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MIPS: scall: Save thread_info.syscall unconditionally on entry

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thread_info.syscall is used by syscall_get_nr to supply syscall nr
over a thread stack frame.

Previously, thread_info.syscall is only saved at syscall_trace_enter
when syscall tracing is enabled. However rest of the kernel code do
expect syscall_get_nr to be available without syscall tracing. The
previous design breaks collect_syscall.

Move saving process to syscall entry to fix it.

Reported-by: Xi Ruoyao <xry111@xry111.site>
Link: https://github.com/util-linux/util-linux/issues/2867
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Jiaxun Yang 2024-03-28 14:27:56 +00:00 committed by Thomas Bogendoerfer
parent 4cece76496
commit 4370b673cc
7 changed files with 42 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/mips/include/asm/ptrace.h
View File

@ -159,7 +159,7 @@ extern unsigned long exception_ip(struct pt_regs *regs);
#define exception_ip(regs) exception_ip(regs)
#define profile_pc(regs) instruction_pointer(regs)
extern asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall);
extern asmlinkage long syscall_trace_enter(struct pt_regs *regs);
extern asmlinkage void syscall_trace_leave(struct pt_regs *regs);
extern void die(const char *, struct pt_regs *) __noreturn;

1
arch/mips/kernel/asm-offsets.c
View File

@ -101,6 +101,7 @@ void output_thread_info_defines(void)
OFFSET(TI_CPU, thread_info, cpu);
OFFSET(TI_PRE_COUNT, thread_info, preempt_count);
OFFSET(TI_REGS, thread_info, regs);
OFFSET(TI_SYSCALL, thread_info, syscall);
DEFINE(_THREAD_SIZE, THREAD_SIZE);
DEFINE(_THREAD_MASK, THREAD_MASK);
DEFINE(_IRQ_STACK_SIZE, IRQ_STACK_SIZE);

15
arch/mips/kernel/ptrace.c
View File

@ -1317,16 +1317,13 @@ long arch_ptrace(struct task_struct *child, long request,
* Notification of system call entry/exit
* - triggered by current->work.syscall_trace
*/
asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
asmlinkage long syscall_trace_enter(struct pt_regs *regs)
{
user_exit();
current_thread_info()->syscall = syscall;
if (test_thread_flag(TIF_SYSCALL_TRACE)) {
if (ptrace_report_syscall_entry(regs))
return -1;
syscall = current_thread_info()->syscall;
}
#ifdef CONFIG_SECCOMP
@ -1335,7 +1332,7 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
struct seccomp_data sd;
unsigned long args[6];
sd.nr = syscall;
sd.nr = current_thread_info()->syscall;
sd.arch = syscall_get_arch(current);
syscall_get_arguments(current, regs, args);
for (i = 0; i < 6; i++)
@ -1345,23 +1342,23 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
ret = __secure_computing(&sd);
if (ret == -1)
return ret;
syscall = current_thread_info()->syscall;
}
#endif
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->regs[2]);
audit_syscall_entry(syscall, regs->regs[4], regs->regs[5],
audit_syscall_entry(current_thread_info()->syscall,
regs->regs[4], regs->regs[5],
regs->regs[6], regs->regs[7]);
/*
* Negative syscall numbers are mistaken for rejected syscalls, but
* won't have had the return value set appropriately, so we do so now.
*/
if (syscall < 0)
if (current_thread_info()->syscall < 0)
syscall_set_return_value(current, regs, -ENOSYS, 0);
return syscall;
return current_thread_info()->syscall;
}
/*

23
arch/mips/kernel/scall32-o32.S
View File

@ -77,6 +77,18 @@ loads_done:
PTR_WD load_a7, bad_stack_a7
.previous
/*
* syscall number is in v0 unless we called syscall(__NR_###)
* where the real syscall number is in a0
*/
subu t2, v0, __NR_O32_Linux
bnez t2, 1f /* __NR_syscall at offset 0 */
LONG_S a0, TI_SYSCALL($28) # Save a0 as syscall number
b 2f
1:
LONG_S v0, TI_SYSCALL($28) # Save v0 as syscall number
2:
lw t0, TI_FLAGS($28) # syscall tracing enabled?
li t1, _TIF_WORK_SYSCALL_ENTRY
and t0, t1
@ -114,16 +126,7 @@ syscall_trace_entry:
SAVE_STATIC
move a0, sp
/*
* syscall number is in v0 unless we called syscall(__NR_###)
* where the real syscall number is in a0
*/
move a1, v0
subu t2, v0, __NR_O32_Linux
bnez t2, 1f /* __NR_syscall at offset 0 */
lw a1, PT_R4(sp)
1: jal syscall_trace_enter
jal syscall_trace_enter
bltz v0, 1f # seccomp failed? Skip syscall

3
arch/mips/kernel/scall64-n32.S
View File

@ -44,6 +44,8 @@ NESTED(handle_sysn32, PT_SIZE, sp)
sd a3, PT_R26(sp) # save a3 for syscall restarting
LONG_S v0, TI_SYSCALL($28) # Store syscall number
li t1, _TIF_WORK_SYSCALL_ENTRY
LONG_L t0, TI_FLAGS($28) # syscall tracing enabled?
and t0, t1, t0
@ -72,7 +74,6 @@ syscall_common:
n32_syscall_trace_entry:
SAVE_STATIC
move a0, sp
move a1, v0
jal syscall_trace_enter
bltz v0, 1f # seccomp failed? Skip syscall

3
arch/mips/kernel/scall64-n64.S
View File

@ -46,6 +46,8 @@ NESTED(handle_sys64, PT_SIZE, sp)
sd a3, PT_R26(sp) # save a3 for syscall restarting
LONG_S v0, TI_SYSCALL($28) # Store syscall number
li t1, _TIF_WORK_SYSCALL_ENTRY
LONG_L t0, TI_FLAGS($28) # syscall tracing enabled?
and t0, t1, t0
@ -82,7 +84,6 @@ n64_syscall_exit:
syscall_trace_entry:
SAVE_STATIC
move a0, sp
move a1, v0
jal syscall_trace_enter
bltz v0, 1f # seccomp failed? Skip syscall

33
arch/mips/kernel/scall64-o32.S
View File

@ -79,6 +79,22 @@ loads_done:
PTR_WD load_a7, bad_stack_a7
.previous
/*
* absolute syscall number is in v0 unless we called syscall(__NR_###)
* where the real syscall number is in a0
* note: NR_syscall is the first O32 syscall but the macro is
* only defined when compiling with -mabi=32 (CONFIG_32BIT)
* therefore __NR_O32_Linux is used (4000)
*/
subu t2, v0, __NR_O32_Linux
bnez t2, 1f /* __NR_syscall at offset 0 */
LONG_S a0, TI_SYSCALL($28) # Save a0 as syscall number
b 2f
1:
LONG_S v0, TI_SYSCALL($28) # Save v0 as syscall number
2:
li t1, _TIF_WORK_SYSCALL_ENTRY
LONG_L t0, TI_FLAGS($28) # syscall tracing enabled?
and t0, t1, t0
@ -113,22 +129,7 @@ trace_a_syscall:
sd a7, PT_R11(sp) # For indirect syscalls
move a0, sp
/*
* absolute syscall number is in v0 unless we called syscall(__NR_###)
* where the real syscall number is in a0
* note: NR_syscall is the first O32 syscall but the macro is
* only defined when compiling with -mabi=32 (CONFIG_32BIT)
* therefore __NR_O32_Linux is used (4000)
*/
.set push
.set reorder
subu t1, v0, __NR_O32_Linux
move a1, v0
bnez t1, 1f /* __NR_syscall at offset 0 */
ld a1, PT_R4(sp) /* Arg1 for __NR_syscall case */
.set pop
1: jal syscall_trace_enter
jal syscall_trace_enter
bltz v0, 1f # seccomp failed? Skip syscall