[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 ===================================================================hifive-unleashed-5.1
serue@us.ibm.com
Chris Wright
parent
b67dbf9d4c
commit
5a73c30875
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@ -118,69 +118,6 @@ MODULE_PARM_DESC(hideHash, "When set to 0, reading seclvl/passwd from sysfs "
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} \
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} while (0)
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/**
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* kobject stuff
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*/
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struct subsystem seclvl_subsys;
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struct seclvl_obj {
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char *name;
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struct list_head slot_list;
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struct kobject kobj;
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};
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/**
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* There is a seclvl_attribute struct for each file in sysfs.
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*
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* In our case, we have one of these structs for "passwd" and another
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* for "seclvl".
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*/
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struct seclvl_attribute {
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struct attribute attr;
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ssize_t(*show) (struct seclvl_obj *, char *);
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ssize_t(*store) (struct seclvl_obj *, const char *, size_t);
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};
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/**
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* When this function is called, one of the files in sysfs is being
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* written to. attribute->store is a function pointer to whatever the
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* struct seclvl_attribute store function pointer points to. It is
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* unique for "passwd" and "seclvl".
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*/
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static ssize_t
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seclvl_attr_store(struct kobject *kobj,
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struct attribute *attr, const char *buf, size_t len)
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{
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struct seclvl_obj *obj = container_of(kobj, struct seclvl_obj, kobj);
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struct seclvl_attribute *attribute =
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container_of(attr, struct seclvl_attribute, attr);
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return attribute->store ? attribute->store(obj, buf, len) : -EIO;
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}
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static ssize_t
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seclvl_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
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{
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struct seclvl_obj *obj = container_of(kobj, struct seclvl_obj, kobj);
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struct seclvl_attribute *attribute =
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container_of(attr, struct seclvl_attribute, attr);
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return attribute->show ? attribute->show(obj, buf) : -EIO;
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}
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/**
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* Callback function pointers for show and store
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*/
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static struct sysfs_ops seclvlfs_sysfs_ops = {
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.show = seclvl_attr_show,
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.store = seclvl_attr_store,
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};
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static struct kobj_type seclvl_ktype = {
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.sysfs_ops = &seclvlfs_sysfs_ops
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};
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decl_subsys(seclvl, &seclvl_ktype, NULL);
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/**
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* The actual security level. Ranges between -1 and 2 inclusive.
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*/
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@ -212,97 +149,44 @@ static int seclvl_sanity(int reqlvl)
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return 0;
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}
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/**
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* Called whenever the user reads the sysfs handle to this kernel
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* object
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*/
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static ssize_t seclvl_read_file(struct seclvl_obj *obj, char *buff)
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{
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return snprintf(buff, PAGE_SIZE, "%d\n", seclvl);
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}
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/**
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* security level advancement rules:
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* Valid levels are -1 through 2, inclusive.
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* From -1, stuck. [ in case compiled into kernel ]
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* From 0 or above, can only increment.
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*/
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static int do_seclvl_advance(int newlvl)
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static void do_seclvl_advance(void *data, u64 val)
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{
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if (newlvl <= seclvl) {
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seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
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"[%d]\n", newlvl);
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return -EINVAL;
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}
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int ret;
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int newlvl = (int)val;
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ret = seclvl_sanity(newlvl);
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if (ret)
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return;
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if (newlvl > 2) {
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seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
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"[%d]\n", newlvl);
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return -EINVAL;
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return;
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}
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if (seclvl == -1) {
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seclvl_printk(1, KERN_WARNING, "Not allowed to advance to "
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"seclvl [%d]\n", seclvl);
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return -EPERM;
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return;
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}
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seclvl = newlvl;
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return 0;
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seclvl = newlvl; /* would it be more "correct" to set *data? */
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return;
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}
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/**
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* Called whenever the user writes to the sysfs handle to this kernel
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* object (seclvl/seclvl). It expects a single-digit number.
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*/
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static ssize_t
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seclvl_write_file(struct seclvl_obj *obj, const char *buff, size_t count)
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static u64 seclvl_int_get(void *data)
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{
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unsigned long val;
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if (count > 2 || (count == 2 && buff[1] != '\n')) {
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seclvl_printk(1, KERN_WARNING, "Invalid value passed to "
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"seclvl: [%s]\n", buff);
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return -EINVAL;
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}
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val = buff[0] - 48;
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if (seclvl_sanity(val)) {
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seclvl_printk(1, KERN_WARNING, "Illegal secure level "
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"requested: [%d]\n", (int)val);
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return -EPERM;
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}
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if (do_seclvl_advance(val)) {
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seclvl_printk(0, KERN_ERR, "Failure advancing security level "
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"to %lu\n", val);
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}
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return count;
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return *(int *)data;
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}
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/* Generate sysfs_attr_seclvl */
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static struct seclvl_attribute sysfs_attr_seclvl =
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__ATTR(seclvl, (S_IFREG | S_IRUGO | S_IWUSR), seclvl_read_file,
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seclvl_write_file);
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DEFINE_SIMPLE_ATTRIBUTE(seclvl_file_ops, seclvl_int_get, do_seclvl_advance, "%lld\n");
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static unsigned char hashedPassword[SHA1_DIGEST_SIZE];
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/**
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* Called whenever the user reads the sysfs passwd handle.
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*/
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static ssize_t seclvl_read_passwd(struct seclvl_obj *obj, char *buff)
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{
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/* So just how good *is* your password? :-) */
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char tmp[3];
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int i = 0;
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buff[0] = '\0';
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if (hideHash) {
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/* Security through obscurity */
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return 0;
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}
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while (i < SHA1_DIGEST_SIZE) {
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snprintf(tmp, 3, "%02x", hashedPassword[i]);
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strncat(buff, tmp, 2);
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i++;
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}
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strcat(buff, "\n");
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return ((SHA1_DIGEST_SIZE * 2) + 1);
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}
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/**
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* Converts a block of plaintext of into its SHA1 hashed value.
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*
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@ -347,12 +231,15 @@ plaintext_to_sha1(unsigned char *hash, const char *plaintext, int len)
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* object. It hashes the password and compares the hashed results.
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*/
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static ssize_t
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seclvl_write_passwd(struct seclvl_obj *obj, const char *buff, size_t count)
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passwd_write_file(struct file * file, const char __user * buf,
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size_t count, loff_t *ppos)
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{
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int i;
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unsigned char tmp[SHA1_DIGEST_SIZE];
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char *page;
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int rc;
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int len;
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if (!*passwd && !*sha1_passwd) {
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seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the "
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"seclvl module, but neither a plain text "
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@ -363,13 +250,26 @@ seclvl_write_passwd(struct seclvl_obj *obj, const char *buff, size_t count)
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"maintainer about this event.\n");
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return -EINVAL;
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}
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len = strlen(buff);
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if (count < 0 || count >= PAGE_SIZE)
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return -ENOMEM;
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if (*ppos != 0) {
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return -EINVAL;
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}
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page = (char *)get_zeroed_page(GFP_KERNEL);
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if (!page)
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return -ENOMEM;
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len = -EFAULT;
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if (copy_from_user(page, buf, count))
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goto out;
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len = strlen(page);
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/* ``echo "secret" > seclvl/passwd'' includes a newline */
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if (buff[len - 1] == '\n') {
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if (page[len - 1] == '\n') {
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len--;
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}
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/* Hash the password, then compare the hashed values */
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if ((rc = plaintext_to_sha1(tmp, buff, len))) {
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if ((rc = plaintext_to_sha1(tmp, page, len))) {
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seclvl_printk(0, KERN_ERR, "Error hashing password: rc = "
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"[%d]\n", rc);
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return rc;
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@ -382,13 +282,16 @@ seclvl_write_passwd(struct seclvl_obj *obj, const char *buff, size_t count)
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seclvl_printk(0, KERN_INFO,
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"Password accepted; seclvl reduced to 0.\n");
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seclvl = 0;
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return count;
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len = count;
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out:
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free_page((unsigned long)page);
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return len;
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}
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/* Generate sysfs_attr_passwd */
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static struct seclvl_attribute sysfs_attr_passwd =
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__ATTR(passwd, (S_IFREG | S_IRUGO | S_IWUSR), seclvl_read_passwd,
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seclvl_write_passwd);
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static struct file_operations passwd_file_ops = {
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.write = passwd_write_file,
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};
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/**
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* Explicitely disallow ptrace'ing the init process.
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@ -647,22 +550,34 @@ static int processPassword(void)
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}
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/**
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* Sysfs registrations
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* securityfs registrations
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*/
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static int doSysfsRegistrations(void)
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struct dentry *dir_ino, *seclvl_ino, *passwd_ino;
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static int seclvlfs_register(void)
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{
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int rc = 0;
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if ((rc = subsystem_register(&seclvl_subsys))) {
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seclvl_printk(0, KERN_WARNING,
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"Error [%d] registering seclvl subsystem\n", rc);
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return rc;
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}
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sysfs_create_file(&seclvl_subsys.kset.kobj, &sysfs_attr_seclvl.attr);
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dir_ino = securityfs_create_dir("seclvl", NULL);
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if (!dir_ino)
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return -EFAULT;
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seclvl_ino = securityfs_create_file("seclvl", S_IRUGO | S_IWUSR,
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dir_ino, &seclvl, &seclvl_file_ops);
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if (!seclvl_ino)
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goto out_deldir;
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if (*passwd || *sha1_passwd) {
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sysfs_create_file(&seclvl_subsys.kset.kobj,
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&sysfs_attr_passwd.attr);
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passwd_ino = securityfs_create_file("passwd", S_IRUGO | S_IWUSR,
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dir_ino, NULL, &passwd_file_ops);
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if (!passwd_ino)
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goto out_delf;
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}
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return 0;
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out_deldir:
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securityfs_remove(dir_ino);
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out_delf:
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securityfs_remove(seclvl_ino);
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return -EFAULT;
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}
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/**
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@ -677,8 +592,6 @@ static int __init seclvl_init(void)
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rc = -EINVAL;
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goto exit;
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}
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sysfs_attr_seclvl.attr.owner = THIS_MODULE;
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sysfs_attr_passwd.attr.owner = THIS_MODULE;
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if (initlvl < -1 || initlvl > 2) {
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seclvl_printk(0, KERN_ERR, "Error: bad initial securelevel "
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"[%d].\n", initlvl);
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@ -706,7 +619,7 @@ static int __init seclvl_init(void)
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} /* if primary module registered */
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secondary = 1;
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} /* if we registered ourselves with the security framework */
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if ((rc = doSysfsRegistrations())) {
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if ((rc = seclvlfs_register())) {
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seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
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goto exit;
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}
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@ -724,12 +637,11 @@ static int __init seclvl_init(void)
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*/
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static void __exit seclvl_exit(void)
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{
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sysfs_remove_file(&seclvl_subsys.kset.kobj, &sysfs_attr_seclvl.attr);
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securityfs_remove(seclvl_ino);
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if (*passwd || *sha1_passwd) {
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sysfs_remove_file(&seclvl_subsys.kset.kobj,
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&sysfs_attr_passwd.attr);
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securityfs_remove(passwd_ino);
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}
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subsystem_unregister(&seclvl_subsys);
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securityfs_remove(dir_ino);
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if (secondary == 1) {
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mod_unreg_security(MY_NAME, &seclvl_ops);
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} else if (unregister_security(&seclvl_ops)) {
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