2022-12-12 14:21:51

by Richard Guy Briggs

Subject: [PATCH v5 1/3] fanotify: Ensure consistent variable type for response

The user space API for the response variable is __u32. This patch makes
sure that the whole path through the kernel uses u32 so that there is
no sign extension or truncation of the user space response.

Suggested-by: Steve Grubb <[email protected]>
Link: https://lore.kernel.org/r/12617626.uLZWGnKmhe@x2
Signed-off-by: Richard Guy Briggs <[email protected]>
---
fs/notify/fanotify/fanotify.h | 2 +-
fs/notify/fanotify/fanotify_user.c | 6 +++---
include/linux/audit.h | 6 +++---
kernel/auditsc.c | 2 +-
4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 57f51a9a3015..f899d610bc08 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -425,7 +425,7 @@ FANOTIFY_PE(struct fanotify_event *event)
struct fanotify_perm_event {
struct fanotify_event fae;
struct path path;
- unsigned short response; /* userspace answer to the event */
+ u32 response; /* userspace answer to the event */
unsigned short state; /* state of the event */
int fd; /* fd we passed to userspace for this event */
};
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 4546da4a54f9..caa1211bac8c 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -289,7 +289,7 @@ static int create_fd(struct fsnotify_group *group, const struct path *path,
*/
static void finish_permission_event(struct fsnotify_group *group,
struct fanotify_perm_event *event,
- unsigned int response)
+ u32 response)
__releases(&group->notification_lock)
{
bool destroy = false;
@@ -310,9 +310,9 @@ static int process_access_response(struct fsnotify_group *group,
{
struct fanotify_perm_event *event;
int fd = response_struct->fd;
- int response = response_struct->response;
+ u32 response = response_struct->response;

- pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
+ pr_debug("%s: group=%p fd=%d response=%u\n", __func__, group,
fd, response);
/*
* make sure the response is valid, if invalid we do nothing and either
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 3608992848d3..d6b7d0c7ce43 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -416,7 +416,7 @@ extern void __audit_log_capset(const struct cred *new, const struct cred *old);
extern void __audit_mmap_fd(int fd, int flags);
extern void __audit_openat2_how(struct open_how *how);
extern void __audit_log_kern_module(char *name);
-extern void __audit_fanotify(unsigned int response);
+extern void __audit_fanotify(u32 response);
extern void __audit_tk_injoffset(struct timespec64 offset);
extern void __audit_ntp_log(const struct audit_ntp_data *ad);
extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
@@ -523,7 +523,7 @@ static inline void audit_log_kern_module(char *name)
__audit_log_kern_module(name);
}

-static inline void audit_fanotify(unsigned int response)
+static inline void audit_fanotify(u32 response)
{
if (!audit_dummy_context())
__audit_fanotify(response);
@@ -679,7 +679,7 @@ static inline void audit_log_kern_module(char *name)
{
}

-static inline void audit_fanotify(unsigned int response)
+static inline void audit_fanotify(u32 response)
{ }

static inline void audit_tk_injoffset(struct timespec64 offset)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 547c88be8a28..d1fb821de104 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2877,7 +2877,7 @@ void __audit_log_kern_module(char *name)
context->type = AUDIT_KERN_MODULE;
}

-void __audit_fanotify(unsigned int response)
+void __audit_fanotify(u32 response)
{
audit_log(audit_context(), GFP_KERNEL,
AUDIT_FANOTIFY, "resp=%u", response);
--
2.27.0

2022-12-21 00:03:42

by Paul Moore

Subject: Re: [PATCH v5 1/3] fanotify: Ensure consistent variable type for response

On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <[email protected]> wrote:
>
> The user space API for the response variable is __u32. This patch makes
> sure that the whole path through the kernel uses u32 so that there is
> no sign extension or truncation of the user space response.
>
> Suggested-by: Steve Grubb <[email protected]>
> Link: https://lore.kernel.org/r/12617626.uLZWGnKmhe@x2
> Signed-off-by: Richard Guy Briggs <[email protected]>
> ---
> fs/notify/fanotify/fanotify.h | 2 +-
> fs/notify/fanotify/fanotify_user.c | 6 +++---
> include/linux/audit.h | 6 +++---
> kernel/auditsc.c | 2 +-
> 4 files changed, 8 insertions(+), 8 deletions(-)

Acked-by: Paul Moore <[email protected]> (audit)

--
paul-moore.com