Author: markj
Date: Tue Dec 6 04:18:09 2016
New Revision: 309593
URL: https://svnweb.freebsd.org/changeset/base/309593
Log:
libproc: Improve .gnu_debuglink support.
As of r278658 libproc looks for debug files under /usr/lib/debug and will
use them if available. This change fleshes out that support a bit further:
- Check for a .gnu_debuglink section and use the file name specified
there if one is present.
- Validate external debug files with the CRC in the .gnu_debuglink
section so as to avoid using stale or corrupt debug files.
- Search for debug files in the directory containing the referencing
object or in the .debug subdirectory, as GDB does.
Added:
head/lib/libproc/crc32.c (contents, props changed)
head/lib/libproc/crc32.h (contents, props changed)
Modified:
head/lib/libproc/Makefile
head/lib/libproc/proc_sym.c
Modified: head/lib/libproc/Makefile
==============================================================================
--- head/lib/libproc/Makefile Tue Dec 6 04:14:20 2016 (r309592)
+++ head/lib/libproc/Makefile Tue Dec 6 04:18:09 2016 (r309593)
@@ -5,7 +5,8 @@
PACKAGE=lib${LIB}
LIB= proc
-SRCS= proc_bkpt.c \
+SRCS= crc32.c \
+ proc_bkpt.c \
proc_create.c \
proc_regs.c \
proc_sym.c \
Added: head/lib/libproc/crc32.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/lib/libproc/crc32.c Tue Dec 6 04:18:09 2016 (r309593)
@@ -0,0 +1,57 @@
+/*-
+ * COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or
+ * code or tables extracted from it, as desired without restriction.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <stdint.h>
+
+#include <crc32.h>
+
+uint32_t crc32_tab[] = {
+ 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
+ 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+ 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
+ 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+ 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+ 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+ 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
+ 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+ 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
+ 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+ 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
+ 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+ 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
+ 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+ 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+ 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+ 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
+ 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+ 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
+ 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+ 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
+ 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+ 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
+ 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+ 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+ 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+ 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
+ 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+ 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
+ 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+ 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
+ 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+ 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
+ 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+ 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+ 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+ 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
+ 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+ 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
+ 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+ 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
+ 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+ 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
Added: head/lib/libproc/crc32.h
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/lib/libproc/crc32.h Tue Dec 6 04:18:09 2016 (r309593)
@@ -0,0 +1,28 @@
+/*-
+ * COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or
+ * code or tables extracted from it, as desired without restriction.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _CRC32_H_
+#define _CRC32_H_
+
+#include <stdint.h> /* uint32_t */
+#include <stdlib.h> /* size_t */
+
+extern uint32_t crc32_tab[];
+
+static __inline uint32_t
+crc32(const void *buf, size_t size)
+{
+ const uint8_t *p = buf;
+ uint32_t crc;
+
+ crc = ~0U;
+ while (size--)
+ crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8);
+ return (crc ^ ~0U);
+}
+
+#endif /* !_CRC32_H_ */
Modified: head/lib/libproc/proc_sym.c
==============================================================================
--- head/lib/libproc/proc_sym.c Tue Dec 6 04:14:20 2016 (r309592)
+++ head/lib/libproc/proc_sym.c Tue Dec 6 04:18:09 2016 (r309593)
@@ -51,8 +51,11 @@ __FBSDID("$FreeBSD$");
#endif
#include <libutil.h>
+#include "crc32.h"
#include "_libproc.h"
+#define PATH_DEBUG_DIR "/usr/lib/debug"
+
#ifdef NO_CTF
typedef struct ctf_file ctf_file_t;
#endif
@@ -63,6 +66,22 @@ extern char *__cxa_demangle(const char *
static void proc_rdl2prmap(rd_loadobj_t *, prmap_t *);
+static int
+crc32_file(int fd, uint32_t *crc)
+{
+ uint8_t buf[PAGE_SIZE], *p;
+ size_t n;
+
+ *crc = ~0;
+ while ((n = read(fd, buf, sizeof(buf))) > 0) {
+ p = &buf[0];
+ while (n-- > 0)
+ *crc = crc32_tab[(*crc ^ *p++) & 0xff] ^ (*crc >> 8);
+ }
+ *crc = ~*crc;
+ return (n);
+}
+
static void
demangle(const char *symbol, char *buf, size_t len)
{
@@ -83,18 +102,150 @@ fail:
}
static int
-find_dbg_obj(const char *path)
+open_debug_file(char *path, const char *debugfile, uint32_t crc)
{
+ size_t n;
+ uint32_t compcrc;
int fd;
- char dbg_path[PATH_MAX];
- snprintf(dbg_path, sizeof(dbg_path),
- "/usr/lib/debug/%s.debug", path);
- fd = open(dbg_path, O_RDONLY);
- if (fd >= 0)
+ fd = -1;
+ if ((n = strlcat(path, "/", PATH_MAX)) >= PATH_MAX)
return (fd);
- else
- return (open(path, O_RDONLY));
+ if (strlcat(path, debugfile, PATH_MAX) >= PATH_MAX)
+ goto out;
+ if ((fd = open(path, O_RDONLY | O_CLOEXEC)) < 0)
+ goto out;
+ if (crc32_file(fd, &compcrc) != 0 || crc != compcrc) {
+ DPRINTFX("ERROR: CRC32 mismatch for %s", path);
+ (void)close(fd);
+ fd = -1;
+ }
+out:
+ path[n] = '\0';
+ return (fd);
+}
+
+/*
+ * Obtain an ELF descriptor for the specified mapped object. If a GNU debuglink
+ * section is present, a descriptor for the corresponding debug file is
+ * returned.
+ */
+static int
+open_object(prmap_t *map, Elf **elfp, int *fdp)
+{
+ char path[PATH_MAX];
+ GElf_Shdr shdr;
+ Elf *e, *e2;
+ Elf_Data *data;
+ Elf_Scn *scn;
+ const char *debugfile, *scnname;
+ size_t ndx;
+ uint32_t crc;
+ int fd, fd2;
+
+ if ((fd = open(map->pr_mapname, O_RDONLY | O_CLOEXEC)) < 0) {
+ DPRINTF("ERROR: open %s failed", map->pr_mapname);
+ return (-1);
+ }
+ if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
+ DPRINTFX("ERROR: elf_begin() failed: %s", elf_errmsg(-1));
+ goto err;
+ }
+
+ scn = NULL;
+ while ((scn = elf_nextscn(e, scn)) != NULL) {
+ if (gelf_getshdr(scn, &shdr) != &shdr) {
+ DPRINTFX("ERROR: gelf_getshdr failed: %s",
+ elf_errmsg(-1));
+ goto err;
+ }
+ if (shdr.sh_type != SHT_PROGBITS)
+ continue;
+ if (elf_getshdrstrndx(e, &ndx) != 0) {
+ DPRINTFX("ERROR: elf_getshdrstrndx failed: %s",
+ elf_errmsg(-1));
+ goto err;
+ }
+ if ((scnname = elf_strptr(e, ndx, shdr.sh_name)) == NULL)
+ continue;
+
+ if (strcmp(scnname, ".gnu_debuglink") == 0)
+ break;
+ }
+ if (scn == NULL)
+ goto internal;
+
+ if ((data = elf_getdata(scn, NULL)) == NULL) {
+ DPRINTFX("ERROR: elf_getdata failed: %s", elf_errmsg(-1));
+ goto err;
+ }
+
+ /*
+ * The data contains a null-terminated file name followed by a 4-byte
+ * CRC.
+ */
+ if (data->d_size < sizeof(crc) + 1) {
+ DPRINTFX("ERROR: debuglink section is too small (%zd bytes)",
+ data->d_size);
+ goto internal;
+ }
+ if (strnlen(data->d_buf, data->d_size) >= data->d_size - sizeof(crc)) {
+ DPRINTFX("ERROR: no null-terminator in gnu_debuglink section");
+ goto internal;
+ }
+
+ debugfile = data->d_buf;
+ memcpy(&crc, (char *)data->d_buf + data->d_size - sizeof(crc),
+ sizeof(crc));
+
+ /*
+ * Search for the debug file using the algorithm described in the gdb
+ * documentation:
+ * - look in the directory containing the object,
+ * - look in the subdirectory ".debug" of the directory containing the
+ * object,
+ * - look in the global debug directories (currently /usr/lib/debug).
+ */
+ (void)strlcpy(path, map->pr_mapname, sizeof(path));
+ (void)dirname(path);
+
+ if ((fd2 = open_debug_file(path, debugfile, crc)) >= 0)
+ goto external;
+
+ if (strlcat(path, "/.debug", sizeof(path)) < sizeof(path) &&
+ (fd2 = open_debug_file(path, debugfile, crc)) >= 0)
+ goto external;
+
+ (void)snprintf(path, sizeof(path), PATH_DEBUG_DIR);
+ if (strlcat(path, map->pr_mapname, sizeof(path)) < sizeof(path)) {
+ (void)dirname(path);
+ if ((fd2 = open_debug_file(path, debugfile, crc)) >= 0)
+ goto external;
+ }
+
+internal:
+ /* We didn't find a debug file, just return the object's descriptor. */
+ *elfp = e;
+ *fdp = fd;
+ return (0);
+
+external:
+ if ((e2 = elf_begin(fd2, ELF_C_READ, NULL)) == NULL) {
+ DPRINTFX("ERROR: elf_begin failed: %s", elf_errmsg(-1));
+ (void)close(fd2);
+ goto err;
+ }
+ (void)elf_end(e);
+ (void)close(fd);
+ *elfp = e2;
+ *fdp = fd2;
+ return (0);
+
+err:
+ if (e != NULL)
+ (void)elf_end(e);
+ (void)close(fd);
+ return (-1);
}
static void
@@ -308,19 +459,17 @@ proc_addr2sym(struct proc_handle *p, uin
u_long symtabstridx = 0, dynsymstridx = 0;
int fd, error = -1;
- if ((map = proc_addr2map(p, addr)) == NULL)
+ if ((map = proc_addr2map(p, addr)) == NULL) {
+ DPRINTFX("ERROR: proc_addr2map failed to resolve 0x%jx", addr);
return (-1);
- if ((fd = find_dbg_obj(map->pr_mapname)) < 0) {
- DPRINTF("ERROR: open %s failed", map->pr_mapname);
- goto err0;
}
- if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
- DPRINTFX("ERROR: elf_begin() failed: %s", elf_errmsg(-1));
- goto err1;
+ if (open_object(map, &e, &fd) != 0) {
+ DPRINTFX("ERROR: failed to open object %s", map->pr_mapname);
+ return (-1);
}
if (gelf_getehdr(e, &ehdr) == NULL) {
DPRINTFX("ERROR: gelf_getehdr() failed: %s", elf_errmsg(-1));
- goto err2;
+ goto err;
}
/*
@@ -354,15 +503,13 @@ proc_addr2sym(struct proc_handle *p, uin
error = lookup_addr(e, symtabscn, symtabstridx, off, addr, &s, symcopy);
if (error != 0)
- goto err2;
+ goto err;
out:
demangle(s, name, namesz);
-err2:
- elf_end(e);
-err1:
- close(fd);
-err0:
+err:
+ (void)elf_end(e);
+ (void)close(fd);
free(map);
return (error);
}
@@ -455,21 +602,18 @@ proc_name2sym(struct proc_handle *p, con
int fd, error = -1;
if ((map = proc_name2map(p, object)) == NULL) {
- DPRINTFX("ERROR: couldn't find object %s", object);
- goto err0;
- }
- if ((fd = find_dbg_obj(map->pr_mapname)) < 0) {
- DPRINTF("ERROR: open %s failed", map->pr_mapname);
- goto err0;
+ DPRINTFX("ERROR: proc_name2map failed to resolve %s", object);
+ return (-1);
}
- if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
- DPRINTFX("ERROR: elf_begin() failed: %s", elf_errmsg(-1));
- goto err1;
+ if (open_object(map, &e, &fd) != 0) {
+ DPRINTFX("ERROR: failed to open object %s", map->pr_mapname);
+ return (-1);
}
if (gelf_getehdr(e, &ehdr) == NULL) {
DPRINTFX("ERROR: gelf_getehdr() failed: %s", elf_errmsg(-1));
- goto err2;
+ goto err;
}
+
/*
* Find the index of the STRTAB and SYMTAB sections to locate
* symbol names.
@@ -505,13 +649,10 @@ out:
off = ehdr.e_type == ET_EXEC ? 0 : map->pr_vaddr;
symcopy->st_value += off;
-err2:
- elf_end(e);
-err1:
- close(fd);
-err0:
+err:
+ (void)elf_end(e);
+ (void)close(fd);
free(map);
-
return (error);
}
@@ -543,7 +684,7 @@ proc_iter_symbyaddr(struct proc_handle *
Elf *e;
int i, fd;
prmap_t *map;
- Elf_Scn *scn, *foundscn = NULL;
+ Elf_Scn *scn, *foundscn;
Elf_Data *data;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
@@ -552,24 +693,22 @@ proc_iter_symbyaddr(struct proc_handle *
char *s;
int error = -1;
- if ((map = proc_name2map(p, object)) == NULL)
+ if ((map = proc_name2map(p, object)) == NULL) {
+ DPRINTFX("ERROR: proc_name2map failed to resolve %s", object);
return (-1);
- if ((fd = find_dbg_obj(map->pr_mapname)) < 0) {
- DPRINTF("ERROR: open %s failed", map->pr_mapname);
- goto err0;
}
- if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
- DPRINTFX("ERROR: elf_begin() failed: %s", elf_errmsg(-1));
- goto err1;
+ if (open_object(map, &e, &fd) != 0) {
+ DPRINTFX("ERROR: failed to open object %s", map->pr_mapname);
+ return (-1);
}
if (gelf_getehdr(e, &ehdr) == NULL) {
DPRINTFX("ERROR: gelf_getehdr() failed: %s", elf_errmsg(-1));
- goto err2;
+ goto err;
}
/*
* Find the section we are looking for.
*/
- scn = NULL;
+ foundscn = scn = NULL;
while ((scn = elf_nextscn(e, scn)) != NULL) {
gelf_getshdr(scn, &shdr);
if (which == PR_SYMTAB &&
@@ -587,7 +726,7 @@ proc_iter_symbyaddr(struct proc_handle *
stridx = shdr.sh_link;
if ((data = elf_getdata(foundscn, NULL)) == NULL) {
DPRINTFX("ERROR: elf_getdata() failed: %s", elf_errmsg(-1));
- goto err2;
+ goto err;
}
for (i = 0; gelf_getsym(data, i, &sym) != NULL; i++) {
if (GELF_ST_BIND(sym.st_info) == STB_LOCAL &&
@@ -618,14 +757,12 @@ proc_iter_symbyaddr(struct proc_handle *
if (ehdr.e_type != ET_EXEC)
sym.st_value += map->pr_vaddr;
if ((error = (*func)(cd, &sym, s)) != 0)
- goto err2;
+ goto err;
}
error = 0;
-err2:
+err:
elf_end(e);
-err1:
close(fd);
-err0:
free(map);
return (error);
}
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