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-rw-r--r--arch/Kconfig14
-rw-r--r--include/asm-generic/siginfo.h2
-rw-r--r--include/linux/seccomp.h1
-rw-r--r--kernel/seccomp.c26
4 files changed, 37 insertions, 6 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index beaab68c13b7..66aef13f6038 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -219,11 +219,15 @@ config ARCH_WANT_OLD_COMPAT_IPC
config HAVE_ARCH_SECCOMP_FILTER
bool
help
- This symbol should be selected by an architecure if it provides
- asm/syscall.h, specifically syscall_get_arguments(),
- syscall_get_arch(), and syscall_set_return_value(). Additionally,
- its system call entry path must respect a return value of -1 from
- __secure_computing() and/or secure_computing().
+ This symbol should be selected by an architecure if it provides:
+ asm/syscall.h:
+ - syscall_get_arch()
+ - syscall_get_arguments()
+ - syscall_rollback()
+ - syscall_set_return_value()
+ SIGSYS siginfo_t support must be implemented.
+ __secure_computing()/secure_computing()'s return value must be
+ checked, with -1 resulting in the syscall being skipped.
config SECCOMP_FILTER
def_bool y
diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h
index 31306f55eb02..af5d0350f84c 100644
--- a/include/asm-generic/siginfo.h
+++ b/include/asm-generic/siginfo.h
@@ -93,7 +93,7 @@ typedef struct siginfo {
/* SIGSYS */
struct {
- void __user *_call_addr; /* calling insn */
+ void __user *_call_addr; /* calling user insn */
int _syscall; /* triggering system call number */
unsigned int _arch; /* AUDIT_ARCH_* of syscall */
} _sigsys;
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index b4ce2c816e06..317ccb78cf40 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -19,6 +19,7 @@
* selects the least permissive choice.
*/
#define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */
+#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 5f78fb6d2212..9c3830692a08 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -332,6 +332,26 @@ void put_seccomp_filter(struct task_struct *tsk)
kfree(freeme);
}
}
+
+/**
+ * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
+ * @syscall: syscall number to send to userland
+ * @reason: filter-supplied reason code to send to userland (via si_errno)
+ *
+ * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
+ */
+static void seccomp_send_sigsys(int syscall, int reason)
+{
+ struct siginfo info;
+ memset(&info, 0, sizeof(info));
+ info.si_signo = SIGSYS;
+ info.si_code = SYS_SECCOMP;
+ info.si_call_addr = (void __user *)KSTK_EIP(current);
+ info.si_errno = reason;
+ info.si_arch = syscall_get_arch(current, task_pt_regs(current));
+ info.si_syscall = syscall;
+ force_sig_info(SIGSYS, &info, current);
+}
#endif /* CONFIG_SECCOMP_FILTER */
/*
@@ -382,6 +402,12 @@ int __secure_computing(int this_syscall)
syscall_set_return_value(current, task_pt_regs(current),
-data, 0);
goto skip;
+ case SECCOMP_RET_TRAP:
+ /* Show the handler the original registers. */
+ syscall_rollback(current, task_pt_regs(current));
+ /* Let the filter pass back 16 bits of data. */
+ seccomp_send_sigsys(this_syscall, data);
+ goto skip;
case SECCOMP_RET_ALLOW:
return 0;
case SECCOMP_RET_KILL: