X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fxattr.c;h=237804cd6b566572177b60b05d68307b7cc207b2;hb=29ed1407ed81086b778ebf12145b048ac3f7e10e;hp=6acd5c63da9113613132492dea834d8304554fd8;hpb=0eeca28300df110bd6ed54b31193c83b87921443;p=safe%2Fjmp%2Flinux-2.6

diff --git a/fs/xattr.c b/fs/xattr.c
index 6acd5c6..237804c 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -9,21 +9,216 @@
  */
 #include <linux/fs.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/file.h>
 #include <linux/xattr.h>
+#include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
 #include <linux/module.h>
 #include <linux/fsnotify.h>
+#include <linux/audit.h>
 #include <asm/uaccess.h>
 
+
+/*
+ * Check permissions for extended attribute access.  This is a bit complicated
+ * because different namespaces have very different rules.
+ */
+static int
+xattr_permission(struct inode *inode, const char *name, int mask)
+{
+	/*
+	 * We can never set or remove an extended attribute on a read-only
+	 * filesystem  or on an immutable / append-only inode.
+	 */
+	if (mask & MAY_WRITE) {
+		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+			return -EPERM;
+	}
+
+	/*
+	 * No restriction for security.* and system.* from the VFS.  Decision
+	 * on these is left to the underlying filesystem / security module.
+	 */
+	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) ||
+	    !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return 0;
+
+	/*
+	 * The trusted.* namespace can only be accessed by a privileged user.
+	 */
+	if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
+		return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM);
+
+	/* In user.* namespace, only regular files and directories can have
+	 * extended attributes. For sticky directories, only the owner and
+	 * privileged user can write attributes.
+	 */
+	if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
+		if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
+			return -EPERM;
+		if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
+		    (mask & MAY_WRITE) && !is_owner_or_cap(inode))
+			return -EPERM;
+	}
+
+	return inode_permission(inode, mask);
+}
+
+int
+vfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		size_t size, int flags)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	mutex_lock(&inode->i_mutex);
+	error = security_inode_setxattr(dentry, name, value, size, flags);
+	if (error)
+		goto out;
+	error = -EOPNOTSUPP;
+	if (inode->i_op->setxattr) {
+		error = inode->i_op->setxattr(dentry, name, value, size, flags);
+		if (!error) {
+			fsnotify_xattr(dentry);
+			security_inode_post_setxattr(dentry, name, value,
+						     size, flags);
+		}
+	} else if (!strncmp(name, XATTR_SECURITY_PREFIX,
+				XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		error = security_inode_setsecurity(inode, suffix, value,
+						   size, flags);
+		if (!error)
+			fsnotify_xattr(dentry);
+	}
+out:
+	mutex_unlock(&inode->i_mutex);
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_setxattr);
+
+ssize_t
+xattr_getsecurity(struct inode *inode, const char *name, void *value,
+			size_t size)
+{
+	void *buffer = NULL;
+	ssize_t len;
+
+	if (!value || !size) {
+		len = security_inode_getsecurity(inode, name, &buffer, false);
+		goto out_noalloc;
+	}
+
+	len = security_inode_getsecurity(inode, name, &buffer, true);
+	if (len < 0)
+		return len;
+	if (size < len) {
+		len = -ERANGE;
+		goto out;
+	}
+	memcpy(value, buffer, len);
+out:
+	security_release_secctx(buffer, len);
+out_noalloc:
+	return len;
+}
+EXPORT_SYMBOL_GPL(xattr_getsecurity);
+
+ssize_t
+vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	error = xattr_permission(inode, name, MAY_READ);
+	if (error)
+		return error;
+
+	error = security_inode_getxattr(dentry, name);
+	if (error)
+		return error;
+
+	if (!strncmp(name, XATTR_SECURITY_PREFIX,
+				XATTR_SECURITY_PREFIX_LEN)) {
+		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
+		int ret = xattr_getsecurity(inode, suffix, value, size);
+		/*
+		 * Only overwrite the return value if a security module
+		 * is actually active.
+		 */
+		if (ret == -EOPNOTSUPP)
+			goto nolsm;
+		return ret;
+	}
+nolsm:
+	if (inode->i_op->getxattr)
+		error = inode->i_op->getxattr(dentry, name, value, size);
+	else
+		error = -EOPNOTSUPP;
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_getxattr);
+
+ssize_t
+vfs_listxattr(struct dentry *d, char *list, size_t size)
+{
+	ssize_t error;
+
+	error = security_inode_listxattr(d);
+	if (error)
+		return error;
+	error = -EOPNOTSUPP;
+	if (d->d_inode->i_op->listxattr) {
+		error = d->d_inode->i_op->listxattr(d, list, size);
+	} else {
+		error = security_inode_listsecurity(d->d_inode, list, size);
+		if (size && error > size)
+			error = -ERANGE;
+	}
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_listxattr);
+
+int
+vfs_removexattr(struct dentry *dentry, const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	if (!inode->i_op->removexattr)
+		return -EOPNOTSUPP;
+
+	error = xattr_permission(inode, name, MAY_WRITE);
+	if (error)
+		return error;
+
+	error = security_inode_removexattr(dentry, name);
+	if (error)
+		return error;
+
+	mutex_lock(&inode->i_mutex);
+	error = inode->i_op->removexattr(dentry, name);
+	mutex_unlock(&inode->i_mutex);
+
+	if (!error)
+		fsnotify_xattr(dentry);
+	return error;
+}
+EXPORT_SYMBOL_GPL(vfs_removexattr);
+
+
 /*
  * Extended attribute SET operations
  */
 static long
-setxattr(struct dentry *d, char __user *name, void __user *value,
+setxattr(struct dentry *d, const char __user *name, const void __user *value,
 	 size_t size, int flags)
 {
 	int error;
@@ -51,66 +246,67 @@ setxattr(struct dentry *d, char __user *name, void __user *value,
 		}
 	}
 
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->setxattr) {
-		down(&d->d_inode->i_sem);
-		error = security_inode_setxattr(d, kname, kvalue, size, flags);
-		if (error)
-			goto out;
-		error = d->d_inode->i_op->setxattr(d, kname, kvalue, size, flags);
-		if (!error) {
-			fsnotify_xattr(d);
-			security_inode_post_setxattr(d, kname, kvalue, size, flags);
-		}
-out:
-		up(&d->d_inode->i_sem);
-	}
-	if (kvalue)
-		kfree(kvalue);
+	error = vfs_setxattr(d, kname, kvalue, size, flags);
+	kfree(kvalue);
 	return error;
 }
 
 asmlinkage long
-sys_setxattr(char __user *path, char __user *name, void __user *value,
-	     size_t size, int flags)
+sys_setxattr(const char __user *pathname, const char __user *name,
+	     const void __user *value, size_t size, int flags)
 {
-	struct nameidata nd;
+	struct path path;
 	int error;
 
-	error = user_path_walk(path, &nd);
+	error = user_path(pathname, &path);
 	if (error)
 		return error;
-	error = setxattr(nd.dentry, name, value, size, flags);
-	path_release(&nd);
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = setxattr(path.dentry, name, value, size, flags);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
 	return error;
 }
 
 asmlinkage long
-sys_lsetxattr(char __user *path, char __user *name, void __user *value,
-	      size_t size, int flags)
+sys_lsetxattr(const char __user *pathname, const char __user *name,
+	      const void __user *value, size_t size, int flags)
 {
-	struct nameidata nd;
+	struct path path;
 	int error;
 
-	error = user_path_walk_link(path, &nd);
+	error = user_lpath(pathname, &path);
 	if (error)
 		return error;
-	error = setxattr(nd.dentry, name, value, size, flags);
-	path_release(&nd);
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = setxattr(path.dentry, name, value, size, flags);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
 	return error;
 }
 
 asmlinkage long
-sys_fsetxattr(int fd, char __user *name, void __user *value,
+sys_fsetxattr(int fd, const char __user *name, const void __user *value,
 	      size_t size, int flags)
 {
 	struct file *f;
+	struct dentry *dentry;
 	int error = -EBADF;
 
 	f = fget(fd);
 	if (!f)
 		return error;
-	error = setxattr(f->f_dentry, name, value, size, flags);
+	dentry = f->f_path.dentry;
+	audit_inode(NULL, dentry);
+	error = mnt_want_write(f->f_path.mnt);
+	if (!error) {
+		error = setxattr(dentry, name, value, size, flags);
+		mnt_drop_write(f->f_path.mnt);
+	}
 	fput(f);
 	return error;
 }
@@ -119,7 +315,8 @@ sys_fsetxattr(int fd, char __user *name, void __user *value,
  * Extended attribute GET operations
  */
 static ssize_t
-getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
+getxattr(struct dentry *d, const char __user *name, void __user *value,
+	 size_t size)
 {
 	ssize_t error;
 	void *kvalue = NULL;
@@ -134,64 +331,56 @@ getxattr(struct dentry *d, char __user *name, void __user *value, size_t size)
 	if (size) {
 		if (size > XATTR_SIZE_MAX)
 			size = XATTR_SIZE_MAX;
-		kvalue = kmalloc(size, GFP_KERNEL);
+		kvalue = kzalloc(size, GFP_KERNEL);
 		if (!kvalue)
 			return -ENOMEM;
 	}
 
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->getxattr) {
-		error = security_inode_getxattr(d, kname);
-		if (error)
-			goto out;
-		error = d->d_inode->i_op->getxattr(d, kname, kvalue, size);
-		if (error > 0) {
-			if (size && copy_to_user(value, kvalue, error))
-				error = -EFAULT;
-		} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
-			/* The file system tried to returned a value bigger
-			   than XATTR_SIZE_MAX bytes. Not possible. */
-			error = -E2BIG;
-		}
+	error = vfs_getxattr(d, kname, kvalue, size);
+	if (error > 0) {
+		if (size && copy_to_user(value, kvalue, error))
+			error = -EFAULT;
+	} else if (error == -ERANGE && size >= XATTR_SIZE_MAX) {
+		/* The file system tried to returned a value bigger
+		   than XATTR_SIZE_MAX bytes. Not possible. */
+		error = -E2BIG;
 	}
-out:
-	if (kvalue)
-		kfree(kvalue);
+	kfree(kvalue);
 	return error;
 }
 
 asmlinkage ssize_t
-sys_getxattr(char __user *path, char __user *name, void __user *value,
-	     size_t size)
+sys_getxattr(const char __user *pathname, const char __user *name,
+	     void __user *value, size_t size)
 {
-	struct nameidata nd;
+	struct path path;
 	ssize_t error;
 
-	error = user_path_walk(path, &nd);
+	error = user_path(pathname, &path);
 	if (error)
 		return error;
-	error = getxattr(nd.dentry, name, value, size);
-	path_release(&nd);
+	error = getxattr(path.dentry, name, value, size);
+	path_put(&path);
 	return error;
 }
 
 asmlinkage ssize_t
-sys_lgetxattr(char __user *path, char __user *name, void __user *value,
+sys_lgetxattr(const char __user *pathname, const char __user *name, void __user *value,
 	      size_t size)
 {
-	struct nameidata nd;
+	struct path path;
 	ssize_t error;
 
-	error = user_path_walk_link(path, &nd);
+	error = user_lpath(pathname, &path);
 	if (error)
 		return error;
-	error = getxattr(nd.dentry, name, value, size);
-	path_release(&nd);
+	error = getxattr(path.dentry, name, value, size);
+	path_put(&path);
 	return error;
 }
 
 asmlinkage ssize_t
-sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size)
+sys_fgetxattr(int fd, const char __user *name, void __user *value, size_t size)
 {
 	struct file *f;
 	ssize_t error = -EBADF;
@@ -199,7 +388,8 @@ sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size)
 	f = fget(fd);
 	if (!f)
 		return error;
-	error = getxattr(f->f_dentry, name, value, size);
+	audit_inode(NULL, f->f_path.dentry);
+	error = getxattr(f->f_path.dentry, name, value, size);
 	fput(f);
 	return error;
 }
@@ -221,52 +411,44 @@ listxattr(struct dentry *d, char __user *list, size_t size)
 			return -ENOMEM;
 	}
 
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->listxattr) {
-		error = security_inode_listxattr(d);
-		if (error)
-			goto out;
-		error = d->d_inode->i_op->listxattr(d, klist, size);
-		if (error > 0) {
-			if (size && copy_to_user(list, klist, error))
-				error = -EFAULT;
-		} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
-			/* The file system tried to returned a list bigger
-			   than XATTR_LIST_MAX bytes. Not possible. */
-			error = -E2BIG;
-		}
+	error = vfs_listxattr(d, klist, size);
+	if (error > 0) {
+		if (size && copy_to_user(list, klist, error))
+			error = -EFAULT;
+	} else if (error == -ERANGE && size >= XATTR_LIST_MAX) {
+		/* The file system tried to returned a list bigger
+		   than XATTR_LIST_MAX bytes. Not possible. */
+		error = -E2BIG;
 	}
-out:
-	if (klist)
-		kfree(klist);
+	kfree(klist);
 	return error;
 }
 
 asmlinkage ssize_t
-sys_listxattr(char __user *path, char __user *list, size_t size)
+sys_listxattr(const char __user *pathname, char __user *list, size_t size)
 {
-	struct nameidata nd;
+	struct path path;
 	ssize_t error;
 
-	error = user_path_walk(path, &nd);
+	error = user_path(pathname, &path);
 	if (error)
 		return error;
-	error = listxattr(nd.dentry, list, size);
-	path_release(&nd);
+	error = listxattr(path.dentry, list, size);
+	path_put(&path);
 	return error;
 }
 
 asmlinkage ssize_t
-sys_llistxattr(char __user *path, char __user *list, size_t size)
+sys_llistxattr(const char __user *pathname, char __user *list, size_t size)
 {
-	struct nameidata nd;
+	struct path path;
 	ssize_t error;
 
-	error = user_path_walk_link(path, &nd);
+	error = user_lpath(pathname, &path);
 	if (error)
 		return error;
-	error = listxattr(nd.dentry, list, size);
-	path_release(&nd);
+	error = listxattr(path.dentry, list, size);
+	path_put(&path);
 	return error;
 }
 
@@ -279,7 +461,8 @@ sys_flistxattr(int fd, char __user *list, size_t size)
 	f = fget(fd);
 	if (!f)
 		return error;
-	error = listxattr(f->f_dentry, list, size);
+	audit_inode(NULL, f->f_path.dentry);
+	error = listxattr(f->f_path.dentry, list, size);
 	fput(f);
 	return error;
 }
@@ -288,7 +471,7 @@ sys_flistxattr(int fd, char __user *list, size_t size)
  * Extended attribute REMOVE operations
  */
 static long
-removexattr(struct dentry *d, char __user *name)
+removexattr(struct dentry *d, const char __user *name)
 {
 	int error;
 	char kname[XATTR_NAME_MAX + 1];
@@ -299,57 +482,62 @@ removexattr(struct dentry *d, char __user *name)
 	if (error < 0)
 		return error;
 
-	error = -EOPNOTSUPP;
-	if (d->d_inode->i_op && d->d_inode->i_op->removexattr) {
-		error = security_inode_removexattr(d, kname);
-		if (error)
-			goto out;
-		down(&d->d_inode->i_sem);
-		error = d->d_inode->i_op->removexattr(d, kname);
-		up(&d->d_inode->i_sem);
-	}
-out:
-	return error;
+	return vfs_removexattr(d, kname);
 }
 
 asmlinkage long
-sys_removexattr(char __user *path, char __user *name)
+sys_removexattr(const char __user *pathname, const char __user *name)
 {
-	struct nameidata nd;
+	struct path path;
 	int error;
 
-	error = user_path_walk(path, &nd);
+	error = user_path(pathname, &path);
 	if (error)
 		return error;
-	error = removexattr(nd.dentry, name);
-	path_release(&nd);
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = removexattr(path.dentry, name);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
 	return error;
 }
 
 asmlinkage long
-sys_lremovexattr(char __user *path, char __user *name)
+sys_lremovexattr(const char __user *pathname, const char __user *name)
 {
-	struct nameidata nd;
+	struct path path;
 	int error;
 
-	error = user_path_walk_link(path, &nd);
+	error = user_lpath(pathname, &path);
 	if (error)
 		return error;
-	error = removexattr(nd.dentry, name);
-	path_release(&nd);
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = removexattr(path.dentry, name);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
 	return error;
 }
 
 asmlinkage long
-sys_fremovexattr(int fd, char __user *name)
+sys_fremovexattr(int fd, const char __user *name)
 {
 	struct file *f;
+	struct dentry *dentry;
 	int error = -EBADF;
 
 	f = fget(fd);
 	if (!f)
 		return error;
-	error = removexattr(f->f_dentry, name);
+	dentry = f->f_path.dentry;
+	audit_inode(NULL, dentry);
+	error = mnt_want_write(f->f_path.mnt);
+	if (!error) {
+		error = removexattr(dentry, name);
+		mnt_drop_write(f->f_path.mnt);
+	}
 	fput(f);
 	return error;
 }