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



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