proc 1/2: do PDE usecounting even for ->read_proc, ->write_proc
struct proc_dir_entry::owner is going to be removed. Now it's only necessary to protect PDEs which are using ->read_proc, ->write_proc hooks. However, ->owner assignments are racy and make it very easy for someone to switch ->owner on live PDE (as some subsystems do) without fixing refcounts and so on. http://bugzilla.kernel.org/show_bug.cgi?id=12454 So, ->owner is on death row. Proxy file operations exist already (proc_file_operations), just bump usecount when necessary. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
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@ -37,7 +37,7 @@ static int proc_match(int len, const char *name, struct proc_dir_entry *de)
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#define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
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static ssize_t
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proc_file_read(struct file *file, char __user *buf, size_t nbytes,
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__proc_file_read(struct file *file, char __user *buf, size_t nbytes,
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loff_t *ppos)
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{
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struct inode * inode = file->f_path.dentry->d_inode;
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@ -182,20 +182,48 @@ proc_file_read(struct file *file, char __user *buf, size_t nbytes,
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return retval;
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}
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static ssize_t
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proc_file_read(struct file *file, char __user *buf, size_t nbytes,
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loff_t *ppos)
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{
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struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
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ssize_t rv = -EIO;
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spin_lock(&pde->pde_unload_lock);
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if (!pde->proc_fops) {
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spin_unlock(&pde->pde_unload_lock);
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return rv;
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}
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pde->pde_users++;
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spin_unlock(&pde->pde_unload_lock);
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rv = __proc_file_read(file, buf, nbytes, ppos);
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pde_users_dec(pde);
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return rv;
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}
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static ssize_t
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proc_file_write(struct file *file, const char __user *buffer,
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size_t count, loff_t *ppos)
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{
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struct inode *inode = file->f_path.dentry->d_inode;
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struct proc_dir_entry * dp;
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dp = PDE(inode);
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struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
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ssize_t rv = -EIO;
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if (!dp->write_proc)
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return -EIO;
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if (pde->write_proc) {
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spin_lock(&pde->pde_unload_lock);
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if (!pde->proc_fops) {
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spin_unlock(&pde->pde_unload_lock);
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return rv;
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}
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pde->pde_users++;
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spin_unlock(&pde->pde_unload_lock);
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/* FIXME: does this routine need ppos? probably... */
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return dp->write_proc(file, buffer, count, dp->data);
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/* FIXME: does this routine need ppos? probably... */
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rv = pde->write_proc(file, buffer, count, pde->data);
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pde_users_dec(pde);
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}
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return rv;
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}
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@ -127,7 +127,7 @@ static void __pde_users_dec(struct proc_dir_entry *pde)
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complete(pde->pde_unload_completion);
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}
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static void pde_users_dec(struct proc_dir_entry *pde)
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void pde_users_dec(struct proc_dir_entry *pde)
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{
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spin_lock(&pde->pde_unload_lock);
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__pde_users_dec(pde);
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@ -91,3 +91,4 @@ struct pde_opener {
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int (*release)(struct inode *, struct file *);
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struct list_head lh;
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};
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void pde_users_dec(struct proc_dir_entry *pde);
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