[PATCH] seclvl securityfs

Once again, the simple_attr in libfs was actually sufficient - I'd
thought the __attribute__(format(printk(1,2))) was more mysterious than
it really is.

At last, here is the full patch to make seclvl use securityfs.

Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
--

 seclvl.c |  228 +++++++++++++++++++--------------------------------------------
 1 files changed, 70 insertions(+), 158 deletions(-)

Index: linux-2.6.13-rc1/security/seclvl.c
===================================================================

1 files changed, 70 insertions, 158 deletions

diff --git a/security/seclvl.c b/security/seclvl.c
index c8e87b22c9bd..f8700e935b33 100644
--- a/security/seclvl.c
+++ b/security/seclvl.c
@@ -119,69 +119,6 @@ MODULE_PARM_DESC(hideHash, "When set to 0, reading seclvl/passwd from sysfs "
         } while (0)
 
 /**
- * kobject stuff
- */
-
-struct subsystem seclvl_subsys;
-
-struct seclvl_obj {
-        char *name;
-        struct list_head slot_list;
-        struct kobject kobj;
-};
-
-/**
- * There is a seclvl_attribute struct for each file in sysfs.
- *
- * In our case, we have one of these structs for "passwd" and another
- * for "seclvl".
- */
-struct seclvl_attribute {
-        struct attribute attr;
-        ssize_t(*show) (struct seclvl_obj *, char *);
-        ssize_t(*store) (struct seclvl_obj *, const char *, size_t);
-};
-
-/**
- * When this function is called, one of the files in sysfs is being
- * written to.  attribute->store is a function pointer to whatever the
- * struct seclvl_attribute store function pointer points to.  It is
- * unique for "passwd" and "seclvl".
- */
-static ssize_t
-seclvl_attr_store(struct kobject *kobj,
-                  struct attribute *attr, const char *buf, size_t len)
-{
-        struct seclvl_obj *obj = container_of(kobj, struct seclvl_obj, kobj);
-        struct seclvl_attribute *attribute =
-            container_of(attr, struct seclvl_attribute, attr);
-        return attribute->store ? attribute->store(obj, buf, len) : -EIO;
-}
-
-static ssize_t
-seclvl_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
-{
-        struct seclvl_obj *obj = container_of(kobj, struct seclvl_obj, kobj);
-        struct seclvl_attribute *attribute =
-            container_of(attr, struct seclvl_attribute, attr);
-        return attribute->show ? attribute->show(obj, buf) : -EIO;
-}
-
-/**
- * Callback function pointers for show and store
- */
-static struct sysfs_ops seclvlfs_sysfs_ops = {
-        .show = seclvl_attr_show,
-        .store = seclvl_attr_store,
-};
-
-static struct kobj_type seclvl_ktype = {
-        .sysfs_ops = &seclvlfs_sysfs_ops
-};
-
-decl_subsys(seclvl, &seclvl_ktype, NULL);
-
-/**
  * The actual security level.  Ranges between -1 and 2 inclusive.
  */
 static int seclvl;
@@ -213,97 +150,44 @@ static int seclvl_sanity(int reqlvl)
 }
 
 /**
- * Called whenever the user reads the sysfs handle to this kernel
- * object
- */
-static ssize_t seclvl_read_file(struct seclvl_obj *obj, char *buff)
-{
-        return snprintf(buff, PAGE_SIZE, "%d\n", seclvl);
-}
-
-/**
  * security level advancement rules:
  *   Valid levels are -1 through 2, inclusive.
  *   From -1, stuck.  [ in case compiled into kernel ]
  *   From 0 or above, can only increment.
  */
-static int do_seclvl_advance(int newlvl)
+static void do_seclvl_advance(void *data, u64 val)
 {
-        if (newlvl <= seclvl) {
-                seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
-                              "[%d]\n", newlvl);
-                return -EINVAL;
-        }
+        int ret;
+        int newlvl = (int)val;
+
+        ret = seclvl_sanity(newlvl);
+        if (ret)
+                return;
+
         if (newlvl > 2) {
                 seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
                               "[%d]\n", newlvl);
-                return -EINVAL;
+                return;
         }
         if (seclvl == -1) {
                 seclvl_printk(1, KERN_WARNING, "Not allowed to advance to "
                               "seclvl [%d]\n", seclvl);
-                return -EPERM;
+                return;
         }
-        seclvl = newlvl;
-        return 0;
+        seclvl = newlvl;  /* would it be more "correct" to set *data? */
+        return;
 }
 
-/**
- * Called whenever the user writes to the sysfs handle to this kernel
- * object (seclvl/seclvl).  It expects a single-digit number.
- */
-static ssize_t
-seclvl_write_file(struct seclvl_obj *obj, const char *buff, size_t count)
+static u64 seclvl_int_get(void *data)
 {
-        unsigned long val;
-        if (count > 2 || (count == 2 && buff[1] != '\n')) {
-                seclvl_printk(1, KERN_WARNING, "Invalid value passed to "
-                              "seclvl: [%s]\n", buff);
-                return -EINVAL;
-        }
-        val = buff[0] - 48;
-        if (seclvl_sanity(val)) {
-                seclvl_printk(1, KERN_WARNING, "Illegal secure level "
-                              "requested: [%d]\n", (int)val);
-                return -EPERM;
-        }
-        if (do_seclvl_advance(val)) {
-                seclvl_printk(0, KERN_ERR, "Failure advancing security level "
-                              "to %lu\n", val);
-        }
-        return count;
+        return *(int *)data;
 }
 
-/* Generate sysfs_attr_seclvl */
-static struct seclvl_attribute sysfs_attr_seclvl =
-__ATTR(seclvl, (S_IFREG | S_IRUGO | S_IWUSR), seclvl_read_file,
-       seclvl_write_file);
+DEFINE_SIMPLE_ATTRIBUTE(seclvl_file_ops, seclvl_int_get, do_seclvl_advance, "%lld\n");
 
 static unsigned char hashedPassword[SHA1_DIGEST_SIZE];
 
 /**
- * Called whenever the user reads the sysfs passwd handle.
- */
-static ssize_t seclvl_read_passwd(struct seclvl_obj *obj, char *buff)
-{
-        /* So just how good *is* your password? :-) */
-        char tmp[3];
-        int i = 0;
-        buff[0] = '\0';
-        if (hideHash) {
-                /* Security through obscurity */
-                return 0;
-        }
-        while (i < SHA1_DIGEST_SIZE) {
-                snprintf(tmp, 3, "%02x", hashedPassword[i]);
-                strncat(buff, tmp, 2);
-                i++;
-        }
-        strcat(buff, "\n");
-        return ((SHA1_DIGEST_SIZE * 2) + 1);
-}
-
-/**
  * Converts a block of plaintext of into its SHA1 hashed value.
  *
  * It would be nice if crypto had a wrapper to do this for us linear
@@ -347,12 +231,15 @@ plaintext_to_sha1(unsigned char *hash, const char *plaintext, int len)
  * object.  It hashes the password and compares the hashed results.
  */
 static ssize_t
-seclvl_write_passwd(struct seclvl_obj *obj, const char *buff, size_t count)
+passwd_write_file(struct file * file, const char __user * buf,
+                                size_t count, loff_t *ppos)
 {
         int i;
         unsigned char tmp[SHA1_DIGEST_SIZE];
+        char *page;
         int rc;
         int len;
+
         if (!*passwd && !*sha1_passwd) {
                 seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the "
                               "seclvl module, but neither a plain text "
@@ -363,13 +250,26 @@ seclvl_write_passwd(struct seclvl_obj *obj, const char *buff, size_t count)
                               "maintainer about this event.\n");
                 return -EINVAL;
         }
-        len = strlen(buff);
+
+        if (count < 0 || count >= PAGE_SIZE)
+                return -ENOMEM;
+        if (*ppos != 0) {
+                return -EINVAL;
+        }
+        page = (char *)get_zeroed_page(GFP_KERNEL);
+        if (!page)
+                return -ENOMEM;
+        len = -EFAULT;
+        if (copy_from_user(page, buf, count))
+                goto out;
+        
+        len = strlen(page);
         /* ``echo "secret" > seclvl/passwd'' includes a newline */
-        if (buff[len - 1] == '\n') {
+        if (page[len - 1] == '\n') {
                 len--;
         }
         /* Hash the password, then compare the hashed values */
-        if ((rc = plaintext_to_sha1(tmp, buff, len))) {
+        if ((rc = plaintext_to_sha1(tmp, page, len))) {
                 seclvl_printk(0, KERN_ERR, "Error hashing password: rc = "
                               "[%d]\n", rc);
                 return rc;
@@ -382,13 +282,16 @@ seclvl_write_passwd(struct seclvl_obj *obj, const char *buff, size_t count)
         seclvl_printk(0, KERN_INFO,
                       "Password accepted; seclvl reduced to 0.\n");
         seclvl = 0;
-        return count;
+        len = count;
+
+out:
+        free_page((unsigned long)page);
+        return len;
 }
 
-/* Generate sysfs_attr_passwd */
-static struct seclvl_attribute sysfs_attr_passwd =
-__ATTR(passwd, (S_IFREG | S_IRUGO | S_IWUSR), seclvl_read_passwd,
-       seclvl_write_passwd);
+static struct file_operations passwd_file_ops = {
+        .write = passwd_write_file,
+};
 
 /**
  * Explicitely disallow ptrace'ing the init process.
@@ -647,22 +550,34 @@ static int processPassword(void)
 }
 
 /**
- * Sysfs registrations
+ * securityfs registrations
  */
-static int doSysfsRegistrations(void)
+struct dentry *dir_ino, *seclvl_ino, *passwd_ino;
+
+static int seclvlfs_register(void)
 {
-        int rc = 0;
-        if ((rc = subsystem_register(&seclvl_subsys))) {
-                seclvl_printk(0, KERN_WARNING,
-                              "Error [%d] registering seclvl subsystem\n", rc);
-                return rc;
-        }
-        sysfs_create_file(&seclvl_subsys.kset.kobj, &sysfs_attr_seclvl.attr);
+        dir_ino = securityfs_create_dir("seclvl", NULL);
+        if (!dir_ino)
+                return -EFAULT;
+
+        seclvl_ino = securityfs_create_file("seclvl", S_IRUGO | S_IWUSR,
+                                dir_ino, &seclvl, &seclvl_file_ops);
+        if (!seclvl_ino)
+                goto out_deldir;
         if (*passwd || *sha1_passwd) {
-                sysfs_create_file(&seclvl_subsys.kset.kobj,
-                                  &sysfs_attr_passwd.attr);
+                passwd_ino = securityfs_create_file("passwd", S_IRUGO | S_IWUSR,
+                                dir_ino, NULL, &passwd_file_ops);
+                if (!passwd_ino)
+                        goto out_delf;
         }
         return 0;
+
+out_deldir:
+        securityfs_remove(dir_ino);
+out_delf:
+        securityfs_remove(seclvl_ino);
+
+        return -EFAULT;
 }
 
 /**
@@ -677,8 +592,6 @@ static int __init seclvl_init(void)
                 rc = -EINVAL;
                 goto exit;
         }
-        sysfs_attr_seclvl.attr.owner = THIS_MODULE;
-        sysfs_attr_passwd.attr.owner = THIS_MODULE;
         if (initlvl < -1 || initlvl > 2) {
                 seclvl_printk(0, KERN_ERR, "Error: bad initial securelevel "
                               "[%d].\n", initlvl);
@@ -706,7 +619,7 @@ static int __init seclvl_init(void)
                 }               /* if primary module registered */
                 secondary = 1;
         }                       /* if we registered ourselves with the security framework */
-        if ((rc = doSysfsRegistrations())) {
+        if ((rc = seclvlfs_register())) {
                 seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
                 goto exit;
         }
@@ -724,12 +637,11 @@ static int __init seclvl_init(void)
  */
 static void __exit seclvl_exit(void)
 {
-        sysfs_remove_file(&seclvl_subsys.kset.kobj, &sysfs_attr_seclvl.attr);
+        securityfs_remove(seclvl_ino);
         if (*passwd || *sha1_passwd) {
-                sysfs_remove_file(&seclvl_subsys.kset.kobj,
-                                  &sysfs_attr_passwd.attr);
+                securityfs_remove(passwd_ino);
         }
-        subsystem_unregister(&seclvl_subsys);
+        securityfs_remove(dir_ino);
         if (secondary == 1) {
                 mod_unreg_security(MY_NAME, &seclvl_ops);
         } else if (unregister_security(&seclvl_ops)) {