[PATCH] add $local user spport for permissions

klibc_fixups.c

@@ -25,6 +25,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <ctype.h>
+#include <fcntl.h>
 #include <sys/types.h>
 
 #include "klibc_fixups.h"
@@ -32,6 +33,8 @@
 
 #define PW_FILE		"/etc/passwd"
 #define GR_FILE		"/etc/group"
+#define UTMP_FILE	"/var/run/utmp"
+
 
 /* return the id of a passwd style line, selected by the users name */
 static unsigned long get_id_by_name(const char *uname, const char *dbfile)
@@ -107,4 +110,38 @@ struct group *getgrnam(const char *name)
 		return &gr;
 }
 
+
+int ufd = -1;
+
+void setutent()
+{
+	if (ufd < 0)
+		ufd = open(UTMP_FILE, O_RDONLY);
+	fcntl(ufd, F_SETFD, FD_CLOEXEC);
+	lseek(ufd, 0, SEEK_SET);
+}
+
+void endutent() {
+	if (ufd < 0)
+		return;
+	close(ufd);
+	ufd = -1;
+}
+
+struct utmp *getutent(void)
+{
+	static struct utmp utmp;
+	int retval;
+
+	if (ufd < 0) {
+		setutent();
+		if (ufd < 0)
+			return NULL;
+	}
+	retval = read(ufd, &utmp, sizeof(struct utmp));
+	if (retval < 1)
+		return NULL;
+	return &utmp;
+}
+
 #endif

klibc_fixups.h

@@ -1,7 +1,7 @@
 #ifdef __KLIBC__
 
 #ifndef KLIBC_FIXUPS_H
-#define KLIBC_FIXUPS_H 
+#define KLIBC_FIXUPS_H
 
 struct passwd {
 	char	*pw_name;	/* user name */
@@ -23,6 +23,49 @@ struct group {
 struct passwd *getpwnam(const char *name);
 struct group *getgrnam(const char *name);
 
-#endif
 
+#define UT_LINESIZE		32
+#define UT_NAMESIZE		32
+#define UT_HOSTSIZE		256
+#define USER_PROCESS		7	/* normal process */
+#define ut_time			ut_tv.tv_sec
+
+
+extern int ufd;
+
+struct exit_status {
+	short int e_termination;	/* process termination status */
+	short int e_exit;		/* process exit status */
+};
+
+struct utmp
+{
+	short int ut_type;		/* type of login */
+	pid_t ut_pid;			/* pid of login process */
+	char ut_line[UT_LINESIZE];	/* devicename */
+	char ut_id[4];			/* Inittab id  */
+	char ut_user[UT_NAMESIZE];	/* username  */
+	char ut_host[UT_HOSTSIZE];	/* hostname for remote login */
+	struct exit_status ut_exit;	/* exit status of a process marked as DEAD_PROCESS */
+	/* The ut_session and ut_tv fields must be the same size for 32 and 64-bit */
+#if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32
+	int32_t ut_session;		/* sid used for windowing */
+	struct {
+		int32_t tv_sec;		/* seconds */
+		int32_t tv_usec;	/* microseconds */
+	} ut_tv;
+#else
+	long int ut_session;
+	struct timeval ut_tv;
 #endif
+	int32_t ut_addr_v6[4];		/* internet address of remote host */
+	char __unused[20];		/* reserved for future use */
+};
+
+struct utmp *getutent(void);
+void setutent(void);
+void endutent(void);
+
+
+#endif /* KLIBC_FIXUPS_H */
+#endif /* __KLIBC__ */

udev-add.c

@@ -32,6 +32,7 @@
 #include <grp.h>
 #ifndef __KLIBC__
 #include <pwd.h>
+#include <utmp.h>
 #endif
 
 #include "libsysfs/sysfs/libsysfs.h"
@@ -44,6 +45,8 @@
 #include "udevdb.h"
 #include "klibc_fixups.h"
 
+#define LOCAL_USER "$local"
+
 /* 
  * Right now the major/minor of a device is stored in a file called
  * "dev" in sysfs.
@@ -132,6 +135,37 @@ static int make_node(char *filename, int major, int minor, unsigned int mode, ui
 	return 0;
 }
 
+/* get the local logged in user */
+static void set_to_local_user(char *user)
+{
+	struct utmp *u;
+	time_t recent = 0;
+
+	strnfieldcpy(user, default_owner_str, OWNER_SIZE);
+	setutent();
+	while (1) {
+		u = getutent();
+		if (u == NULL)
+			break;
+
+		/* is this a user login ? */
+		if (u->ut_type != USER_PROCESS)
+			continue;
+
+		/* is this a local login ? */
+		if (strcmp(u->ut_host, ""))
+			continue;
+
+		if (u->ut_time > recent) {
+			recent = u->ut_time;
+			strfieldcpy(user, u->ut_user);
+			dbg("local user is '%s'", user);
+			break;
+		}
+	}
+	endutent();
+}
+
 static int create_node(struct udevice *dev, int fake)
 {
 	struct stat stats;
@@ -175,6 +209,9 @@ static int create_node(struct udevice *dev, int fake)
 		if (endptr[0] == '\0')
 			uid = (uid_t) id;
 		else {
+			if (strncmp(dev->owner, LOCAL_USER, sizeof(LOCAL_USER)) == 0)
+				set_to_local_user(dev->owner);
+
 			struct passwd *pw = getpwnam(dev->owner);
 			if (pw == NULL)
 				dbg("specified user unknown '%s'", dev->owner);