parser: add support for attach_disconnected.ipc flag

The attach_disconnected.ipc flag allows the use of disconnected paths
on posix mqueues. This flag is a subset of attach_disconnected, and it
does not allow disconnected paths for all files.

Signed-off-by: Georgia Garcia <georgia.garcia@canonical.com>

parser/apparmor.d.pod

@@ -115,6 +115,7 @@ B<PROFILE FLAG CONDS> =  [ 'flags=' ] '(' comma or white space separated list of
 
 B<PROFILE FLAGS> = I<PROFILE MODE> | I<AUDIT_MODE> | 'mediate_deleted'
 | 'attach_disconnected' | 'attach_disconneced.path='I<ABS PATH> | 'chroot_relative'
+| 'attach_disconnected.ipc' | 'attach_disconnected.ipc='I<ABS PATH>
 | 'debug' | 'interruptible' | 'kill.signal='I<SIGNAL> | 'error='I<ERROR CODE>
 
 B<ERROR CODE> = (case insensitive error code name starting with 'E'; see errno(3))
@@ -560,6 +561,14 @@ allowed. Its intent is a debug and policy development tool.
 attach disconnected objects to the supplied path instead of the root of
 the namespace.
 
+=item B<attach_disconnected.ipc> A subset of attach_disconnected, but specific
+for IPC namespaces. It allows attaching disconnected IPC paths without having
+to allow attaching all types of files.
+
+=item B<attach_disconnected.ipc>=I<ABS PATH> Like attach_disconnected.ipc, but
+attach disconnected posix mqueue to the supplied path instead of the root of
+the namespace.
+
 =item B<chroot_relative> This forces file names to be relative to a
 chroot and behave as if the chroot is a mount namespace.
 

parser/parser.h

@@ -189,7 +189,7 @@ extern int preprocess_only;
 #define PATH_DELEGATE_DELETED 0x20
 #define PATH_ATTACH 0x40
 #define PATH_NO_ATTACH 0x80
-
+#define PATH_IPC_ATTACH 0x100
 
 
 #ifdef DEBUG
@@ -334,6 +334,7 @@ extern int features_supports_io_uring;
 extern int features_supports_flag_interruptible;
 extern int features_supports_flag_signal;
 extern int features_supports_flag_error;
+extern int features_supports_flag_disconnected_ipc;
 extern int kernel_supports_oob;
 extern int kernel_supports_promptdev;
 extern int kernel_supports_permstable32;

parser/parser_common.c

@@ -86,6 +86,7 @@ int features_supports_io_uring = 0;	/* kernel supports io_uring rules */
 int features_supports_flag_interruptible = 0;
 int features_supports_flag_signal = 0;
 int features_supports_flag_error = 0;
+int features_supports_flag_disconnected_ipc = 0;	/* kernel supports disconnected paths for ipc ns */
 int kernel_supports_oob = 0;		/* out of band transitions */
 int kernel_supports_promptdev = 0;	/* prompt via audit perms */
 int kernel_supports_permstable32 = 0;	/* extended permissions */

parser/parser_interface.c

@@ -474,6 +474,11 @@ void sd_serialize_profile(std::ostringstream &buf, Profile *profile,
 				"disconnected");
 	}
 
+	if (profile->flags.disconnected_ipc && features_supports_flag_disconnected_ipc) {
+		sd_write_string(buf, profile->flags.disconnected_ipc,
+				"disconnected_ipc");
+	}
+
 	if (profile->flags.signal && features_supports_flag_signal) {
 		sd_write_name(buf, "kill");
 		sd_write_uint32(buf, profile->flags.signal);
@@ -500,6 +505,8 @@ void sd_serialize_profile(std::ostringstream &buf, Profile *profile,
 			flags |= 0x4;
 		if (profile->flags.path & PATH_CHROOT_NSATTACH)
 			flags |= 0x10;
+		if (profile->flags.path & PATH_IPC_ATTACH)
+			flags |= 0x20;
 
 		sd_write_name(buf, "path_flags");
 		sd_write_uint32(buf, flags);

parser/parser_main.c

@@ -991,6 +991,9 @@ void set_supported_features()
 	features_supports_flag_error = features_intersect(kernel_features,
 							  policy_features,
 							  "policy/profile/error");
+	features_supports_flag_disconnected_ipc = features_intersect(kernel_features,
+								     policy_features,
+								     "domain/disconnected.ipc");
 }
 
 static bool do_print_cache_dir(aa_features *features, int dirfd, const char *path)

parser/parser_variable.c

@@ -272,6 +272,23 @@ static int process_variables_in_rules(Profile &prof)
 	return 0;
 }
 
+
+static int process_variable_in_attach_disconnected(char **disconnected)
+{
+	int error = expand_entry_variables(disconnected);
+	if (error)
+		return error;
+	filter_slashes(*disconnected);
+	// TODO: semantic check should go somewhere else
+	if ((*disconnected)[0] != '/')
+		yyerror(_("attach_disconnected path must begin with a /"));
+	int n = strlen(*disconnected);
+	// removing trailing / */
+	while (n && (*disconnected)[n-1] == '/')
+		(*disconnected)[--n] = 0;
+	return error;
+}
+
 static int process_variables_in_name(Profile &prof)
 {
 	/* this needs to be done before alias expansion, ie. altnames are
@@ -280,20 +297,10 @@ static int process_variables_in_name(Profile &prof)
 	int error = expand_entry_variables(&prof.name);
 	if (!error && prof.attachment)
 		error = expand_entry_variables(&prof.attachment);
-	if (!error && prof.flags.disconnected_path) {
+	if (!error && prof.flags.disconnected_path)
-		error = expand_entry_variables(&prof.flags.disconnected_path);
+		error = process_variable_in_attach_disconnected(&prof.flags.disconnected_path);
-		if (error)
+	if (!error && prof.flags.disconnected_ipc)
-			return error;
+		error = process_variable_in_attach_disconnected(&prof.flags.disconnected_ipc);
-		filter_slashes(prof.flags.disconnected_path);
-		// TODO: semantic check should go somewhere else
-		if (prof.flags.disconnected_path[0] != '/')
-			yyerror(_("attach_disconnected_path value must begin with a /"));
-		int n = strlen(prof.flags.disconnected_path);
-		// removing trailing / */
-		while (n && prof.flags.disconnected_path[n-1] == '/')
-			prof.flags.disconnected_path[--n] = 0;
-
-	}
 	return error;
 }
 

parser/profile.cc

@@ -97,6 +97,8 @@ Profile::~Profile()
 		free(attachment);
 	if (flags.disconnected_path)
 		free(flags.disconnected_path);
+	if (flags.disconnected_ipc)
+		free(flags.disconnected_ipc);
 	if (ns)
 		free(ns);
 	for (int i = (AA_EXEC_LOCAL >> 10) + 1; i < AA_EXEC_COUNT; i++)

parser/profile.h

@@ -159,6 +159,7 @@ public:
 	int audit;
 	int path;
 	char *disconnected_path;
+	char *disconnected_ipc;
 	int signal;
 	int error;
 
@@ -170,6 +171,7 @@ public:
 		audit = 0;
 		path = 0;
 		disconnected_path = NULL;
+		disconnected_ipc = NULL;
 		signal = 0;
 		error = 0;
 	}
@@ -216,6 +218,12 @@ public:
 				yyerror("unknown error code specified for error=\'%s\'\n", str + 6);
 		} else if (strcmp(str, "interruptible") == 0) {
 				flags |= FLAG_INTERRUPTIBLE;
+		} else if (strcmp(str, "attach_disconnected.ipc") == 0) {
+			path |= PATH_IPC_ATTACH;
+		} else if (strncmp(str, "attach_disconnected.ipc=", 24) == 0) {
+			/* TODO: make this a proper parse */
+			path |= PATH_IPC_ATTACH;
+			disconnected_ipc = strdup(str + 24);
 		} else {
 			yyerror(_("Invalid profile flag: %s."), str);
 		}
@@ -237,6 +245,8 @@ public:
 			os << ", kill.signal=" << signal;
 		if (error)
 			os << ", error=" << find_error_name_mapping(error);
+		if (disconnected_ipc)
+			os << ", attach_disconnected.ipc=" << disconnected_ipc;
 
 		if (flags & FLAG_PROMPT_COMPAT)
 			os << ", prompt_dev";
@@ -277,6 +287,9 @@ public:
 		if ((path & (PATH_ATTACH | PATH_NO_ATTACH)) ==
 		    (PATH_ATTACH | PATH_NO_ATTACH))
 			yyerror(_("Profile flag attach_disconnected conflicts with no_attach_disconnected"));
+		if ((path & (PATH_IPC_ATTACH | PATH_NO_ATTACH)) ==
+		    (PATH_IPC_ATTACH | PATH_NO_ATTACH))
+			yyerror(_("Profile flag attach_disconnected.ipc conflicts with no_attach_disconnected"));
 		if ((path & (PATH_CHROOT_NSATTACH | PATH_CHROOT_NO_ATTACH)) ==
 		    (PATH_CHROOT_NSATTACH | PATH_CHROOT_NO_ATTACH))
 			yyerror(_("Profile flag chroot_attach conflicts with chroot_no_attach"));
@@ -291,6 +304,16 @@ public:
 				disconnected_path = rhs.disconnected_path;
 			}
 		}
+		if (rhs.disconnected_ipc) {
+			if (disconnected_ipc) {
+				if (strcmp(disconnected_ipc, rhs.disconnected_ipc) != 0) {
+					yyerror(_("Profile flag attach_disconnected set to conflicting values: '%s' and '%s'"), disconnected_ipc, rhs.disconnected_ipc);
+				}
+				// same so do nothing
+			} else {
+				disconnected_ipc = rhs.disconnected_ipc;
+			}
+		}
 		if (rhs.signal) {
 			if (signal) {
 				if (signal != rhs.signal) {