The terminator for the mode 1 syscalls list was a 0, but that could be
a valid syscall number (e.g. x86_64 __NR_read). By luck, __NR_read was
listed first and the loop construct would not test it, so there was no
bug. However, this is fragile. Replace the terminator with -1 instead,
and make the variable name for mode 1 syscall lists more descriptive.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
I'll be putting this into my for-next/seccomp tree. I would love a MIPS
ack, if someone's got a moment to double-check this. :)
---
arch/mips/include/asm/seccomp.h | 4 ++--
include/asm-generic/seccomp.h | 2 +-
kernel/seccomp.c | 10 +++++-----
3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/mips/include/asm/seccomp.h b/arch/mips/include/asm/seccomp.h
index e383d7e27b93..aa809589a181 100644
--- a/arch/mips/include/asm/seccomp.h
+++ b/arch/mips/include/asm/seccomp.h
@@ -9,12 +9,12 @@ static inline const int *get_compat_mode1_syscalls(void)
static const int syscalls_O32[] = {
__NR_O32_Linux + 3, __NR_O32_Linux + 4,
__NR_O32_Linux + 1, __NR_O32_Linux + 193,
- 0, /* null terminated */
+ -1, /* negative terminated */
};
static const int syscalls_N32[] = {
__NR_N32_Linux + 0, __NR_N32_Linux + 1,
__NR_N32_Linux + 58, __NR_N32_Linux + 211,
- 0, /* null terminated */
+ -1, /* negative terminated */
};
if (IS_ENABLED(CONFIG_MIPS32_O32) && test_thread_flag(TIF_32BIT_REGS))
diff --git a/include/asm-generic/seccomp.h b/include/asm-generic/seccomp.h
index 1321ac7821d7..6b6f42bc58f9 100644
--- a/include/asm-generic/seccomp.h
+++ b/include/asm-generic/seccomp.h
@@ -33,7 +33,7 @@ static inline const int *get_compat_mode1_syscalls(void)
static const int mode1_syscalls_32[] = {
__NR_seccomp_read_32, __NR_seccomp_write_32,
__NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
- 0, /* null terminated */
+ -1, /* negative terminated */
};
return mode1_syscalls_32;
}
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 0ed57e8c49d0..866a432cd746 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -742,20 +742,20 @@ static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
*/
static const int mode1_syscalls[] = {
__NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
- 0, /* null terminated */
+ -1, /* negative terminated */
};
static void __secure_computing_strict(int this_syscall)
{
- const int *syscall_whitelist = mode1_syscalls;
+ const int *allowed_syscalls = mode1_syscalls;
#ifdef CONFIG_COMPAT
if (in_compat_syscall())
- syscall_whitelist = get_compat_mode1_syscalls();
+ allowed_syscalls = get_compat_mode1_syscalls();
#endif
do {
- if (*syscall_whitelist == this_syscall)
+ if (*allowed_syscalls == this_syscall)
return;
- } while (*++syscall_whitelist);
+ } while (*++allowed_syscalls != -1);
#ifdef SECCOMP_DEBUG
dump_stack();
--
2.25.1
--
Kees Cook
