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([2804:1b3:a7c2:94e:ee04:b0d3:203c:7e3]) by smtp.gmail.com with ESMTPSA id a4-20020a170902ee8400b001c9d011581dsm9736021pld.164.2023.11.22.04.36.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Nov 2023 04:36:09 -0800 (PST) From: Adhemerval Zanella To: libc-alpha@sourceware.org, siddhesh@sourceware.org Subject: [PATCH v4 2/4] elf: Ignore loader debug env vars for setuid Date: Wed, 22 Nov 2023 09:35:59 -0300 Message-Id: <20231122123601.603315-3-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231122123601.603315-1-adhemerval.zanella@linaro.org> References: <20231122123601.603315-1-adhemerval.zanella@linaro.org> MIME-Version: 1.0 X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org 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. --- 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 0553c05edb..d1017ba9e9 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -2550,13 +2550,15 @@ 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; @@ -2571,7 +2573,8 @@ 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; @@ -2630,7 +2633,8 @@ 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; @@ -2651,7 +2655,8 @@ 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 @@ -2673,9 +2678,10 @@ 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" \