From bce9c2e34006dd70fb77a72f8cce1ead8a01db9e Mon Sep 17 00:00:00 2001 From: Dmitry Chagin Date: Fri, 1 Sep 2023 11:11:02 +0300 Subject: [PATCH] linux(4): Return ENOTSUP from xattr syscalls instead of EPERM FreeBSD does not permits manipulating extended attributes in the system namespace by unprivileged accounts, even if account has appropriate privileges to access filesystem object. In Linux the system namespace is used to preserve posix acls. Some Gnu coreutils binaries uses posix acls, eg, install, ls. And fails if we unexpectedly return EPERM error from xattr system calls. In the other hands, in Linux read and write access to the system namespace depend on the policy implemented for each filesystem, so we'll mimics we're a filesystem that prohibits this for unpriveleged accounts. Reported by: zirias Tested by: zirias MFC after: 1 week (cherry picked from commit 1bfc4574f78653e4b64ac9dd31518c96a17fe52b) --- sys/compat/linux/linux_xattr.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/sys/compat/linux/linux_xattr.c b/sys/compat/linux/linux_xattr.c index 2b46cf708c7..74b47f1cbae 100644 --- a/sys/compat/linux/linux_xattr.c +++ b/sys/compat/linux/linux_xattr.c @@ -87,6 +87,16 @@ struct removexattr_args { static char *extattr_namespace_names[] = EXTATTR_NAMESPACE_NAMES; +static int +error_to_xattrerror(int attrnamespace, int error) +{ + + if (attrnamespace == EXTATTR_NAMESPACE_SYSTEM && error == EPERM) + return (ENOTSUP); + else + return (error); +} + static int xatrr_to_extattr(const char *uattrname, int *attrnamespace, char *attrname) { @@ -188,7 +198,7 @@ listxattr(struct thread *td, struct listxattr_args *args) if (error == 0) td->td_retval[0] = cnt; free(data, M_LINUX); - return (error); + return (error_to_xattrerror(attrnamespace, error)); } int @@ -248,7 +258,7 @@ removexattr(struct thread *td, struct removexattr_args *args) else error = kern_extattr_delete_fd(td, args->fd, attrnamespace, attrname); - return (error); + return (error_to_xattrerror(attrnamespace, error)); } int @@ -392,7 +402,7 @@ setxattr(struct thread *td, struct setxattr_args *args) attrname, args->value, args->size); out: td->td_retval[0] = 0; - return (error); + return (error_to_xattrerror(attrnamespace, error)); } int