[RFC] sysfs: bin_attr permission checking

Commit Message

Chris Wright May 12, 2010, 6:47 p.m. UTC

None

Patch

--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -23,6 +23,7 @@ 
 #include <linux/mm.h>
 #include <linux/capability.h>
 #include <linux/pci-aspm.h>
+#include <linux/fs.h>
 #include "pci.h"
 
 static int sysfs_initialized;	/* = 0 */
@@ -356,16 +357,18 @@  boot_vga_show(struct device *dev, struct
 struct device_attribute vga_attr = __ATTR_RO(boot_vga);
 
 static ssize_t
-pci_read_config(struct kobject *kobj, struct bin_attribute *bin_attr,
-		char *buf, loff_t off, size_t count)
+pci_read_config(struct file *file, struct kobject *kobj,
+		struct bin_attribute *bin_attr, char *buf, loff_t off,
+		size_t count)
 {
 	struct pci_dev *dev = to_pci_dev(container_of(kobj,struct device,kobj));
+	struct inode *inode = file->f_path.dentry->d_inode;
 	unsigned int size = 64;
 	loff_t init_off = off;
 	u8 *data = (u8*) buf;
 
 	/* Several chips lock up trying to read undefined config space */
-	if (capable(CAP_SYS_ADMIN)) {
+	if (capable(CAP_SYS_ADMIN) || is_owner_or_cap(inode)) {
 		size = dev->cfg_size;
 	} else if (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) {
 		size = 128;
@@ -924,7 +927,7 @@  static struct bin_attribute pci_config_a
 		.mode = S_IRUGO | S_IWUSR,
 	},
 	.size = PCI_CFG_SPACE_SIZE,
-	.read = pci_read_config,
+	.read_file = pci_read_config,
 	.write = pci_write_config,
 };
 
@@ -934,7 +937,7 @@  static struct bin_attribute pcie_config_
 		.mode = S_IRUGO | S_IWUSR,
 	},
 	.size = PCI_CFG_SPACE_EXP_SIZE,
-	.read = pci_read_config,
+	.read_file = pci_read_config,
 	.write = pci_write_config,
 };
 
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -46,9 +46,9 @@  struct bin_buffer {
 };
 
 static int
-fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
+fill_read(struct file *file, char *buffer, loff_t off, size_t count)
 {
-	struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
 	int rc;
@@ -58,7 +58,9 @@  fill_read(struct dentry *dentry, char *b
 		return -ENODEV;
 
 	rc = -EIO;
-	if (attr->read)
+	if (attr->read_file)
+		rc = attr->read_file(file, kobj, attr, buffer, off, count);
+	else if (attr->read)
 		rc = attr->read(kobj, attr, buffer, off, count);
 
 	sysfs_put_active_two(attr_sd);
@@ -70,8 +72,7 @@  static ssize_t
 read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
 {
 	struct bin_buffer *bb = file->private_data;
-	struct dentry *dentry = file->f_path.dentry;
-	int size = dentry->d_inode->i_size;
+	int size = file->f_path.dentry->d_inode->i_size;
 	loff_t offs = *off;
 	int count = min_t(size_t, bytes, PAGE_SIZE);
 	char *temp;
@@ -92,7 +93,7 @@  read(struct file *file, char __user *use
 
 	mutex_lock(&bb->mutex);
 
-	count = fill_read(dentry, bb->buffer, offs, count);
+	count = fill_read(file, bb->buffer, offs, count);
 	if (count < 0) {
 		mutex_unlock(&bb->mutex);
 		goto out_free;
@@ -405,7 +406,8 @@  static int open(struct inode * inode, st
 	error = -EACCES;
 	if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 		goto err_out;
-	if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
+	if ((file->f_mode & FMODE_READ) &&
+	    !(attr->read || attr->read_file || attr->mmap))
 		goto err_out;
 
 	error = -ENOMEM;
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -66,6 +66,8 @@  struct bin_attribute {
 	struct attribute	attr;
 	size_t			size;
 	void			*private;
+	ssize_t (*read_file)(struct file *,struct kobject *, struct bin_attribute *,
+			char *, loff_t, size_t);
 	ssize_t (*read)(struct kobject *, struct bin_attribute *,
 			char *, loff_t, size_t);
 	ssize_t (*write)(struct kobject *, struct bin_attribute *,