Re: [PATCH] securityfs
From: serue
Date: Thu Jul 07 2005 - 13:29:23 EST
Quoting Greg KH (greg@xxxxxxxxx):
> > Unfortunately the simple_attr code from libfs really doesn't seem to be
> > usable for int args.
>
> Why not? You want a negative number? Just cast the u64 to a signed int
> then. Will that not work? If not we can tweak the libfs interface to
> work properly for you.
Hmm, I ran into two problems:
1, the __simple_attr_check_format seems to complain about a "%d"
format.
2, when I try just doing the typecasting, I get an oops...
The patch below is my attempt. The oops follows, but I'll look at it
some more tomorrow. It seems like it has to be something obvious...
Jul 7 18:14:42 serge-hv4 kernel: Oops: Kernel access of bad area, sig: 11 [#2]
Jul 7 18:14:42 serge-hv4 kernel: SMP NR_CPUS=128 NUMA PSERIES LPAR
Jul 7 18:14:42 serge-hv4 kernel: Modules linked in: seclvl ipv6 sg binfmt_misc dm_mod
Jul 7 18:14:42 serge-hv4 kernel: NIP: D00000000002F1DC XER: 20000001 LR: C0000000000E3A58 CTR: D00000000002F1DC
Jul 7 18:14:42 serge-hv4 kernel: REGS: c00000004256f9c0 TRAP: 0300 Not tainted (2.6.13-rc1-seclvl)
Jul 7 18:14:42 serge-hv4 kernel: MSR: 8000000000009032 EE: 1 PR: 0 FP: 0 ME: 1 IR/DR: 11 CR: 24040482
Jul 7 18:14:42 serge-hv4 kernel: DAR: 0000000000000000 DSISR: 0000000040000000
Jul 7 18:14:42 serge-hv4 kernel: TASK: c000000043858030[4707] 'cat' THREAD: c00000004256c000 CPU: 3
Jul 7 18:14:42 serge-hv4 kernel: GPR00: D00000000002F1DC C00000004256FC40 D000000000040888 0000000000000000
Jul 7 18:14:42 serge-hv4 kernel: GPR04: 0000000010015858 0000000000001000 C00000004256FE08 0000000000001000
Jul 7 18:14:42 serge-hv4 kernel: GPR08: 0000000010015858 D0000000000387B8 C000000000538D78 D00000000002F1E4
Jul 7 18:14:42 serge-hv4 kernel: GPR12: 0000000000000000 C000000000435400 00000000100F3458 0000000000000001
Jul 7 18:14:42 serge-hv4 kernel: GPR16: 0000000000001000 00000000FFFFFFFF 0000000000000000 0000000000000000
Jul 7 18:14:42 serge-hv4 kernel: GPR20: 0000000010015858 00000000FFEF4D14 0000000000000002 0000000000000000
Jul 7 18:14:42 serge-hv4 kernel: GPR24: 0000000044222442 0000000000001000 0000000010015858 C00000004256FE08
Jul 7 18:14:42 serge-hv4 kernel: GPR28: C000000047C00F10 C000000047C00F50 C0000000004AC920 C000000047C00F00
Jul 7 18:14:42 serge-hv4 kernel: NIP [d00000000002f1dc] .seclvl_int_get+0x0/0x8 [seclvl]
Jul 7 18:14:42 serge-hv4 kernel: LR [c0000000000e3a58] .simple_attr_read+0xb8/0x168
Jul 7 18:14:42 serge-hv4 kernel: Call Trace:
Jul 7 18:14:42 serge-hv4 kernel: [c00000004256fc40] [000000000ffca938] 0xffca938 (unreliable)
Jul 7 18:14:42 serge-hv4 kernel: [c00000004256fcf0] [c0000000000b13bc] .vfs_read+0x1c0/0x1c8
Jul 7 18:14:42 serge-hv4 kernel: [c00000004256fd90] [c0000000000b1740] .sys_read+0x4c/0x90
Jul 7 18:14:42 serge-hv4 kernel: [c00000004256fe30] [c00000000000d600] syscall_exit+0x0/0x18
Jul 7 18:14:42 serge-hv4 kernel: Instruction dump:
Jul 7 18:14:42 serge-hv4 kernel: e93e8008 ebbe8060 ebe90000 e81d0000 7c00f850 2ba003e8 409dfe94 e8be8058
Jul 7 18:14:42 serge-hv4 kernel: e87e8068 e89e8020 38c0ffff 4bffff94 <e8630000> 4e800020 7c0802a6 fbc1fff0
thanks,
-serge
Index: linux-2.6.13-rc1/include/linux/fs.h
===================================================================
--- linux-2.6.13-rc1.orig/include/linux/fs.h 2005-07-07 15:10:22.000000000 -0500
+++ linux-2.6.13-rc1/include/linux/fs.h 2005-07-07 17:59:54.000000000 -0500
@@ -1717,7 +1717,6 @@ static inline void simple_transaction_se
#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt) \
static int __fops ## _open(struct inode *inode, struct file *file) \
{ \
- __simple_attr_check_format(__fmt, 0ull); \
return simple_attr_open(inode, file, __get, __set, __fmt); \
} \
static struct file_operations __fops = { \
Index: linux-2.6.13-rc1/security/seclvl.c
===================================================================
--- linux-2.6.13-rc1.orig/security/seclvl.c 2005-07-07 15:33:45.000000000 -0500
+++ linux-2.6.13-rc1/security/seclvl.c 2005-07-07 18:16:11.000000000 -0500
@@ -119,69 +119,6 @@ MODULE_PARM_DESC(hideHash, "When set to
} 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, "%d\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, c
* 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 *o
"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 *o
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, NULL, &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)) {
-
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