[PATCH 2/2] perf/probe: verify instruction/offset in perf before adding a uprobe

[Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>]

Read instructions from the library/executable and verify the
uprobe location for instruction validity and offset into the function.


Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
---

 tools/perf/arch/x86/Makefile           |    4 ++
 tools/perf/arch/x86/util/probe-event.c |   83 ++++++++++++++++++++++++++++++++
 tools/perf/util/include/linux/string.h |    1 
 tools/perf/util/probe-event.c          |   22 ++++++++
 tools/perf/util/probe-event.h          |    2 +
 tools/perf/util/symbol.c               |    2 +
 tools/perf/util/symbol.h               |    1 
 7 files changed, 114 insertions(+), 1 deletions(-)
 create mode 100644 tools/perf/arch/x86/util/probe-event.c

diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile
index 744e629..beec155 100644
--- a/tools/perf/arch/x86/Makefile
+++ b/tools/perf/arch/x86/Makefile
@@ -1,5 +1,9 @@
+BASIC_CFLAGS += -I. -I../../arch/$(ARCH)/include
 ifndef NO_DWARF
 PERF_HAVE_DWARF_REGS := 1
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
 endif
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/probe-event.o
+LIB_OBJS += $(OUTPUT)../../arch/$(ARCH)/lib/inat.o
+LIB_OBJS += $(OUTPUT)../../arch/$(ARCH)/lib/insn.o
diff --git a/tools/perf/arch/x86/util/probe-event.c b/tools/perf/arch/x86/util/probe-event.c
new file mode 100644
index 0000000..7a47b22
--- /dev/null
+++ b/tools/perf/arch/x86/util/probe-event.c
@@ -0,0 +1,83 @@
+/*
+ * probe-event.c : x86 specific perf-probe definition
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2011
+ * Authors:
+ *	Prashanth Nageshappa
+ */
+
+#include <util/types.h>
+#include <util/probe-event.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <asm/insn.h>
+
+/*
+ * Check if a given offset from start of a function is valid or not
+ */
+bool can_probe(char *name, unsigned long long vaddr, unsigned long offset,
+		u8 class)
+{
+	unsigned long long eaddr, saddr;
+	unsigned long fileoffset, readbytes;
+	int fd = 0;
+	bool ret = false;
+	char *buf = NULL;
+	struct insn insn;
+
+	fd = open(name, O_RDONLY);
+	if (fd == -1) {
+		pr_warning("Failed to open %s: %s\n", name, strerror(errno));
+		return ret;
+	}
+	buf = (char *)malloc(offset + MAX_INSN_SIZE);
+	if (buf == NULL) {
+		pr_warning("Failed to allocate memory");
+		goto out;
+	}
+	fileoffset = lseek(fd, vaddr, SEEK_SET);
+	if (fileoffset != vaddr) {
+		pr_warning("Failed to lseek %s: %s\n", name, strerror(errno));
+		goto out;
+	}
+	saddr = (unsigned long long)buf;
+	eaddr = (unsigned long long)buf + offset;
+	readbytes = read(fd, buf, offset + MAX_INSN_SIZE);
+	if (readbytes != offset+16) {
+		pr_warning("Failed to read %s: %s\n", name, strerror(errno));
+		goto out;
+	}
+	while (saddr < eaddr) {
+		insn_init(&insn, (void *)saddr, class - 1);
+		insn_get_length(&insn);
+		saddr += insn.length;
+	}
+	ret = (saddr == eaddr);
+
+out:
+	if (buf)
+		free(buf);
+
+	if (fd)
+		close(fd);
+
+	return ret;
+}
diff --git a/tools/perf/util/include/linux/string.h b/tools/perf/util/include/linux/string.h
index 3b2f590..9d5eb21 100644
--- a/tools/perf/util/include/linux/string.h
+++ b/tools/perf/util/include/linux/string.h
@@ -1 +1,2 @@
 #include <string.h>
+#include <perf.h>
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index b7dec82..a2dd0b5 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2254,6 +2254,17 @@ int show_available_funcs(const char *target, struct strfilter *_filter,
 }

 /*
+ * Check if a given offset from start of a function is valid or not
+ */
+bool __attribute__((weak)) can_probe(char *name __used,
+					unsigned long long vaddr __used,
+					unsigned long offset __used,
+					u8 class __used)
+{
+	return true;
+}
+
+/*
  * uprobe_events only accepts address:
  * Convert function and any offset to address
  */
@@ -2307,7 +2318,16 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)

 	if (map->start > sym->start)
 		vaddr = map->start;
-	vaddr += sym->start + pp->offset + map->pgoff;
+
+	vaddr += sym->start + map->pgoff;
+	if (pp->offset)
+		if ((vaddr+pp->offset > sym->end) ||
+			!can_probe(name, vaddr, pp->offset,
+					map->dso->class)) {
+			pr_err("Failed to insert probe, ensure offset is within function and on insn boundary.\n");
+			return -EINVAL;
+		}
+	vaddr += pp->offset;
 	pp->offset = 0;

 	if (!pev->event) {
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index f9f3de8..e89b1bf 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -137,4 +137,6 @@ extern int show_available_funcs(const char *module, struct strfilter *filter,
 /* Maximum index number of event-name postfix */
 #define MAX_EVENT_INDEX	1024

+extern bool can_probe(char *name, unsigned long long vaddr,
+			unsigned long offset, u8 type);
 #endif /*_PROBE_EVENT_H */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index caaf75a..be58b06 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1184,6 +1184,7 @@ static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
 		goto out_close;
 	}

+	dso->class = gelf_getclass(elf);
 	if (gelf_getehdr(elf, &ehdr) == NULL) {
 		pr_debug("%s: cannot get elf header.\n", __func__);
 		goto out_elf_end;
@@ -1326,6 +1327,7 @@ static int dso__load_sym(struct dso *dso, struct map *map, const char *name,
 				curr_dso->kernel = dso->kernel;
 				curr_dso->long_name = dso->long_name;
 				curr_dso->long_name_len = dso->long_name_len;
+				curr_dso->class = dso->class;
 				curr_map = map__new2(start, curr_dso,
 						     map->type);
 				if (curr_map == NULL) {
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 9e7742c..1d0cc28 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -174,6 +174,7 @@ struct dso {
 	char	 	 *long_name;
 	u16		 long_name_len;
 	u16		 short_name_len;
+	u8		 class;
 	char		 name[0];
 };