introduce new LSM hooks where vfsmount is available.

Add new LSM hooks for path-based checks. Call them on directory-modifying operations at the points where we still know the vfsmount involved. Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-12-17 13:24:15 +09:00 · 2008-12-17 13:24:15 +09:00 · be6d3e56a6
--- a/fs/namei.c
+++ b/fs/namei.c
@ -1556,6 +1556,9 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
 		 * Refuse to truncate files with mandatory locks held on them.
 		 */
 		error = locks_verify_locked(inode);
+		if (!error)
+			error = security_path_truncate(&nd->path, 0,
+					       ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
 		if (!error) {
 			DQUOT_INIT(inode);

@ -1586,7 +1589,11 @@ static int __open_namei_create(struct nameidata *nd, struct path *path,

 	if (!IS_POSIXACL(dir->d_inode))
 		mode &= ~current->fs->umask;
+	error = security_path_mknod(&nd->path, path->dentry, mode, 0);
+	if (error)
+		goto out_unlock;
 	error = vfs_create(dir->d_inode, path->dentry, mode, nd);
+out_unlock:
 	mutex_unlock(&dir->d_inode->i_mutex);
 	dput(nd->path.dentry);
 	nd->path.dentry = path->dentry;
@ -1999,6 +2006,9 @@ asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
 	error = mnt_want_write(nd.path.mnt);
 	if (error)
 		goto out_dput;
+	error = security_path_mknod(&nd.path, dentry, mode, dev);
+	if (error)
+		goto out_drop_write;
 	switch (mode & S_IFMT) {
 		case 0: case S_IFREG:
 			error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
@ -2011,6 +2021,7 @@ asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
 			error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
 			break;
 	}
+out_drop_write:
 	mnt_drop_write(nd.path.mnt);
 out_dput:
 	dput(dentry);
@ -2070,7 +2081,11 @@ asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
 	error = mnt_want_write(nd.path.mnt);
 	if (error)
 		goto out_dput;
+	error = security_path_mkdir(&nd.path, dentry, mode);
+	if (error)
+		goto out_drop_write;
 	error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+out_drop_write:
 	mnt_drop_write(nd.path.mnt);
 out_dput:
 	dput(dentry);
@ -2180,7 +2195,11 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	error = mnt_want_write(nd.path.mnt);
 	if (error)
 		goto exit3;
+	error = security_path_rmdir(&nd.path, dentry);
+	if (error)
+		goto exit4;
 	error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+exit4:
 	mnt_drop_write(nd.path.mnt);
 exit3:
 	dput(dentry);
@ -2265,7 +2284,11 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 		error = mnt_want_write(nd.path.mnt);
 		if (error)
 			goto exit2;
+		error = security_path_unlink(&nd.path, dentry);
+		if (error)
+			goto exit3;
 		error = vfs_unlink(nd.path.dentry->d_inode, dentry);
+exit3:
 		mnt_drop_write(nd.path.mnt);
 	exit2:
 		dput(dentry);
@ -2346,7 +2369,11 @@ asmlinkage long sys_symlinkat(const char __user *oldname,
 	error = mnt_want_write(nd.path.mnt);
 	if (error)
 		goto out_dput;
+	error = security_path_symlink(&nd.path, dentry, from);
+	if (error)
+		goto out_drop_write;
 	error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
+out_drop_write:
 	mnt_drop_write(nd.path.mnt);
 out_dput:
 	dput(dentry);
@ -2443,7 +2470,11 @@ asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
 	error = mnt_want_write(nd.path.mnt);
 	if (error)
 		goto out_dput;
+	error = security_path_link(old_path.dentry, &nd.path, new_dentry);
+	if (error)
+		goto out_drop_write;
 	error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
+out_drop_write:
 	mnt_drop_write(nd.path.mnt);
 out_dput:
 	dput(new_dentry);
@ -2679,8 +2710,13 @@ asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
 	error = mnt_want_write(oldnd.path.mnt);
 	if (error)
 		goto exit5;
+	error = security_path_rename(&oldnd.path, old_dentry,
+				     &newnd.path, new_dentry);
+	if (error)
+		goto exit6;
 	error = vfs_rename(old_dir->d_inode, old_dentry,
 				   new_dir->d_inode, new_dentry);
+exit6:
 	mnt_drop_write(oldnd.path.mnt);
 exit5:
 	dput(new_dentry);
--- a/fs/open.c
+++ b/fs/open.c
@ -272,6 +272,8 @@ static long do_sys_truncate(const char __user *pathname, loff_t length)
 		goto put_write_and_out;

 	error = locks_verify_truncate(inode, NULL, length);
+	if (!error)
+		error = security_path_truncate(&path, length, 0);
 	if (!error) {
 		DQUOT_INIT(inode);
 		error = do_truncate(path.dentry, length, 0, NULL);
@ -328,6 +330,9 @@ static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 		goto out_putf;

 	error = locks_verify_truncate(inode, file, length);
+	if (!error)
+		error = security_path_truncate(&file->f_path, length,
+					       ATTR_MTIME|ATTR_CTIME);
 	if (!error)
 		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
 out_putf:
--- a/include/linux/security.h
+++ b/include/linux/security.h
@ -335,17 +335,37 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
 *	@dir contains the inode structure of the parent directory of the new link.
 *	@new_dentry contains the dentry structure for the new link.
 *	Return 0 if permission is granted.
+ * @path_link:
+ *	Check permission before creating a new hard link to a file.
+ *	@old_dentry contains the dentry structure for an existing link
+ *	to the file.
+ *	@new_dir contains the path structure of the parent directory of
+ *	the new link.
+ *	@new_dentry contains the dentry structure for the new link.
+ *	Return 0 if permission is granted.
 * @inode_unlink:
 *	Check the permission to remove a hard link to a file.
 *	@dir contains the inode structure of parent directory of the file.
 *	@dentry contains the dentry structure for file to be unlinked.
 *	Return 0 if permission is granted.
+ * @path_unlink:
+ *	Check the permission to remove a hard link to a file.
+ *	@dir contains the path structure of parent directory of the file.
+ *	@dentry contains the dentry structure for file to be unlinked.
+ *	Return 0 if permission is granted.
 * @inode_symlink:
 *	Check the permission to create a symbolic link to a file.
 *	@dir contains the inode structure of parent directory of the symbolic link.
 *	@dentry contains the dentry structure of the symbolic link.
 *	@old_name contains the pathname of file.
 *	Return 0 if permission is granted.
+ * @path_symlink:
+ *	Check the permission to create a symbolic link to a file.
+ *	@dir contains the path structure of parent directory of
+ *	the symbolic link.
+ *	@dentry contains the dentry structure of the symbolic link.
+ *	@old_name contains the pathname of file.
+ *	Return 0 if permission is granted.
 * @inode_mkdir:
 *	Check permissions to create a new directory in the existing directory
 *	associated with inode strcture @dir.
@ -353,11 +373,25 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
 *	@dentry contains the dentry structure of new directory.
 *	@mode contains the mode of new directory.
 *	Return 0 if permission is granted.
+ * @path_mkdir:
+ *	Check permissions to create a new directory in the existing directory
+ *	associated with path strcture @path.
+ *	@dir containst the path structure of parent of the directory
+ *	to be created.
+ *	@dentry contains the dentry structure of new directory.
+ *	@mode contains the mode of new directory.
+ *	Return 0 if permission is granted.
 * @inode_rmdir:
 *	Check the permission to remove a directory.
 *	@dir contains the inode structure of parent of the directory to be removed.
 *	@dentry contains the dentry structure of directory to be removed.
 *	Return 0 if permission is granted.
+ * @path_rmdir:
+ *	Check the permission to remove a directory.
+ *	@dir contains the path structure of parent of the directory to be
+ *	removed.
+ *	@dentry contains the dentry structure of directory to be removed.
+ *	Return 0 if permission is granted.
 * @inode_mknod:
 *	Check permissions when creating a special file (or a socket or a fifo
 *	file created via the mknod system call).  Note that if mknod operation
@ -368,6 +402,15 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
 *	@mode contains the mode of the new file.
 *	@dev contains the device number.
 *	Return 0 if permission is granted.
+ * @path_mknod:
+ *	Check permissions when creating a file. Note that this hook is called
+ *	even if mknod operation is being done for a regular file.
+ *	@dir contains the path structure of parent of the new file.
+ *	@dentry contains the dentry structure of the new file.
+ *	@mode contains the mode of the new file.
+ *	@dev contains the undecoded device number. Use new_decode_dev() to get
+ *	the decoded device number.
+ *	Return 0 if permission is granted.
 * @inode_rename:
 *	Check for permission to rename a file or directory.
 *	@old_dir contains the inode structure for parent of the old link.
@ -375,6 +418,13 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
 *	@new_dir contains the inode structure for parent of the new link.
 *	@new_dentry contains the dentry structure of the new link.
 *	Return 0 if permission is granted.
+ * @path_rename:
+ *	Check for permission to rename a file or directory.
+ *	@old_dir contains the path structure for parent of the old link.
+ *	@old_dentry contains the dentry structure of the old link.
+ *	@new_dir contains the path structure for parent of the new link.
+ *	@new_dentry contains the dentry structure of the new link.
+ *	Return 0 if permission is granted.
 * @inode_readlink:
 *	Check the permission to read the symbolic link.
 *	@dentry contains the dentry structure for the file link.
@ -403,6 +453,12 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
 *	@dentry contains the dentry structure for the file.
 *	@attr is the iattr structure containing the new file attributes.
 *	Return 0 if permission is granted.
+ * @path_truncate:
+ *	Check permission before truncating a file.
+ *	@path contains the path structure for the file.
+ *	@length is the new length of the file.
+ *	@time_attrs is the flags passed to do_truncate().
+ *	Return 0 if permission is granted.
 * @inode_getattr:
 *	Check permission before obtaining file attributes.
 *	@mnt is the vfsmount where the dentry was looked up
@ -1331,6 +1387,22 @@ struct security_operations {
 				   struct super_block *newsb);
 	int (*sb_parse_opts_str) (char *options, struct security_mnt_opts *opts);

+#ifdef CONFIG_SECURITY_PATH
+	int (*path_unlink) (struct path *dir, struct dentry *dentry);
+	int (*path_mkdir) (struct path *dir, struct dentry *dentry, int mode);
+	int (*path_rmdir) (struct path *dir, struct dentry *dentry);
+	int (*path_mknod) (struct path *dir, struct dentry *dentry, int mode,
+			   unsigned int dev);
+	int (*path_truncate) (struct path *path, loff_t length,
+			      unsigned int time_attrs);
+	int (*path_symlink) (struct path *dir, struct dentry *dentry,
+			     const char *old_name);
+	int (*path_link) (struct dentry *old_dentry, struct path *new_dir,
+			  struct dentry *new_dentry);
+	int (*path_rename) (struct path *old_dir, struct dentry *old_dentry,
+			    struct path *new_dir, struct dentry *new_dentry);
+#endif
+
 	int (*inode_alloc_security) (struct inode *inode);
 	void (*inode_free_security) (struct inode *inode);
 	int (*inode_init_security) (struct inode *inode, struct inode *dir,
@ -2705,6 +2777,71 @@ static inline void security_skb_classify_flow(struct sk_buff *skb, struct flowi

 #endif	/* CONFIG_SECURITY_NETWORK_XFRM */

+#ifdef CONFIG_SECURITY_PATH
+int security_path_unlink(struct path *dir, struct dentry *dentry);
+int security_path_mkdir(struct path *dir, struct dentry *dentry, int mode);
+int security_path_rmdir(struct path *dir, struct dentry *dentry);
+int security_path_mknod(struct path *dir, struct dentry *dentry, int mode,
+			unsigned int dev);
+int security_path_truncate(struct path *path, loff_t length,
+			   unsigned int time_attrs);
+int security_path_symlink(struct path *dir, struct dentry *dentry,
+			  const char *old_name);
+int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+		       struct dentry *new_dentry);
+int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+			 struct path *new_dir, struct dentry *new_dentry);
+#else	/* CONFIG_SECURITY_PATH */
+static inline int security_path_unlink(struct path *dir, struct dentry *dentry)
+{
+	return 0;
+}
+
+static inline int security_path_mkdir(struct path *dir, struct dentry *dentry,
+				      int mode)
+{
+	return 0;
+}
+
+static inline int security_path_rmdir(struct path *dir, struct dentry *dentry)
+{
+	return 0;
+}
+
+static inline int security_path_mknod(struct path *dir, struct dentry *dentry,
+				      int mode, unsigned int dev)
+{
+	return 0;
+}
+
+static inline int security_path_truncate(struct path *path, loff_t length,
+					 unsigned int time_attrs)
+{
+	return 0;
+}
+
+static inline int security_path_symlink(struct path *dir, struct dentry *dentry,
+					const char *old_name)
+{
+	return 0;
+}
+
+static inline int security_path_link(struct dentry *old_dentry,
+				     struct path *new_dir,
+				     struct dentry *new_dentry)
+{
+	return 0;
+}
+
+static inline int security_path_rename(struct path *old_dir,
+				       struct dentry *old_dentry,
+				       struct path *new_dir,
+				       struct dentry *new_dentry)
+{
+	return 0;
+}
+#endif	/* CONFIG_SECURITY_PATH */
+
 #ifdef CONFIG_KEYS
 #ifdef CONFIG_SECURITY

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@ -836,7 +836,11 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 		err = mnt_want_write(nd.path.mnt);
 		if (err)
 			goto out_mknod_dput;
+		err = security_path_mknod(&nd.path, dentry, mode, 0);
+		if (err)
+			goto out_mknod_drop_write;
 		err = vfs_mknod(nd.path.dentry->d_inode, dentry, mode, 0);
+out_mknod_drop_write:
 		mnt_drop_write(nd.path.mnt);
 		if (err)
 			goto out_mknod_dput;
--- a/security/Kconfig
+++ b/security/Kconfig
@ -81,6 +81,15 @@ config SECURITY_NETWORK_XFRM
 	  IPSec.
 	  If you are unsure how to answer this question, answer N.

+config SECURITY_PATH
+	bool "Security hooks for pathname based access control"
+	depends on SECURITY
+	help
+	  This enables the security hooks for pathname based access control.
+	  If enabled, a security module can use these hooks to
+	  implement pathname based access controls.
+	  If you are unsure how to answer this question, answer N.
+
 config SECURITY_FILE_CAPABILITIES
 	bool "File POSIX Capabilities"
 	default n
--- a/security/capability.c
+++ b/security/capability.c
@ -263,6 +263,53 @@ static void cap_inode_getsecid(const struct inode *inode, u32 *secid)
 	*secid = 0;
 }

+#ifdef CONFIG_SECURITY_PATH
+static int cap_path_mknod(struct path *dir, struct dentry *dentry, int mode,
+			  unsigned int dev)
+{
+	return 0;
+}
+
+static int cap_path_mkdir(struct path *dir, struct dentry *dentry, int mode)
+{
+	return 0;
+}
+
+static int cap_path_rmdir(struct path *dir, struct dentry *dentry)
+{
+	return 0;
+}
+
+static int cap_path_unlink(struct path *dir, struct dentry *dentry)
+{
+	return 0;
+}
+
+static int cap_path_symlink(struct path *dir, struct dentry *dentry,
+			    const char *old_name)
+{
+	return 0;
+}
+
+static int cap_path_link(struct dentry *old_dentry, struct path *new_dir,
+			 struct dentry *new_dentry)
+{
+	return 0;
+}
+
+static int cap_path_rename(struct path *old_path, struct dentry *old_dentry,
+			   struct path *new_path, struct dentry *new_dentry)
+{
+	return 0;
+}
+
+static int cap_path_truncate(struct path *path, loff_t length,
+			     unsigned int time_attrs)
+{
+	return 0;
+}
+#endif
+
 static int cap_file_permission(struct file *file, int mask)
 {
 	return 0;
@ -883,6 +930,16 @@ void security_fixup_ops(struct security_operations *ops)
 	set_to_cap_if_null(ops, inode_setsecurity);
 	set_to_cap_if_null(ops, inode_listsecurity);
 	set_to_cap_if_null(ops, inode_getsecid);
+#ifdef CONFIG_SECURITY_PATH
+	set_to_cap_if_null(ops, path_mknod);
+	set_to_cap_if_null(ops, path_mkdir);
+	set_to_cap_if_null(ops, path_rmdir);
+	set_to_cap_if_null(ops, path_unlink);
+	set_to_cap_if_null(ops, path_symlink);
+	set_to_cap_if_null(ops, path_link);
+	set_to_cap_if_null(ops, path_rename);
+	set_to_cap_if_null(ops, path_truncate);
+#endif
 	set_to_cap_if_null(ops, file_permission);
 	set_to_cap_if_null(ops, file_alloc_security);
 	set_to_cap_if_null(ops, file_free_security);
--- a/security/security.c
+++ b/security/security.c
@ -355,6 +355,72 @@ int security_inode_init_security(struct inode *inode, struct inode *dir,
 }
 EXPORT_SYMBOL(security_inode_init_security);

+#ifdef CONFIG_SECURITY_PATH
+int security_path_mknod(struct path *path, struct dentry *dentry, int mode,
+			unsigned int dev)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_mknod(path, dentry, mode, dev);
+}
+EXPORT_SYMBOL(security_path_mknod);
+
+int security_path_mkdir(struct path *path, struct dentry *dentry, int mode)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_mkdir(path, dentry, mode);
+}
+
+int security_path_rmdir(struct path *path, struct dentry *dentry)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_rmdir(path, dentry);
+}
+
+int security_path_unlink(struct path *path, struct dentry *dentry)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_unlink(path, dentry);
+}
+
+int security_path_symlink(struct path *path, struct dentry *dentry,
+			  const char *old_name)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_symlink(path, dentry, old_name);
+}
+
+int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+		       struct dentry *new_dentry)
+{
+	if (unlikely(IS_PRIVATE(old_dentry->d_inode)))
+		return 0;
+	return security_ops->path_link(old_dentry, new_dir, new_dentry);
+}
+
+int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+			 struct path *new_dir, struct dentry *new_dentry)
+{
+	if (unlikely(IS_PRIVATE(old_dentry->d_inode) ||
+		     (new_dentry->d_inode && IS_PRIVATE(new_dentry->d_inode))))
+		return 0;
+	return security_ops->path_rename(old_dir, old_dentry, new_dir,
+					 new_dentry);
+}
+
+int security_path_truncate(struct path *path, loff_t length,
+			   unsigned int time_attrs)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_truncate(path, length, time_attrs);
+}
+#endif
+
 int security_inode_create(struct inode *dir, struct dentry *dentry, int mode)
 {
 	if (unlikely(IS_PRIVATE(dir)))