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[PATCH] seclvl securityfs

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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
===================================================================
This commit is contained in:
serue@us.ibm.com 2005-07-08 15:44:19 -05:00 committed by Chris Wright
parent b67dbf9d4c
commit 5a73c30875
1 changed files with 70 additions and 158 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

228
security/seclvl.c
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@ -118,69 +118,6 @@ MODULE_PARM_DESC(hideHash, "When set to 0, reading seclvl/passwd from sysfs "
} \ } \
} while (0) } 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. * The actual security level. Ranges between -1 and 2 inclusive.
*/ */
@ -212,97 +149,44 @@ static int seclvl_sanity(int reqlvl)
return 0; return 0;
} }
/**
* 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: * security level advancement rules:
* Valid levels are -1 through 2, inclusive. * Valid levels are -1 through 2, inclusive.
* From -1, stuck. [ in case compiled into kernel ] * From -1, stuck. [ in case compiled into kernel ]
* From 0 or above, can only increment. * 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) { int ret;
seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl " int newlvl = (int)val;
"[%d]\n", newlvl);
return -EINVAL; ret = seclvl_sanity(newlvl);
} if (ret)
return;
if (newlvl > 2) { if (newlvl > 2) {
seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl " seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
"[%d]\n", newlvl); "[%d]\n", newlvl);
return -EINVAL; return;
} }
if (seclvl == -1) { if (seclvl == -1) {
seclvl_printk(1, KERN_WARNING, "Not allowed to advance to " seclvl_printk(1, KERN_WARNING, "Not allowed to advance to "
"seclvl [%d]\n", seclvl); "seclvl [%d]\n", seclvl);
return -EPERM; return;
} }
seclvl = newlvl; seclvl = newlvl; /* would it be more "correct" to set *data? */
return 0; return;
} }
/** static u64 seclvl_int_get(void *data)
* 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)
{ {
unsigned long val; return *(int *)data;
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;
} }
/* Generate sysfs_attr_seclvl */ DEFINE_SIMPLE_ATTRIBUTE(seclvl_file_ops, seclvl_int_get, do_seclvl_advance, "%lld\n");
static struct seclvl_attribute sysfs_attr_seclvl =
__ATTR(seclvl, (S_IFREG | S_IRUGO | S_IWUSR), seclvl_read_file,
seclvl_write_file);
static unsigned char hashedPassword[SHA1_DIGEST_SIZE]; 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. * Converts a block of plaintext of into its SHA1 hashed value.
* *
@ -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. * object. It hashes the password and compares the hashed results.
*/ */
static ssize_t 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; int i;
unsigned char tmp[SHA1_DIGEST_SIZE]; unsigned char tmp[SHA1_DIGEST_SIZE];
char *page;
int rc; int rc;
int len; int len;
if (!*passwd && !*sha1_passwd) { if (!*passwd && !*sha1_passwd) {
seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the " seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the "
"seclvl module, but neither a plain text " "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"); "maintainer about this event.\n");
return -EINVAL; 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 */ /* ``echo "secret" > seclvl/passwd'' includes a newline */
if (buff[len - 1] == '\n') { if (page[len - 1] == '\n') {
len--; len--;
} }
/* Hash the password, then compare the hashed values */ /* 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 = " seclvl_printk(0, KERN_ERR, "Error hashing password: rc = "
"[%d]\n", rc); "[%d]\n", rc);
return 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, seclvl_printk(0, KERN_INFO,
"Password accepted; seclvl reduced to 0.\n"); "Password accepted; seclvl reduced to 0.\n");
seclvl = 0; seclvl = 0;
return count; len = count;
out:
free_page((unsigned long)page);
return len;
} }
/* Generate sysfs_attr_passwd */ static struct file_operations passwd_file_ops = {
static struct seclvl_attribute sysfs_attr_passwd = .write = passwd_write_file,
__ATTR(passwd, (S_IFREG | S_IRUGO | S_IWUSR), seclvl_read_passwd, };
seclvl_write_passwd);
/** /**
* Explicitely disallow ptrace'ing the init process. * 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; dir_ino = securityfs_create_dir("seclvl", NULL);
if ((rc = subsystem_register(&seclvl_subsys))) { if (!dir_ino)
seclvl_printk(0, KERN_WARNING, return -EFAULT;
"Error [%d] registering seclvl subsystem\n", rc);
return rc; seclvl_ino = securityfs_create_file("seclvl", S_IRUGO | S_IWUSR,
} dir_ino, &seclvl, &seclvl_file_ops);
sysfs_create_file(&seclvl_subsys.kset.kobj, &sysfs_attr_seclvl.attr); if (!seclvl_ino)
goto out_deldir;
if (*passwd || *sha1_passwd) { if (*passwd || *sha1_passwd) {
sysfs_create_file(&seclvl_subsys.kset.kobj, passwd_ino = securityfs_create_file("passwd", S_IRUGO | S_IWUSR,
&sysfs_attr_passwd.attr); dir_ino, NULL, &passwd_file_ops);
if (!passwd_ino)
goto out_delf;
} }
return 0; 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; rc = -EINVAL;
goto exit; goto exit;
} }
sysfs_attr_seclvl.attr.owner = THIS_MODULE;
sysfs_attr_passwd.attr.owner = THIS_MODULE;
if (initlvl < -1 || initlvl > 2) { if (initlvl < -1 || initlvl > 2) {
seclvl_printk(0, KERN_ERR, "Error: bad initial securelevel " seclvl_printk(0, KERN_ERR, "Error: bad initial securelevel "
"[%d].\n", initlvl); "[%d].\n", initlvl);
@ -706,7 +619,7 @@ static int __init seclvl_init(void)
} /* if primary module registered */ } /* if primary module registered */
secondary = 1; secondary = 1;
} /* if we registered ourselves with the security framework */ } /* 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"); seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
goto exit; goto exit;
} }
@ -724,12 +637,11 @@ static int __init seclvl_init(void)
*/ */
static void __exit seclvl_exit(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) { if (*passwd || *sha1_passwd) {
sysfs_remove_file(&seclvl_subsys.kset.kobj, securityfs_remove(passwd_ino);
&sysfs_attr_passwd.attr);
} }
subsystem_unregister(&seclvl_subsys); securityfs_remove(dir_ino);
if (secondary == 1) { if (secondary == 1) {
mod_unreg_security(MY_NAME, &seclvl_ops); mod_unreg_security(MY_NAME, &seclvl_ops);
} else if (unregister_security(&seclvl_ops)) { } else if (unregister_security(&seclvl_ops)) {