[PATCH v8 1/4] elf: Add la_activity during application exit
Jonathon Anderson
janderson@rice.edu
Tue Dec 28 17:59:38 GMT 2021
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:
> la_activity is not called during application exit, even though
> la_objclose is.
>
> Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
>
> Reviewed-by: Florian Weimer<fweimer@redhat.com>
> ---
> elf/Makefile | 8 +-
> elf/dl-fini.c | 10 ++
> elf/tst-audit23.c | 214 +++++++++++++++++++++++++++++++++++++++++++
> elf/tst-audit23mod.c | 23 +++++
> elf/tst-auditmod23.c | 74 +++++++++++++++
> 5 files changed, 328 insertions(+), 1 deletion(-)
> create mode 100644 elf/tst-audit23.c
> create mode 100644 elf/tst-audit23mod.c
> create mode 100644 elf/tst-auditmod23.c
>
> diff --git a/elf/Makefile b/elf/Makefile
> index d920586701..861c351510 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -234,7 +234,7 @@ 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 \
> @@ -386,6 +386,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
> tst-audit19bmod \
> tst-auditmod20 \
> tst-auditmod22 \
> + tst-auditmod23 \
> + tst-audit23mod \
>
> # Most modules build with _ISOMAC defined, but those filtered out
> # depend on internal headers.
> @@ -1604,6 +1606,10 @@ 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..1c2194f1a8
> --- /dev/null
> +++ b/elf/tst-audit23.c
> @@ -0,0 +1,214 @@
> +/* 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 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).
> + 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?
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?
> + }
> + 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?
> + }
> + }
> +
> + 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.
> +
> + 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;
> +}
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