smack-util: revise smack-util apis and add read smack attr apis

- Add smack xattr lookup table
- Unify all of mac_smack_apply_xxx{_fd}() to mac_smack_apply() and
  mac_smack_apply_fd().
- Add smack xattr read apis similar with apply apis as
  mac_smack_read{_fd}().

4 files changed, 88 insertions, 63 deletions

diff --git a/src/basic/smack-util.c b/src/basic/smack-util.c
index 047aa294f4..6d5c205117 100644
--- a/src/basic/smack-util.c
+++ b/src/basic/smack-util.c
@@ -32,109 +32,93 @@
 #define SMACK_FLOOR_LABEL "_"
 #define SMACK_STAR_LABEL  "*"
 
-bool mac_smack_use(void) {
 #ifdef HAVE_SMACK
+bool mac_smack_use(void) {
         static int cached_use = -1;
 
         if (cached_use < 0)
                 cached_use = access("/sys/fs/smackfs/", F_OK) >= 0;
 
         return cached_use;
-#else
-        return false;
-#endif
 }
 
-int mac_smack_apply(const char *path, const char *label) {
-        int r = 0;
+static const char* const smack_attr_table[_SMACK_ATTR_MAX] = {
+        [SMACK_ATTR_ACCESS]     = "security.SMACK64",
+        [SMACK_ATTR_EXEC]       = "security.SMACK64EXEC",
+        [SMACK_ATTR_MMAP]       = "security.SMACK64MMAP",
+        [SMACK_ATTR_TRANSMUTE]  = "security.SMACK64TRANSMUTE",
+        [SMACK_ATTR_IPIN]       = "security.SMACK64IPIN",
+        [SMACK_ATTR_IPOUT]      = "security.SMACK64IPOUT",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(smack_attr, SmackAttr);
 
+int mac_smack_read(const char *path, SmackAttr attr, char **label) {
         assert(path);
+        assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
+        assert(label);
 
-#ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
-        if (label)
-                r = lsetxattr(path, "security.SMACK64", label, strlen(label), 0);
-        else
-                r = lremovexattr(path, "security.SMACK64");
-        if (r < 0)
-                return -errno;
-#endif
-
-        return r;
+        return getxattr_malloc(path, smack_attr_to_string(attr), label, true);
 }
 
-int mac_smack_apply_fd(int fd, const char *label) {
-        int r = 0;
-
+int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
         assert(fd >= 0);
+        assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
+        assert(label);
 
-#ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
-        if (label)
-                r = fsetxattr(fd, "security.SMACK64", label, strlen(label), 0);
-        else
-                r = fremovexattr(fd, "security.SMACK64");
-        if (r < 0)
-                return -errno;
-#endif
-
-        return r;
+        return fgetxattr_malloc(fd, smack_attr_to_string(attr), label);
 }
 
-int mac_smack_apply_ip_out_fd(int fd, const char *label) {
-        int r = 0;
+int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
+        int r;
 
-        assert(fd >= 0);
+        assert(path);
+        assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
 
-#ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
         if (label)
-                r = fsetxattr(fd, "security.SMACK64IPOUT", label, strlen(label), 0);
+                r = lsetxattr(path, smack_attr_to_string(attr), label, strlen(label), 0);
         else
-                r = fremovexattr(fd, "security.SMACK64IPOUT");
+                r = lremovexattr(path, smack_attr_to_string(attr));
         if (r < 0)
                 return -errno;
-#endif
 
-        return r;
+        return 0;
 }
 
-int mac_smack_apply_ip_in_fd(int fd, const char *label) {
-        int r = 0;
+int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label) {
+        int r;
 
         assert(fd >= 0);
+        assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
 
-#ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
         if (label)
-                r = fsetxattr(fd, "security.SMACK64IPIN", label, strlen(label), 0);
+                r = fsetxattr(fd, smack_attr_to_string(attr), label, strlen(label), 0);
         else
-                r = fremovexattr(fd, "security.SMACK64IPIN");
+                r = fremovexattr(fd, smack_attr_to_string(attr));
         if (r < 0)
                 return -errno;
-#endif
 
-        return r;
+        return 0;
 }
 
 int mac_smack_apply_pid(pid_t pid, const char *label) {
-
-#ifdef HAVE_SMACK
         const char *p;
-#endif
         int r = 0;
 
         assert(label);
 
-#ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
@@ -142,21 +126,16 @@ int mac_smack_apply_pid(pid_t pid, const char *label) {
         r = write_string_file(p, label, 0);
         if (r < 0)
                 return r;
-#endif
 
         return r;
 }
 
 int mac_smack_fix(const char *path, bool ignore_enoent, bool ignore_erofs) {
-
-#ifdef HAVE_SMACK
         struct stat st;
-#endif
         int r = 0;
 
         assert(path);
 
-#ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
@@ -202,7 +181,37 @@ int mac_smack_fix(const char *path, bool ignore_enoent, bool ignore_erofs) {
 
                 r = log_debug_errno(errno, "Unable to fix SMACK label of %s: %m", path);
         }
-#endif
 
         return r;
 }
+
+
+#else
+bool mac_smack_use(void) {
+        return false;
+}
+
+int mac_smack_read(const char *path, SmackAttr attr, char **label) {
+        return -EOPNOTSUPP;
+}
+
+int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
+        return -EOPNOTSUPP;
+}
+
+int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
+        return 0;
+}
+
+int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label) {
+        return 0;
+}
+
+int mac_smack_apply_pid(pid_t pid, const char *label) {
+        return 0;
+}
+
+int mac_smack_fix(const char *path, bool ignore_enoent, bool ignore_erofs) {
+        return 0;
+}
+#endif
diff --git a/src/basic/smack-util.h b/src/basic/smack-util.h
index 50f55b1f4b..1052cecf4c 100644
--- a/src/basic/smack-util.h
+++ b/src/basic/smack-util.h
@@ -25,12 +25,28 @@
 
 #include <stdbool.h>
 
+#include "macro.h"
+
+typedef enum SmackAttr {
+        SMACK_ATTR_ACCESS = 0,
+        SMACK_ATTR_EXEC = 1,
+        SMACK_ATTR_MMAP = 2,
+        SMACK_ATTR_TRANSMUTE = 3,
+        SMACK_ATTR_IPIN = 4,
+        SMACK_ATTR_IPOUT = 5,
+        _SMACK_ATTR_MAX,
+        _SMACK_ATTR_INVALID = -1,
+} SmackAttr;
+
 bool mac_smack_use(void);
 
 int mac_smack_fix(const char *path, bool ignore_enoent, bool ignore_erofs);
 
-int mac_smack_apply(const char *path, const char *label);
-int mac_smack_apply_fd(int fd, const char *label);
+const char* smack_attr_to_string(SmackAttr i) _const_;
+SmackAttr smack_attr_from_string(const char *s) _pure_;
+int mac_smack_read(const char *path, SmackAttr attr, char **label);
+int mac_smack_read_fd(int fd, SmackAttr attr, char **label);
+int mac_smack_apply(const char *path, SmackAttr attr, const char *label);
+int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label);
+
 int mac_smack_apply_pid(pid_t pid, const char *label);
-int mac_smack_apply_ip_in_fd(int fd, const char *label);
-int mac_smack_apply_ip_out_fd(int fd, const char *label);
diff --git a/src/core/socket.c b/src/core/socket.c
index 87631f8753..a387057473 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -923,13 +923,13 @@ static void socket_apply_socket_options(Socket *s, int fd) {
                         log_unit_warning_errno(UNIT(s), errno, "TCP_CONGESTION failed: %m");
 
         if (s->smack_ip_in) {
-                r = mac_smack_apply_ip_in_fd(fd, s->smack_ip_in);
+                r = mac_smack_apply_fd(fd, SMACK_ATTR_IPIN, s->smack_ip_in);
                 if (r < 0)
                         log_unit_error_errno(UNIT(s), r, "mac_smack_apply_ip_in_fd: %m");
         }
 
         if (s->smack_ip_out) {
-                r = mac_smack_apply_ip_out_fd(fd, s->smack_ip_out);
+                r = mac_smack_apply_fd(fd, SMACK_ATTR_IPOUT, s->smack_ip_out);
                 if (r < 0)
                         log_unit_error_errno(UNIT(s), r, "mac_smack_apply_ip_out_fd: %m");
         }
@@ -946,7 +946,7 @@ static void socket_apply_fifo_options(Socket *s, int fd) {
                         log_unit_warning_errno(UNIT(s), errno, "F_SETPIPE_SZ: %m");
 
         if (s->smack) {
-                r = mac_smack_apply_fd(fd, s->smack);
+                r = mac_smack_apply_fd(fd, SMACK_ATTR_ACCESS, s->smack);
                 if (r < 0)
                         log_unit_error_errno(UNIT(s), r, "mac_smack_apply_fd: %m");
         }
diff --git a/src/udev/udev-node.c b/src/udev/udev-node.c
index d824172b89..e730fb45f1 100644
--- a/src/udev/udev-node.c
+++ b/src/udev/udev-node.c
@@ -309,7 +309,7 @@ static int node_permissions_apply(struct udev_device *dev, bool apply,
                         } else if (streq(name, "smack")) {
                                 smack = true;
 
-                                r = mac_smack_apply(devnode, label);
+                                r = mac_smack_apply(devnode, SMACK_ATTR_ACCESS, label);
                                 if (r < 0)
                                         log_error_errno(r, "SECLABEL: failed to set SMACK label '%s': %m", label);
                                 else
@@ -323,7 +323,7 @@ static int node_permissions_apply(struct udev_device *dev, bool apply,
                 if (!selinux)
                         mac_selinux_fix(devnode, true, false);
                 if (!smack)
-                        mac_smack_apply(devnode, NULL);
+                        mac_smack_apply(devnode, SMACK_ATTR_ACCESS, NULL);
         }
 
         /* always update timestamp when we re-use the node, like on media change events */