[PATCH 6.1 123/236] MIPS: scall: Save thread_info.syscall unconditionally on entry

Greg Kroah-Hartman
2024-05-14T11:33:13Z

From: Jiaxun Yang <jiaxun.yang@flygoat.com>

[ Upstream commit 4370b673ccf240bf7587b0cb8e6726a5ccaf1f17 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/mips/include/asm/ptrace.h | 2 +-
arch/mips/kernel/asm-offsets.c | 1 +
arch/mips/kernel/ptrace.c | 15 ++++++---------
arch/mips/kernel/scall32-o32.S | 23 +++++++++++++----------
arch/mips/kernel/scall64-n32.S | 3 ++-
arch/mips/kernel/scall64-n64.S | 3 ++-
arch/mips/kernel/scall64-o32.S | 33 +++++++++++++++++----------------
7 files changed, 42 insertions(+), 38 deletions(-)

diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
index b3e4dd6be7e20..428b9f1cf1de2 100644
--- a/arch/mips/include/asm/ptrace.h
+++ b/arch/mips/include/asm/ptrace.h
@@ -157,7 +157,7 @@ static inline long regs_return_value(struct pt_regs *regs)
#define instruction_pointer(regs) ((regs)->cp0_epc)
#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;
diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c
index c4501897b870b..08342b9eccdbd 100644
--- a/arch/mips/kernel/asm-offsets.c
+++ b/arch/mips/kernel/asm-offsets.c
@@ -98,6 +98,7 @@ 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);
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 567aec4abac0f..a8e569830ec8d 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -1309,16 +1309,13 @@ 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
@@ -1327,7 +1324,7 @@ 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++)
@@ -1337,23 +1334,23 @@ 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;
}

/*
diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
index 18dc9b3450561..2c604717e6308 100644
--- a/arch/mips/kernel/scall32-o32.S
+++ b/arch/mips/kernel/scall32-o32.S
@@ -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

diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S
index 97456b2ca7dc3..97788859238c3 100644
--- a/arch/mips/kernel/scall64-n32.S
+++ b/arch/mips/kernel/scall64-n32.S
@@ -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
diff --git a/arch/mips/kernel/scall64-n64.S b/arch/mips/kernel/scall64-n64.S
index e6264aa62e457..be11ea5cc67e0 100644
--- a/arch/mips/kernel/scall64-n64.S
+++ b/arch/mips/kernel/scall64-n64.S
@@ -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
diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
index d3c2616cba226..7a5abb73e5312 100644
--- a/arch/mips/kernel/scall64-o32.S
+++ b/arch/mips/kernel/scall64-o32.S
@@ -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

--
2.43.0