diff options
| -rw-r--r-- | arch/Kconfig | 6 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/unwind.h | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/stacktrace.c | 96 | ||||
| -rw-r--r-- | arch/x86/kernel/unwind_frame.c | 2 | ||||
| -rw-r--r-- | include/linux/stacktrace.h | 9 | ||||
| -rw-r--r-- | kernel/stacktrace.c | 12 |
7 files changed, 126 insertions, 6 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index cd211a14a88f..6ad00ad73459 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -713,6 +713,12 @@ config HAVE_STACK_VALIDATION Architecture supports the 'objtool check' host tool command, which performs compile-time stack metadata validation. +config HAVE_RELIABLE_STACKTRACE + bool + help + Architecture has a save_stack_trace_tsk_reliable() function which + only returns a stack trace if it can guarantee the trace is reliable. + config HAVE_ARCH_HASH bool default n diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index cc98d5a294ee..2a26852c11b6 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -160,6 +160,7 @@ config X86 select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_REGS_AND_STACK_ACCESS_API + select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER && STACK_VALIDATION select HAVE_STACK_VALIDATION if X86_64 select HAVE_SYSCALL_TRACEPOINTS select HAVE_UNSTABLE_SCHED_CLOCK diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h index 6fa75b17aec3..137e9cce2ab4 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -11,6 +11,7 @@ struct unwind_state { unsigned long stack_mask; struct task_struct *task; int graph_idx; + bool error; #ifdef CONFIG_FRAME_POINTER unsigned long *bp, *orig_sp; struct pt_regs *regs; @@ -40,6 +41,11 @@ void unwind_start(struct unwind_state *state, struct task_struct *task, __unwind_start(state, task, regs, first_frame); } +static inline bool unwind_error(struct unwind_state *state) +{ + return state->error; +} + #ifdef CONFIG_FRAME_POINTER static inline diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 8e2b79b88e51..8dabd7bf1673 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -76,6 +76,101 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) } EXPORT_SYMBOL_GPL(save_stack_trace_tsk); +#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE + +#define STACKTRACE_DUMP_ONCE(task) ({ \ + static bool __section(.data.unlikely) __dumped; \ + \ + if (!__dumped) { \ + __dumped = true; \ + WARN_ON(1); \ + show_stack(task, NULL); \ + } \ +}) + +static int __save_stack_trace_reliable(struct stack_trace *trace, + struct task_struct *task) +{ + struct unwind_state state; + struct pt_regs *regs; + unsigned long addr; + + for (unwind_start(&state, task, NULL, NULL); !unwind_done(&state); + unwind_next_frame(&state)) { + + regs = unwind_get_entry_regs(&state); + if (regs) { + /* + * Kernel mode registers on the stack indicate an + * in-kernel interrupt or exception (e.g., preemption + * or a page fault), which can make frame pointers + * unreliable. + */ + if (!user_mode(regs)) + return -EINVAL; + + /* + * The last frame contains the user mode syscall + * pt_regs. Skip it and finish the unwind. + */ + unwind_next_frame(&state); + if (!unwind_done(&state)) { + STACKTRACE_DUMP_ONCE(task); + return -EINVAL; + } + break; + } + + addr = unwind_get_return_address(&state); + + /* + * A NULL or invalid return address probably means there's some + * generated code which __kernel_text_address() doesn't know + * about. + */ + if (!addr) { + STACKTRACE_DUMP_ONCE(task); + return -EINVAL; + } + + if (save_stack_address(trace, addr, false)) + return -EINVAL; + } + + /* Check for stack corruption */ + if (unwind_error(&state)) { + STACKTRACE_DUMP_ONCE(task); + return -EINVAL; + } + + if (trace->nr_entries < trace->max_entries) + trace->entries[trace->nr_entries++] = ULONG_MAX; + + return 0; +} + +/* + * This function returns an error if it detects any unreliable features of the + * stack. Otherwise it guarantees that the stack trace is reliable. + * + * If the task is not 'current', the caller *must* ensure the task is inactive. + */ +int save_stack_trace_tsk_reliable(struct task_struct *tsk, + struct stack_trace *trace) +{ + int ret; + + if (!try_get_task_stack(tsk)) + return -EINVAL; + + ret = __save_stack_trace_reliable(trace, tsk); + + put_task_stack(tsk); + + return ret; +} +#endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */ + /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */ struct stack_frame_user { @@ -138,4 +233,3 @@ void save_stack_trace_user(struct stack_trace *trace) if (trace->nr_entries < trace->max_entries) trace->entries[trace->nr_entries++] = ULONG_MAX; } - diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index 478d15dbaee4..5ed43910e04b 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -225,6 +225,8 @@ bool unwind_next_frame(struct unwind_state *state) return true; bad_address: + state->error = true; + /* * When unwinding a non-current task, the task might actually be * running on another CPU, in which case it could be modifying its diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h index 0a34489a46b6..4205f71a5f0e 100644 --- a/include/linux/stacktrace.h +++ b/include/linux/stacktrace.h @@ -18,6 +18,8 @@ extern void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace); extern void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace); +extern int save_stack_trace_tsk_reliable(struct task_struct *tsk, + struct stack_trace *trace); extern void print_stack_trace(struct stack_trace *trace, int spaces); extern int snprint_stack_trace(char *buf, size_t size, @@ -29,12 +31,13 @@ extern void save_stack_trace_user(struct stack_trace *trace); # define save_stack_trace_user(trace) do { } while (0) #endif -#else +#else /* !CONFIG_STACKTRACE */ # define save_stack_trace(trace) do { } while (0) # define save_stack_trace_tsk(tsk, trace) do { } while (0) # define save_stack_trace_user(trace) do { } while (0) # define print_stack_trace(trace, spaces) do { } while (0) # define snprint_stack_trace(buf, size, trace, spaces) do { } while (0) -#endif +# define save_stack_trace_tsk_reliable(tsk, trace) ({ -ENOSYS; }) +#endif /* CONFIG_STACKTRACE */ -#endif +#endif /* __LINUX_STACKTRACE_H */ diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c index 9c15a9124e83..f8edee9c792d 100644 --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -54,8 +54,8 @@ int snprint_stack_trace(char *buf, size_t size, EXPORT_SYMBOL_GPL(snprint_stack_trace); /* - * Architectures that do not implement save_stack_trace_tsk or - * save_stack_trace_regs get this weak alias and a once-per-bootup warning + * Architectures that do not implement save_stack_trace_*() + * get these weak aliases and once-per-bootup warnings * (whenever this facility is utilized - for example by procfs): */ __weak void @@ -69,3 +69,11 @@ save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) { WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n"); } + +__weak int +save_stack_trace_tsk_reliable(struct task_struct *tsk, + struct stack_trace *trace) +{ + WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n"); + return -ENOSYS; +} |