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104 lines
4.3 KiB
104 lines
4.3 KiB
2 years ago
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Partial backport without the new tst-dlopen-aout-pie test. The test
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fails because the a self-dlopen of a PIE binary succeeds, as commit
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23d2e5faf0bca6d9b31bef4aa162b95ee64cbfc6 ("elf: Self-dlopen failure
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with explict loader invocation [BZ #24900]") has not been backported.
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commit 77523d5e43cb5721c23855eb6045b0607a3b30a0
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Fri Oct 4 21:23:51 2019 +0200
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elf: Assign TLS modid later during dlopen [BZ #24930]
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Commit a42faf59d6d9f82e5293a9ebcc26d9c9e562b12b ("Fix BZ #16634.")
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attempted to fix a TLS modid consistency issue by adding additional
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checks to the open_verify function. However, this is fragile
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because open_verify cannot reliably predict whether
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_dl_map_object_from_fd will later fail in the more complex cases
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(such as memory allocation failures). Therefore, this commit
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assigns the TLS modid as late as possible. At that point, the link
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map pointer will eventually be passed to _dl_close, which will undo
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the TLS modid assignment.
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Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>
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diff --git a/elf/dl-load.c b/elf/dl-load.c
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index bb839ef70ff46f37..b190b28e32e47391 100644
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--- a/elf/dl-load.c
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+++ b/elf/dl-load.c
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@@ -1134,27 +1134,21 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
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offset. We will adjust it later. */
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l->l_tls_initimage = (void *) ph->p_vaddr;
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- /* If not loading the initial set of shared libraries,
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- check whether we should permit loading a TLS segment. */
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- if (__glibc_likely (l->l_type == lt_library)
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- /* If GL(dl_tls_dtv_slotinfo_list) == NULL, then rtld.c did
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- not set up TLS data structures, so don't use them now. */
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- || __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL))
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- {
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- /* Assign the next available module ID. */
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- l->l_tls_modid = _dl_next_tls_modid ();
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- break;
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- }
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+ /* l->l_tls_modid is assigned below, once there is no
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+ possibility for failure. */
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+ if (l->l_type != lt_library
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+ && GL(dl_tls_dtv_slotinfo_list) == NULL)
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+ {
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#ifdef SHARED
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- /* We are loading the executable itself when the dynamic
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- linker was executed directly. The setup will happen
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- later. Otherwise, the TLS data structures are already
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- initialized, and we assigned a TLS modid above. */
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- assert (l->l_prev == NULL || (mode & __RTLD_AUDIT) != 0);
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+ /* We are loading the executable itself when the dynamic
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+ linker was executed directly. The setup will happen
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+ later. */
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+ assert (l->l_prev == NULL || (mode & __RTLD_AUDIT) != 0);
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#else
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- assert (false && "TLS not initialized in static application");
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+ assert (false && "TLS not initialized in static application");
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#endif
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+ }
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break;
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case PT_GNU_STACK:
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@@ -1395,6 +1389,18 @@ cannot enable executable stack as shared object requires");
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add_name_to_object (l, ((const char *) D_PTR (l, l_info[DT_STRTAB])
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+ l->l_info[DT_SONAME]->d_un.d_val));
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+ /* _dl_close can only eventually undo the module ID assignment (via
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+ remove_slotinfo) if this function returns a pointer to a link
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+ map. Therefore, delay this step until all possibilities for
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+ failure have been excluded. */
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+ if (l->l_tls_blocksize > 0
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+ && (__glibc_likely (l->l_type == lt_library)
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+ /* If GL(dl_tls_dtv_slotinfo_list) == NULL, then rtld.c did
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+ not set up TLS data structures, so don't use them now. */
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+ || __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL)))
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+ /* Assign the next available module ID. */
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+ l->l_tls_modid = _dl_next_tls_modid ();
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+
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#ifdef DL_AFTER_LOAD
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DL_AFTER_LOAD (l);
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#endif
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@@ -1662,17 +1668,6 @@ open_verify (const char *name, int fd,
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errstring = N_("only ET_DYN and ET_EXEC can be loaded");
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goto call_lose;
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}
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- else if (__glibc_unlikely (ehdr->e_type == ET_EXEC
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- && (mode & __RTLD_OPENEXEC) == 0))
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- {
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- /* BZ #16634. It is an error to dlopen ET_EXEC (unless
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- __RTLD_OPENEXEC is explicitly set). We return error here
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- so that code in _dl_map_object_from_fd does not try to set
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- l_tls_modid for this module. */
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-
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- errstring = N_("cannot dynamically load executable");
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- goto call_lose;
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- }
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else if (__glibc_unlikely (ehdr->e_phentsize != sizeof (ElfW(Phdr))))
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{
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errstring = N_("ELF file's phentsize not the expected size");
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