diff options
Diffstat (limited to 'arch/riscv/kernel/entry.S')
| -rw-r--r-- | arch/riscv/kernel/entry.S | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 89aecba63f49..a1349ca64669 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -228,8 +228,25 @@ check_syscall_nr: /* Check to make sure we don't jump to a bogus syscall number. */ li t0, __NR_syscalls la s0, sys_ni_syscall - /* Syscall number held in a7 */ - bgeu a7, t0, 1f + /* + * The tracer can change syscall number to valid/invalid value. + * We use syscall_set_nr helper in syscall_trace_enter thus we + * cannot trust the current value in a7 and have to reload from + * the current task pt_regs. + */ + REG_L a7, PT_A7(sp) + /* + * Syscall number held in a7. + * If syscall number is above allowed value, redirect to ni_syscall. + */ + bge a7, t0, 1f + /* + * Check if syscall is rejected by tracer or seccomp, i.e., a7 == -1. + * If yes, we pretend it was executed. + */ + li t1, -1 + beq a7, t1, ret_from_syscall_rejected + /* Call syscall */ la s0, sys_call_table slli t0, a7, RISCV_LGPTR add s0, s0, t0 @@ -240,6 +257,12 @@ check_syscall_nr: ret_from_syscall: /* Set user a0 to kernel a0 */ REG_S a0, PT_A0(sp) + /* + * We didn't execute the actual syscall. + * Seccomp already set return value for the current task pt_regs. + * (If it was configured with SECCOMP_RET_ERRNO/TRACE) + */ +ret_from_syscall_rejected: /* Trace syscalls, but only if requested by the user. */ REG_L t0, TASK_TI_FLAGS(tp) andi t0, t0, _TIF_SYSCALL_WORK |