[PATCH 10/14] fs: add a __kernel_read helper
From: Christoph Hellwig <hch@lst.de>
Date: 2020-05-28 05:41:22
Also in:
linux-fsdevel, lkml, netfilter-devel
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
This is the counterpart to __kernel_write, and skip the rw_verify_area call compared to kernel_read. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/read_write.c | 21 +++++++++++++++++++++ include/linux/fs.h | 1 + 2 files changed, 22 insertions(+)
diff --git a/fs/read_write.c b/fs/read_write.c
index 8cfca5f8fc3ce..bd12af8a895c8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c@@ -430,6 +430,27 @@ 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 (!(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 21f126957c2cf..6441aaa25f8f2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -3011,6 +3011,7 @@ 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 *);
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2.26.2