lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 20 Nov 2020 17:14:29 -0600 From: "Eric W. Biederman" <ebiederm@...ssion.com> To: linux-kernel@...r.kernel.org Cc: linux-fsdevel@...r.kernel.org, criu@...nvz.org, bpf@...r.kernel.org, Linus Torvalds <torvalds@...ux-foundation.org>, Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <christian.brauner@...ntu.com>, Oleg Nesterov <oleg@...hat.com>, Cyrill Gorcunov <gorcunov@...il.com>, Jann Horn <jann@...jh.net>, Kees Cook <keescook@...omium.org>, Daniel P . Berrangé <berrange@...hat.com>, Jeff Layton <jlayton@...hat.com>, Miklos Szeredi <miklos@...redi.hu>, Matthew Wilcox <willy@...radead.org>, "J. Bruce Fields" <bfields@...ldses.org>, Trond Myklebust <trond.myklebust@...merspace.com>, Chris Wright <chrisw@...hat.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, Andrii Nakryiko <andriin@...com>, John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...omium.org>, "Eric W. Biederman" <ebiederm@...ssion.com> Subject: [PATCH v2 12/24] proc/fd: In tid_fd_mode use task_lookup_fd_rcu When discussing[1] exec and posix file locks it was realized that none of the callers of get_files_struct fundamentally needed to call get_files_struct, and that by switching them to helper functions instead it will both simplify their code and remove unnecessary increments of files_struct.count. Those unnecessary increments can result in exec unnecessarily unsharing files_struct which breaking posix locks, and it can result in fget_light having to fallback to fget reducing system performance. Instead of manually coding finding the files struct for a task and then calling files_lookup_fd_rcu, use the helper task_lookup_fd_rcu that combines those to steps. Making the code simpler and removing the need to get a reference on a files_struct. [1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com Suggested-by: Oleg Nesterov <oleg@...hat.com> Acked-by: Christian Brauner <christian.brauner@...ntu.com> v1: https://lkml.kernel.org/r/20200817220425.9389-7-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com> --- fs/proc/fd.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 3dec44d7c5c5..c1a984f3c4df 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -83,18 +83,13 @@ static const struct file_operations proc_fdinfo_file_operations = { static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode) { - struct files_struct *files = get_files_struct(task); struct file *file; - if (!files) - return false; - rcu_read_lock(); - file = files_lookup_fd_rcu(files, fd); + file = task_lookup_fd_rcu(task, fd); if (file) *mode = file->f_mode; rcu_read_unlock(); - put_files_struct(files); return !!file; } -- 2.25.0
Powered by blists - more mailing lists