| Message ID | 20231106202552.3404059-13-adhemerval.zanella@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Improve loader environment variable handling | expand |
On 2023-11-06 15:25, Adhemerval Zanella wrote: > Loader does not ignore LD_PROFILE in secure-execution mode (different > than man-page states [1]), rather it uses a different path > (/var/profile) and ignore LD_PROFILE_OUTPUT. > > Allowing secure-execution profiling is already a non good security > boundary, since it enables different code paths and extra OS access by > the process. But by ignoring LD_PROFILE_OUTPUT, the resulting profile > file might also be acceded in a racy manner since the file name does not > use any process-specific information (such as pid, timing, etc.). > > Another side-effect is it forces lazy binding even on libraries that > might be with DF_BIND_NOW. > > [1] https://man7.org/linux/man-pages/man8/ld.so.8.html > --- LGTM. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org> > elf/Makefile | 3 +++ > elf/rtld.c | 8 +++----- > elf/tst-env-setuid.c | 12 +++++++++++- > 3 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/elf/Makefile b/elf/Makefile > index 52981c19d0..08896bb895 100644 > --- a/elf/Makefile > +++ b/elf/Makefile > @@ -2983,3 +2983,6 @@ $(objpfx)tst-dlclose-lazy.out: \ > $(objpfx)tst-dlclose-lazy-mod1.so $(objpfx)tst-dlclose-lazy-mod2.so > > tst-env-setuid-ARGS = -- $(host-test-program-cmd) > + > +# Reuse a module with a SONAME, to specific as the LD_PROFILE. > +$(objpfx)tst-env-setuid: $(objpfx)tst-sonamemove-runmod2.so > diff --git a/elf/rtld.c b/elf/rtld.c > index 51b6d9f326..a09cf2a9df 100644 > --- a/elf/rtld.c > +++ b/elf/rtld.c > @@ -361,6 +361,7 @@ struct rtld_global_ro _rtld_global_ro attribute_relro = > ._dl_fpu_control = _FPU_DEFAULT, > ._dl_pagesize = EXEC_PAGESIZE, > ._dl_inhibit_cache = 0, > + ._dl_profile_output = "/var/tmp", > > /* Function pointers. */ > ._dl_debug_printf = _dl_debug_printf, > @@ -2534,10 +2535,6 @@ process_envvars (struct dl_main_state *state) > char *envline; > char *debug_output = NULL; > > - /* This is the default place for profiling data file. */ > - GLRO(dl_profile_output) > - = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0]; > - > while ((envline = _dl_next_ld_env_entry (&runp)) != NULL) > { > size_t len = 0; > @@ -2586,7 +2583,8 @@ process_envvars (struct dl_main_state *state) > } > > /* Which shared object shall be profiled. */ > - if (memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0') > + if (!__libc_enable_secure > + && memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0') > GLRO(dl_profile) = &envline[8]; > break; > > diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c > index ba295a6a14..76b8e1fb45 100644 > --- a/elf/tst-env-setuid.c > +++ b/elf/tst-env-setuid.c > @@ -34,6 +34,9 @@ static char SETGID_CHILD[] = "setgid-child"; > > #define FILTERED_VALUE "some-filtered-value" > #define UNFILTERED_VALUE "some-unfiltered-value" > +/* It assumes no other programs is being profile with a library with same > + SONAME using the default folder. */ > +#define PROFILE_LIB "tst-sonamemove-runmod2.so" > > struct envvar_t > { > @@ -50,7 +53,7 @@ static const struct envvar_t filtered_envvars[] = > { "LD_HWCAP_MASK", FILTERED_VALUE }, > { "LD_LIBRARY_PATH", FILTERED_VALUE }, > { "LD_PRELOAD", FILTERED_VALUE }, > - { "LD_PROFILE", FILTERED_VALUE }, > + { "LD_PROFILE", "tst-sonamemove-runmod2.so" }, > { "MALLOC_ARENA_MAX", FILTERED_VALUE }, > { "MALLOC_PERTURB_", FILTERED_VALUE }, > { "MALLOC_TRACE", FILTERED_VALUE }, > @@ -87,6 +90,13 @@ test_child (void) > ret |= !(env != NULL && strcmp (env, e->value) == 0); > } > > + /* Also check if no profile file was created. */ > + { > + char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB); > + ret |= !access (profilepath, R_OK); > + free (profilepath); > + } > + > return ret; > } >
diff --git a/elf/Makefile b/elf/Makefile index 52981c19d0..08896bb895 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -2983,3 +2983,6 @@ $(objpfx)tst-dlclose-lazy.out: \ $(objpfx)tst-dlclose-lazy-mod1.so $(objpfx)tst-dlclose-lazy-mod2.so tst-env-setuid-ARGS = -- $(host-test-program-cmd) + +# Reuse a module with a SONAME, to specific as the LD_PROFILE. +$(objpfx)tst-env-setuid: $(objpfx)tst-sonamemove-runmod2.so diff --git a/elf/rtld.c b/elf/rtld.c index 51b6d9f326..a09cf2a9df 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -361,6 +361,7 @@ struct rtld_global_ro _rtld_global_ro attribute_relro = ._dl_fpu_control = _FPU_DEFAULT, ._dl_pagesize = EXEC_PAGESIZE, ._dl_inhibit_cache = 0, + ._dl_profile_output = "/var/tmp", /* Function pointers. */ ._dl_debug_printf = _dl_debug_printf, @@ -2534,10 +2535,6 @@ process_envvars (struct dl_main_state *state) char *envline; char *debug_output = NULL; - /* This is the default place for profiling data file. */ - GLRO(dl_profile_output) - = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0]; - while ((envline = _dl_next_ld_env_entry (&runp)) != NULL) { size_t len = 0; @@ -2586,7 +2583,8 @@ process_envvars (struct dl_main_state *state) } /* Which shared object shall be profiled. */ - if (memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0') + if (!__libc_enable_secure + && memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0') GLRO(dl_profile) = &envline[8]; break; diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c index ba295a6a14..76b8e1fb45 100644 --- a/elf/tst-env-setuid.c +++ b/elf/tst-env-setuid.c @@ -34,6 +34,9 @@ static char SETGID_CHILD[] = "setgid-child"; #define FILTERED_VALUE "some-filtered-value" #define UNFILTERED_VALUE "some-unfiltered-value" +/* It assumes no other programs is being profile with a library with same + SONAME using the default folder. */ +#define PROFILE_LIB "tst-sonamemove-runmod2.so" struct envvar_t { @@ -50,7 +53,7 @@ static const struct envvar_t filtered_envvars[] = { "LD_HWCAP_MASK", FILTERED_VALUE }, { "LD_LIBRARY_PATH", FILTERED_VALUE }, { "LD_PRELOAD", FILTERED_VALUE }, - { "LD_PROFILE", FILTERED_VALUE }, + { "LD_PROFILE", "tst-sonamemove-runmod2.so" }, { "MALLOC_ARENA_MAX", FILTERED_VALUE }, { "MALLOC_PERTURB_", FILTERED_VALUE }, { "MALLOC_TRACE", FILTERED_VALUE }, @@ -87,6 +90,13 @@ test_child (void) ret |= !(env != NULL && strcmp (env, e->value) == 0); } + /* Also check if no profile file was created. */ + { + char *profilepath = xasprintf ("/var/tmp/%s.profile", PROFILE_LIB); + ret |= !access (profilepath, R_OK); + free (profilepath); + } + return ret; }