[PATCH RFC v3 07/26] crypto: ccp: use scoped_with_init_fs() for SEV file access

Christian Brauner
2026-03-11T21:56:29Z

Replace the manual init_task root retrieval with scoped_with_init_fs()
to temporarily override current->fs. This allows using the simpler
filp_open() instead of the init_root() + file_open_root() pattern.

open_file_as_root() ← sev_read_init_ex_file() / sev_write_init_ex_file()
← sev_platform_init() ← __sev_guest_init() ← KVM ioctl — user process context

Needs init's root because the SEV init_ex file path should resolve
against the real root, not a KVM user's chroot.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
drivers/crypto/ccp/sev-dev.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 096f993974d1..4320054da0f6 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -260,20 +260,16 @@ static int sev_cmd_buffer_len(int cmd)

static struct file *open_file_as_root(const char *filename, int flags, umode_t mode)
{
- struct path root __free(path_put) = {};
-
- task_lock(&init_task);
- get_fs_root(init_task.fs, &root);
- task_unlock(&init_task);
-
CLASS(prepare_creds, cred)();
if (!cred)
return ERR_PTR(-ENOMEM);

cred->fsuid = GLOBAL_ROOT_UID;

- scoped_with_creds(cred)
- return file_open_root(&root, filename, flags, mode);
+ scoped_with_init_fs() {
+ scoped_with_creds(cred)
+ return filp_open(filename, flags, mode);
+ }
}

static int sev_read_init_ex_file(void)

--
2.47.3