For backing file operations, users are expected to pass credentials
that will outlive the backing file common operations.
Use the specialized guard statements to override/revert the
credentials.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
---
fs/backing-file.c | 124 ++++++++++++++++++++++------------------------
1 file changed, 60 insertions(+), 64 deletions(-)
diff --git a/fs/backing-file.c b/fs/backing-file.c
index a681f38d84d8..9874f09f860f 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -140,7 +140,7 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
struct backing_file_ctx *ctx)
{
struct backing_aio *aio = NULL;
- const struct cred *old_cred;
+ const struct cred *old_cred = ctx->cred;
ssize_t ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
@@ -153,29 +153,28 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
!(file->f_mode & FMODE_CAN_ODIRECT))
return -EINVAL;
- old_cred = override_creds(ctx->cred);
- if (is_sync_kiocb(iocb)) {
- rwf_t rwf = iocb_to_rw_flags(flags);
+ scoped_guard(cred, old_cred) {
+ if (is_sync_kiocb(iocb)) {
+ rwf_t rwf = iocb_to_rw_flags(flags);
- ret = vfs_iter_read(file, iter, &iocb->ki_pos, rwf);
- } else {
- ret = -ENOMEM;
- aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
- if (!aio)
- goto out;
+ ret = vfs_iter_read(file, iter, &iocb->ki_pos, rwf);
+ } else {
+ ret = -ENOMEM;
+ aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
+ if (!aio)
+ goto out;
- aio->orig_iocb = iocb;
- kiocb_clone(&aio->iocb, iocb, get_file(file));
- aio->iocb.ki_complete = backing_aio_rw_complete;
- refcount_set(&aio->ref, 2);
- ret = vfs_iocb_iter_read(file, &aio->iocb, iter);
- backing_aio_put(aio);
- if (ret != -EIOCBQUEUED)
- backing_aio_cleanup(aio, ret);
+ aio->orig_iocb = iocb;
+ kiocb_clone(&aio->iocb, iocb, get_file(file));
+ aio->iocb.ki_complete = backing_aio_rw_complete;
+ refcount_set(&aio->ref, 2);
+ ret = vfs_iocb_iter_read(file, &aio->iocb, iter);
+ backing_aio_put(aio);
+ if (ret != -EIOCBQUEUED)
+ backing_aio_cleanup(aio, ret);
+ }
}
out:
- revert_creds(old_cred);
-
if (ctx->accessed)
ctx->accessed(ctx->user_file);
@@ -187,7 +186,7 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
struct kiocb *iocb, int flags,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
+ const struct cred *old_cred = ctx->cred;
ssize_t ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
@@ -210,39 +209,37 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
*/
flags &= ~IOCB_DIO_CALLER_COMP;
- old_cred = override_creds(ctx->cred);
- if (is_sync_kiocb(iocb)) {
- rwf_t rwf = iocb_to_rw_flags(flags);
+ scoped_guard(cred, old_cred) {
+ if (is_sync_kiocb(iocb)) {
+ rwf_t rwf = iocb_to_rw_flags(flags);
- ret = vfs_iter_write(file, iter, &iocb->ki_pos, rwf);
- if (ctx->end_write)
- ctx->end_write(ctx->user_file);
- } else {
- struct backing_aio *aio;
+ ret = vfs_iter_write(file, iter, &iocb->ki_pos, rwf);
+ if (ctx->end_write)
+ ctx->end_write(ctx->user_file);
+ } else {
+ struct backing_aio *aio;
- ret = backing_aio_init_wq(iocb);
- if (ret)
- goto out;
+ ret = backing_aio_init_wq(iocb);
+ if (ret)
+ return ret;
- ret = -ENOMEM;
- aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
- if (!aio)
- goto out;
+ ret = -ENOMEM;
+ aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
+ if (!aio)
+ return ret;
- aio->orig_iocb = iocb;
- aio->end_write = ctx->end_write;
- kiocb_clone(&aio->iocb, iocb, get_file(file));
- aio->iocb.ki_flags = flags;
- aio->iocb.ki_complete = backing_aio_queue_completion;
- refcount_set(&aio->ref, 2);
- ret = vfs_iocb_iter_write(file, &aio->iocb, iter);
- backing_aio_put(aio);
- if (ret != -EIOCBQUEUED)
- backing_aio_cleanup(aio, ret);
+ aio->orig_iocb = iocb;
+ aio->end_write = ctx->end_write;
+ kiocb_clone(&aio->iocb, iocb, get_file(file));
+ aio->iocb.ki_flags = flags;
+ aio->iocb.ki_complete = backing_aio_queue_completion;
+ refcount_set(&aio->ref, 2);
+ ret = vfs_iocb_iter_write(file, &aio->iocb, iter);
+ backing_aio_put(aio);
+ if (ret != -EIOCBQUEUED)
+ backing_aio_cleanup(aio, ret);
+ }
}
-out:
- revert_creds(old_cred);
-
return ret;
}
EXPORT_SYMBOL_GPL(backing_file_write_iter);
@@ -252,15 +249,15 @@ ssize_t backing_file_splice_read(struct file *in, loff_t *ppos,
unsigned int flags,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
+ const struct cred *old_cred = ctx->cred;
ssize_t ret;
if (WARN_ON_ONCE(!(in->f_mode & FMODE_BACKING)))
return -EIO;
- old_cred = override_creds(ctx->cred);
- ret = vfs_splice_read(in, ppos, pipe, len, flags);
- revert_creds(old_cred);
+ scoped_guard(cred, old_cred) {
+ ret = vfs_splice_read(in, ppos, pipe, len, flags);
+ }
if (ctx->accessed)
ctx->accessed(ctx->user_file);
@@ -274,7 +271,7 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
unsigned int flags,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
+ const struct cred *old_cred = ctx->cred;
ssize_t ret;
if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING)))
@@ -284,12 +281,11 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
if (ret)
return ret;
- old_cred = override_creds(ctx->cred);
- file_start_write(out);
- ret = iter_file_splice_write(pipe, out, ppos, len, flags);
- file_end_write(out);
- revert_creds(old_cred);
-
+ scoped_guard(cred, old_cred) {
+ file_start_write(out);
+ ret = iter_file_splice_write(pipe, out, ppos, len, flags);
+ file_end_write(out);
+ }
if (ctx->end_write)
ctx->end_write(ctx->user_file);
@@ -300,7 +296,7 @@ EXPORT_SYMBOL_GPL(backing_file_splice_write);
int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
+ const struct cred *old_cred = ctx->cred;
int ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) ||
@@ -312,9 +308,9 @@ int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
vma_set_file(vma, file);
- old_cred = override_creds(ctx->cred);
- ret = call_mmap(vma->vm_file, vma);
- revert_creds(old_cred);
+ scoped_guard(cred, old_cred) {
+ ret = call_mmap(vma->vm_file, vma);
+ }
if (ctx->accessed)
ctx->accessed(ctx->user_file);
--
2.43.0
