Add debug logging for memtag level
Test: adb logcat 'libc:D' | grep memtag
Bug: 272596642
Change-Id: I764a0ea4fd71b547d1c5b82a1537e50016578e0f
diff --git a/libc/bionic/gwp_asan_wrappers.cpp b/libc/bionic/gwp_asan_wrappers.cpp
index 251633d..fab29ef 100644
--- a/libc/bionic/gwp_asan_wrappers.cpp
+++ b/libc/bionic/gwp_asan_wrappers.cpp
@@ -307,8 +307,10 @@
sysprop_names[3] = persist_default_sysprop;
}
+ // TODO(mitchp): Log overrides using this.
+ const char* source;
return get_config_from_env_or_sysprops(env_var, sysprop_names, arraysize(sysprop_names),
- value_out, PROP_VALUE_MAX);
+ value_out, PROP_VALUE_MAX, &source);
}
bool GetGwpAsanIntegerOption(unsigned long long* result,
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index d64d402..0935cd6 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -217,16 +217,13 @@
// Returns true if there's an environment setting (either sysprop or env var)
// that should overwrite the ELF note, and places the equivalent heap tagging
// level into *level.
-static bool get_environment_memtag_setting(HeapTaggingLevel* level) {
+static bool get_environment_memtag_setting(const char* basename, HeapTaggingLevel* level) {
static const char kMemtagPrognameSyspropPrefix[] = "arm64.memtag.process.";
static const char kMemtagGlobalSysprop[] = "persist.arm64.memtag.default";
static const char kMemtagOverrideSyspropPrefix[] =
"persist.device_config.memory_safety_native.mode_override.process.";
- const char* progname = __libc_shared_globals()->init_progname;
- if (progname == nullptr) return false;
-
- const char* basename = __gnu_basename(progname);
+ if (basename == nullptr) return false;
char options_str[PROP_VALUE_MAX];
char sysprop_name[512];
@@ -237,8 +234,9 @@
kMemtagOverrideSyspropPrefix, basename);
const char* sys_prop_names[] = {sysprop_name, remote_sysprop_name, kMemtagGlobalSysprop};
+ const char* source = nullptr;
if (!get_config_from_env_or_sysprops("MEMTAG_OPTIONS", sys_prop_names, arraysize(sys_prop_names),
- options_str, sizeof(options_str))) {
+ options_str, sizeof(options_str), &source)) {
return false;
}
@@ -249,27 +247,35 @@
} else if (strcmp("off", options_str) == 0) {
*level = M_HEAP_TAGGING_LEVEL_TBI;
} else {
- async_safe_format_log(
- ANDROID_LOG_ERROR, "libc",
- "unrecognized memtag level: \"%s\" (options are \"sync\", \"async\", or \"off\").",
- options_str);
+ async_safe_format_log(ANDROID_LOG_ERROR, "libc",
+ "%s: unrecognized memtag level in %s: \"%s\" (options are \"sync\", "
+ "\"async\", or \"off\").",
+ basename, source, options_str);
return false;
}
-
+ async_safe_format_log(ANDROID_LOG_DEBUG, "libc", "%s: chose memtag level \"%s\" from %s.",
+ basename, options_str, source);
return true;
}
+static void log_elf_memtag_level(const char* basename, const char* level) {
+ async_safe_format_log(ANDROID_LOG_DEBUG, "libc", "%s: chose memtag level \"%s\" from ELF note",
+ basename ?: "<unknown>", level);
+}
+
// Returns the initial heap tagging level. Note: This function will never return
// M_HEAP_TAGGING_LEVEL_NONE, if MTE isn't enabled for this process we enable
// M_HEAP_TAGGING_LEVEL_TBI.
static HeapTaggingLevel __get_heap_tagging_level(const void* phdr_start, size_t phdr_ct,
uintptr_t load_bias, bool* stack) {
+ const char* progname = __libc_shared_globals()->init_progname;
+ const char* basename = progname ? __gnu_basename(progname) : nullptr;
unsigned note_val =
__get_memtag_note(reinterpret_cast<const ElfW(Phdr)*>(phdr_start), phdr_ct, load_bias);
*stack = note_val & NT_MEMTAG_STACK;
HeapTaggingLevel level;
- if (get_environment_memtag_setting(&level)) return level;
+ if (get_environment_memtag_setting(basename, &level)) return level;
// Note, previously (in Android 12), any value outside of bits [0..3] resulted
// in a check-fail. In order to be permissive of further extensions, we
@@ -284,14 +290,17 @@
// by anyone, but we note it (heh) here for posterity, in case the zero
// level becomes meaningful, and binaries with this note can be executed
// on Android 12 devices.
+ log_elf_memtag_level(basename, "off");
return M_HEAP_TAGGING_LEVEL_TBI;
case NT_MEMTAG_LEVEL_ASYNC:
+ log_elf_memtag_level(basename, "async");
return M_HEAP_TAGGING_LEVEL_ASYNC;
case NT_MEMTAG_LEVEL_SYNC:
default:
// We allow future extensions to specify mode 3 (currently unused), with
// the idea that it might be used for ASYMM mode or something else. On
// this version of Android, it falls back to SYNC mode.
+ log_elf_memtag_level(basename, "sync");
return M_HEAP_TAGGING_LEVEL_SYNC;
}
}
diff --git a/libc/bionic/sysprop_helpers.cpp b/libc/bionic/sysprop_helpers.cpp
index 5627034..2051330 100644
--- a/libc/bionic/sysprop_helpers.cpp
+++ b/libc/bionic/sysprop_helpers.cpp
@@ -57,18 +57,22 @@
}
bool get_config_from_env_or_sysprops(const char* env_var_name, const char* const* sys_prop_names,
- size_t sys_prop_names_size, char* options,
- size_t options_size) {
+ size_t sys_prop_names_size, char* options, size_t options_size,
+ const char** chosen_source) {
const char* env = getenv(env_var_name);
if (env && *env != '\0') {
strncpy(options, env, options_size);
options[options_size - 1] = '\0'; // Ensure null-termination.
+ *chosen_source = env_var_name;
return true;
}
for (size_t i = 0; i < sys_prop_names_size; ++i) {
if (sys_prop_names[i] == nullptr) continue;
- if (get_property_value(sys_prop_names[i], options, options_size)) return true;
+ if (get_property_value(sys_prop_names[i], options, options_size)) {
+ *chosen_source = sys_prop_names[i];
+ return true;
+ }
}
return false;
}
diff --git a/libc/bionic/sysprop_helpers.h b/libc/bionic/sysprop_helpers.h
index a02c2dc..84e7af1 100644
--- a/libc/bionic/sysprop_helpers.h
+++ b/libc/bionic/sysprop_helpers.h
@@ -36,10 +36,13 @@
// 2. System properties, in the order they're specified in sys_prop_names.
// If neither of these options are specified (or they're both an empty string),
// this function returns false. Otherwise, it returns true, and the presiding
-// options string is written to the `options` buffer of size `size`. If this
-// function returns true, `options` is guaranteed to be null-terminated.
+// options string is written to the `options` buffer of size `size`. It will
+// store a pointer to either env_var_name, or into the relevant entry of
+// sys_prop_names into choicen_source, indiciating which value was used. If
+// this function returns true, `options` is guaranteed to be null-terminated.
// `options_size` should be at least PROP_VALUE_MAX.
__LIBC_HIDDEN__ bool get_config_from_env_or_sysprops(const char* env_var_name,
const char* const* sys_prop_names,
size_t sys_prop_names_size, char* options,
- size_t options_size);
+ size_t options_size,
+ const char** chosen_source);