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99 lines
4.1 KiB
99 lines
4.1 KiB
2 years ago
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Downstream-only patch to change rtld_active () to return true during
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early audit operations. GLRO (_dl_profile_output) is initialized much
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earlier than GLRO (dl_init_all_dirs), before auditors run, so it is a
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good replacement.
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This is addressed downstream very differently, in this commit:
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commit 8dcb6d0af07fda3607b541857e4f3970a74ed55b
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Tue Apr 26 14:23:02 2022 +0200
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dlfcn: Do not use rtld_active () to determine ld.so state (bug 29078)
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When audit modules are loaded, ld.so initialization is not yet
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complete, and rtld_active () returns false even though ld.so is
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mostly working. Instead, the static dlopen hook is used, but that
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does not work at all because this is not a static dlopen situation.
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Commit 466c1ea15f461edb8e3ffaf5d86d708876343bbf ("dlfcn: Rework
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static dlopen hooks") moved the hook pointer into _rtld_global_ro,
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which means that separate protection is not needed anymore and the
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hook pointer can be checked directly.
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The guard for disabling libio vtable hardening in _IO_vtable_check
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should stay for now.
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Fixes commit 8e1472d2c1e25e6eabc2059170731365f6d5b3d1 ("ld.so:
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Examine GLRO to detect inactive loader [BZ #20204]").
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Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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diff --git a/elf/rtld.c b/elf/rtld.c
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index 22cceeab40319582..b47e84ca2fb6f03c 100644
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--- a/elf/rtld.c
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+++ b/elf/rtld.c
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@@ -2352,9 +2352,7 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
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GLRO(dl_initial_searchlist) = *GL(dl_ns)[LM_ID_BASE]._ns_main_searchlist;
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/* Remember the last search directory added at startup, now that
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- malloc will no longer be the one from dl-minimal.c. As a side
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- effect, this marks ld.so as initialized, so that the rtld_active
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- function returns true from now on. */
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+ malloc will no longer be the one from dl-minimal.c. */
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GLRO(dl_init_all_dirs) = GL(dl_all_dirs);
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/* Print scope information. */
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@@ -2675,7 +2673,9 @@ process_envvars (struct dl_main_state *state)
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char *envline;
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char *debug_output = NULL;
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- /* This is the default place for profiling data file. */
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+ /* This is the default place for profiling data file. As a side
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+ effect, this marks ld.so as initialized, so that the rtld_active
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+ function returns true from now on. */
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GLRO(dl_profile_output)
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= &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
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diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
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index d4f70211c34d1c59..9dec9e3d3b6d6aa2 100644
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--- a/sysdeps/generic/ldsodefs.h
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+++ b/sysdeps/generic/ldsodefs.h
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@@ -600,18 +600,18 @@ struct rtld_global_ro
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/* Name of the shared object to be profiled (if any). */
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EXTERN const char *_dl_profile;
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- /* Filename of the output file. */
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+ /* Filename of the output file. This is assigned a
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+ non-NULL pointer by the ld.so startup code (after initialization
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+ to NULL), so this can also serve as an indicator whether a copy
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+ of ld.so is initialized and active. See the rtld_active function
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+ below. */
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EXTERN const char *_dl_profile_output;
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/* Name of the object we want to trace the prelinking. */
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EXTERN const char *_dl_trace_prelink;
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/* Map of shared object to be prelink traced. */
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EXTERN struct link_map *_dl_trace_prelink_map;
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- /* All search directories defined at startup. This is assigned a
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- non-NULL pointer by the ld.so startup code (after initialization
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- to NULL), so this can also serve as an indicator whether a copy
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- of ld.so is initialized and active. See the rtld_active function
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- below. */
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+ /* All search directories defined at startup. */
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EXTERN struct r_search_path_elem *_dl_init_all_dirs;
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#ifdef NEED_DL_SYSINFO
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@@ -1259,9 +1259,9 @@ static inline bool
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rtld_active (void)
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{
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/* The default-initialized variable does not have a non-zero
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- dl_init_all_dirs member, so this allows us to recognize an
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+ dl_profile_output member, so this allows us to recognize an
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initialized and active ld.so copy. */
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- return GLRO(dl_init_all_dirs) != NULL;
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+ return GLRO(dl_profile_output) != NULL;
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}
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static inline struct auditstate *
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