes.text, "ax"
 ENTRY(save_paranoid)
         XCPT_FRAME 1 RDI+8
         cld
@@ -517,7 +515,6 @@ ENTRY(save_paranoid)
 1:      ret
         CFI_ENDPROC
 END(save_paranoid)
-        .popsection
 
 /*
  * A newly forked process directly context switches into this address.
@@ -975,10 +972,6 @@ END(interrupt)
         call \func
         .endm
 
-/*
- * Interrupt entry/exit should be protected against kprobes
- */
-        .pushsection .kprobes.text, "ax"
         /*
          * The interrupt stubs push (~vector+0x80) onto the stack and
          * then jump to common_interrupt.
@@ -1113,10 +1106,6 @@ ENTRY(retint_kernel)
 
         CFI_ENDPROC
 END(common_interrupt)
-/*
- * End of kprobes section
- */
-       .popsection
 
 /*
  * APIC interrupts.
@@ -1477,11 +1466,6 @@ apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \
         hyperv_callback_vector hyperv_vector_handler
 #endif /* CONFIG_HYPERV */
 
-/*
- * Some functions should be protected against kprobes
- */
-        .pushsection .kprobes.text, "ax"
-
 paranoidzeroentry_ist debug do_debug DEBUG_STACK
 paranoidzeroentry_ist int3 do_int3 DEBUG_STACK
 paranoiderrorentry stack_segment do_stack_segment
@@ -1898,7 +1882,3 @@ ENTRY(ignore_sysret)
         CFI_ENDPROC
 END(ignore_sysret)
 
-/*
- * End of kprobes section
- */
-        .popsection
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index da7bdaa3ce15..7751b3dee53a 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1065,6 +1065,14 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
         return 0;
 }
 
+bool arch_within_kprobe_blacklist(unsigned long addr)
+{
+        return  (addr >= (unsigned long)__kprobes_text_start &&
+                 addr < (unsigned long)__kprobes_text_end) ||
+                (addr >= (unsigned long)__entry_text_start &&
+                 addr < (unsigned long)__entry_text_end);
+}
+
 int __init arch_init_kprobes(void)
 {
         return 0;
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 925eaf28fca9..cdf9251f8249 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -265,6 +265,7 @@ extern void arch_disarm_kprobe(struct kprobe *p);
 extern int arch_init_kprobes(void);
 extern void show_registers(struct pt_regs *regs);
 extern void kprobes_inc_nmissed_count(struct kprobe *p);
+extern bool arch_within_kprobe_blacklist(unsigned long addr);
 
 struct kprobe_insn_cache {
         struct mutex mutex;
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index ceeadfcabb76..5b5ac76671e7 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -96,9 +96,6 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
 static struct kprobe_blackpoint kprobe_blacklist[] = {
         {"preempt_schedule",},
         {"native_get_debugreg",},
-        {"irq_entries_start",},
-        {"common_interrupt",},
-        {"mcount",},    /* mcount can be called from everywhere */
         {NULL}    /* Terminator */
 };
 
@@ -1324,12 +1321,18 @@ out:
         return ret;
 }
 
+bool __weak arch_within_kprobe_blacklist(unsigned long addr)
+{
+        /* The __kprobes marked functions and entry code must not be probed */
+        return addr >= (unsigned long)__kprobes_text_start &&
+               addr < (unsigned long)__kprobes_text_end;
+}
+
 static int __kprobes in_kprobes_functions(unsigned long addr)
 {
         struct kprobe_blackpoint *kb;
 
-        if (addr >= (unsigned long)__kprobes_text_start &&
-            addr < (unsigned long)__kprobes_text_end)
+        if (arch_within_kprobe_blacklist(addr))
                 return -EINVAL;
         /*
          * If there exists a kprobe_blacklist, verify and