From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Jonathon Anderson <janderson@rice.edu>, libc-alpha@sourceware.org
Cc: John Mellor-Crummey <johnmc@rice.edu>,
Ben Woodard <woodard@redhat.com>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH v8 1/4] elf: Add la_activity during application exit
Date: Wed, 29 Dec 2021 16:54:44 -0300 [thread overview]
Message-ID: <1da21f47-10df-bc0f-ca21-3e32b389eca6@linaro.org> (raw)
In-Reply-To: <fb7eee5a-af6e-da6a-c5e7-8fd24b8abe16@rice.edu>
On 28/12/2021 14:59, Jonathon Anderson wrote:
> Thanks for the updated patch! The test looks much better now, I have a few minor comments on the details below.
>
> -Jonathon
>
> On 12/28/21 05:50, Adhemerval Zanella wrote:
>> + /* The expected la_objopen/la_objclose:
>> + 1. executable
>> + 2. loader
>> + 3. libc.so
>> + 4. tst-audit23mod.so
>> + 5. libc.so (LM_ID_NEWLM).
>> + 6. vdso (optional and ignored). */
>> + enum { max_objs = 6 };
>> + struct la_obj_t
>> + {
>> + char *lname;
>> + uintptr_t laddr;
>> + Lmid_t lmid;
>> + bool closed;
>> + } objs[max_objs] = { [0 ... max_objs-1] = { .closed = false } };
>> + size_t nobjs = 0;
>> +
>> + /* The expected namespaces are one for the audit module and another for
>> + the application. */
> This should be 2 namespaces for the application, the audit module does not get la_* callbacks for itself. AFAICT the second namespace is used by the dlmopen call in the test body (handle_restart).
You are right, I forgot about the dlmopen usage. I have adjusted the comment
to:
/* The expected namespaces are one for the audit module, one for the
application, and another for the dlmopen on handle_restart. */
>> + enum { max_ns = 2 };
>> + uintptr_t acts[max_ns];
>> + size_t nacts = 0;
>> + int last_act = -1;
>> + uintptr_t last_act_cookie = -1;
>> +
>> + FILE *out = fmemopen (result.err.buffer, result.err.length, "r");
>> + TEST_VERIFY (out != NULL);
>> + char *buffer = NULL;
>> + size_t buffer_length = 0;
>> + while (xgetline (&buffer, &buffer_length, out))
>> + {
>> + printf ("%s", buffer);
>> + if (startswith (buffer, "la_activity: "))
>> + {
>> + uintptr_t cookie;
>> + int r = sscanf (buffer + strlen ("la_activity: "),
>> + "%d %"SCNxPTR"", &last_act, &cookie);
>> + TEST_COMPARE (r, 2);
>> + /* The cookie identifies the object at the head of the link map,
>> + so we only add a new namespace if it changes from previous
>> + one. */
>> + if (last_act == LA_ACT_ADD && acts[nacts - 1] != cookie)
>> + acts[nacts++] = cookie;
> This works since the dlmopen is second/last in the test body. If there was another dlopen this would consider it a third namespace. Should this be noted in the comment?
I thin it is worth to comment it, I have changed the comment to:
/* The cookie identifies the object at the head of the link map,
so we only add a new namespace if it changes from previous
one. This work since dlmopen is the last in the test body. */
>
> This also does not abort if nacts > max_ns, which could cause a stack buffer overflow.
>> + /* The LA_ACT_DELETE is called in the reverse order of
>> + LA_ACT_ADD. */
>> + else if (last_act == LA_ACT_DELETE && cookie != last_act_cookie)
>> + {
>> + last_act_cookie = acts[--nacts];
>> + TEST_COMPARE (acts[nacts], cookie);
>> + acts[nacts] = 0;
>> + }
> Not sure about this one yet. Is this always the case or only because there are exactly 2 audited namespaces?
>
> Also, this works since la_activity(LA_ACT_DELETE) is only called at program termination. If dlclose was called in the test body (or a dlopen of a library missing dependencies) this might fail. Should this be noted in the comment?
Yeah, this works because there is no dlclose before program termination
and tst-audit23mod.so does not have any dependency not already mapped.
I have changed the comment to:
/* The LA_ACT_DELETE is called in the reverse order of LA_ACT_ADD
at program termination (if the tests adds a dlclose or a library
with extra dependencies this require to be adapted). */
>> + }
>> + else if (startswith (buffer, "la_objopen: "))
>> + {
>> + char *lname;
>> + uintptr_t laddr;
>> + Lmid_t lmid;
>> + uintptr_t cookie;
>> + int r = sscanf (buffer + strlen ("la_objopen: "),
>> + "%"SCNxPTR" %ms %"SCNxPTR" %ld", &cookie, &lname,
>> + &laddr, &lmid);
>> + TEST_COMPARE (r, 4);
>> +
>> + /* la_objclose is not triggered by vDSO because glibc does not
>> + unload it. */
>> + if (is_vdso (lname))
>> + continue;
>> + if (nobjs == max_objs)
>> + FAIL_EXIT1 ("non expected la_objopen: %s %"PRIxPTR" %ld",
>> + lname, laddr, lmid);
>> + objs[nobjs].lname = lname;
>> + objs[nobjs].laddr = laddr;
>> + objs[nobjs].lmid = lmid;
>> + objs[nobjs].closed = false;
>> + nobjs++;
>> + }
>> + else if (startswith (buffer, "la_objclose: "))
>> + {
>> + char *lname;
>> + uintptr_t laddr;
>> + Lmid_t lmid;
>> + uintptr_t cookie;
>> + int r = sscanf (buffer + strlen ("la_objclose: "),
>> + "%"SCNxPTR" %ms %"SCNxPTR" %ld", &cookie, &lname,
>> + &laddr, &lmid);
>> + TEST_COMPARE (r, 4);
>> +
>> + for (size_t i = 0; i < nobjs; i++)
>> + {
>> + if (strcmp (lname, objs[i].lname) == 0 && lmid == objs[i].lmid)
>> + {
>> + TEST_COMPARE (objs[i].closed, false);
>> + objs[i].closed = true;
>> + break;
>> + }
>> + }
>> +
>> + /* la_objclose should be called after la_activity(LA_ACT_DELETE) for
>> + the closed object's namespace. */
>> + TEST_COMPARE (last_act, LA_ACT_DELETE);
>> + if (last_act_cookie != 0)
>> + {
>> + TEST_COMPARE (last_act_cookie, cookie);
>> + last_act_cookie = 0;
>> + }
> This works because the la_objclose order for program termination is the same as the order in the link map (implementation detail), and because la_objclose is only called during program termination in this test. If dlclose was called in the test body this would fail. Should this be noted in the comment?
I think it makes way more sense to tie to the DT_FINI/DT_FINI_ARRAY execution
order, but I agree it is an implementation detail (we could just iterate over
the namespace lists and call it for each objects as well).
I think the above comments it should be clear that if someone want to test
dlclose or shared objects with more dependencies, the tests will need to be
adapted.
>> + }
>> + }
>> +
>> + for (size_t i = 0; i < nobjs; i++)
>> + {
>> + TEST_COMPARE (objs[i].closed, true);
>> + free (objs[i].lname);
>> + }
>> +
>> + /* la_activity(LA_ACT_CONSISTENT) should be the last callback received for
>> + every namespace. */
>> + TEST_COMPARE (last_act, LA_ACT_CONSISTENT);
> This only checks the last la_activity notification (AFAICT the main namespace), rather than the last for each namespace.
>> + /* Sanity check to check if all LA_ACT_DELETE are matched with
>> + la_objclose. */
>> + TEST_COMPARE (last_act_cookie, 0);
> Similarly, this only checks the last LA_ACT_DELETE notification, rather than last for each namespace.
Indeed I agree we can increase the coverage of both tests, I have added
a better la_activity and LA_ACT_DELETE one.
Below it is the updated version:
--
diff --git a/elf/Makefile b/elf/Makefile
index b23d17fd39..fe1a50fac0 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -240,7 +240,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-audit19b \
tst-audit20 \
tst-audit22 \
- tst-rtld-run-static \
+ tst-audit23 \
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@@ -393,6 +393,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-audit19bmod \
tst-auditmod20 \
tst-auditmod22 \
+ tst-auditmod23 \
+ tst-audit23mod \
tst-dl_find_object-mod1 \
tst-dl_find_object-mod2 \
tst-dl_find_object-mod3 \
@@ -1620,6 +1622,10 @@ tst-audit20-ENV = LD_AUDIT=$(objpfx)tst-auditmod20.so
$(objpfx)tst-audit22.out: $(objpfx)tst-auditmod22.so
tst-audit22-ARGS = -- $(host-test-program-cmd)
+$(objpfx)tst-audit23.out: $(objpfx)tst-auditmod23.so \
+ $(objpfx)tst-audit23mod.so
+tst-audit23-ARGS = -- $(host-test-program-cmd)
+
# tst-sonamemove links against an older implementation of the library.
LDFLAGS-tst-sonamemove-linkmod1.so = \
-Wl,--version-script=tst-sonamemove-linkmod1.map \
diff --git a/elf/dl-fini.c b/elf/dl-fini.c
index b789cfb9f2..a955d0e207 100644
--- a/elf/dl-fini.c
+++ b/elf/dl-fini.c
@@ -64,6 +64,11 @@ _dl_fini (void)
__rtld_lock_unlock_recursive (GL(dl_load_lock));
else
{
+#ifdef SHARED
+ /* Auditing checkpoint: we will start deleting objects. */
+ _dl_audit_activity_nsid (ns, LA_ACT_DELETE);
+#endif
+
/* Now we can allocate an array to hold all the pointers and
copy the pointers in. */
struct link_map *maps[nloaded];
@@ -153,6 +158,11 @@ _dl_fini (void)
/* Correct the previous increment. */
--l->l_direct_opencount;
}
+
+#ifdef SHARED
+ /* Auditing checkpoint: we will start deleting objects. */
+ _dl_audit_activity_nsid (ns, LA_ACT_CONSISTENT);
+#endif
}
}
diff --git a/elf/tst-audit23.c b/elf/tst-audit23.c
new file mode 100644
index 0000000000..63a0b3311b
--- /dev/null
+++ b/elf/tst-audit23.c
@@ -0,0 +1,222 @@
+/* Check DT_AUDIT la_objopen and la_objclose for all objects.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <getopt.h>
+#include <link.h>
+#include <limits.h>
+#include <inttypes.h>
+#include <gnu/lib-names.h>
+#include <string.h>
+#include <stdlib.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+#include <support/xdlfcn.h>
+#include <support/support.h>
+
+static int restart;
+#define CMDLINE_OPTIONS \
+ { "restart", no_argument, &restart, 1 },
+
+static int
+handle_restart (void)
+{
+ xdlopen ("tst-audit23mod.so", RTLD_NOW);
+ xdlmopen (LM_ID_NEWLM, LIBC_SO, RTLD_NOW);
+
+ return 0;
+}
+
+static inline bool
+startswith (const char *str, const char *pre)
+{
+ size_t lenpre = strlen (pre);
+ size_t lenstr = strlen (str);
+ return lenstr >= lenpre && memcmp (pre, str, lenpre) == 0;
+}
+
+static inline bool
+is_vdso (const char *str)
+{
+ return startswith (str, "linux-gate")
+ || startswith (str, "linux-vdso");
+}
+
+static int
+do_test (int argc, char *argv[])
+{
+ /* We must have either:
+ - One our fource parameters left if called initially:
+ + path to ld.so optional
+ + "--library-path" optional
+ + the library path optional
+ + the application name */
+ if (restart)
+ return handle_restart ();
+
+ char *spargv[9];
+ int i = 0;
+ for (; i < argc - 1; i++)
+ spargv[i] = argv[i + 1];
+ spargv[i++] = (char *) "--direct";
+ spargv[i++] = (char *) "--restart";
+ spargv[i] = NULL;
+
+ setenv ("LD_AUDIT", "tst-auditmod23.so", 0);
+ struct support_capture_subprocess result
+ = support_capture_subprogram (spargv[0], spargv);
+ support_capture_subprocess_check (&result, "tst-audit22", 0, sc_allow_stderr);
+
+ /* The expected la_objopen/la_objclose:
+ 1. executable
+ 2. loader
+ 3. libc.so
+ 4. tst-audit23mod.so
+ 5. libc.so (LM_ID_NEWLM).
+ 6. vdso (optional and ignored). */
+ enum { max_objs = 6 };
+ struct la_obj_t
+ {
+ char *lname;
+ uintptr_t laddr;
+ Lmid_t lmid;
+ bool closed;
+ } objs[max_objs] = { [0 ... max_objs-1] = { .closed = false } };
+ size_t nobjs = 0;
+
+ /* The expected namespaces are one for the audit module, one for the
+ application, and another for the dlmopen on handle_restart. */
+ enum { max_ns = 3 };
+ uintptr_t acts[max_ns];
+ size_t nacts = 0;
+ int last_act = -1;
+ uintptr_t last_act_cookie = -1;
+ bool first_objclose = false;
+
+ FILE *out = fmemopen (result.err.buffer, result.err.length, "r");
+ TEST_VERIFY (out != NULL);
+ char *buffer = NULL;
+ size_t buffer_length = 0;
+ while (xgetline (&buffer, &buffer_length, out))
+ {
+ printf ("%s", buffer);
+ if (startswith (buffer, "la_activity: "))
+ {
+ uintptr_t cookie;
+ int r = sscanf (buffer + strlen ("la_activity: "),
+ "%d %"SCNxPTR"", &last_act, &cookie);
+ TEST_COMPARE (r, 2);
+ /* The cookie identifies the object at the head of the link map,
+ so we only add a new namespace if it changes from previous
+ one. This work since dlmopen is the last in the test body. */
+ if (last_act == LA_ACT_ADD && acts[nacts - 1] != cookie)
+ {
+ acts[nacts++] = cookie;
+ last_act_cookie = cookie;
+ }
+ /* The LA_ACT_DELETE is called in the reverse order of LA_ACT_ADD
+ at program termination (if the tests adds a dlclose or a library
+ with extra dependencies this require to be adapted). */
+ else if (last_act == LA_ACT_DELETE) // && cookie != last_act_cookie)
+ {
+ last_act_cookie = acts[--nacts];
+ TEST_COMPARE (acts[nacts], cookie);
+ acts[nacts] = 0;
+ }
+ else if (last_act == LA_ACT_CONSISTENT)
+ TEST_COMPARE (cookie, last_act_cookie);
+
+ first_objclose = false;
+ }
+ else if (startswith (buffer, "la_objopen: "))
+ {
+ char *lname;
+ uintptr_t laddr;
+ Lmid_t lmid;
+ uintptr_t cookie;
+ int r = sscanf (buffer + strlen ("la_objopen: "),
+ "%"SCNxPTR" %ms %"SCNxPTR" %ld", &cookie, &lname,
+ &laddr, &lmid);
+ TEST_COMPARE (r, 4);
+
+ /* la_objclose is not triggered by vDSO because glibc does not
+ unload it. */
+ if (is_vdso (lname))
+ continue;
+ if (nobjs == max_objs)
+ FAIL_EXIT1 ("non expected la_objopen: %s %"PRIxPTR" %ld",
+ lname, laddr, lmid);
+ objs[nobjs].lname = lname;
+ objs[nobjs].laddr = laddr;
+ objs[nobjs].lmid = lmid;
+ objs[nobjs].closed = false;
+ nobjs++;
+
+ first_objclose = false;
+ }
+ else if (startswith (buffer, "la_objclose: "))
+ {
+ char *lname;
+ uintptr_t laddr;
+ Lmid_t lmid;
+ uintptr_t cookie;
+ int r = sscanf (buffer + strlen ("la_objclose: "),
+ "%"SCNxPTR" %ms %"SCNxPTR" %ld", &cookie, &lname,
+ &laddr, &lmid);
+ TEST_COMPARE (r, 4);
+
+ for (size_t i = 0; i < nobjs; i++)
+ {
+ if (strcmp (lname, objs[i].lname) == 0 && lmid == objs[i].lmid)
+ {
+ TEST_COMPARE (objs[i].closed, false);
+ objs[i].closed = true;
+ break;
+ }
+ }
+
+ /* la_objclose should be called after la_activity(LA_ACT_DELETE) for
+ the closed object's namespace. */
+ TEST_COMPARE (last_act, LA_ACT_DELETE);
+ if (!first_objclose)
+ {
+ TEST_COMPARE (last_act_cookie, cookie);
+ first_objclose = true;
+ }
+ }
+ }
+
+ for (size_t i = 0; i < nobjs; i++)
+ {
+ TEST_COMPARE (objs[i].closed, true);
+ free (objs[i].lname);
+ }
+
+ /* la_activity(LA_ACT_CONSISTENT) should be the last callback received for
+ every namespace. */
+ TEST_COMPARE (last_act, LA_ACT_CONSISTENT);
+
+ free (buffer);
+ xfclose (out);
+
+ return 0;
+}
+
+#define TEST_FUNCTION_ARGV do_test
+#include <support/test-driver.c>
diff --git a/elf/tst-audit23mod.c b/elf/tst-audit23mod.c
new file mode 100644
index 0000000000..4ca66cf772
--- /dev/null
+++ b/elf/tst-audit23mod.c
@@ -0,0 +1,23 @@
+/* Extra modules for tst-audit23
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+int
+foo (void)
+{
+ return 0;
+}
diff --git a/elf/tst-auditmod23.c b/elf/tst-auditmod23.c
new file mode 100644
index 0000000000..7a6d24ee80
--- /dev/null
+++ b/elf/tst-auditmod23.c
@@ -0,0 +1,74 @@
+/* Audit modules loaded by tst-audit23.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <link.h>
+#include <inttypes.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/auxv.h>
+
+unsigned int
+la_version (unsigned int version)
+{
+ return LAV_CURRENT;
+}
+
+struct map_desc_t
+{
+ char *lname;
+ uintptr_t laddr;
+ Lmid_t lmid;
+};
+
+void
+la_activity (uintptr_t *cookie, unsigned int flag)
+{
+ fprintf (stderr, "%s: %d %"PRIxPTR"\n", __func__, flag, (uintptr_t) cookie);
+}
+
+unsigned int
+la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
+{
+ const char *l_name = map->l_name[0] == '\0' ? "mainapp" : map->l_name;
+ fprintf (stderr, "%s: %"PRIxPTR" %s %"PRIxPTR" %ld\n", __func__,
+ (uintptr_t) cookie, l_name, map->l_addr, lmid);
+
+ struct map_desc_t *map_desc = malloc (sizeof (struct map_desc_t));
+ if (map_desc == NULL)
+ abort ();
+
+ map_desc->lname = strdup (l_name);
+ map_desc->laddr = map->l_addr;
+ map_desc->lmid = lmid;
+
+ *cookie = (uintptr_t) map_desc;
+
+ return 0;
+}
+
+unsigned int
+la_objclose (uintptr_t *cookie)
+{
+ struct map_desc_t *map_desc = (struct map_desc_t *) *cookie;
+ fprintf (stderr, "%s: %"PRIxPTR" %s %"PRIxPTR" %ld\n", __func__,
+ (uintptr_t) cookie, map_desc->lname, map_desc->laddr,
+ map_desc->lmid);
+
+ return 0;
+}
next prev parent reply other threads:[~2021-12-29 19:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-28 11:50 [PATCH v8 0/4] Multiple rtld-audit fixes Adhemerval Zanella
2021-12-28 11:50 ` [PATCH v8 1/4] elf: Add la_activity during application exit Adhemerval Zanella
2021-12-28 17:59 ` Jonathon Anderson
2021-12-29 19:54 ` Adhemerval Zanella [this message]
2021-12-30 21:35 ` Jonathon Anderson
2021-12-31 12:24 ` Adhemerval Zanella
2021-12-28 11:50 ` [PATCH v8 2/4] elf: Fix initial-exec TLS access on audit modules (BZ #28096) Adhemerval Zanella
2021-12-31 12:25 ` Adhemerval Zanella
2021-12-28 11:50 ` [PATCH v8 3/4] elf: Issue la_symbind for bind-now (BZ #23734) Adhemerval Zanella
2021-12-28 11:50 ` [PATCH v8 4/4] elf: Fix runtime linker auditing on aarch64 (BZ #26643) Adhemerval Zanella
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1da21f47-10df-bc0f-ca21-3e32b389eca6@linaro.org \
--to=adhemerval.zanella@linaro.org \
--cc=fweimer@redhat.com \
--cc=janderson@rice.edu \
--cc=johnmc@rice.edu \
--cc=libc-alpha@sourceware.org \
--cc=woodard@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).