Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754036AbYADPTp (ORCPT ); Fri, 4 Jan 2008 10:19:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752208AbYADPTh (ORCPT ); Fri, 4 Jan 2008 10:19:37 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:59992 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751825AbYADPTg (ORCPT ); Fri, 4 Jan 2008 10:19:36 -0500 Date: Fri, 4 Jan 2008 15:19:31 +0000 From: Al Viro To: Guillaume Chazarain Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] proc: return -EPERM when preventing read of /proc/*/maps Message-ID: <20080104151931.GC27894@ZenIV.linux.org.uk> References: <20080104135731.2908.90012.stgit@localhost.localdomain> <20080104141443.GB27894@ZenIV.linux.org.uk> <20080104153557.13e24970@inria.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080104153557.13e24970@inria.fr> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5581 Lines: 208 On Fri, Jan 04, 2008 at 03:35:57PM +0100, Guillaume Chazarain wrote: > Al Viro wrote: > > > vma_stop() doesn't need changes either... > > Hmmm, not sure ;-) Umm... Actually, m_next() and m_stop() both appear to be too convoluted. * m_next() never gets v == NULL * the only reason why we do that mmput et.al. both from ->next() and ->stop() is that we try to avoid having priv->mm; why bother? * why the _hell_ is proc_maps_private defined in include/linux/proc_fs.h, of all places? * while we are at it, why is it in any header at all? Having that sucker in task_mmu.c and task_nommu.c would be more than enough (and we'd avoid that ifdef in definition, while we are at it). How about this: diff --git a/fs/proc/base.c b/fs/proc/base.c index 7411bfb..3aebc85 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -219,7 +219,7 @@ out: task_unlock(task); up_read(&mm->mmap_sem); mmput(mm); - return NULL; + return ERR_PTR(-EPERM); } static int proc_pid_cmdline(struct task_struct *task, char * buffer) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 8043a3e..75bef20 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -131,12 +131,19 @@ struct pmd_walker { unsigned long, void *); }; +struct proc_maps_private { + struct pid *pid; + struct task_struct *task; + struct vm_area_struct *tail_vma; + struct mm_struct *mm; +}; + static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats *mss) { struct proc_maps_private *priv = m->private; struct task_struct *task = priv->task; + struct mm_struct *mm = priv->mm; struct vm_area_struct *vma = v; - struct mm_struct *mm = vma->vm_mm; struct file *file = vma->vm_file; int flags = vma->vm_flags; unsigned long ino = 0; @@ -381,6 +388,7 @@ static void *m_start(struct seq_file *m, loff_t *pos) /* Clear the per syscall fields in priv */ priv->task = NULL; + priv->mm = NULL; priv->tail_vma = NULL; /* @@ -398,10 +406,11 @@ static void *m_start(struct seq_file *m, loff_t *pos) return NULL; mm = mm_for_maps(priv->task); - if (!mm) - return NULL; + if (!mm || IS_ERR(mm)) + return ERR_CAST(mm); priv->tail_vma = tail_vma = get_gate_vma(priv->task); + priv->mm = mm; /* Start with last addr hint */ if (last_addr && (vma = find_vma(mm, last_addr))) { @@ -430,20 +439,9 @@ out: /* End of vmas has been reached */ m->version = (tail_vma != NULL)? 0: -1UL; - up_read(&mm->mmap_sem); - mmput(mm); return tail_vma; } -static void vma_stop(struct proc_maps_private *priv, struct vm_area_struct *vma) -{ - if (vma && vma != priv->tail_vma) { - struct mm_struct *mm = vma->vm_mm; - up_read(&mm->mmap_sem); - mmput(mm); - } -} - static void *m_next(struct seq_file *m, void *v, loff_t *pos) { struct proc_maps_private *priv = m->private; @@ -451,18 +449,22 @@ static void *m_next(struct seq_file *m, void *v, loff_t *pos) struct vm_area_struct *tail_vma = priv->tail_vma; (*pos)++; - if (vma && (vma != tail_vma) && vma->vm_next) + if (vma == tail_vma) + return NULL; + else if (vma->vm_next) return vma->vm_next; - vma_stop(priv, vma); - return (vma != tail_vma)? tail_vma: NULL; + else + return tail_vma; } static void m_stop(struct seq_file *m, void *v) { struct proc_maps_private *priv = m->private; - struct vm_area_struct *vma = v; - vma_stop(priv, vma); + if (priv->mm) { + up_read(&priv->mm->mmap_sem); + mmput(priv->mm); + } if (priv->task) put_task_struct(priv->task); } diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c index 1932c2c..a156b62 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -138,6 +138,12 @@ out: return result; } +struct proc_maps_private { + struct pid *pid; + struct task_struct *task; + struct mm_struct *mm; +}; + /* * display mapping lines for a particular process's /proc/pid/maps */ @@ -161,16 +167,16 @@ static void *m_start(struct seq_file *m, loff_t *pos) loff_t n = *pos; /* pin the task and mm whilst we play with them */ + priv->mm = NULL; priv->task = get_pid_task(priv->pid, PIDTYPE_PID); if (!priv->task) return NULL; mm = mm_for_maps(priv->task); - if (!mm) { - put_task_struct(priv->task); - priv->task = NULL; - return NULL; - } + if (!mm || IS_ERR(mm)) + return ERR_CAST(mm); + + priv->mm = mm; /* start from the Nth VMA */ for (vml = mm->context.vmlist; vml; vml = vml->next) @@ -183,12 +189,12 @@ static void m_stop(struct seq_file *m, void *_vml) { struct proc_maps_private *priv = m->private; - if (priv->task) { - struct mm_struct *mm = priv->task->mm; - up_read(&mm->mmap_sem); - mmput(mm); - put_task_struct(priv->task); + if (priv->mm) { + up_read(&priv->mm->mmap_sem); + mmput(priv->mm); } + if (priv->task) + put_task_struct(priv->task); } static void *m_next(struct seq_file *m, void *_vml, loff_t *pos) diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index a531682..192a5c4 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -286,12 +286,4 @@ static inline struct net *PDE_NET(struct proc_dir_entry *pde) struct net *get_proc_net(const struct inode *inode); -struct proc_maps_private { - struct pid *pid; - struct task_struct *task; -#ifdef CONFIG_MMU - struct vm_area_struct *tail_vma; -#endif -}; - #endif /* _LINUX_PROC_FS_H */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/