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author | Florian Weimer <fweimer@redhat.com> | 2022-08-24 17:35:36 +0200 |
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committer | Florian Weimer <fweimer@redhat.com> | 2022-08-24 17:35:57 +0200 |
commit | 6f85dbf102ad7982409ba0fe96886caeb6389fef (patch) | |
tree | 430440c34027af70ebf69884a6b4541d7055c3d2 /elf | |
parent | 06e4033c83276ed349d315bfbf651be56c3e2954 (diff) | |
download | glibc-6f85dbf102ad7982409ba0fe96886caeb6389fef.tar.gz glibc-6f85dbf102ad7982409ba0fe96886caeb6389fef.tar.xz glibc-6f85dbf102ad7982409ba0fe96886caeb6389fef.zip |
Detect ld.so and libc.so version inconsistency during startup
The files NEWS, include/link.h, and sysdeps/generic/ldsodefs.h contribute to the version fingerprint used for detection. The fingerprint can be further refined using the --with-extra-version-id configure argument. _dl_call_libc_early_init is replaced with _dl_lookup_libc_early_init. The new function is used store a pointer to libc.so's __libc_early_init function in the libc_map_early_init member of the ld.so namespace structure. This function pointer can then be called directly, so the separate invocation function is no longer needed. The versioned symbol lookup needs the symbol versioning data structures, so the initialization of libc_map and libc_map_early_init is now done from _dl_check_map_versions, after this information becomes available. (_dl_map_object_from_fd does not set this up in time, so the initialization code had to be moved from there.) This means that the separate initialization code can be removed from dl_main because _dl_check_map_versions covers all maps, including the initial executable loaded by the kernel. The lookup still happens before relocation and the invocation of IFUNC resolvers, so IFUNC resolvers are protected from ABI mismatch. The __libc_early_init function pointer is not protected because so little code runs between the pointer write and the invocation (only dynamic linker code and IFUNC resolvers). Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Diffstat (limited to 'elf')
-rw-r--r-- | elf/Makefile | 2 | ||||
-rw-r--r-- | elf/Versions | 4 | ||||
-rw-r--r-- | elf/dl-load.c | 9 | ||||
-rw-r--r-- | elf/dl-lookup_libc_early_init.c (renamed from elf/dl-call-libc-early-init.c) | 23 | ||||
-rw-r--r-- | elf/dl-open.c | 4 | ||||
-rw-r--r-- | elf/dl-version.c | 18 | ||||
-rw-r--r-- | elf/libc-early-init.h | 21 | ||||
-rw-r--r-- | elf/rtld.c | 12 |
8 files changed, 49 insertions, 44 deletions
diff --git a/elf/Makefile b/elf/Makefile index 3928a08787..bc68150a37 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -52,7 +52,6 @@ routines = \ # The core dynamic linking functions are in libc for the static and # profiled libraries. dl-routines = \ - dl-call-libc-early-init \ dl-close \ dl-debug \ dl-debug-symbols \ @@ -65,6 +64,7 @@ dl-routines = \ dl-load \ dl-lookup \ dl-lookup-direct \ + dl-lookup_libc_early_init \ dl-minimal-malloc \ dl-misc \ dl-object \ diff --git a/elf/Versions b/elf/Versions index a9ff278de7..6260c0fe03 100644 --- a/elf/Versions +++ b/elf/Versions @@ -29,8 +29,8 @@ libc { __placeholder_only_for_empty_version_map; } GLIBC_PRIVATE { - # functions used in other libraries - __libc_early_init; + # A pattern is needed here because the suffix is dynamically generated. + __libc_early_init_*; # Internal error handling support. Interposes the functions in ld.so. _dl_signal_exception; _dl_catch_exception; diff --git a/elf/dl-load.c b/elf/dl-load.c index 1ad0868dad..00e08b5500 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -31,7 +31,6 @@ #include <sys/param.h> #include <sys/stat.h> #include <sys/types.h> -#include <gnu/lib-names.h> /* Type for the buffer we put the ELF header and hopefully the program header. This buffer does not really have to be too large. In most @@ -1466,14 +1465,6 @@ cannot enable executable stack as shared object requires"); add_name_to_object (l, ((const char *) D_PTR (l, l_info[DT_STRTAB]) + l->l_info[DT_SONAME]->d_un.d_val)); - /* If we have newly loaded libc.so, update the namespace - description. */ - if (GL(dl_ns)[nsid].libc_map == NULL - && l->l_info[DT_SONAME] != NULL - && strcmp (((const char *) D_PTR (l, l_info[DT_STRTAB]) - + l->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0) - GL(dl_ns)[nsid].libc_map = l; - /* _dl_close can only eventually undo the module ID assignment (via remove_slotinfo) if this function returns a pointer to a link map. Therefore, delay this step until all possibilities for diff --git a/elf/dl-call-libc-early-init.c b/elf/dl-lookup_libc_early_init.c index ee9860e3ab..64bc287a05 100644 --- a/elf/dl-call-libc-early-init.c +++ b/elf/dl-lookup_libc_early_init.c @@ -1,4 +1,4 @@ -/* Invoke the early initialization function in libc.so. +/* Find the address of the __libc_early_init function. Copyright (C) 2020-2022 Free Software Foundation, Inc. This file is part of the GNU C Library. @@ -16,26 +16,21 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ -#include <assert.h> #include <ldsodefs.h> #include <libc-early-init.h> #include <link.h> #include <stddef.h> -void -_dl_call_libc_early_init (struct link_map *libc_map, _Bool initial) +__typeof (__libc_early_init) * +_dl_lookup_libc_early_init (struct link_map *libc_map) { - /* There is nothing to do if we did not actually load libc.so. */ - if (libc_map == NULL) - return; - const ElfW(Sym) *sym - = _dl_lookup_direct (libc_map, "__libc_early_init", - 0x069682ac, /* dl_new_hash output. */ + = _dl_lookup_direct (libc_map, LIBC_EARLY_INIT_NAME_STRING, + LIBC_EARLY_INIT_GNU_HASH, "GLIBC_PRIVATE", 0x0963cf85); /* _dl_elf_hash output. */ - assert (sym != NULL); - __typeof (__libc_early_init) *early_init - = DL_SYMBOL_ADDRESS (libc_map, sym); - early_init (initial); + if (sym == NULL) + _dl_signal_error (0, libc_map->l_name, NULL, "\ +ld.so/libc.so mismatch detected (upgrade in progress?)"); + return DL_SYMBOL_ADDRESS (libc_map, sym); } diff --git a/elf/dl-open.c b/elf/dl-open.c index a23e65926b..dcc24130fe 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -760,8 +760,8 @@ dl_open_worker_begin (void *a) if (!args->libc_already_loaded) { /* dlopen cannot be used to load an initial libc by design. */ - struct link_map *libc_map = GL(dl_ns)[args->nsid].libc_map; - _dl_call_libc_early_init (libc_map, false); + if (GL(dl_ns)[args->nsid].libc_map != NULL) + GL(dl_ns)[args->nsid].libc_map_early_init (false); } args->worker_continue = true; diff --git a/elf/dl-version.c b/elf/dl-version.c index cda0889209..d9ec44eed6 100644 --- a/elf/dl-version.c +++ b/elf/dl-version.c @@ -23,6 +23,8 @@ #include <string.h> #include <ldsodefs.h> #include <_itoa.h> +#include <gnu/lib-names.h> +#include <libc-early-init.h> #include <assert.h> @@ -359,6 +361,22 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode) } } + /* Detect a libc.so loaded into this namespace. The + __libc_early_init lookup below means that we have to do this + after parsing the version data. */ + if (GL(dl_ns)[map->l_ns].libc_map == NULL + && map->l_info[DT_SONAME] != NULL + && strcmp (((const char *) D_PTR (map, l_info[DT_STRTAB]) + + map->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0) + { + /* Look up this symbol early to trigger a mismatch error before + relocation (which may call IFUNC resolvers, and those can + have an internal ABI dependency). */ + GL(dl_ns)[map->l_ns].libc_map_early_init + = _dl_lookup_libc_early_init (map); + GL(dl_ns)[map->l_ns].libc_map = map; + } + /* When there is a DT_VERNEED entry with libc.so on DT_NEEDED, issue an error if there is a DT_RELR entry without GLIBC_ABI_DT_RELR dependency. */ diff --git a/elf/libc-early-init.h b/elf/libc-early-init.h index a8edfadfb0..ac8c204bc7 100644 --- a/elf/libc-early-init.h +++ b/elf/libc-early-init.h @@ -19,12 +19,9 @@ #ifndef _LIBC_EARLY_INIT_H #define _LIBC_EARLY_INIT_H -struct link_map; +#include <libc_early_init_name.h> -/* If LIBC_MAP is not NULL, look up the __libc_early_init symbol in it - and call this function, with INITIAL as the argument. */ -void _dl_call_libc_early_init (struct link_map *libc_map, _Bool initial) - attribute_hidden; +struct link_map; /* In the shared case, this function is defined in libc.so and invoked from ld.so (or on the fist static dlopen) after complete relocation @@ -33,6 +30,18 @@ void _dl_call_libc_early_init (struct link_map *libc_map, _Bool initial) startup code. If INITIAL is true, the libc being initialized is the libc for the main program. INITIAL is false for libcs loaded for audit modules, dlmopen, and static dlopen. */ -void __libc_early_init (_Bool initial); +void __libc_early_init (_Bool initial) +#ifdef SHARED +/* Redirect to the actual implementation name. */ + __asm__ (LIBC_EARLY_INIT_NAME_STRING) +#endif + ; + +/* Attempts to find the appropriately named __libc_early_init function + in LIBC_MAP. On lookup failure, an exception is signaled, + indicating an ld.so/libc.so mismatch. */ +__typeof (__libc_early_init) *_dl_lookup_libc_early_init (struct link_map * + libc_map) + attribute_hidden; #endif /* _LIBC_EARLY_INIT_H */ diff --git a/elf/rtld.c b/elf/rtld.c index cbbaf4a331..910075c37f 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -1707,15 +1707,6 @@ dl_main (const ElfW(Phdr) *phdr, /* Extract the contents of the dynamic section for easy access. */ elf_get_dynamic_info (main_map, false, false); - /* If the main map is libc.so, update the base namespace to - refer to this map. If libc.so is loaded later, this happens - in _dl_map_object_from_fd. */ - if (main_map->l_info[DT_SONAME] != NULL - && (strcmp (((const char *) D_PTR (main_map, l_info[DT_STRTAB]) - + main_map->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) - == 0)) - GL(dl_ns)[LM_ID_BASE].libc_map = main_map; - /* Set up our cache of pointers into the hash table. */ _dl_setup_hash (main_map); } @@ -2386,7 +2377,8 @@ dl_main (const ElfW(Phdr) *phdr, /* Relocation is complete. Perform early libc initialization. This is the initial libc, even if audit modules have been loaded with other libcs. */ - _dl_call_libc_early_init (GL(dl_ns)[LM_ID_BASE].libc_map, true); + if (GL(dl_ns)[LM_ID_BASE].libc_map != NULL) + GL(dl_ns)[LM_ID_BASE].libc_map_early_init (true); /* Do any necessary cleanups for the startup OS interface code. We do these now so that no calls are made after rtld re-relocation |