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liveupdate: validate session type before performing operation

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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: 16cec0d265 ("liveupdate: luo_session: add ioctls for file preservation")
Cc: stable@vger.kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Link: https://patch.msgid.link/20260519122428.2378446-1-pratyush@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
This commit is contained in:
Pratyush Yadav (Google) 2026-05-19 14:24:26 +02:00 committed by Mike Rapoport (Microsoft)
parent 051a224c49
commit 507e3b479f
1 changed files with 33 additions and 6 deletions
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39
kernel/liveupdate/luo_session.c
View File

@ -309,34 +309,60 @@ union ucmd_buffer {
struct liveupdate_session_get_name get_name;
};
/* 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),
IOCTL_OP(LIVEUPDATE_SESSION_GET_NAME, luo_session_get_name,
struct liveupdate_session_get_name, name),
struct liveupdate_session_retrieve_fd, token, LUO_IOCTL_ALL),
};
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)
{
@ -361,6 +387,8 @@ 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;
@ -631,4 +659,3 @@ int luo_session_serialize(void)
return err;
}