1 files changed, 288 insertions, 0 deletions
diff --git a/src/basic/smack-util.c b/src/basic/smack-util.c
new file mode 100644
index 0000000..3362ee3
--- /dev/null
+++ b/src/basic/smack-util.c
@@ -0,0 +1,288 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2013 Intel Corporation
+
+  Author: Auke Kok <auke-jan.h.kok@intel.com>
+***/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/xattr.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "log.h"
+#include "macro.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "smack-util.h"
+#include "stdio-util.h"
+#include "string-table.h"
+#include "xattr-util.h"
+
+#if ENABLE_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;
+}
+
+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);
+
+        if (!mac_smack_use())
+                return 0;
+
+        return getxattr_malloc(path, smack_attr_to_string(attr), label, true);
+}
+
+int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
+        assert(fd >= 0);
+        assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
+        assert(label);
+
+        if (!mac_smack_use())
+                return 0;
+
+        return fgetxattr_malloc(fd, smack_attr_to_string(attr), label);
+}
+
+int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
+        int r;
+
+        assert(path);
+        assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
+
+        if (!mac_smack_use())
+                return 0;
+
+        if (label)
+                r = lsetxattr(path, smack_attr_to_string(attr), label, strlen(label), 0);
+        else
+                r = lremovexattr(path, smack_attr_to_string(attr));
+        if (r < 0)
+                return -errno;
+
+        return 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);
+
+        if (!mac_smack_use())
+                return 0;
+
+        if (label)
+                r = fsetxattr(fd, smack_attr_to_string(attr), label, strlen(label), 0);
+        else
+                r = fremovexattr(fd, smack_attr_to_string(attr));
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}
+
+int mac_smack_apply_pid(pid_t pid, const char *label) {
+        const char *p;
+        int r;
+
+        assert(label);
+
+        if (!mac_smack_use())
+                return 0;
+
+        p = procfs_file_alloca(pid, "attr/current");
+        r = write_string_file(p, label, WRITE_STRING_FILE_DISABLE_BUFFER);
+        if (r < 0)
+                return r;
+
+        return r;
+}
+
+static int smack_fix_fd(int fd , const char *abspath, LabelFixFlags flags) {
+        char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+        const char *label;
+        struct stat st;
+        int r;
+
+        /* The caller should have done the sanity checks. */
+        assert(abspath);
+        assert(path_is_absolute(abspath));
+
+        /* Path must be in /dev. */
+        if (!path_startswith(abspath, "/dev"))
+                return 0;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        /*
+         * Label directories and character devices "*".
+         * Label symlinks "_".
+         * Don't change anything else.
+         */
+
+        if (S_ISDIR(st.st_mode))
+                label = SMACK_STAR_LABEL;
+        else if (S_ISLNK(st.st_mode))
+                label = SMACK_FLOOR_LABEL;
+        else if (S_ISCHR(st.st_mode))
+                label = SMACK_STAR_LABEL;
+        else
+                return 0;
+
+        xsprintf(procfs_path, "/proc/self/fd/%i", fd);
+        if (setxattr(procfs_path, "security.SMACK64", label, strlen(label), 0) < 0) {
+                _cleanup_free_ char *old_label = NULL;
+
+                r = -errno;
+
+                /* If the FS doesn't support labels, then exit without warning */
+                if (r == -EOPNOTSUPP)
+                        return 0;
+
+                /* It the FS is read-only and we were told to ignore failures caused by that, suppress error */
+                if (r == -EROFS && (flags & LABEL_IGNORE_EROFS))
+                        return 0;
+
+                /* If the old label is identical to the new one, suppress any kind of error */
+                if (getxattr_malloc(procfs_path, "security.SMACK64", &old_label, false) >= 0 &&
+                    streq(old_label, label))
+                        return 0;
+
+                return log_debug_errno(r, "Unable to fix SMACK label of %s: %m", abspath);
+        }
+
+        return 0;
+}
+
+int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags) {
+        _cleanup_free_ char *p = NULL;
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(path);
+
+        if (!mac_smack_use())
+                return 0;
+
+        fd = openat(dirfd, path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+        if (fd < 0) {
+                if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
+                        return 0;
+
+                return -errno;
+        }
+
+        if (!path_is_absolute(path)) {
+                r = fd_get_path(fd, &p);
+                if (r < 0)
+                        return r;
+                path = p;
+        }
+
+        return smack_fix_fd(fd, path, flags);
+}
+
+int mac_smack_fix_container(const char *path, const char *inside_path, LabelFixFlags flags) {
+        _cleanup_free_ char *abspath = NULL;
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(path);
+
+        if (!mac_smack_use())
+                return 0;
+
+        r = path_make_absolute_cwd(path, &abspath);
+        if (r < 0)
+                return r;
+
+        fd = open(abspath, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+        if (fd < 0) {
+                if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
+                        return 0;
+
+                return -errno;
+        }
+
+        return smack_fix_fd(fd, inside_path, flags);
+}
+
+int mac_smack_copy(const char *dest, const char *src) {
+        int r;
+        _cleanup_free_ char *label = NULL;
+
+        assert(dest);
+        assert(src);
+
+        r = mac_smack_read(src, SMACK_ATTR_ACCESS, &label);
+        if (r < 0)
+                return r;
+
+        r = mac_smack_apply(dest, SMACK_ATTR_ACCESS, label);
+        if (r < 0)
+                return r;
+
+        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_container(const char *path, const char *inside_path, LabelFixFlags flags) {
+        return 0;
+}
+
+int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags) {
+        return 0;
+}
+
+int mac_smack_copy(const char *dest, const char *src) {
+        return 0;
+}
+#endif