From 5e876fb43dbf24c941a323139752bcb2f0a80da0 Mon Sep 17 00:00:00 2001 From: Sargun Dhillon Date: Tue, 7 Jan 2020 09:59:24 -0800 Subject: vfs, fdtable: Add fget_task helper This introduces a function which can be used to fetch a file, given an arbitrary task. As long as the user holds a reference (refcnt) to the task_struct it is safe to call, and will either return NULL on failure, or a pointer to the file, with a refcnt. This patch is based on Oleg Nesterov's (cf. [1]) patch from September 2018. [1]: Link: https://lore.kernel.org/r/20180915160423.GA31461@redhat.com Signed-off-by: Sargun Dhillon Suggested-by: Oleg Nesterov Acked-by: Christian Brauner Reviewed-by: Arnd Bergmann Link: https://lore.kernel.org/r/20200107175927.4558-2-sargun@sargun.me Signed-off-by: Christian Brauner --- include/linux/file.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/file.h') diff --git a/include/linux/file.h b/include/linux/file.h index 3fcddff56bc4..c6c7b24ea9f7 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -16,6 +16,7 @@ extern void fput(struct file *); extern void fput_many(struct file *, unsigned int); struct file_operations; +struct task_struct; struct vfsmount; struct dentry; struct inode; @@ -47,6 +48,7 @@ static inline void fdput(struct fd fd) extern struct file *fget(unsigned int fd); extern struct file *fget_many(unsigned int fd, unsigned int refs); extern struct file *fget_raw(unsigned int fd); +extern struct file *fget_task(struct task_struct *task, unsigned int fd); extern unsigned long __fdget(unsigned int fd); extern unsigned long __fdget_raw(unsigned int fd); extern unsigned long __fdget_pos(unsigned int fd); -- cgit v1.2.3 From 4022e7af86be2dd62975dedb6b7ea551d108695e Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 19 Mar 2020 19:23:18 -0600 Subject: io_uring: make sure openat/openat2 honor rlimit nofile Dmitry reports that a test case shows that io_uring isn't honoring a modified rlimit nofile setting. get_unused_fd_flags() checks the task signal->rlimi[] for the limits. As this isn't easily inheritable, provide a __get_unused_fd_flags() that takes the value instead. Then we can grab it when the request is prepared (from the original task), and pass that in when we do the async part part of the open. Reported-by: Dmitry Kadashev Tested-by: Dmitry Kadashev Acked-by: David S. Miller Signed-off-by: Jens Axboe --- fs/file.c | 7 ++++++- fs/io_uring.c | 5 ++++- include/linux/file.h | 1 + 3 files changed, 11 insertions(+), 2 deletions(-) (limited to 'include/linux/file.h') diff --git a/fs/file.c b/fs/file.c index a364e1a9b7e8..c8a4e4c86e55 100644 --- a/fs/file.c +++ b/fs/file.c @@ -540,9 +540,14 @@ static int alloc_fd(unsigned start, unsigned flags) return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags); } +int __get_unused_fd_flags(unsigned flags, unsigned long nofile) +{ + return __alloc_fd(current->files, 0, nofile, flags); +} + int get_unused_fd_flags(unsigned flags) { - return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags); + return __get_unused_fd_flags(flags, rlimit(RLIMIT_NOFILE)); } EXPORT_SYMBOL(get_unused_fd_flags); diff --git a/fs/io_uring.c b/fs/io_uring.c index b1fbc4424aa6..fe5ded7c74ef 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -397,6 +397,7 @@ struct io_open { struct filename *filename; struct statx __user *buffer; struct open_how how; + unsigned long nofile; }; struct io_files_update { @@ -2577,6 +2578,7 @@ static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return ret; } + req->open.nofile = rlimit(RLIMIT_NOFILE); req->flags |= REQ_F_NEED_CLEANUP; return 0; } @@ -2618,6 +2620,7 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return ret; } + req->open.nofile = rlimit(RLIMIT_NOFILE); req->flags |= REQ_F_NEED_CLEANUP; return 0; } @@ -2636,7 +2639,7 @@ static int io_openat2(struct io_kiocb *req, struct io_kiocb **nxt, if (ret) goto err; - ret = get_unused_fd_flags(req->open.how.flags); + ret = __get_unused_fd_flags(req->open.how.flags, req->open.nofile); if (ret < 0) goto err; diff --git a/include/linux/file.h b/include/linux/file.h index c6c7b24ea9f7..142d102f285e 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -85,6 +85,7 @@ extern int f_dupfd(unsigned int from, struct file *file, unsigned flags); extern int replace_fd(unsigned fd, struct file *file, unsigned flags); extern void set_close_on_exec(unsigned int fd, int flag); extern bool get_close_on_exec(unsigned int fd); +extern int __get_unused_fd_flags(unsigned flags, unsigned long nofile); extern int get_unused_fd_flags(unsigned flags); extern void put_unused_fd(unsigned int fd); -- cgit v1.2.3