From e65ce2a50cf6af216bea6fd80d771fcbb4c0aaa1 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:27 +0100 Subject: acl: handle idmapped mounts The posix acl permission checking helpers determine whether a caller is privileged over an inode according to the acls associated with the inode. Add helpers that make it possible to handle acls on idmapped mounts. The vfs and the filesystems targeted by this first iteration make use of posix_acl_fix_xattr_from_user() and posix_acl_fix_xattr_to_user() to translate basic posix access and default permissions such as the ACL_USER and ACL_GROUP type according to the initial user namespace (or the superblock's user namespace) to and from the caller's current user namespace. Adapt these two helpers to handle idmapped mounts whereby we either map from or into the mount's user namespace depending on in which direction we're translating. Similarly, cap_convert_nscap() is used by the vfs to translate user namespace and non-user namespace aware filesystem capabilities from the superblock's user namespace to the caller's user namespace. Enable it to handle idmapped mounts by accounting for the mount's user namespace. In addition the fileystems targeted in the first iteration of this patch series make use of the posix_acl_chmod() and, posix_acl_update_mode() helpers. Both helpers perform permission checks on the target inode. Let them handle idmapped mounts. These two helpers are called when posix acls are set by the respective filesystems to handle this case we extend the ->set() method to take an additional user namespace argument to pass the mount's user namespace down. Link: https://lore.kernel.org/r/20210121131959.646623-9-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- fs/xattr.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'fs/xattr.c') diff --git a/fs/xattr.c b/fs/xattr.c index c669922e1bde..d777025121e0 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -175,7 +175,8 @@ __vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name, return -EOPNOTSUPP; if (size == 0) value = ""; /* empty EA, do not remove */ - return handler->set(handler, dentry, inode, name, value, size, flags); + return handler->set(handler, &init_user_ns, dentry, inode, name, value, + size, flags); } EXPORT_SYMBOL(__vfs_setxattr); @@ -281,7 +282,7 @@ vfs_setxattr(struct dentry *dentry, const char *name, const void *value, int error; if (size && strcmp(name, XATTR_NAME_CAPS) == 0) { - error = cap_convert_nscap(dentry, &value, size); + error = cap_convert_nscap(&init_user_ns, dentry, &value, size); if (error < 0) return error; size = error; @@ -450,7 +451,8 @@ __vfs_removexattr(struct dentry *dentry, const char *name) return PTR_ERR(handler); if (!handler->set) return -EOPNOTSUPP; - return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE); + return handler->set(handler, &init_user_ns, dentry, inode, name, NULL, + 0, XATTR_REPLACE); } EXPORT_SYMBOL(__vfs_removexattr); @@ -548,7 +550,8 @@ setxattr(struct dentry *d, const char __user *name, const void __user *value, } if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) - posix_acl_fix_xattr_from_user(kvalue, size); + posix_acl_fix_xattr_from_user(&init_user_ns, kvalue, + size); } error = vfs_setxattr(d, kname, kvalue, size, flags); @@ -642,7 +645,8 @@ getxattr(struct dentry *d, const char __user *name, void __user *value, if (error > 0) { if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) || (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)) - posix_acl_fix_xattr_to_user(kvalue, error); + posix_acl_fix_xattr_to_user(&init_user_ns, kvalue, + error); if (size && copy_to_user(value, kvalue, error)) error = -EFAULT; } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { -- cgit v1.2.3