forked from rpms/glibc
110 lines
4.3 KiB
Diff
110 lines
4.3 KiB
Diff
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commit 23d2e5faf0bca6d9b31bef4aa162b95ee64cbfc6
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Thu Aug 15 14:37:50 2019 +0200
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elf: Self-dlopen failure with explict loader invocation [BZ #24900]
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In case of an explicit loader invocation, ld.so essentially performs
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a dlopen call to load the main executable. Since the pathname of
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the executable is known at this point, it gets stored in the link
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map. In regular mode, the pathname is not known and "" is used
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instead.
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As a result, if a program calls dlopen on the pathname of the main
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program, the dlopen call succeeds and returns a handle for the main
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map. This results in an unnecessary difference between glibc
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testing (without --enable-hardcoded-path-in-tests) and production
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usage.
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This commit discards the names when building the link map in
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_dl_new_object for the main executable, but it still determines
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the origin at this point in case of an explict loader invocation.
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The reason is that the specified pathname has to be used; the kernel
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has a different notion of the main executable.
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Conflicts:
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elf/Makefile
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elf/tst-dlopen-aout.c
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(Differences due to the complicated history of the test.
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The new test elf/tst-dlopen-aout-container is not backported
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here.)
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diff --git a/elf/dl-object.c b/elf/dl-object.c
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index b37bcc1295f475f6..f6544a8fec45bdce 100644
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--- a/elf/dl-object.c
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+++ b/elf/dl-object.c
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@@ -57,14 +57,30 @@ struct link_map *
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_dl_new_object (char *realname, const char *libname, int type,
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struct link_map *loader, int mode, Lmid_t nsid)
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{
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+#ifdef SHARED
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+ unsigned int naudit;
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+ if (__glibc_unlikely ((mode & __RTLD_OPENEXEC) != 0))
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+ {
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+ assert (type == lt_executable);
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+ assert (nsid == LM_ID_BASE);
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+
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+ /* Ignore the specified libname for the main executable. It is
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+ only known with an explicit loader invocation. */
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+ libname = "";
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+
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+ /* We create the map for the executable before we know whether
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+ we have auditing libraries and if yes, how many. Assume the
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+ worst. */
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+ naudit = DL_NNS;
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+ }
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+ else
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+ naudit = GLRO (dl_naudit);
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+#endif
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+
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size_t libname_len = strlen (libname) + 1;
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struct link_map *new;
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struct libname_list *newname;
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#ifdef SHARED
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- /* We create the map for the executable before we know whether we have
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- auditing libraries and if yes, how many. Assume the worst. */
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- unsigned int naudit = GLRO(dl_naudit) ?: ((mode & __RTLD_OPENEXEC)
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- ? DL_NNS : 0);
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size_t audit_space = naudit * sizeof (new->l_audit[0]);
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#else
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# define audit_space 0
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@@ -91,8 +107,20 @@ _dl_new_object (char *realname, const char *libname, int type,
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and won't get dumped during core file generation. Therefore to assist
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gdb and to create more self-contained core files we adjust l_name to
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point at the newly allocated copy (which will get dumped) instead of
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- the ld.so rodata copy. */
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- new->l_name = *realname ? realname : (char *) newname->name + libname_len - 1;
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+ the ld.so rodata copy.
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+
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+ Furthermore, in case of explicit loader invocation, discard the
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+ name of the main executable, to match the regular behavior, where
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+ name of the executable is not known. */
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+#ifdef SHARED
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+ if (*realname != '\0' && (mode & __RTLD_OPENEXEC) == 0)
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+#else
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+ if (*realname != '\0')
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+#endif
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+ new->l_name = realname;
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+ else
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+ new->l_name = (char *) newname->name + libname_len - 1;
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+
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new->l_type = type;
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/* If we set the bit now since we know it is never used we avoid
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dirtying the cache line later. */
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@@ -149,7 +177,14 @@ _dl_new_object (char *realname, const char *libname, int type,
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new->l_local_scope[0] = &new->l_searchlist;
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- /* Don't try to find the origin for the main map which has the name "". */
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+ /* Determine the origin. If allocating the link map for the main
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+ executable, the realname is not known and "". In this case, the
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+ origin needs to be determined by other means. However, in case
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+ of an explicit loader invocation, the pathname of the main
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+ executable is known and needs to be processed here: From the
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+ point of view of the kernel, the main executable is the
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+ dynamic loader, and this would lead to a computation of the wrong
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+ origin. */
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if (realname[0] != '\0')
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{
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size_t realname_len = strlen (realname) + 1;
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