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Subject[PATCH 06/15] Introduce sysfs_sd_setattr and fix sysfs_chmod

Currently sysfs_chmod calls sys_setattr which in turn calls
inode_change_ok which checks to see if it is ok for the current user
space process to change tha attributes. Since sysfs_chmod_file has
only kernel mode clients denying them permission if user space is the
problem is completely inappropriate.

Therefore factor out sysfs_sd_setattr which does not call
inode_change_ok and modify sysfs_chmod_file to call it.

In addition setting victim_sd->s_mode explicitly in sysfs_chmod_file
is redundant so remove that as well.

Thanks to Tejun Heo <htejun@gmail.com>, and
Daniel Lezcano <dlezcano@fr.ibm.com> for working on this
and spotting this case.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/sysfs/file.c | 5 +----
fs/sysfs/inode.c | 23 ++++++++++++++++-------
fs/sysfs/sysfs.h | 1 +
3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index cb5dd3f..1304b3a 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -600,13 +600,10 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
newattrs.ia_ctime = current_fs_time(inode->i_sb);
- rc = sysfs_setattr(victim, &newattrs);
+ rc = sysfs_sd_setattr(victim_sd, inode, &newattrs);

if (rc == 0) {
fsnotify_change(victim, newattrs.ia_valid);
- mutex_lock(&sysfs_mutex);
- victim_sd->s_mode = newattrs.ia_mode;
- mutex_unlock(&sysfs_mutex);
}

mutex_unlock(&inode->i_mutex);
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index eb53c63..80f8fd4 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -42,10 +42,9 @@ int __init sysfs_inode_init(void)
return bdi_init(&sysfs_backing_dev_info);
}

-int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
+int sysfs_sd_setattr(struct sysfs_dirent *sd, struct inode *inode,
+ struct iattr * iattr)
{
- struct inode * inode = dentry->d_inode;
- struct sysfs_dirent * sd = dentry->d_fsdata;
struct iattr * sd_iattr;
unsigned int ia_valid = iattr->ia_valid;
int error;
@@ -55,10 +54,6 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)

sd_iattr = sd->s_iattr;

- error = inode_change_ok(inode, iattr);
- if (error)
- return error;
-
iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */

error = inode_setattr(inode, iattr);
@@ -104,6 +99,20 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
return error;
}

+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+ struct inode * inode = dentry->d_inode;
+ struct sysfs_dirent * sd = dentry->d_fsdata;
+ int error;
+
+ error = inode_change_ok(inode, iattr);
+ if (error)
+ return error;
+
+ return sysfs_sd_setattr(sd, inode, iattr);
+}
+
+
static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
{
inode->i_mode = mode;
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index b1bdc6e..5ee5d0a 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -154,6 +154,7 @@ static inline void sysfs_put(struct sysfs_dirent *sd)
* inode.c
*/
struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
+int sysfs_sd_setattr(struct sysfs_dirent *sd, struct inode *inode, struct iattr *iattr);
int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
int sysfs_inode_init(void);
--
1.5.3.rc6.17.g1911


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