Clean up property set error handling

Currently we only report why a property set call has failed but drop
the context of what was trying to set the property.  This change
adds information about why a property was trying to be set when it
fails.

It also unifies property_set() within init to go through the same
HandlePropertySet() function as normal processes do, removing unneeded
special cases.

Test: boot bullhead
Test: attempt to set invalid properties and see better error messages
Change-Id: I5cd3a40086fd3b226e9c8a5e3a84cb3b31399c0d

5 files changed, 64 insertions, 47 deletions

diff --git a/init/host_init_stubs.cpp b/init/host_init_stubs.cpp
index cde747de0..e6cc08a9a 100644
--- a/init/host_init_stubs.cpp
+++ b/init/host_init_stubs.cpp
@@ -43,8 +43,8 @@ std::string default_console = "/dev/console";
 
 // property_service.h
 uint32_t (*property_set)(const std::string& name, const std::string& value) = nullptr;
-uint32_t HandlePropertySet(const std::string&, const std::string&, const std::string&,
-                           const ucred&) {
+uint32_t HandlePropertySet(const std::string&, const std::string&, const std::string&, const ucred&,
+                           std::string*) {
     return 0;
 }
 
diff --git a/init/host_init_stubs.h b/init/host_init_stubs.h
index af96aea15..f31ece60c 100644
--- a/init/host_init_stubs.h
+++ b/init/host_init_stubs.h
@@ -48,7 +48,7 @@ extern std::string default_console;
 // property_service.h
 extern uint32_t (*property_set)(const std::string& name, const std::string& value);
 uint32_t HandlePropertySet(const std::string& name, const std::string& value,
-                           const std::string& source_context, const ucred& cr);
+                           const std::string& source_context, const ucred& cr, std::string* error);
 
 // selinux.h
 void SelabelInitialize();
diff --git a/init/property_service.cpp b/init/property_service.cpp
index 338c05aec..624780f64 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -117,23 +117,21 @@ static bool CheckMacPerms(const std::string& name, const char* target_context,
     return has_access;
 }
 
-static uint32_t PropertySetImpl(const std::string& name, const std::string& value) {
+static uint32_t PropertySet(const std::string& name, const std::string& value, std::string* error) {
     size_t valuelen = value.size();
 
     if (!IsLegalPropertyName(name)) {
-        LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: bad name";
+        *error = "Illegal property name";
         return PROP_ERROR_INVALID_NAME;
     }
 
     if (valuelen >= PROP_VALUE_MAX && !StartsWith(name, "ro.")) {
-        LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
-                   << "value too long";
+        *error = "Property value too long";
         return PROP_ERROR_INVALID_VALUE;
     }
 
     if (mbstowcs(nullptr, value.data(), 0) == static_cast<std::size_t>(-1)) {
-        LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
-                   << "value not a UTF8 encoded string";
+        *error = "Value is not a UTF8 encoded string";
         return PROP_ERROR_INVALID_VALUE;
     }
 
@@ -141,8 +139,7 @@ static uint32_t PropertySetImpl(const std::string& name, const std::string& valu
     if (pi != nullptr) {
         // ro.* properties are actually "write-once".
         if (StartsWith(name, "ro.")) {
-            LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
-                       << "property already set";
+            *error = "Read-only property was already set";
             return PROP_ERROR_READ_ONLY_PROPERTY;
         }
 
@@ -150,8 +147,7 @@ static uint32_t PropertySetImpl(const std::string& name, const std::string& valu
     } else {
         int rc = __system_property_add(name.c_str(), name.size(), value.c_str(), valuelen);
         if (rc < 0) {
-            LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
-                       << "__system_property_add failed";
+            *error = "__system_property_add failed";
             return PROP_ERROR_SET_FAILED;
         }
     }
@@ -205,8 +201,10 @@ bool PropertyChildReap(pid_t pid) {
     if (info.pid != pid) {
         return false;
     }
-    if (PropertySetImpl(info.name, info.value) != PROP_SUCCESS) {
-        LOG(ERROR) << "Failed to set async property " << info.name;
+    std::string error;
+    if (PropertySet(info.name, info.value, &error) != PROP_SUCCESS) {
+        LOG(ERROR) << "Failed to set async property " << info.name << " to " << info.value << ": "
+                   << error;
     }
     property_children.pop();
     if (!property_children.empty()) {
@@ -216,9 +214,9 @@ bool PropertyChildReap(pid_t pid) {
 }
 
 static uint32_t PropertySetAsync(const std::string& name, const std::string& value,
-                                 PropertyAsyncFunc func) {
+                                 PropertyAsyncFunc func, std::string* error) {
     if (value.empty()) {
-        return PropertySetImpl(name, value);
+        return PropertySet(name, value, error);
     }
 
     PropertyChildInfo info;
@@ -236,30 +234,27 @@ static int RestoreconRecursiveAsync(const std::string& name, const std::string&
     return selinux_android_restorecon(value.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE);
 }
 
-uint32_t PropertySet(const std::string& name, const std::string& value) {
-    if (name == "selinux.restorecon_recursive") {
-        return PropertySetAsync(name, value, RestoreconRecursiveAsync);
-    }
-
-    return PropertySetImpl(name, value);
-}
-
 uint32_t InitPropertySet(const std::string& name, const std::string& value) {
     if (StartsWith(name, "ctl.")) {
-        LOG(ERROR) << "Do not set ctl. properties from init; call the Service functions directly";
+        LOG(ERROR) << "InitPropertySet: Do not set ctl. properties from init; call the Service "
+                      "functions directly";
+        return PROP_ERROR_INVALID_NAME;
+    }
+    if (name == "selinux.restorecon_recursive") {
+        LOG(ERROR) << "InitPropertySet: Do not set selinux.restorecon_recursive from init; use the "
+                      "restorecon builtin directly";
         return PROP_ERROR_INVALID_NAME;
     }
 
-    const char* type = nullptr;
-    property_info_area->GetPropertyInfo(name.c_str(), nullptr, &type);
-
-    if (type == nullptr || !CheckType(type, value)) {
-        LOG(ERROR) << "property_set: name: '" << name << "' type check failed, type: '"
-                   << (type ?: "(null)") << "' value: '" << value << "'";
-        return PROP_ERROR_INVALID_VALUE;
+    uint32_t result = 0;
+    ucred cr = {.pid = 1, .uid = 0, .gid = 0};
+    std::string error;
+    result = HandlePropertySet(name, value, kInitContext.c_str(), cr, &error);
+    if (result != PROP_SUCCESS) {
+        LOG(ERROR) << "Init cannot set '" << name << "' to '" << value << "': " << error;
     }
 
-    return PropertySet(name, value);
+    return result;
 }
 
 class SocketConnection {
@@ -390,9 +385,9 @@ class SocketConnection {
 
 // This returns one of the enum of PROP_SUCCESS or PROP_ERROR*.
 uint32_t HandlePropertySet(const std::string& name, const std::string& value,
-                           const std::string& source_context, const ucred& cr) {
+                           const std::string& source_context, const ucred& cr, std::string* error) {
     if (!IsLegalPropertyName(name)) {
-        LOG(ERROR) << "PropertySet: illegal property name \"" << name << "\"";
+        *error = "Illegal property name";
         return PROP_ERROR_INVALID_NAME;
     }
 
@@ -405,9 +400,7 @@ uint32_t HandlePropertySet(const std::string& name, const std::string& value,
         const char* type = nullptr;
         property_info_area->GetPropertyInfo(control_string.c_str(), &target_context, &type);
         if (!CheckMacPerms(control_string, target_context, source_context.c_str(), cr)) {
-            LOG(ERROR) << "PropertySet: Unable to " << (name.c_str() + 4) << " service ctl ["
-                       << value << "]"
-                       << " uid:" << cr.uid << " gid:" << cr.gid << " pid:" << cr.pid;
+            *error = StringPrintf("Unable to '%s' service %s", name.c_str() + 4, value.c_str());
             return PROP_ERROR_HANDLE_CONTROL_MESSAGE;
         }
 
@@ -420,13 +413,13 @@ uint32_t HandlePropertySet(const std::string& name, const std::string& value,
     property_info_area->GetPropertyInfo(name.c_str(), &target_context, &type);
 
     if (!CheckMacPerms(name, target_context, source_context.c_str(), cr)) {
-        LOG(ERROR) << "PropertySet: permission denied uid:" << cr.uid << " name:" << name;
+        *error = "SELinux permission check failed";
         return PROP_ERROR_PERMISSION_DENIED;
     }
 
     if (type == nullptr || !CheckType(type, value)) {
-        LOG(ERROR) << "PropertySet: name: '" << name << "' type check failed, type: '"
-                   << (type ?: "(null)") << "' value: '" << value << "'";
+        *error = StringPrintf("Property type check failed, value doesn't match expected type '%s'",
+                              (type ?: "(null)"));
         return PROP_ERROR_INVALID_VALUE;
     }
 
@@ -445,7 +438,11 @@ uint32_t HandlePropertySet(const std::string& name, const std::string& value,
                   << process_log_string;
     }
 
-    return PropertySet(name, value);
+    if (name == "selinux.restorecon_recursive") {
+        return PropertySetAsync(name, value, RestoreconRecursiveAsync, error);
+    }
+
+    return PropertySet(name, value, error);
 }
 
 static void handle_property_set_fd() {
@@ -488,7 +485,16 @@ static void handle_property_set_fd() {
         prop_name[PROP_NAME_MAX-1] = 0;
         prop_value[PROP_VALUE_MAX-1] = 0;
 
-        HandlePropertySet(prop_value, prop_value, socket.source_context(), socket.cred());
+        const auto& cr = socket.cred();
+        std::string error;
+        uint32_t result =
+            HandlePropertySet(prop_name, prop_value, socket.source_context(), cr, &error);
+        if (result != PROP_SUCCESS) {
+            LOG(ERROR) << "Unable to set property '" << prop_name << "' to '" << prop_value
+                       << "' from uid:" << cr.uid << " gid:" << cr.gid << " pid:" << cr.pid << ": "
+                       << error;
+        }
+
         break;
       }
 
@@ -502,7 +508,14 @@ static void handle_property_set_fd() {
           return;
         }
 
-        auto result = HandlePropertySet(name, value, socket.source_context(), socket.cred());
+        const auto& cr = socket.cred();
+        std::string error;
+        uint32_t result = HandlePropertySet(name, value, socket.source_context(), cr, &error);
+        if (result != PROP_SUCCESS) {
+            LOG(ERROR) << "Unable to set property '" << name << "' to '" << value
+                       << "' from uid:" << cr.uid << " gid:" << cr.gid << " pid:" << cr.pid << ": "
+                       << error;
+        }
         socket.SendUint32(result);
         break;
       }
diff --git a/init/property_service.h b/init/property_service.h
index d4973fc89..29eaaa901 100644
--- a/init/property_service.h
+++ b/init/property_service.h
@@ -32,7 +32,7 @@ struct property_audit_data {
 extern uint32_t (*property_set)(const std::string& name, const std::string& value);
 
 uint32_t HandlePropertySet(const std::string& name, const std::string& value,
-                           const std::string& source_context, const ucred& cr);
+                           const std::string& source_context, const ucred& cr, std::string* error);
 
 extern bool PropertyChildReap(pid_t pid);
 
diff --git a/init/subcontext.cpp b/init/subcontext.cpp
index faab36848..762492c87 100644
--- a/init/subcontext.cpp
+++ b/init/subcontext.cpp
@@ -297,7 +297,11 @@ Result<Success> Subcontext::Execute(const std::vector<std::string>& args) {
 
     for (const auto& property : subcontext_reply->properties_to_set()) {
         ucred cr = {.pid = pid_, .uid = 0, .gid = 0};
-        HandlePropertySet(property.name(), property.value(), context_, cr);
+        std::string error;
+        if (HandlePropertySet(property.name(), property.value(), context_, cr, &error) != 0) {
+            LOG(ERROR) << "Subcontext init could not set '" << property.name() << "' to '"
+                       << property.value() << "': " << error;
+        }
     }
 
     if (subcontext_reply->reply_case() == SubcontextReply::kFailure) {