210 lines
6.6 KiB
Diff
210 lines
6.6 KiB
Diff
From ba67ba3275d47e0080f0e5f09d9f5102c000c97e Mon Sep 17 00:00:00 2001
|
|
Message-Id: <ba67ba3275d47e0080f0e5f09d9f5102c000c97e.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 20:44:52 +0200
|
|
Subject: [PATCH 3/3] rtld: Reject overly long LD_AUDIT path elements
|
|
To: libc-alpha@sourceware.org
|
|
|
|
Also only process the last LD_AUDIT entry.
|
|
---
|
|
elf/rtld.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++---------
|
|
1 file changed, 95 insertions(+), 15 deletions(-)
|
|
|
|
diff --git a/elf/rtld.c b/elf/rtld.c
|
|
index 30f0cae..89d8573 100644
|
|
--- a/elf/rtld.c
|
|
+++ b/elf/rtld.c
|
|
@@ -116,13 +116,95 @@ dso_name_valid_for_suid (const char *p)
|
|
return *p != '\0';
|
|
}
|
|
|
|
-/* List of auditing DSOs. */
|
|
+/* LD_AUDIT variable contents. Must be processed before the
|
|
+ audit_list below. */
|
|
+const char *audit_list_string;
|
|
+
|
|
+/* Cyclic list of auditing DSOs. audit_list->next is the first
|
|
+ element. */
|
|
static struct audit_list
|
|
{
|
|
const char *name;
|
|
struct audit_list *next;
|
|
} *audit_list;
|
|
|
|
+/* Iterator for audit_list_string followed by audit_list. */
|
|
+struct audit_list_iter
|
|
+{
|
|
+ /* Tail of audit_list_string still needing processing, or NULL. */
|
|
+ const char *audit_list_tail;
|
|
+
|
|
+ /* The list element returned in the previous iteration. NULL before
|
|
+ the first element. */
|
|
+ struct audit_list *previous;
|
|
+
|
|
+ /* Scratch buffer for returning a name which is part of
|
|
+ audit_list_string. */
|
|
+#ifdef PATH_MAX
|
|
+ char fname[PATH_MAX];
|
|
+#else
|
|
+ char fname[4096];
|
|
+#endif
|
|
+};
|
|
+
|
|
+/* Initialize an audit list iterator. */
|
|
+static void
|
|
+audit_list_iter_init (struct audit_list_iter *iter)
|
|
+{
|
|
+ iter->audit_list_tail = audit_list_string;
|
|
+ iter->previous = NULL;
|
|
+}
|
|
+
|
|
+/* Iterate through both audit_list_string and audit_list. */
|
|
+static const char *
|
|
+audit_list_iter_next (struct audit_list_iter *iter)
|
|
+{
|
|
+ if (iter->audit_list_tail != NULL)
|
|
+ {
|
|
+ /* First iterate over audit_list_string. */
|
|
+ while (*iter->audit_list_tail != '\0')
|
|
+ {
|
|
+ /* Split audit list at colon. */
|
|
+ size_t len = strcspn (iter->audit_list_tail, ":");
|
|
+ if (len > 0 && len < sizeof(iter->fname))
|
|
+ {
|
|
+ memcpy (iter->fname, iter->audit_list_tail, len);
|
|
+ iter->fname[len] = '\0';
|
|
+ }
|
|
+ else
|
|
+ /* Do not return this name to the caller. */
|
|
+ iter->fname[0] = '\0';
|
|
+
|
|
+ /* Skip over the substring and the following delimiter. */
|
|
+ iter->audit_list_tail += len;
|
|
+ if (*iter->audit_list_tail == ':')
|
|
+ ++iter->audit_list_tail;
|
|
+
|
|
+ /* If the name is valid, return it. */
|
|
+ if (dso_name_valid_for_suid (iter->fname))
|
|
+ return iter->fname;
|
|
+ /* Otherwise, wrap around and try the next name. */
|
|
+ }
|
|
+ /* Fall through to the procesing of audit_list. */
|
|
+ }
|
|
+
|
|
+ if (iter->previous == NULL)
|
|
+ {
|
|
+ if (audit_list == NULL)
|
|
+ /* No pre-parsed audit list. */
|
|
+ return NULL;
|
|
+ /* Start of audit list. The first list element is at
|
|
+ audit_list->next (cyclic list). */
|
|
+ iter->previous = audit_list->next;
|
|
+ return iter->previous->name;
|
|
+ }
|
|
+ if (iter->previous == audit_list)
|
|
+ /* Cyclic list wrap-around. */
|
|
+ return NULL;
|
|
+ iter->previous = iter->previous->next;
|
|
+ return iter->previous->name;
|
|
+}
|
|
+
|
|
#ifndef HAVE_INLINED_SYSCALLS
|
|
/* Set nonzero during loading and initialization of executable and
|
|
libraries, cleared before the executable's entry point runs. This
|
|
@@ -1290,11 +1368,13 @@ of this helper program; chances are you did not intend to run this program.\n\
|
|
GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
|
|
|
|
/* If we have auditing DSOs to load, do it now. */
|
|
- if (__glibc_unlikely (audit_list != NULL))
|
|
+ bool need_security_init = true;
|
|
+ if (__glibc_unlikely (audit_list != NULL)
|
|
+ || __glibc_unlikely (audit_list_string != NULL))
|
|
{
|
|
- /* Iterate over all entries in the list. The order is important. */
|
|
struct audit_ifaces *last_audit = NULL;
|
|
- struct audit_list *al = audit_list->next;
|
|
+ struct audit_list_iter al_iter;
|
|
+ audit_list_iter_init (&al_iter);
|
|
|
|
/* Since we start using the auditing DSOs right away we need to
|
|
initialize the data structures now. */
|
|
@@ -1305,9 +1385,14 @@ of this helper program; chances are you did not intend to run this program.\n\
|
|
use different values (especially the pointer guard) and will
|
|
fail later on. */
|
|
security_init ();
|
|
+ need_security_init = false;
|
|
|
|
- do
|
|
+ while (true)
|
|
{
|
|
+ const char *name = audit_list_iter_next (&al_iter);
|
|
+ if (name == NULL)
|
|
+ break;
|
|
+
|
|
int tls_idx = GL(dl_tls_max_dtv_idx);
|
|
|
|
/* Now it is time to determine the layout of the static TLS
|
|
@@ -1316,7 +1401,7 @@ of this helper program; chances are you did not intend to run this program.\n\
|
|
no DF_STATIC_TLS bit is set. The reason is that we know
|
|
glibc will use the static model. */
|
|
struct dlmopen_args dlmargs;
|
|
- dlmargs.fname = al->name;
|
|
+ dlmargs.fname = name;
|
|
dlmargs.map = NULL;
|
|
|
|
const char *objname;
|
|
@@ -1329,7 +1414,7 @@ of this helper program; chances are you did not intend to run this program.\n\
|
|
not_loaded:
|
|
_dl_error_printf ("\
|
|
ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
|
|
- al->name, err_str);
|
|
+ name, err_str);
|
|
if (malloced)
|
|
free ((char *) err_str);
|
|
}
|
|
@@ -1433,10 +1518,7 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
|
|
goto not_loaded;
|
|
}
|
|
}
|
|
-
|
|
- al = al->next;
|
|
}
|
|
- while (al != audit_list->next);
|
|
|
|
/* If we have any auditing modules, announce that we already
|
|
have two objects loaded. */
|
|
@@ -1700,7 +1782,7 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
|
|
if (tcbp == NULL)
|
|
tcbp = init_tls ();
|
|
|
|
- if (__glibc_likely (audit_list == NULL))
|
|
+ if (__glibc_likely (need_security_init))
|
|
/* Initialize security features. But only if we have not done it
|
|
earlier. */
|
|
security_init ();
|
|
@@ -2331,9 +2413,7 @@ process_dl_audit (char *str)
|
|
char *p;
|
|
|
|
while ((p = (strsep) (&str, ":")) != NULL)
|
|
- if (p[0] != '\0'
|
|
- && (__builtin_expect (! __libc_enable_secure, 1)
|
|
- || strchr (p, '/') == NULL))
|
|
+ if (dso_name_valid_for_suid (p))
|
|
{
|
|
/* This is using the local malloc, not the system malloc. The
|
|
memory can never be freed. */
|
|
@@ -2397,7 +2477,7 @@ process_envvars (enum mode *modep)
|
|
break;
|
|
}
|
|
if (memcmp (envline, "AUDIT", 5) == 0)
|
|
- process_dl_audit (&envline[6]);
|
|
+ audit_list_string = &envline[6];
|
|
break;
|
|
|
|
case 7:
|
|
--
|
|
2.9.4
|
|
|