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From: Adhemerval Zanella <azanella@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] elf: Ignore loader debug env vars for setuid Date: Tue, 5 Dec 2023 20:34:04 +0000 (GMT) [thread overview] Message-ID: <20231205203404.B85373858C60@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=876a12e51323b4c0f7b6f32ec76f4a5280b7f0b9 commit 876a12e51323b4c0f7b6f32ec76f4a5280b7f0b9 Author: Adhemerval Zanella <adhemerval.zanella@linaro.org> Date: Wed Nov 22 17:43:23 2023 -0300 elf: Ignore loader debug env vars for setuid Loader already ignores LD_DEBUG, LD_DEBUG_OUTPUT, and LD_TRACE_LOADED_OBJECTS. Both LD_WARN and LD_VERBOSE are similar to LD_DEBUG, in the sense they enable additional checks and debug information, so it makes sense to disable them. Also add both LD_VERBOSE and LD_WARN on filtered environment variables for setuid binaries. Checked on x86_64-linux-gnu. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org> Diff: --- elf/rtld.c | 22 ++++++++++++++-------- elf/tst-env-setuid.c | 4 ++++ sysdeps/generic/unsecvars.h | 2 ++ 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/elf/rtld.c b/elf/rtld.c index 19bedcd4a6..55cdb4836e 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -2556,13 +2556,15 @@ process_envvars (struct dl_main_state *state) { case 4: /* Warning level, verbose or not. */ - if (memcmp (envline, "WARN", 4) == 0) + if (!__libc_enable_secure + && memcmp (envline, "WARN", 4) == 0) GLRO(dl_verbose) = envline[5] != '\0'; break; case 5: /* Debugging of the dynamic linker? */ - if (memcmp (envline, "DEBUG", 5) == 0) + if (!__libc_enable_secure + && memcmp (envline, "DEBUG", 5) == 0) { process_dl_debug (state, &envline[6]); break; @@ -2577,7 +2579,8 @@ process_envvars (struct dl_main_state *state) case 7: /* Print information about versions. */ - if (memcmp (envline, "VERBOSE", 7) == 0) + if (!__libc_enable_secure + && memcmp (envline, "VERBOSE", 7) == 0) { state->version_info = envline[8] != '\0'; break; @@ -2636,7 +2639,8 @@ process_envvars (struct dl_main_state *state) } /* Where to place the profiling data file. */ - if (memcmp (envline, "DEBUG_OUTPUT", 12) == 0) + if (!__libc_enable_secure + && memcmp (envline, "DEBUG_OUTPUT", 12) == 0) { debug_output = &envline[13]; break; @@ -2657,7 +2661,8 @@ process_envvars (struct dl_main_state *state) case 20: /* The mode of the dynamic linker can be set. */ - if (memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0) + if (!__libc_enable_secure + && memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0) { state->mode = rtld_mode_trace; state->mode_trace_program @@ -2679,9 +2684,10 @@ process_envvars (struct dl_main_state *state) } while (*nextp != '\0'); - GLRO(dl_debug_mask) = 0; - - if (state->mode != rtld_mode_normal) + if (GLRO(dl_debug_mask) != 0 + || GLRO(dl_verbose) != 0 + || state->mode != rtld_mode_normal + || state->version_info) _exit (5); } /* If we have to run the dynamic linker in debugging mode and the diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c index 76b8e1fb45..b1d64ac085 100644 --- a/elf/tst-env-setuid.c +++ b/elf/tst-env-setuid.c @@ -59,6 +59,10 @@ static const struct envvar_t filtered_envvars[] = { "MALLOC_TRACE", FILTERED_VALUE }, { "MALLOC_TRIM_THRESHOLD_", FILTERED_VALUE }, { "RES_OPTIONS", FILTERED_VALUE }, + { "LD_DEBUG", "all" }, + { "LD_DEBUG_OUTPUT", "/tmp/some-file" }, + { "LD_WARN", FILTERED_VALUE }, + { "LD_VERBOSE", FILTERED_VALUE }, }; static const struct envvar_t unfiltered_envvars[] = diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h index f7ebed60e5..8975df4a14 100644 --- a/sysdeps/generic/unsecvars.h +++ b/sysdeps/generic/unsecvars.h @@ -16,6 +16,8 @@ "LD_PRELOAD\0" \ "LD_PROFILE\0" \ "LD_SHOW_AUXV\0" \ + "LD_VERBOSE\0" \ + "LD_WARN\0" \ "LOCALDOMAIN\0" \ "LOCPATH\0" \ "MALLOC_ARENA_MAX\0" \
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