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elf: Refuse to dlopen PIE objects [BZ #24323]

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Another executable has already been mapped, so the dynamic linker
cannot perform relocations correctly for the second executable.
This commit is contained in:
Florian Weimer
2019-06-18 16:42:10 +02:00
parent 02d8b5ab1c
commit 2c75b545de
5 changed files with 79 additions and 6 deletions
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18
elf/dl-load.c
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@ -1158,6 +1158,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
goto call_lose;
}
/* dlopen of an executable is not valid because it is not possible
to perform proper relocations, handle static TLS, or run the
ELF constructors. For PIE, the check needs the dynamic
section, so there is another check below. */
if (__glibc_unlikely (type != ET_DYN)
&& __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0))
{
@ -1194,9 +1198,11 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
elf_get_dynamic_info (l, NULL);
/* Make sure we are not dlopen'ing an object that has the
DF_1_NOOPEN flag set. */
if (__glibc_unlikely (l->l_flags_1 & DF_1_NOOPEN)
&& (mode & __RTLD_DLOPEN))
DF_1_NOOPEN flag set, or a PIE object. */
if ((__glibc_unlikely (l->l_flags_1 & DF_1_NOOPEN)
&& (mode & __RTLD_DLOPEN))
|| (__glibc_unlikely (l->l_flags_1 & DF_1_PIE)
&& __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0)))
{
/* We are not supposed to load this object. Free all resources. */
_dl_unmap_segments (l);
@ -1207,7 +1213,11 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
if (l->l_phdr_allocated)
free ((void *) l->l_phdr);
errstring = N_("shared object cannot be dlopen()ed");
if (l->l_flags_1 & DF_1_PIE)
errstring
= N_("cannot dynamically load position-independent executable");
else
errstring = N_("shared object cannot be dlopen()ed");
goto call_lose;
}