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Date: Wed, 24 Jun 2020 18:13:30 +0200 From: Christoph Hellwig <hch@....de> To: Al Viro <viro@...iv.linux.org.uk> Cc: Linus Torvalds <torvalds@...ux-foundation.org>, Ian Kent <raven@...maw.net>, David Howells <dhowells@...hat.com>, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-security-module@...r.kernel.org, netfilter-devel@...r.kernel.org Subject: [PATCH 09/14] fs: add a __kernel_read helper This is the counterpart to __kernel_write, and skip the rw_verify_area call compared to kernel_read. Signed-off-by: Christoph Hellwig <hch@....de> --- fs/read_write.c | 23 +++++++++++++++++++++++ include/linux/fs.h | 1 + 2 files changed, 24 insertions(+) diff --git a/fs/read_write.c b/fs/read_write.c index bd46c959799e97..cc8e0b4f3cd697 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -430,6 +430,29 @@ ssize_t __vfs_read(struct file *file, char __user *buf, size_t count, return -EINVAL; } +ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) +{ + mm_segment_t old_fs = get_fs(); + ssize_t ret; + + if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ))) + return -EINVAL; + if (!(file->f_mode & FMODE_CAN_READ)) + return -EINVAL; + + if (count > MAX_RW_COUNT) + count = MAX_RW_COUNT; + set_fs(KERNEL_DS); + ret = __vfs_read(file, (void __user *)buf, count, pos); + set_fs(old_fs); + if (ret > 0) { + fsnotify_access(file); + add_rchar(current, ret); + } + inc_syscr(current); + return ret; +} + ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) { mm_segment_t old_fs; diff --git a/include/linux/fs.h b/include/linux/fs.h index 3f881a892ea746..22cbe7b2e91994 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3033,6 +3033,7 @@ extern int kernel_read_file_from_path_initns(const char *, void **, loff_t *, lo extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t, enum kernel_read_file_id); extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *); +ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos); extern ssize_t kernel_write(struct file *, const void *, size_t, loff_t *); extern ssize_t __kernel_write(struct file *, const void *, size_t, loff_t *); extern struct file * open_exec(const char *); -- 2.26.2
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