88 lines
3.1 KiB
Diff
88 lines
3.1 KiB
Diff
From bbbc88e65bb8036be1fe3386c0061d9be4c5a442 Mon Sep 17 00:00:00 2001
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From: Jiri Olsa <jolsa@kernel.org>
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Date: Wed, 12 Feb 2025 23:04:33 +0100
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Subject: uprobes/x86: Harden uretprobe syscall trampoline check
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Jann reported a possible issue when trampoline_check_ip returns
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address near the bottom of the address space that is allowed to
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call into the syscall if uretprobes are not set up:
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https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf
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Though the mmap minimum address restrictions will typically prevent
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creating mappings there, let's make sure uretprobe syscall checks
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for that.
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Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe")
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Reported-by: Jann Horn <jannh@google.com>
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Signed-off-by: Jiri Olsa <jolsa@kernel.org>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Reviewed-by: Oleg Nesterov <oleg@redhat.com>
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Reviewed-by: Kees Cook <kees@kernel.org>
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Acked-by: Andrii Nakryiko <andrii@kernel.org>
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Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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Acked-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: stable@vger.kernel.org
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Link: https://lore.kernel.org/r/20250212220433.3624297-1-jolsa@kernel.org
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---
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arch/x86/kernel/uprobes.c | 14 +++++++++-----
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include/linux/uprobes.h | 2 ++
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kernel/events/uprobes.c | 2 +-
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3 files changed, 12 insertions(+), 6 deletions(-)
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--- a/arch/x86/kernel/uprobes.c
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+++ b/arch/x86/kernel/uprobes.c
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@@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned lo
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return &insn;
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}
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-static unsigned long trampoline_check_ip(void)
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+static unsigned long trampoline_check_ip(unsigned long tramp)
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{
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- unsigned long tramp = uprobe_get_trampoline_vaddr();
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-
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return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry);
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}
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SYSCALL_DEFINE0(uretprobe)
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{
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struct pt_regs *regs = task_pt_regs(current);
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- unsigned long err, ip, sp, r11_cx_ax[3];
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+ unsigned long err, ip, sp, r11_cx_ax[3], tramp;
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+
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+ /* If there's no trampoline, we are called from wrong place. */
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+ tramp = uprobe_get_trampoline_vaddr();
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+ if (unlikely(tramp == UPROBE_NO_TRAMPOLINE_VADDR))
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+ goto sigill;
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- if (regs->ip != trampoline_check_ip())
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+ /* Make sure the ip matches the only allowed sys_uretprobe caller. */
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+ if (unlikely(regs->ip != trampoline_check_ip(tramp)))
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goto sigill;
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err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax));
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--- a/include/linux/uprobes.h
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+++ b/include/linux/uprobes.h
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@@ -39,6 +39,8 @@ struct page;
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#define MAX_URETPROBE_DEPTH 64
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+#define UPROBE_NO_TRAMPOLINE_VADDR (~0UL)
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+
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struct uprobe_consumer {
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/*
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* handler() can return UPROBE_HANDLER_REMOVE to signal the need to
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--- a/kernel/events/uprobes.c
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+++ b/kernel/events/uprobes.c
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@@ -2169,8 +2169,8 @@ void uprobe_copy_process(struct task_str
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*/
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unsigned long uprobe_get_trampoline_vaddr(void)
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{
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+ unsigned long trampoline_vaddr = UPROBE_NO_TRAMPOLINE_VADDR;
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struct xol_area *area;
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- unsigned long trampoline_vaddr = -1;
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/* Pairs with xol_add_vma() smp_store_release() */
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area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */
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