115 lines
3.7 KiB
Diff
115 lines
3.7 KiB
Diff
From 65ff0b7a085b85271ec8fde99f542281b495e3bc Mon Sep 17 00:00:00 2001
|
|
Message-Id: <65ff0b7a085b85271ec8fde99f542281b495e3bc.1495998948.git.fweimer@redhat.com>
|
|
In-Reply-To: <cover.1495998948.git.fweimer@redhat.com>
|
|
References: <cover.1495998948.git.fweimer@redhat.com>
|
|
From: Florian Weimer <fweimer@redhat.com>
|
|
Date: Sun, 28 May 2017 20:57:40 +0200
|
|
Subject: [PATCH 2/3] rtld: Reject overly long LD_PRELOAD path elements
|
|
To: libc-alpha@sourceware.org
|
|
|
|
---
|
|
elf/rtld.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++---------------
|
|
1 file changed, 53 insertions(+), 16 deletions(-)
|
|
|
|
diff --git a/elf/rtld.c b/elf/rtld.c
|
|
index 824b6cf..30f0cae 100644
|
|
--- a/elf/rtld.c
|
|
+++ b/elf/rtld.c
|
|
@@ -99,6 +99,22 @@ uintptr_t __pointer_chk_guard_local
|
|
strong_alias (__pointer_chk_guard_local, __pointer_chk_guard)
|
|
#endif
|
|
|
|
+/* Check that AT_SECURE=0, or that the passed name does not contain
|
|
+ directories and is not overly long. Reject empty names
|
|
+ unconditionally. */
|
|
+static bool
|
|
+dso_name_valid_for_suid (const char *p)
|
|
+{
|
|
+ if (__glibc_unlikely (__libc_enable_secure))
|
|
+ {
|
|
+ /* Ignore pathnames with directories for AT_SECURE=1
|
|
+ programs, and also skip overlong names. */
|
|
+ size_t len = strlen (p);
|
|
+ if (len >= NAME_MAX || memchr (p, '/', len) != NULL)
|
|
+ return false;
|
|
+ }
|
|
+ return *p != '\0';
|
|
+}
|
|
|
|
/* List of auditing DSOs. */
|
|
static struct audit_list
|
|
@@ -716,6 +732,46 @@ static const char *preloadlist attribute_relro;
|
|
/* Nonzero if information about versions has to be printed. */
|
|
static int version_info attribute_relro;
|
|
|
|
+/* The LD_PRELOAD environment variable gives list of libraries
|
|
+ separated by white space or colons that are loaded before the
|
|
+ executable's dependencies and prepended to the global scope list.
|
|
+ (If the binary is running setuid all elements containing a '/' are
|
|
+ ignored since it is insecure.) Return the number of preloads
|
|
+ performed. */
|
|
+unsigned int
|
|
+handle_ld_preload (const char *preloadlist, struct link_map *main_map)
|
|
+{
|
|
+ unsigned int npreloads = 0;
|
|
+ const char *p = preloadlist;
|
|
+#ifdef PATH_MAX
|
|
+ char fname[PATH_MAX];
|
|
+#else
|
|
+ char fname[4096];
|
|
+#endif
|
|
+
|
|
+ while (*p != '\0')
|
|
+ {
|
|
+ /* Split preload list at space/colon. */
|
|
+ size_t len = strcspn (p, " :");
|
|
+ if (len > 0 && len < sizeof(fname))
|
|
+ {
|
|
+ memcpy (fname, p, len);
|
|
+ fname[len] = '\0';
|
|
+ }
|
|
+ else
|
|
+ fname[0] = '\0';
|
|
+
|
|
+ /* Skip over the substring and the following delimiter. */
|
|
+ p += len;
|
|
+ if (*p == ' ' || *p == ':')
|
|
+ ++p;
|
|
+
|
|
+ if (dso_name_valid_for_suid (fname))
|
|
+ npreloads += do_preload (fname, main_map, "LD_PRELOAD");
|
|
+ }
|
|
+ return npreloads;
|
|
+}
|
|
+
|
|
static void
|
|
dl_main (const ElfW(Phdr) *phdr,
|
|
ElfW(Word) phnum,
|
|
@@ -1462,23 +1514,8 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
|
|
|
|
if (__glibc_unlikely (preloadlist != NULL))
|
|
{
|
|
- /* The LD_PRELOAD environment variable gives list of libraries
|
|
- separated by white space or colons that are loaded before the
|
|
- executable's dependencies and prepended to the global scope
|
|
- list. If the binary is running setuid all elements
|
|
- containing a '/' are ignored since it is insecure. */
|
|
- char *list = strdupa (preloadlist);
|
|
- char *p;
|
|
-
|
|
HP_TIMING_NOW (start);
|
|
-
|
|
- /* Prevent optimizing strsep. Speed is not important here. */
|
|
- while ((p = (strsep) (&list, " :")) != NULL)
|
|
- if (p[0] != '\0'
|
|
- && (__builtin_expect (! __libc_enable_secure, 1)
|
|
- || strchr (p, '/') == NULL))
|
|
- npreloads += do_preload (p, main_map, "LD_PRELOAD");
|
|
-
|
|
+ npreloads += handle_ld_preload (preloadlist, main_map);
|
|
HP_TIMING_NOW (stop);
|
|
HP_TIMING_DIFF (diff, start, stop);
|
|
HP_TIMING_ACCUM_NT (load_time, diff);
|
|
--
|
|
2.9.4
|
|
|