[PATCH v16 01/18] seccomp: Convert __secure_computing() to return boolean
Jinjie Ruan
ruanjinjie at huawei.com
Mon Jun 29 06:05:59 PDT 2026
The return value of __secure_computing() currently uses 0 to indicate
that a system call should be allowed, and -1 to indicate that it should
be blocked/killed. This 0/-1 pattern is non-intuitive for a security
check function and makes the control flow at the call sites less readable.
Furthermore, any potential future changes to these return values would
require a high-risk, error-prone audit of all its users across different
architectures.
Sanitize this logic by converting the return type of __secure_computing()
to a proper boolean, where 'true' explicitly means 'allow' and 'false'
means 'fail/deny'.
Update all the two dozen or so call sites across the tree to align with
this new boolean semantic. No functional changes are intended, as the
callers still return -1 to the lower-level assembly entry code upon
seccomp denial.
Suggested-by: Thomas Gleixner <tglx at kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
arch/alpha/kernel/ptrace.c | 2 +-
arch/arm/kernel/ptrace.c | 2 +-
arch/arm64/kernel/ptrace.c | 2 +-
arch/csky/kernel/ptrace.c | 2 +-
arch/m68k/kernel/ptrace.c | 2 +-
arch/mips/kernel/ptrace.c | 2 +-
arch/parisc/kernel/ptrace.c | 2 +-
arch/sh/kernel/ptrace_32.c | 2 +-
arch/um/kernel/skas/syscall.c | 2 +-
arch/x86/entry/vsyscall/vsyscall_64.c | 2 +-
arch/xtensa/kernel/ptrace.c | 3 +--
include/linux/entry-common.h | 7 +++---
include/linux/seccomp.h | 10 ++++----
kernel/seccomp.c | 34 +++++++++++++--------------
14 files changed, 36 insertions(+), 38 deletions(-)
diff --git a/arch/alpha/kernel/ptrace.c b/arch/alpha/kernel/ptrace.c
index 0687760ea466..27d9847b1082 100644
--- a/arch/alpha/kernel/ptrace.c
+++ b/arch/alpha/kernel/ptrace.c
@@ -387,7 +387,7 @@ asmlinkage unsigned long syscall_trace_enter(void)
* If this fails, seccomp may already have set up the return value
* (e.g. SECCOMP_RET_ERRNO / TRACE).
*/
- if (secure_computing() == -1) {
+ if (!secure_computing()) {
if (regs->r19 == 0 && regs->r0 == (unsigned long)-1)
syscall_set_return_value(current, regs, -ENOSYS, 0);
syscall_set_nr(current, regs, -1);
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 7951b2c06fec..5210745725ca 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -855,7 +855,7 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs)
/* Do seccomp after ptrace; syscall may have changed. */
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
- if (secure_computing() == -1)
+ if (!secure_computing())
return -1;
#else
/* XXX: remove this once OABI gets fixed */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 4d08598e2891..2ca6fab39a37 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2420,7 +2420,7 @@ int syscall_trace_enter(struct pt_regs *regs)
}
/* Do the secure computing after ptrace; failures should be fast. */
- if (secure_computing() == -1)
+ if (!secure_computing())
return NO_SYSCALL;
if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c
index 6bb685a2646b..11c5eff41e9d 100644
--- a/arch/csky/kernel/ptrace.c
+++ b/arch/csky/kernel/ptrace.c
@@ -323,7 +323,7 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs)
if (ptrace_report_syscall_entry(regs))
return -1;
- if (secure_computing() == -1)
+ if (!secure_computing())
return -1;
if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
diff --git a/arch/m68k/kernel/ptrace.c b/arch/m68k/kernel/ptrace.c
index cfa2df24eced..d2411404b9df 100644
--- a/arch/m68k/kernel/ptrace.c
+++ b/arch/m68k/kernel/ptrace.c
@@ -281,7 +281,7 @@ asmlinkage int syscall_trace_enter(void)
if (test_thread_flag(TIF_SYSCALL_TRACE))
ret = ptrace_report_syscall_entry(task_pt_regs(current));
- if (secure_computing() == -1)
+ if (!secure_computing())
return -1;
return ret;
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 3f4c94c88124..0d809cda7542 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -1328,7 +1328,7 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs)
return -1;
}
- if (secure_computing())
+ if (!secure_computing())
return -1;
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index 8a17ab7e6e0b..565b51a48c8a 100644
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -351,7 +351,7 @@ long do_syscall_trace_enter(struct pt_regs *regs)
}
/* Do the secure computing check after ptrace. */
- if (secure_computing() == -1)
+ if (!secure_computing())
return -1;
#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 06f765d71a29..8687f17cbe5a 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -460,7 +460,7 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
return -1;
}
- if (secure_computing() == -1)
+ if (!secure_computing())
return -1;
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index ba7494f9bfe4..916cd7acceaf 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -27,7 +27,7 @@ void handle_syscall(struct uml_pt_regs *r)
goto out;
/* Do the seccomp check after ptrace; failures should be fast. */
- if (secure_computing() == -1)
+ if (!secure_computing())
goto out;
syscall = UPT_SYSCALL_NR(r);
diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index ea36de9fa864..6aed3987b9f9 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c
@@ -198,7 +198,7 @@ static bool __emulate_vsyscall(struct pt_regs *regs, unsigned long address)
regs->orig_ax = syscall_nr;
regs->ax = -ENOSYS;
tmp = secure_computing();
- if ((!tmp && regs->orig_ax != syscall_nr) || regs->ip != address) {
+ if ((tmp && regs->orig_ax != syscall_nr) || regs->ip != address) {
warn_bad_vsyscall(KERN_DEBUG, regs,
"seccomp tried to change syscall nr or ip");
force_exit_sig(SIGSYS);
diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index b80d54b2ea34..ef78fcd318ff 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -553,8 +553,7 @@ int do_syscall_trace_enter(struct pt_regs *regs)
return 0;
}
- if (regs->syscall == NO_SYSCALL ||
- secure_computing() == -1) {
+ if (regs->syscall == NO_SYSCALL || !secure_computing()) {
do_syscall_trace_leave(regs);
return 0;
}
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 416a3352261f..3f66320e46d3 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -100,9 +100,8 @@ static __always_inline long syscall_trace_enter(struct pt_regs *regs, unsigned l
/* Do seccomp after ptrace, to catch any tracer changes. */
if (work & SYSCALL_WORK_SECCOMP) {
- ret = __secure_computing();
- if (ret == -1L)
- return ret;
+ if (!__secure_computing())
+ return -1L;
}
/* Either of the above might have changed the syscall number */
@@ -113,7 +112,7 @@ static __always_inline long syscall_trace_enter(struct pt_regs *regs, unsigned l
syscall_enter_audit(regs, syscall);
- return ret ? : syscall;
+ return syscall;
}
/**
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index 9b959972bf4a..7af3173f40e9 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -22,14 +22,14 @@
#include <linux/atomic.h>
#include <asm/seccomp.h>
-extern int __secure_computing(void);
+extern bool __secure_computing(void);
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
-static inline int secure_computing(void)
+static inline bool secure_computing(void)
{
if (unlikely(test_syscall_work(SECCOMP)))
return __secure_computing();
- return 0;
+ return true;
}
#else
extern void secure_computing_strict(int this_syscall);
@@ -50,11 +50,11 @@ static inline int seccomp_mode(struct seccomp *s)
struct seccomp_data;
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
-static inline int secure_computing(void) { return 0; }
+static inline bool secure_computing(void) { return true; }
#else
static inline void secure_computing_strict(int this_syscall) { return; }
#endif
-static inline int __secure_computing(void) { return 0; }
+static inline bool __secure_computing(void) { return true; }
static inline long prctl_get_seccomp(void)
{
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 066909393c38..1fec6efedab6 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -1100,12 +1100,12 @@ void secure_computing_strict(int this_syscall)
else
BUG();
}
-int __secure_computing(void)
+bool __secure_computing(void)
{
int this_syscall = syscall_get_nr(current, current_pt_regs());
secure_computing_strict(this_syscall);
- return 0;
+ return true;
}
#else
@@ -1256,7 +1256,7 @@ static int seccomp_do_user_notification(int this_syscall,
return -1;
}
-static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
+static bool __seccomp_filter(int this_syscall, const bool recheck_after_trace)
{
u32 filter_ret, action;
struct seccomp_data sd;
@@ -1294,7 +1294,7 @@ static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
case SECCOMP_RET_TRACE:
/* We've been put in this state by the ptracer already. */
if (recheck_after_trace)
- return 0;
+ return true;
/* ENOSYS these calls if there is no tracer attached. */
if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
@@ -1330,19 +1330,19 @@ static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
* a skip would have already been reported.
*/
if (__seccomp_filter(this_syscall, true))
- return -1;
+ return false;
- return 0;
+ return true;
case SECCOMP_RET_USER_NOTIF:
if (seccomp_do_user_notification(this_syscall, match, &sd))
goto skip;
- return 0;
+ return true;
case SECCOMP_RET_LOG:
seccomp_log(this_syscall, 0, action, true);
- return 0;
+ return true;
case SECCOMP_RET_ALLOW:
/*
@@ -1350,7 +1350,7 @@ static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
* this action since SECCOMP_RET_ALLOW is the starting
* state in seccomp_run_filters().
*/
- return 0;
+ return true;
case SECCOMP_RET_KILL_THREAD:
case SECCOMP_RET_KILL_PROCESS:
@@ -1367,46 +1367,46 @@ static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
} else {
do_exit(SIGSYS);
}
- return -1; /* skip the syscall go directly to signal handling */
+ return false; /* skip the syscall go directly to signal handling */
}
unreachable();
skip:
seccomp_log(this_syscall, 0, action, match ? match->log : false);
- return -1;
+ return false;
}
#else
-static int __seccomp_filter(int this_syscall, const bool recheck_after_trace)
+static bool __seccomp_filter(int this_syscall, const bool recheck_after_trace)
{
BUG();
- return -1;
+ return false;
}
#endif
-int __secure_computing(void)
+bool __secure_computing(void)
{
int mode = current->seccomp.mode;
int this_syscall;
if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
- return 0;
+ return true;
this_syscall = syscall_get_nr(current, current_pt_regs());
switch (mode) {
case SECCOMP_MODE_STRICT:
__secure_computing_strict(this_syscall); /* may call do_exit */
- return 0;
+ return true;
case SECCOMP_MODE_FILTER:
return __seccomp_filter(this_syscall, false);
/* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
case SECCOMP_MODE_DEAD:
WARN_ON_ONCE(1);
do_exit(SIGKILL);
- return -1;
+ return false;
default:
BUG();
}
--
2.34.1
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