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SubjectRe: [PATCH 2.6.16-rc1-git4] accessfs: a permission managing filesystem
From
Date
Andrew Morton <akpm@osdl.org> writes:

> Olaf Dietsche <olaf+list.linux-kernel@olafdietsche.de> wrote:
>>
>> Can you please include this patch in -mm, to give it wider testing?
>
> I doubt if it'll get a lot of runtime testing.

Well, this review alone was worth the effort. Thanks.

>> Accessfs is a permission managing filesystem. It allows to control
>> access to system resources, based on file permissions. It also
>> includes two modules. One module allows granting capabilities based
>> on user-/groupid. The second module allows to grant access to lower
>> numbered IP ports based on user-/groupid.
>>
>
> It seems to be network-centric?

It could be used anywhere, where you want access control on a file
permission (user, group, other) basis.
But yes, currently I use it that way only.

> Do these capabilities really need to be implemented via a brand-new
> security infrastructure, rather then by enhancing the existing one(s)?

This doesn't change the existing security infrastructure. It just
permits users and/or groups to get selected privileges. But I won't
insist on this one, since I use filesystem capabilities anyway.

>> + To use this option, you need to mount the access file system
>> + and do a chown on the appropriate ports:
>> +
>> + # mount -t accessfs none /proc/access
>> + # chown www /proc/access/net/ip/bind/80
>> + # chown mail /proc/access/net/ip/bind/25
>
> Documenting a feature in Kconfig is a bit odd. I assume proper
> Documentation is forthcoming?

When I encounter a new item in Kconfig, I expect help, which explains,
what it is good for. Anyway, I moved a few lines to
Documentation/filesystems/accessfs.txt

>> +struct accessfs_direntry *accessfs_make_dirpath(const char *name)
>> +{
>> + struct accessfs_direntry *dir = &accessfs_rootdir;
>> + const char *slash;
>> + down(&accessfs_sem);
>
> Shouldn't that lock be per-superblock?

Like procfs or sysfs there's only one instance, so I don't think this
is necessary.

>> +static void accessfs_read_inode(struct inode *inode)
>> +{
>> + ino_t ino = inode->i_ino;
>> + struct list_head *list;
>> + down(&accessfs_sem);
>> + list_for_each(list, &hash) {
>> + struct accessfs_entry *pe;
>> + pe = list_entry(list, struct accessfs_entry, hash);
>> + if (pe->ino == ino) {
>> + accessfs_init_inode(inode, pe);
>> + break;
>> + }
>> + }
>
> That's not a hash!

Do you think it should be? accessfs_read_inode() is not a frequently
called function.

I think, I addressed all your remaining points. If you have further
concerns, I won't respond until next weekend.

Regards, Olaf.

Signed-off-by: Olaf Dietsche <olaf+list.linux-kernel@olafdietsche.de>

---
Documentation/filesystems/accessfs.txt | 41 +++
fs/Kconfig | 1
fs/Makefile | 1
fs/accessfs/Kconfig | 50 +++
fs/accessfs/Makefile | 11
fs/accessfs/capabilities.c | 107 ++++++++
fs/accessfs/inode.c | 426 +++++++++++++++++++++++++++++++++
fs/accessfs/ip.c | 95 +++++++
include/linux/accessfs_fs.h | 43 +++
include/net/sock.h | 43 +++
net/Kconfig | 11
net/Makefile | 1
net/hooks.c | 55 ++++
net/ipv4/af_inet.c | 2
net/ipv6/af_inet6.c | 2
15 files changed, 887 insertions(+), 2 deletions(-)
diff -urN a/Documentation/filesystems/accessfs.txt b/Documentation/filesystems/accessfs.txt
--- a/Documentation/filesystems/accessfs.txt Thu Jan 1 01:00:00 1970
+++ b/Documentation/filesystems/accessfs.txt Sun Jan 29 16:16:31 2006
@@ -0,0 +1,41 @@
+Accessfs is a permission managing filesystem. It allows to control access to
+system resources, based on file permissions. The recommended mount point for
+this file-system is /proc/access, which will appear automatically in the
+/proc filesystem.
+
+Currently there are two modules using accessfs, userports and usercaps.
+
+With userports, you will be able to control access to IP ports based
+on user-/groupid.
+
+There's no need anymore to run internet daemons as root. You can
+individually configure which user/program can bind to protected ports
+(by default, below 1024).
+
+For example, you can say, user www is allowed to bind to port 80 or
+user mail is allowed to bind to port 25. Then, you can run apache as
+user www and sendmail as user mail. Now, you don't have to rely on
+apache or sendmail giving up superuser rights to enhance security.
+
+To use this option, you need to mount the access file system
+and do a chown on the appropriate ports:
+
+# mount -t accessfs none /proc/access
+# chown www /proc/access/net/ip/bind/80
+# chown mail /proc/access/net/ip/bind/25
+
+You can grant access to a group for individual ports as well. Just say:
+
+# chgrp lp /proc/access/net/ip/bind/515
+# chown g+x /proc/access/net/ip/bind/515
+
+With usercaps, you will be able to grant capabilities based on
+user-/groupid (root by default).
+
+For example you can create a group raw and change the capability
+net_raw to this group:
+
+# chgrp raw /proc/access/capabilities/net_raw
+# chmod ug+x /proc/access/capabilities/net_raw
+# chgrp raw /sbin/ping
+# chmod u-s /sbin/ping; chmod g+s /sbin/ping
diff -urN a/fs/Kconfig b/fs/Kconfig
--- a/fs/Kconfig Fri Jan 27 23:52:40 2006
+++ b/fs/Kconfig Sat Jan 28 12:47:19 2006
@@ -1253,6 +1253,7 @@
It's currently broken, so for now:
answer N.

+source "fs/accessfs/Kconfig"


config SYSV_FS
diff -urN a/fs/Makefile b/fs/Makefile
--- a/fs/Makefile Fri Jan 27 23:52:40 2006
+++ b/fs/Makefile Sat Jan 28 12:48:03 2006
@@ -103,3 +103,4 @@
obj-$(CONFIG_DEBUG_FS) += debugfs/
obj-$(CONFIG_CONFIGFS_FS) += configfs/
obj-$(CONFIG_OCFS2_FS) += ocfs2/
+obj-$(CONFIG_ACCESS_FS) += accessfs/
diff -urN a/fs/accessfs/Kconfig b/fs/accessfs/Kconfig
--- a/fs/accessfs/Kconfig Thu Jan 1 01:00:00 1970
+++ b/fs/accessfs/Kconfig Sun Jan 29 23:18:33 2006
@@ -0,0 +1,50 @@
+config ACCESS_FS
+ tristate "Accessfs support (Experimental)"
+ depends on EXPERIMENTAL
+ default n
+ help
+ This is a new file system to manage permissions. It is not very
+ useful on its own. You need to enable other options below.
+
+ If you're unsure, say N.
+
+config ACCESSFS_USER_PORTS
+ tristate "User permission based IP ports"
+ depends on ACCESS_FS
+ select NET_HOOKS
+ default n
+ help
+ If you say Y here, you will be able to control access to IP ports
+ based on user-/groupid. For this to work, you must say Y
+ to CONFIG_NET_HOOKS.
+
+ If you're unsure, say N.
+
+config ACCESSFS_PROT_SOCK
+ int "Range of protected ports (1024-65536)"
+ depends on ACCESSFS_USER_PORTS
+ default 1024
+ help
+ Here you can extend the range of protected ports. This is
+ from 1-1023 inclusive on normal unix systems. One use for this
+ could be to reserve ports for X11 (port 6000) or database
+ servers (port 3306 for mysql), so nobody else could grab this port.
+ The default permission for extended ports is --x--x--x.
+
+ If you build this as a module, you can specify the range of
+ protected ports at module load time (max_prot_sock).
+
+ If you're unsure, say 1024.
+
+config ACCESSFS_USER_CAPABILITIES
+ tristate "User permission based capabilities"
+ depends on ACCESS_FS
+ select SECURITY
+ default n
+ help
+ If you say Y here, you will be able to grant capabilities based on
+ user-/groupid (root by default). For this to work, you must say M or
+ N to CONFIG_SECURITY_CAPABILITIES.
+
+ If you're unsure, say N.
+
diff -urN a/fs/accessfs/Makefile b/fs/accessfs/Makefile
--- a/fs/accessfs/Makefile Thu Jan 1 01:00:00 1970
+++ b/fs/accessfs/Makefile Sat Jan 28 12:47:19 2006
@@ -0,0 +1,11 @@
+#
+# Makefile for the linux accessfs routines.
+#
+
+obj-$(CONFIG_ACCESS_FS) += accessfs.o
+obj-$(CONFIG_ACCESSFS_USER_CAPABILITIES) += usercaps.o
+obj-$(CONFIG_ACCESSFS_USER_PORTS) += userports.o
+
+accessfs-objs := inode.o
+usercaps-objs := capabilities.o
+userports-objs := ip.o
diff -urN a/fs/accessfs/capabilities.c b/fs/accessfs/capabilities.c
--- a/fs/accessfs/capabilities.c Thu Jan 1 01:00:00 1970
+++ b/fs/accessfs/capabilities.c Sun Jan 29 23:20:31 2006
@@ -0,0 +1,107 @@
+/* Copyright (c) 2002-2006 Olaf Dietsche
+ *
+ * User based capabilities for Linux.
+ */
+
+#include <linux/accessfs_fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/security.h>
+
+static const char *names[] = {
+ "chown",
+ "dac_override",
+ "dac_read_search",
+ "fowner",
+ "fsetid",
+ "kill",
+ "setgid",
+ "setuid",
+ "setpcap",
+ "linux_immutable",
+ "net_bind_service",
+ "net_broadcast",
+ "net_admin",
+ "net_raw",
+ "ipc_lock",
+ "ipc_owner",
+ "sys_module",
+ "sys_rawio",
+ "sys_chroot",
+ "sys_ptrace",
+ "sys_pacct",
+ "sys_admin",
+ "sys_boot",
+ "sys_nice",
+ "sys_resource",
+ "sys_time",
+ "sys_tty_config",
+ "mknod",
+ "lease"
+};
+
+static struct access_attr caps[ARRAY_SIZE(names)];
+
+static int accessfs_capable(struct task_struct *tsk, int cap)
+{
+ if (accessfs_permitted(&caps[cap], MAY_EXEC)) {
+ /* capability granted */
+ tsk->flags |= PF_SUPERPRIV;
+ return 0;
+ }
+
+ /* capability denied */
+ return -EPERM;
+}
+
+static struct security_operations accessfs_security_ops = {
+ .capable = accessfs_capable,
+};
+
+static void unregister_capabilities(struct accessfs_direntry *dir, int n)
+{
+ int i;
+ for (i = 0; i < n; ++i)
+ accessfs_unregister(dir, names[i]);
+}
+
+static int __init init_capabilities(void)
+{
+ struct accessfs_direntry *dir;
+ int i, err;
+ dir = accessfs_make_dirpath("capabilities");
+ if (dir == 0)
+ return -ENOTDIR;
+
+ for (i = 0; i < ARRAY_SIZE(caps); ++i) {
+ caps[i].uid = 0;
+ caps[i].gid = 0;
+ caps[i].mode = S_IXUSR;
+ err = accessfs_register(dir, names[i], &caps[i]);
+ if (err) {
+ unregister_capabilities(dir, i);
+ return err;
+ }
+ }
+
+ err = register_security(&accessfs_security_ops);
+ if (err != 0)
+ unregister_capabilities(dir, ARRAY_SIZE(names));
+
+ return err;
+}
+
+static void __exit exit_capabilities(void)
+{
+ struct accessfs_direntry *dir;
+ dir = accessfs_make_dirpath("capabilities");
+ unregister_security(&accessfs_security_ops);
+ unregister_capabilities(dir, ARRAY_SIZE(names));
+}
+
+module_init(init_capabilities)
+module_exit(exit_capabilities)
+
+MODULE_AUTHOR("Olaf Dietsche");
+MODULE_DESCRIPTION("User based capabilities");
+MODULE_LICENSE("GPL");
diff -urN a/fs/accessfs/inode.c b/fs/accessfs/inode.c
--- a/fs/accessfs/inode.c Thu Jan 1 01:00:00 1970
+++ b/fs/accessfs/inode.c Sun Jan 29 23:20:20 2006
@@ -0,0 +1,426 @@
+/* Copyright (c) 2001-2006 Olaf Dietsche
+ *
+ * Access permission filesystem for Linux.
+ *
+ * 2002 Ben Clifford, create mount point at /proc/access
+ * 2002 Ben Clifford, trying to make it work under 2.5.5-dj2
+ * (see comments: BENC255 for reminders and todos)
+ *
+ *
+ * BENC255: the kernel doesn't lock BKL for us when entering methods
+ * (see Documentation/fs/porting.txt)
+ * Need to look at code here and see if we need either the BKL
+ * or our own lock - I think probably not.
+ *
+ */
+
+#include <linux/accessfs_fs.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/proc_fs.h>
+#include <asm/statfs.h>
+#include <asm/semaphore.h>
+#include <asm/uaccess.h>
+
+#define ACCESSFS_MAGIC 0x3c1d36e7
+
+static struct proc_dir_entry *mountdir = NULL;
+
+static DEFINE_MUTEX(accessfs_sem);
+
+static struct inode_operations accessfs_inode_operations;
+static struct file_operations accessfs_dir_file_operations;
+static struct inode_operations accessfs_dir_inode_operations;
+
+static inline void accessfs_readdir_aux(struct file *filp,
+ struct accessfs_direntry *dir,
+ int start, void *dirent,
+ filldir_t filldir)
+{
+ struct list_head *list;
+ int i = 2;
+ list_for_each(list, &dir->children) {
+ struct accessfs_entry *de;
+ if (i++ < start)
+ continue;
+
+ de = list_entry(list, struct accessfs_entry, siblings);
+ if (filldir(dirent, de->name, strlen(de->name), filp->f_pos,
+ de->ino, DT_UNKNOWN) < 0)
+ break;
+
+ ++filp->f_pos;
+ }
+}
+
+static int accessfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+ int i;
+ struct dentry *dentry = filp->f_dentry;
+ struct accessfs_direntry *dir;
+
+ i = filp->f_pos;
+ switch (i) {
+ case 0:
+ if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino,
+ DT_DIR) < 0)
+ break;
+
+ ++i;
+ ++filp->f_pos;
+ /* NO break; */
+ case 1:
+ if (filldir(dirent, "..", 2, i,
+ dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
+ break;
+
+ ++i;
+ ++filp->f_pos;
+ /* NO break; */
+ default:
+ mutex_lock(&accessfs_sem);
+ dir = dentry->d_inode->u.generic_ip;
+ accessfs_readdir_aux(filp, dir, i, dirent, filldir);
+ mutex_unlock(&accessfs_sem);
+ break;
+ }
+
+ return 0;
+}
+
+static struct accessfs_entry *accessfs_lookup_entry(struct accessfs_entry *pe,
+ const char *name, int len)
+{
+ struct list_head *list;
+ struct accessfs_direntry *dir;
+ struct accessfs_entry *de;
+ if (!S_ISDIR(pe->attr->mode))
+ return NULL;
+
+ dir = (struct accessfs_direntry *) pe;
+ de = NULL;
+ list_for_each(list, &dir->children) {
+ de = list_entry(list, struct accessfs_entry, siblings);
+ if (strncmp(de->name, name, len) == 0 && de->name[len] == 0)
+ break;
+ }
+
+ return de;
+}
+
+static struct dentry *accessfs_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct inode *inode = NULL;
+ struct accessfs_entry *pe;
+ mutex_lock(&accessfs_sem);
+ pe = accessfs_lookup_entry(dir->u.generic_ip, dentry->d_name.name,
+ dentry->d_name.len);
+ mutex_unlock(&accessfs_sem);
+ if (pe)
+ inode = iget(dir->i_sb, pe->ino);
+
+ d_add(dentry, inode);
+ return NULL;
+}
+
+static struct accessfs_direntry accessfs_rootdir = {
+ { "/",
+ LIST_HEAD_INIT(accessfs_rootdir.node.hash),
+ LIST_HEAD_INIT(accessfs_rootdir.node.siblings),
+ 1, &accessfs_rootdir.attr },
+ NULL, LIST_HEAD_INIT(accessfs_rootdir.children),
+ { 0, 0, S_IFDIR | 0755 }
+};
+
+static void accessfs_init_inode(struct inode *inode, struct accessfs_entry *pe)
+{
+ static const struct timespec epoch = {0, 0};
+ inode->u.generic_ip = pe;
+ inode->i_uid = pe->attr->uid;
+ inode->i_gid = pe->attr->gid;
+ inode->i_mode = pe->attr->mode;
+/*
+ inode->i_blksize = PAGE_CACHE_SIZE;
+ inode->i_blocks = 0;
+ inode->i_rdev = NODEV;
+*/
+ inode->i_atime = inode->i_mtime = inode->i_ctime = epoch;
+ switch (inode->i_mode & S_IFMT) {
+ case S_IFREG:
+ inode->i_op = &accessfs_inode_operations;
+ break;
+ case S_IFDIR:
+ inode->i_op = &accessfs_dir_inode_operations;
+ inode->i_fop = &accessfs_dir_file_operations;
+ break;
+ default:
+ BUG();
+ break;
+ }
+}
+
+static struct inode *accessfs_get_root_inode(struct super_block *sb)
+{
+ struct inode *inode = new_inode(sb);
+ if (inode) {
+ mutex_lock(&accessfs_sem);
+/* inode->i_ino = accessfs_rootdir.node.ino; */
+ accessfs_init_inode(inode, &accessfs_rootdir.node);
+ accessfs_rootdir.node.ino = inode->i_ino;
+ mutex_unlock(&accessfs_sem);
+ }
+
+ return inode;
+}
+
+static LIST_HEAD(hash);
+
+static int accessfs_node_init(struct accessfs_direntry *parent,
+ struct accessfs_entry *de, const char *name,
+ size_t len, struct access_attr *attr, mode_t mode)
+{
+ static unsigned long ino = 1;
+ de->name = kmalloc(len + 1, GFP_KERNEL);
+ if (de->name == NULL)
+ return -ENOMEM;
+
+ strncpy(de->name, name, len);
+ de->name[len] = 0;
+ de->ino = ++ino;
+ de->attr = attr;
+ de->attr->uid = 0;
+ de->attr->gid = 0;
+ de->attr->mode = mode;
+
+ list_add_tail(&de->hash, &hash);
+ list_add_tail(&de->siblings, &parent->children);
+ return 0;
+}
+
+static int accessfs_mknod(struct accessfs_direntry *dir, const char *name,
+ struct access_attr *attr)
+{
+ struct accessfs_entry *pe;
+ pe = kmalloc(sizeof(struct accessfs_entry), GFP_KERNEL);
+ if (pe == NULL)
+ return -ENOMEM;
+
+ accessfs_node_init(dir, pe, name, strlen(name), attr,
+ S_IFREG | attr->mode);
+ return 0;
+}
+
+static struct accessfs_direntry *accessfs_mkdir(struct accessfs_direntry *parent,
+ const char *name, size_t len)
+{
+ int err;
+ struct accessfs_direntry *dir;
+ dir = kmalloc(sizeof(struct accessfs_direntry), GFP_KERNEL);
+ if (dir == NULL)
+ return NULL;
+
+ dir->parent = parent;
+ INIT_LIST_HEAD(&dir->children);
+ err = accessfs_node_init(parent, &dir->node, name, len, &dir->attr,
+ S_IFDIR | 0755);
+ if (err) {
+ kfree(dir);
+ dir = 0;
+ }
+
+ return dir;
+}
+
+struct accessfs_direntry *accessfs_make_dirpath(const char *name)
+{
+ struct accessfs_direntry *dir = &accessfs_rootdir;
+ const char *slash;
+ mutex_lock(&accessfs_sem);
+ do {
+ struct accessfs_entry *de;
+ size_t len;
+ while (*name == '/')
+ ++name;
+
+ slash = strchr(name, '/');
+ len = slash ? slash - name : strlen(name);
+ de = accessfs_lookup_entry(&dir->node, name, len);
+ if (de == NULL) {
+ dir = accessfs_mkdir(dir, name, len);
+ } else if (S_ISDIR(de->attr->mode)) {
+ dir = (struct accessfs_direntry *) de;
+ } else {
+ dir = NULL;
+ }
+
+ if (dir == NULL)
+ break;
+
+ name = slash + 1;
+ } while (slash != NULL);
+
+ mutex_unlock(&accessfs_sem);
+ return dir;
+}
+
+static void accessfs_unlink(struct accessfs_entry *pe)
+{
+ list_del_init(&pe->hash);
+ list_del_init(&pe->siblings);
+ kfree(pe->name);
+ kfree(pe);
+}
+
+static int accessfs_notify_change(struct dentry *dentry, struct iattr *iattr)
+{
+ struct inode *i = dentry->d_inode;
+ int err = inode_setattr(i, iattr);
+ if (!err) {
+ struct accessfs_entry *pe;
+ pe = (struct accessfs_entry *) i->u.generic_ip;
+ pe->attr->uid = i->i_uid;
+ pe->attr->gid = i->i_gid;
+ pe->attr->mode = i->i_mode;
+ }
+
+ return err;
+}
+
+static void accessfs_read_inode(struct inode *inode)
+{
+ ino_t ino = inode->i_ino;
+ struct list_head *list;
+ mutex_lock(&accessfs_sem);
+ list_for_each(list, &hash) {
+ struct accessfs_entry *pe;
+ pe = list_entry(list, struct accessfs_entry, hash);
+ if (pe->ino == ino) {
+ accessfs_init_inode(inode, pe);
+ break;
+ }
+ }
+
+ mutex_unlock(&accessfs_sem);
+}
+
+static struct inode_operations accessfs_inode_operations = {
+ .setattr = accessfs_notify_change,
+};
+
+static struct inode_operations accessfs_dir_inode_operations = {
+ .lookup = accessfs_lookup,
+ .setattr = accessfs_notify_change,
+};
+
+static struct file_operations accessfs_dir_file_operations = {
+ .readdir = accessfs_readdir,
+};
+
+static struct super_operations accessfs_ops = {
+ .read_inode = accessfs_read_inode,
+ .statfs = simple_statfs,
+};
+
+static int accessfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct inode *inode;
+ struct dentry *root;
+
+ sb->s_blocksize = PAGE_CACHE_SIZE;
+ sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+ sb->s_magic = ACCESSFS_MAGIC;
+ sb->s_op = &accessfs_ops;
+ inode = accessfs_get_root_inode(sb);
+ if (!inode)
+ return -ENOMEM;
+
+ root = d_alloc_root(inode);
+ if (!root) {
+ iput(inode);
+ return -ENOMEM;
+ }
+
+ sb->s_root = root;
+ return 0;
+}
+
+static struct super_block *accessfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name,
+ void *data)
+{
+ return get_sb_single(fs_type, flags, data, accessfs_fill_super);
+}
+
+int accessfs_permitted(struct access_attr *p, int mask)
+{
+ mode_t mode = p->mode;
+ if (current->fsuid == p->uid)
+ mode >>= 6;
+ else if (in_group_p(p->gid))
+ mode >>= 3;
+
+ return (mode & mask) == mask;
+}
+
+int accessfs_register(struct accessfs_direntry *dir, const char *name,
+ struct access_attr *attr)
+{
+ int err;
+ if (dir == 0)
+ return -EINVAL;
+
+ mutex_lock(&accessfs_sem);
+ err = accessfs_mknod(dir, name, attr);
+ mutex_unlock(&accessfs_sem);
+ return err;
+}
+
+void accessfs_unregister(struct accessfs_direntry *dir, const char *name)
+{
+ struct accessfs_entry *pe;
+ mutex_lock(&accessfs_sem);
+ pe = accessfs_lookup_entry(&dir->node, name, strlen(name));
+ if (pe) {
+ accessfs_unlink(pe);
+ }
+
+ mutex_unlock(&accessfs_sem);
+}
+
+static struct file_system_type accessfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "accessfs",
+ .get_sb = accessfs_get_sb,
+ .kill_sb = kill_anon_super,
+};
+
+static int __init init_accessfs_fs(void)
+{
+
+ /* create mount point for accessfs */
+ mountdir = proc_mkdir("access",&proc_root);
+ return register_filesystem(&accessfs_fs_type);
+}
+
+static void __exit exit_accessfs_fs(void)
+{
+ unregister_filesystem(&accessfs_fs_type);
+ remove_proc_entry("access",&proc_root);
+}
+
+module_init(init_accessfs_fs)
+module_exit(exit_accessfs_fs)
+
+MODULE_AUTHOR("Olaf Dietsche");
+MODULE_DESCRIPTION("Access Filesystem");
+MODULE_LICENSE("GPL");
+
+EXPORT_SYMBOL(accessfs_permitted);
+EXPORT_SYMBOL(accessfs_make_dirpath);
+EXPORT_SYMBOL(accessfs_register);
+EXPORT_SYMBOL(accessfs_unregister);
diff -urN a/fs/accessfs/ip.c b/fs/accessfs/ip.c
--- a/fs/accessfs/ip.c Thu Jan 1 01:00:00 1970
+++ b/fs/accessfs/ip.c Sun Jan 29 23:20:39 2006
@@ -0,0 +1,95 @@
+/* Copyright (c) 2002-2006 Olaf Dietsche
+ *
+ * User permission based port access for Linux.
+ */
+
+#include <linux/accessfs_fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <net/sock.h>
+
+static int max_prot_sock = CONFIG_ACCESSFS_PROT_SOCK;
+static struct access_attr *bind_to_port;
+
+static int accessfs_ip_prot_sock(struct socket *sock,
+ struct sockaddr *uaddr, int addr_len)
+{
+ struct sockaddr_in *addr = (struct sockaddr_in *) uaddr;
+ unsigned short snum = ntohs(addr->sin_port);
+ if (snum && snum < max_prot_sock
+ && !accessfs_permitted(&bind_to_port[snum], MAY_EXEC)
+ && !capable(CAP_NET_BIND_SERVICE))
+ return -EACCES;
+
+ return 0;
+}
+
+static int accessfs_ip6_prot_sock(struct socket *sock,
+ struct sockaddr *uaddr, int addr_len)
+{
+ struct sockaddr_in6 *addr = (struct sockaddr_in6 *) uaddr;
+ unsigned short snum = ntohs(addr->sin6_port);
+ if (snum && snum < max_prot_sock
+ && !accessfs_permitted(&bind_to_port[snum], MAY_EXEC)
+ && !capable(CAP_NET_BIND_SERVICE))
+ return -EACCES;
+
+ return 0;
+}
+
+static struct net_hook_operations ip_net_ops = {
+ .ip_prot_sock = accessfs_ip_prot_sock,
+ .ip6_prot_sock = accessfs_ip6_prot_sock,
+};
+
+static int __init init_ip(void)
+{
+ struct accessfs_direntry *dir = accessfs_make_dirpath("net/ip/bind");
+ int i;
+
+ if (max_prot_sock < PROT_SOCK)
+ max_prot_sock = PROT_SOCK;
+ else if (max_prot_sock > 65536)
+ max_prot_sock = 65536;
+
+ bind_to_port = kmalloc(max_prot_sock * sizeof(*bind_to_port),
+ GFP_KERNEL);
+ if (bind_to_port == 0)
+ return -ENOMEM;
+
+ for (i = 1; i < max_prot_sock; ++i) {
+ char buf[sizeof("65536")];
+ bind_to_port[i].uid = 0;
+ bind_to_port[i].gid = 0;
+ bind_to_port[i].mode = i < PROT_SOCK ? S_IXUSR : S_IXUGO;
+ sprintf(buf, "%d", i);
+ accessfs_register(dir, buf, &bind_to_port[i]);
+ }
+
+ net_hooks_register(&ip_net_ops);
+ return 0;
+}
+
+static void __exit exit_ip(void)
+{
+ struct accessfs_direntry *dir = accessfs_make_dirpath("net/ip/bind");
+ int i;
+ net_hooks_unregister(&ip_net_ops);
+ for (i = 1; i < max_prot_sock; ++i) {
+ char buf[sizeof("65536")];
+ sprintf(buf, "%d", i);
+ accessfs_unregister(dir, buf);
+ }
+
+ if (bind_to_port != NULL)
+ kfree(bind_to_port);
+}
+
+module_init(init_ip)
+module_exit(exit_ip)
+
+MODULE_AUTHOR("Olaf Dietsche");
+MODULE_DESCRIPTION("User based IP ports permission");
+MODULE_LICENSE("GPL");
+module_param(max_prot_sock, int, 0);
+MODULE_PARM_DESC(max_prot_sock, "Number of protected ports");
diff -urN a/include/linux/accessfs_fs.h b/include/linux/accessfs_fs.h
--- a/include/linux/accessfs_fs.h Thu Jan 1 01:00:00 1970
+++ b/include/linux/accessfs_fs.h Sun Jan 29 13:58:52 2006
@@ -0,0 +1,43 @@
+/* -*- mode: c -*- */
+#ifndef __accessfs_fs_h_included__
+#define __accessfs_fs_h_included__ 1
+
+/* Copyright (c) 2001 Olaf Dietsche
+ *
+ * Access permission filesystem for Linux.
+ */
+
+#include <linux/config.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <net/sock.h>
+
+struct access_attr {
+ uid_t uid;
+ gid_t gid;
+ mode_t mode;
+};
+
+struct accessfs_entry {
+ char *name;
+ struct list_head hash;
+ struct list_head siblings;
+ ino_t ino;
+ struct access_attr *attr;
+};
+
+struct accessfs_direntry {
+ struct accessfs_entry node;
+ struct accessfs_direntry *parent;
+ struct list_head children;
+ struct access_attr attr;
+};
+
+extern int accessfs_permitted(struct access_attr *p, int mask);
+extern struct accessfs_direntry *accessfs_make_dirpath(const char *name);
+extern int accessfs_register(struct accessfs_direntry *dir, const char *name, struct access_attr *attr);
+extern void accessfs_unregister(struct accessfs_direntry *dir, const char *name);
+
+#endif
diff -urN a/include/net/sock.h b/include/net/sock.h
--- a/include/net/sock.h Fri Jan 27 23:53:13 2006
+++ b/include/net/sock.h Sun Jan 29 15:29:13 2006
@@ -1417,4 +1417,47 @@
extern __u32 sysctl_wmem_default;
extern __u32 sysctl_rmem_default;

+/* Networking hooks */
+extern int default_ip_prot_sock(struct socket *sock, struct sockaddr *uaddr,
+ int addr_len);
+extern int default_ip6_prot_sock(struct socket *sock, struct sockaddr *uaddr,
+ int addr_len);
+#ifdef CONFIG_NET_HOOKS
+struct net_hook_operations {
+ int (*ip_prot_sock)(struct socket *sock,
+ struct sockaddr *uaddr, int addr_len);
+ int (*ip6_prot_sock)(struct socket *sock,
+ struct sockaddr *uaddr, int addr_len);
+};
+
+extern struct net_hook_operations *net_ops;
+
+extern void net_hooks_register(struct net_hook_operations *ops);
+extern void net_hooks_unregister(struct net_hook_operations *ops);
+
+static inline int ip_prot_sock(struct socket *sock, struct sockaddr *uaddr,
+ int addr_len)
+{
+ return net_ops->ip_prot_sock(sock, uaddr, addr_len);
+}
+
+static inline int ip6_prot_sock(struct socket *sock, struct sockaddr *uaddr,
+ int addr_len)
+{
+ return net_ops->ip6_prot_sock(sock, uaddr, addr_len);
+}
+#else
+static inline int ip_prot_sock(struct socket *sock, struct sockaddr *uaddr,
+ int addr_len)
+{
+ return default_ip_prot_sock(sock, uaddr, addr_len);
+}
+
+static inline int ip6_prot_sock(struct socket *sock, struct sockaddr *uaddr,
+ int addr_len)
+{
+ return default_ip6_prot_sock(sock, uaddr, addr_len);
+}
+#endif
+
#endif /* _SOCK_H */
diff -urN a/net/Kconfig b/net/Kconfig
--- a/net/Kconfig Sat Jan 28 12:46:23 2006
+++ b/net/Kconfig Sat Jan 28 12:47:19 2006
@@ -56,6 +56,17 @@
if INET
source "net/ipv4/Kconfig"
source "net/ipv6/Kconfig"
+config NET_HOOKS
+ bool "IP: Networking hooks (Experimental)"
+ depends on INET && EXPERIMENTAL
+ default n
+ help
+ This option enables other kernel parts or modules to hook into the
+ networking area and provide fine grained control over the access to
+ IP ports.
+
+ If you're unsure, say N.
+

endif # if INET

diff -urN a/net/Makefile b/net/Makefile
--- a/net/Makefile Fri Jan 27 23:53:18 2006
+++ b/net/Makefile Sat Jan 28 12:48:26 2006
@@ -46,6 +46,7 @@
obj-$(CONFIG_IP_SCTP) += sctp/
obj-$(CONFIG_IEEE80211) += ieee80211/
obj-$(CONFIG_TIPC) += tipc/
+obj-$(CONFIG_NET_HOOKS) += hooks.o

ifeq ($(CONFIG_NET),y)
obj-$(CONFIG_SYSCTL) += sysctl_net.o
diff -urN a/net/hooks.c b/net/hooks.c
--- a/net/hooks.c Thu Jan 1 01:00:00 1970
+++ b/net/hooks.c Sun Jan 29 15:29:00 2006
@@ -0,0 +1,55 @@
+/* Copyright (c) 2002 Olaf Dietsche
+ *
+ * Networking hooks. Currently for IPv4 and IPv6 only.
+ */
+
+#include <linux/module.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <net/sock.h>
+
+int default_ip_prot_sock(struct socket *sock, struct sockaddr *uaddr, int addr_len)
+{
+ struct sockaddr_in *addr = (struct sockaddr_in *) uaddr;
+ unsigned short snum = ntohs(addr->sin_port);
+ if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
+ return -EACCES;
+
+ return 0;
+}
+
+int default_ip6_prot_sock(struct socket *sock, struct sockaddr *uaddr, int addr_len)
+{
+ struct sockaddr_in6 *addr = (struct sockaddr_in6 *) uaddr;
+ unsigned short snum = ntohs(addr->sin6_port);
+ if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
+ return -EACCES;
+
+ return 0;
+}
+
+EXPORT_SYMBOL(default_ip_prot_sock);
+EXPORT_SYMBOL(default_ip6_prot_sock);
+
+#ifdef CONFIG_NET_HOOKS
+static struct net_hook_operations default_net_ops = {
+ .ip_prot_sock = default_ip_prot_sock,
+ .ip6_prot_sock = default_ip6_prot_sock,
+};
+
+struct net_hook_operations *net_ops = &default_net_ops;
+
+void net_hooks_register(struct net_hook_operations *ops)
+{
+ net_ops = ops;
+}
+
+void net_hooks_unregister(struct net_hook_operations *ops)
+{
+ net_ops = &default_net_ops;
+}
+
+EXPORT_SYMBOL(net_ops);
+EXPORT_SYMBOL(net_hooks_register);
+EXPORT_SYMBOL(net_hooks_unregister);
+#endif
diff -urN a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
--- a/net/ipv4/af_inet.c Fri Jan 27 23:53:20 2006
+++ b/net/ipv4/af_inet.c Sun Jan 29 15:29:48 2006
@@ -431,7 +431,7 @@

snum = ntohs(addr->sin_port);
err = -EACCES;
- if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
+ if (ip_prot_sock(sock, uaddr, addr_len))
goto out;

/* We keep a pair of addresses. rcv_saddr is the one
diff -urN a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
--- a/net/ipv6/af_inet6.c Fri Jan 27 23:53:23 2006
+++ b/net/ipv6/af_inet6.c Sun Jan 29 15:28:49 2006
@@ -260,7 +260,7 @@
return -EINVAL;

snum = ntohs(addr->sin6_port);
- if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
+ if (ip6_prot_sock(sock, uaddr, addr_len))
return -EACCES;

lock_sock(sk);
-
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