From: "Pratyush Yadav (Google)" <[email protected]>
The sessions ioctls are not applicable to all session types. PRESERVE_FD
is only applicable to outgoing sessions. RETRIEVE_FD and FINISH are only
valid for incoming session. Calling a incoming ioctl on an outgoing
session is invalid and can cause file handlers to run into unexpected
errors.
For example, a user can create a (outgoing) session, preserve a memfd,
and then immediately do a retrieve without doing a kexec in between.
This would result in memfd's retrieve handler to run. The handlers
expects to be called from a post-kexec context, and will try to do a
kho_restore_vmalloc() or kho_restore_folio() to try and restore memory.
KHO catches this (thanks to KHO_PAGE_MAGIC) and returns an error, but
since this is considered an internal error and KHO throws out a bunch of
WARN()s.
Associate a type with each ioctl op and validate the type in
luo_session_ioctl() before dispatching the ioctl handler to make sure
the op is being called for the right session type.
Fixes: 16cec0d26521 ("liveupdate: luo_session: add ioctls for file
preservation")
Cc: [email protected]
Signed-off-by: Pratyush Yadav (Google) <[email protected]>
---
Notes:
I added LUO_IOCTL_ALL but there is no user in this patch. The type is
for LIVEUPDATE_SESSION_GET_NAME which is supported for both session
types. The support for GET_NAME is in next and this patch should go
through fixes.
Alternatively, we can remove LUO_IOCTL_ALL from this patch and add it to
the LIVEUPDATE_SESSION_GET_NAME patch in next. But that would need us to
rebase to an rc that contains this fix.
kernel/liveupdate/luo_session.c | 36 +++++++++++++++++++++++++++++----
1 file changed, 32 insertions(+), 4 deletions(-)
diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c
index a3327a28fc1f..e84218e3cacb 100644
--- a/kernel/liveupdate/luo_session.c
+++ b/kernel/liveupdate/luo_session.c
@@ -295,32 +295,58 @@ union ucmd_buffer {
struct liveupdate_session_retrieve_fd retrieve;
};
+/* Type of sessions the ioctl applies to. */
+enum luo_ioctl_type {
+ LUO_IOCTL_INCOMING,
+ LUO_IOCTL_OUTGOING,
+ LUO_IOCTL_ALL,
+};
+
struct luo_ioctl_op {
unsigned int size;
unsigned int min_size;
unsigned int ioctl_num;
+ enum luo_ioctl_type type;
int (*execute)(struct luo_session *session, struct luo_ucmd *ucmd);
};
-#define IOCTL_OP(_ioctl, _fn, _struct, _last)
\
+#define IOCTL_OP(_ioctl, _fn, _struct, _last, _type)
\
[_IOC_NR(_ioctl) - LIVEUPDATE_CMD_SESSION_BASE] = { \
.size = sizeof(_struct) + \
BUILD_BUG_ON_ZERO(sizeof(union ucmd_buffer) < \
sizeof(_struct)), \
.min_size = offsetofend(_struct, _last), \
.ioctl_num = _ioctl, \
+ .type = _type, \
.execute = _fn, \
}
static const struct luo_ioctl_op luo_session_ioctl_ops[] = {
IOCTL_OP(LIVEUPDATE_SESSION_FINISH, luo_session_finish,
- struct liveupdate_session_finish, reserved),
+ struct liveupdate_session_finish, reserved,
LUO_IOCTL_INCOMING),
IOCTL_OP(LIVEUPDATE_SESSION_PRESERVE_FD, luo_session_preserve_fd,
- struct liveupdate_session_preserve_fd, token),
+ struct liveupdate_session_preserve_fd, token,
LUO_IOCTL_OUTGOING),
IOCTL_OP(LIVEUPDATE_SESSION_RETRIEVE_FD, luo_session_retrieve_fd,
- struct liveupdate_session_retrieve_fd, token),
+ struct liveupdate_session_retrieve_fd, token,
LUO_IOCTL_INCOMING),
};
+static bool luo_ioctl_type_valid(struct luo_session *session,
+ const struct luo_ioctl_op *op)
+{
+ switch (op->type) {
+ case LUO_IOCTL_INCOMING:
+ /* Retrieved is only set on incoming sessions */
+ return session->retrieved;
+ case LUO_IOCTL_OUTGOING:
+ return !session->retrieved;
+ case LUO_IOCTL_ALL:
+ return true;
+ }
+
+ /* Catch-all. */
+ return false;
+}
+
static long luo_session_ioctl(struct file *filep, unsigned int cmd,
unsigned long arg)
{
@@ -345,6 +371,8 @@ static long luo_session_ioctl(struct file *filep, unsigned
int cmd,
op = &luo_session_ioctl_ops[nr - LIVEUPDATE_CMD_SESSION_BASE];
if (op->ioctl_num != cmd)
return -ENOIOCTLCMD;
+ if (!luo_ioctl_type_valid(session, op))
+ return -EINVAL;
if (ucmd.user_size < op->min_size)
return -EINVAL;
base-commit: b1378127003b61930ce30064328640503ad3ef6d
--
2.54.0.563.g4f69b47b94-goog
