diff options
Diffstat (limited to 'arch/x86/kernel/ptrace.c')
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 48 |
1 files changed, 32 insertions, 16 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 3c5bbe8e4120..f0e1ddbc2fd7 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -42,6 +42,7 @@ #include <asm/traps.h> #include <asm/syscall.h> #include <asm/fsgsbase.h> +#include <asm/io_bitmap.h> #include "tls.h" @@ -181,6 +182,9 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset) static int set_segment_reg(struct task_struct *task, unsigned long offset, u16 value) { + if (WARN_ON_ONCE(task == current)) + return -EIO; + /* * The value argument was already truncated to 16 bits. */ @@ -208,10 +212,7 @@ static int set_segment_reg(struct task_struct *task, break; case offsetof(struct user_regs_struct, gs): - if (task == current) - set_user_gs(task_pt_regs(task), value); - else - task_user_gs(task) = value; + task_user_gs(task) = value; } return 0; @@ -271,32 +272,41 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset) static int set_segment_reg(struct task_struct *task, unsigned long offset, u16 value) { + if (WARN_ON_ONCE(task == current)) + return -EIO; + /* * The value argument was already truncated to 16 bits. */ if (invalid_selector(value)) return -EIO; + /* + * This function has some ABI oddities. + * + * A 32-bit ptracer probably expects that writing FS or GS will change + * FSBASE or GSBASE respectively. In the absence of FSGSBASE support, + * this code indeed has that effect. When FSGSBASE is added, this + * will require a special case. + * + * For existing 64-bit ptracers, writing FS or GS *also* currently + * changes the base if the selector is nonzero the next time the task + * is run. This behavior may not be needed, and trying to preserve it + * when FSGSBASE is added would be complicated at best. + */ + switch (offset) { case offsetof(struct user_regs_struct,fs): task->thread.fsindex = value; - if (task == current) - loadsegment(fs, task->thread.fsindex); break; case offsetof(struct user_regs_struct,gs): task->thread.gsindex = value; - if (task == current) - load_gs_index(task->thread.gsindex); break; case offsetof(struct user_regs_struct,ds): task->thread.ds = value; - if (task == current) - loadsegment(ds, task->thread.ds); break; case offsetof(struct user_regs_struct,es): task->thread.es = value; - if (task == current) - loadsegment(es, task->thread.es); break; /* @@ -374,6 +384,9 @@ static int putreg(struct task_struct *child, * When changing the FS base, use do_arch_prctl_64() * to set the index to zero and to set the base * as requested. + * + * NB: This behavior is nonsensical and likely needs to + * change when FSGSBASE support is added. */ if (child->thread.fsbase != value) return do_arch_prctl_64(child, ARCH_SET_FS, value); @@ -697,7 +710,9 @@ static int ptrace_set_debugreg(struct task_struct *tsk, int n, static int ioperm_active(struct task_struct *target, const struct user_regset *regset) { - return target->thread.io_bitmap_max / regset->size; + struct io_bitmap *iobm = target->thread.io_bitmap; + + return iobm ? DIV_ROUND_UP(iobm->max, regset->size) : 0; } static int ioperm_get(struct task_struct *target, @@ -705,12 +720,13 @@ static int ioperm_get(struct task_struct *target, unsigned int pos, unsigned int count, void *kbuf, void __user *ubuf) { - if (!target->thread.io_bitmap_ptr) + struct io_bitmap *iobm = target->thread.io_bitmap; + + if (!iobm) return -ENXIO; return user_regset_copyout(&pos, &count, &kbuf, &ubuf, - target->thread.io_bitmap_ptr, - 0, IO_BITMAP_BYTES); + iobm->bitmap, 0, IO_BITMAP_BYTES); } /* |