linux-kernel - [PATCH 2/3] seccomp: change return type of seccomp_get

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Message-Id: <20180928154648.6320-2-tycho@tycho.ws>
Date:   Fri, 28 Sep 2018 09:46:47 -0600
From:   Tycho Andersen <tycho@...ho.ws>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Jann Horn <jannh@...gle.com>,
        Tycho Andersen <tycho@...ho.ws>,
        Andy Lutomirski <luto@...capital.net>
Subject: [PATCH 2/3] seccomp: change return type of seccomp_get_filter to int

As Jann pointed out in another thread, ptrace_requiest() returns an int, so
it makes sense for seccomp_get_filter() to return an int as well. The
return type of seccomp_get_filter() is bounded by the BPF_MAXINSNS check in
seccomp_prepare_filter(), so this conversion is safe.

Signed-off-by: Tycho Andersen <tycho@...ho.ws>
Reported-by: Jann Horn <jannh@...gle.com>
CC: Kees Cook <keescook@...omium.org>
CC: Andy Lutomirski <luto@...capital.net>
---
 include/linux/seccomp.h | 6 +++---
 kernel/seccomp.c        | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index af972549a7b4..8429bdda947a 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -94,13 +94,13 @@ static inline void get_seccomp_filter(struct task_struct *tsk)
 #endif /* CONFIG_SECCOMP_FILTER */
 
 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
-extern long seccomp_get_filter(struct task_struct *task,
+extern int seccomp_get_filter(struct task_struct *task,
 			       unsigned long filter_off, void __user *data);
 extern int seccomp_get_metadata(struct task_struct *task,
 				unsigned long filter_off, void __user *data);
 #else
-static inline long seccomp_get_filter(struct task_struct *task,
-				      unsigned long n, void __user *data)
+static inline int seccomp_get_filter(struct task_struct *task,
+				     unsigned long n, void __user *data)
 {
 	return -EINVAL;
 }
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 9f3721849747..ef80dd19f268 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -1030,12 +1030,12 @@ static struct seccomp_filter *get_nth_filter(struct task_struct *task,
 	return filter;
 }
 
-long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
-			void __user *data)
+int seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
+		       void __user *data)
 {
 	struct seccomp_filter *filter;
 	struct sock_fprog_kern *fprog;
-	long ret;
+	int ret;
 
 	if (!capable(CAP_SYS_ADMIN) ||
 	    current->seccomp.mode != SECCOMP_MODE_DISABLED) {
-- 
2.17.1