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authorAmir Goldstein <amir73il@gmail.com>2023-07-16 14:47:14 +0300
committerChristian Brauner <brauner@kernel.org>2023-11-24 10:37:44 +0100
commit1c8aa833034a00617866ea4738a40491e3e23902 (patch)
tree94471c01ab560aba5e832a1ebfb6c4e884be6493 /fs/read_write.c
parent269aed7014b3db9acdbc5a5e163d8a6c62e0e770 (diff)
fs: move permission hook out of do_iter_write()
In many of the vfs helpers, the rw_verity_area() checks are called before taking sb_start_write(), making them "start-write-safe". do_iter_write() is an exception to this rule. do_iter_write() has two callers - vfs_iter_write() and vfs_writev(). Move rw_verify_area() and other checks from do_iter_write() out to its callers to make them "start-write-safe". Move also the fsnotify_modify() hook to align with similar pattern used in vfs_write() and other vfs helpers. This is needed for fanotify "pre content" events. Suggested-by: Jan Kara <jack@suse.cz> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/r/20231122122715.2561213-12-amir73il@gmail.com Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/read_write.c')
-rw-r--r--fs/read_write.c86
1 files changed, 48 insertions, 38 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
index 3aa3bce18075..d08d0a3ff7de 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -838,33 +838,6 @@ ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
}
EXPORT_SYMBOL(vfs_iter_read);
-static ssize_t do_iter_write(struct file *file, struct iov_iter *iter,
- loff_t *pos, rwf_t flags)
-{
- size_t tot_len;
- ssize_t ret = 0;
-
- if (!(file->f_mode & FMODE_WRITE))
- return -EBADF;
- if (!(file->f_mode & FMODE_CAN_WRITE))
- return -EINVAL;
-
- tot_len = iov_iter_count(iter);
- if (!tot_len)
- return 0;
- ret = rw_verify_area(WRITE, file, pos, tot_len);
- if (ret < 0)
- return ret;
-
- if (file->f_op->write_iter)
- ret = do_iter_readv_writev(file, iter, pos, WRITE, flags);
- else
- ret = do_loop_readv_writev(file, iter, pos, WRITE, flags);
- if (ret > 0)
- fsnotify_modify(file);
- return ret;
-}
-
ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
struct iov_iter *iter)
{
@@ -896,13 +869,28 @@ EXPORT_SYMBOL(vfs_iocb_iter_write);
ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
rwf_t flags)
{
- int ret;
+ size_t tot_len;
+ ssize_t ret;
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EBADF;
+ if (!(file->f_mode & FMODE_CAN_WRITE))
+ return -EINVAL;
if (!file->f_op->write_iter)
return -EINVAL;
+ tot_len = iov_iter_count(iter);
+ if (!tot_len)
+ return 0;
+
+ ret = rw_verify_area(WRITE, file, ppos, tot_len);
+ if (ret < 0)
+ return ret;
+
file_start_write(file);
- ret = do_iter_write(file, iter, ppos, flags);
+ ret = do_iter_readv_writev(file, iter, ppos, WRITE, flags);
+ if (ret > 0)
+ fsnotify_modify(file);
file_end_write(file);
return ret;
@@ -927,20 +915,42 @@ static ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
}
static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
- unsigned long vlen, loff_t *pos, rwf_t flags)
+ unsigned long vlen, loff_t *pos, rwf_t flags)
{
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
- ssize_t ret;
+ size_t tot_len;
+ ssize_t ret = 0;
- ret = import_iovec(ITER_SOURCE, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
- if (ret >= 0) {
- file_start_write(file);
- ret = do_iter_write(file, &iter, pos, flags);
- file_end_write(file);
- kfree(iov);
- }
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EBADF;
+ if (!(file->f_mode & FMODE_CAN_WRITE))
+ return -EINVAL;
+
+ ret = import_iovec(ITER_SOURCE, vec, vlen, ARRAY_SIZE(iovstack), &iov,
+ &iter);
+ if (ret < 0)
+ return ret;
+
+ tot_len = iov_iter_count(&iter);
+ if (!tot_len)
+ goto out;
+
+ ret = rw_verify_area(WRITE, file, pos, tot_len);
+ if (ret < 0)
+ goto out;
+
+ file_start_write(file);
+ if (file->f_op->write_iter)
+ ret = do_iter_readv_writev(file, &iter, pos, WRITE, flags);
+ else
+ ret = do_loop_readv_writev(file, &iter, pos, WRITE, flags);
+ if (ret > 0)
+ fsnotify_modify(file);
+ file_end_write(file);
+out:
+ kfree(iov);
return ret;
}