From: Dave Anderson <anderson@redhat.com>
Date: Wed, 23 Jan 2008 15:18:48 -0500
Subject: [misc] kprobes: support kretprobe blacklist
Message-id: 4797A128.1000702@redhat.com
O-Subject: [RHEL5.2 PATCH 2/4] kprobes: BZ #232489: need kprobes improvement patches
Bugzilla: 232489

BZ #232489: need kprobes improvement patches
https://bugzilla.redhat.com/show_bug.cgi?id=232489
linux-2.6.git-f438d914b220051d4cbc65cbc5d98e163c85c93b

Backport of this commit, which required the paring down of
the file list to not include unsupported RHEL5 architectures
and to deal with the upstream collusion of the i386 and x86_64
directories.  It touches files for all supported architectures,
but only affects x86 and x86_64:

   commit f438d914b220051d4cbc65cbc5d98e163c85c93b
   Author: Masami Hiramatsu <mhiramat@redhat.com>
   Date:   Tue Oct 16 01:27:49 2007 -0700

   kprobes: support kretprobe blacklist

   Introduce architecture dependent kretprobe blacklists to prohibit users
   from inserting return probes on the function in which kprobes can be
   inserted but kretprobes can not.

   This patch also removes "__kprobes" mark from "__switch_to" on x86_64 and
   registers "__switch_to" to the blacklist on x86-64, because that mark is to
   prohibit user from inserting only kretprobe.

   Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
   Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
   Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
   Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
   Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Tested by me on x86 and x86_64.

diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index afe6505..fbcad23 100644
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -41,6 +41,13 @@ void jprobe_return_end(void);
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
+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);
+
 /* insert a jmp code */
 static __always_inline void set_jmp_op(void *from, void *to)
 {
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 4f87e63..570d938 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -40,6 +40,8 @@ extern void jprobe_inst_return(void);
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
+struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
+
 enum instruction_type {A, I, M, F, B, L, X, u};
 static enum instruction_type bundle_encoding[32][3] = {
   { M, I, I },				/* 00 */
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index cd65c36..9cb1f9d 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -38,6 +38,8 @@
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
+struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
+
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
 	int ret = 0;
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 66a16a8..6363356 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -33,6 +33,8 @@
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
+struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
+
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
 	/* Make sure the probe isn't going on a difficult instruction */
diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index ffc73ac..ad9d2f4 100644
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -49,6 +49,13 @@ static void __kprobes arch_copy_kprobe(struct kprobe *p);
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
+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);
+
 /*
  * returns non-zero if opcode modifies the interrupt flag.
  */
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index 24836bd..cce5327 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -510,7 +510,7 @@ out:
  *
  * Kprobes not supported here. Set the probe on schedule instead.
  */
-__kprobes struct task_struct *
+struct task_struct *
 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 {
 	struct thread_struct *prev = &prev_p->thread,
diff --git a/include/asm-i386/kprobes.h b/include/asm-i386/kprobes.h
index 8774d06..912d8a3 100644
--- a/include/asm-i386/kprobes.h
+++ b/include/asm-i386/kprobes.h
@@ -47,6 +47,8 @@ typedef u8 kprobe_opcode_t;
 #define  ARCH_INACTIVE_KPROBE_COUNT 0
 #define flush_insn_slot(p)	do { } while (0)
 
+extern const int kretprobe_blacklist_size;
+
 void arch_remove_kprobe(struct kprobe *p);
 void kretprobe_trampoline(void);
 
diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h
index 1b45b71..8301061 100644
--- a/include/asm-ia64/kprobes.h
+++ b/include/asm-ia64/kprobes.h
@@ -83,6 +83,7 @@ struct kprobe_ctlblk {
 #define JPROBE_ENTRY(pentry)	(kprobe_opcode_t *)pentry
 
 #define ARCH_SUPPORTS_KRETPROBES
+#define kretprobe_blacklist_size 0
 #define  ARCH_INACTIVE_KPROBE_COUNT 1
 
 #define SLOT0_OPCODE_SHIFT	(37)
diff --git a/include/asm-powerpc/kprobes.h b/include/asm-powerpc/kprobes.h
index 3aa8cd5..4522a15 100644
--- a/include/asm-powerpc/kprobes.h
+++ b/include/asm-powerpc/kprobes.h
@@ -80,6 +80,7 @@ typedef unsigned int kprobe_opcode_t;
 #define ARCH_SUPPORTS_KRETPROBES
 #define  ARCH_INACTIVE_KPROBE_COUNT 1
 #define flush_insn_slot(p)	do { } while (0)
+#define kretprobe_blacklist_size 0
 
 void kretprobe_trampoline(void);
 extern void arch_remove_kprobe(struct kprobe *p);
diff --git a/include/asm-s390/kprobes.h b/include/asm-s390/kprobes.h
index 2fef8d6..022dd9a 100644
--- a/include/asm-s390/kprobes.h
+++ b/include/asm-s390/kprobes.h
@@ -49,6 +49,7 @@ typedef u16 kprobe_opcode_t;
 #define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry)
 
 #define ARCH_SUPPORTS_KRETPROBES
+#define kretprobe_blacklist_size 0
 #define ARCH_INACTIVE_KPROBE_COUNT 0
 #define flush_insn_slot(p)	do { } while (0)
 
diff --git a/include/asm-x86_64/kprobes.h b/include/asm-x86_64/kprobes.h
index cf53178..63dfa21 100644
--- a/include/asm-x86_64/kprobes.h
+++ b/include/asm-x86_64/kprobes.h
@@ -43,6 +43,7 @@ typedef u8 kprobe_opcode_t;
 
 #define JPROBE_ENTRY(pentry)	(kprobe_opcode_t *)pentry
 #define ARCH_SUPPORTS_KRETPROBES
+extern const int kretprobe_blacklist_size;
 #define  ARCH_INACTIVE_KPROBE_COUNT 1
 
 void kretprobe_trampoline(void);
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index a5c5a0c..5fd9323 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -157,6 +157,12 @@ struct kretprobe_instance {
 	struct task_struct *task;
 };
 
+struct kretprobe_blackpoint {
+	const char *name;
+	void *addr;
+};
+extern struct kretprobe_blackpoint kretprobe_blacklist[];
+
 extern spinlock_t kretprobe_lock;
 extern struct mutex kprobe_mutex;
 extern int arch_prepare_kprobe(struct kprobe *p);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f66b8e6..419dab6 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -649,6 +649,18 @@ int __kprobes register_kretprobe(struct kretprobe *rp)
 	int ret = 0;
 	struct kretprobe_instance *inst;
 	int i;
+	void *addr = rp->kp.addr;
+
+	if (kretprobe_blacklist_size) {
+		if (addr == NULL)
+			kprobe_lookup_name(rp->kp.symbol_name, addr);
+		addr += rp->kp.offset;
+
+		for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+			if (kretprobe_blacklist[i].addr == addr)
+				return -EINVAL;
+		}
+	}
 
 	rp->kp.pre_handler = pre_handler_kretprobe;
 	rp->kp.post_handler = NULL;
@@ -718,6 +730,18 @@ static int __init init_kprobes(void)
 		INIT_HLIST_HEAD(&kprobe_table[i]);
 		INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
 	}
+
+	if (kretprobe_blacklist_size) {
+		/* lookup the function address from its name */
+		for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+			kprobe_lookup_name(kretprobe_blacklist[i].name,
+					   kretprobe_blacklist[i].addr);
+			if (!kretprobe_blacklist[i].addr)
+				printk("kretprobe: lookup failed: %s\n",
+					kretprobe_blacklist[i].name);
+		}
+	}
+
 	atomic_set(&kprobe_count, 0);
 
 	err = arch_init_kprobes();