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authorFlorian Weimer <fweimer@redhat.com>2014-05-12 15:24:12 +0200
committerFlorian Weimer <fweimer@redhat.com>2014-07-10 16:29:55 +0200
commit4e8f95a0df7c2300b830ec12c0ae1e161bc8a8a3 (patch)
tree9d423c33dd357da456df66249c30e086f25fb0dd /locale
parentd183645616b0533b3acee28f1a95570bffbdf50f (diff)
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_nl_find_locale: Improve handling of crafted locale names [BZ #17137]
Prevent directory traversal in locale-related environment variables (CVE-2014-0475).
Diffstat (limited to 'locale')
-rw-r--r--locale/findlocale.c74
1 files changed, 61 insertions, 13 deletions
diff --git a/locale/findlocale.c b/locale/findlocale.c
index bbaf708..22e8b53 100644
--- a/locale/findlocale.c
+++ b/locale/findlocale.c
@@ -17,6 +17,7 @@
<http://www.gnu.org/licenses/>. */
#include <assert.h>
+#include <errno.h>
#include <locale.h>
#include <stdlib.h>
#include <string.h>
@@ -57,6 +58,45 @@ struct loaded_l10nfile *_nl_locale_file_list[__LC_LAST];
const char _nl_default_locale_path[] attribute_hidden = LOCALEDIR;
+/* Checks if the name is actually present, that is, not NULL and not
+ empty. */
+static inline int
+name_present (const char *name)
+{
+ return name != NULL && name[0] != '\0';
+}
+
+/* Checks that the locale name neither extremely long, nor contains a
+ ".." path component (to prevent directory traversal). */
+static inline int
+valid_locale_name (const char *name)
+{
+ /* Not set. */
+ size_t namelen = strlen (name);
+ /* Name too long. The limit is arbitrary and prevents stack overflow
+ issues later. */
+ if (__glibc_unlikely (namelen > 255))
+ return 0;
+ /* Directory traversal attempt. */
+ static const char slashdot[4] = {'/', '.', '.', '/'};
+ if (__glibc_unlikely (memmem (name, namelen,
+ slashdot, sizeof (slashdot)) != NULL))
+ return 0;
+ if (namelen == 2 && __glibc_unlikely (name[0] == '.' && name [1] == '.'))
+ return 0;
+ if (namelen >= 3
+ && __glibc_unlikely (((name[0] == '.'
+ && name[1] == '.'
+ && name[2] == '/')
+ || (name[namelen - 3] == '/'
+ && name[namelen - 2] == '.'
+ && name[namelen - 1] == '.'))))
+ return 0;
+ /* If there is a slash in the name, it must start with one. */
+ if (__glibc_unlikely (memchr (name, '/', namelen) != NULL) && name[0] != '/')
+ return 0;
+ return 1;
+}
struct __locale_data *
internal_function
@@ -65,7 +105,7 @@ _nl_find_locale (const char *locale_path, size_t locale_path_len,
{
int mask;
/* Name of the locale for this category. */
- char *loc_name;
+ char *loc_name = (char *) *name;
const char *language;
const char *modifier;
const char *territory;
@@ -73,31 +113,39 @@ _nl_find_locale (const char *locale_path, size_t locale_path_len,
const char *normalized_codeset;
struct loaded_l10nfile *locale_file;
- if ((*name)[0] == '\0')
+ if (loc_name[0] == '\0')
{
/* The user decides which locale to use by setting environment
variables. */
- *name = getenv ("LC_ALL");
- if (*name == NULL || (*name)[0] == '\0')
- *name = getenv (_nl_category_names.str
+ loc_name = getenv ("LC_ALL");
+ if (!name_present (loc_name))
+ loc_name = getenv (_nl_category_names.str
+ _nl_category_name_idxs[category]);
- if (*name == NULL || (*name)[0] == '\0')
- *name = getenv ("LANG");
+ if (!name_present (loc_name))
+ loc_name = getenv ("LANG");
+ if (!name_present (loc_name))
+ loc_name = (char *) _nl_C_name;
}
- if (*name == NULL || (*name)[0] == '\0'
- || (__builtin_expect (__libc_enable_secure, 0)
- && strchr (*name, '/') != NULL))
- *name = (char *) _nl_C_name;
+ /* We used to fall back to the C locale if the name contains a slash
+ character '/', but we now check for directory traversal in
+ valid_locale_name, so this is no longer necessary. */
- if (__builtin_expect (strcmp (*name, _nl_C_name), 1) == 0
- || __builtin_expect (strcmp (*name, _nl_POSIX_name), 1) == 0)
+ if (__builtin_expect (strcmp (loc_name, _nl_C_name), 1) == 0
+ || __builtin_expect (strcmp (loc_name, _nl_POSIX_name), 1) == 0)
{
/* We need not load anything. The needed data is contained in
the library itself. */
*name = (char *) _nl_C_name;
return _nl_C[category];
}
+ else if (!valid_locale_name (loc_name))
+ {
+ __set_errno (EINVAL);
+ return NULL;
+ }
+
+ *name = loc_name;
/* We really have to load some data. First we try the archive,
but only if there was no LOCPATH environment variable specified. */