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Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c109
1 files changed, 72 insertions, 37 deletions
diff --git a/fs/namei.c b/fs/namei.c
index c6dcb4c8f86c..2ccc35c4dc24 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -315,31 +315,22 @@ static inline int do_inode_permission(struct inode *inode, int mask)
}
/**
- * inode_permission - check for access rights to a given inode
- * @inode: inode to check permission on
- * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
+ * __inode_permission - Check for access rights to a given inode
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
- * Used to check for read/write/execute permissions on an inode.
- * We use "fsuid" for this, letting us set arbitrary permissions
- * for filesystem access without changing the "normal" uids which
- * are used for other things.
+ * Check for read/write/execute permissions on an inode.
*
* When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
+ *
+ * This does not check for a read-only file system. You probably want
+ * inode_permission().
*/
-int inode_permission(struct inode *inode, int mask)
+int __inode_permission(struct inode *inode, int mask)
{
int retval;
if (unlikely(mask & MAY_WRITE)) {
- umode_t mode = inode->i_mode;
-
- /*
- * Nobody gets write access to a read-only fs.
- */
- if (IS_RDONLY(inode) &&
- (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
- return -EROFS;
-
/*
* Nobody gets write access to an immutable file.
*/
@@ -359,6 +350,47 @@ int inode_permission(struct inode *inode, int mask)
}
/**
+ * sb_permission - Check superblock-level permissions
+ * @sb: Superblock of inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Separate out file-system wide checks from inode-specific permission checks.
+ */
+static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
+{
+ if (unlikely(mask & MAY_WRITE)) {
+ umode_t mode = inode->i_mode;
+
+ /* Nobody gets write access to a read-only fs. */
+ if ((sb->s_flags & MS_RDONLY) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ return -EROFS;
+ }
+ return 0;
+}
+
+/**
+ * inode_permission - Check for access rights to a given inode
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Check for read/write/execute permissions on an inode. We use fs[ug]id for
+ * this, letting us set arbitrary permissions for filesystem access without
+ * changing the "normal" UIDs which are used for other things.
+ *
+ * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
+ */
+int inode_permission(struct inode *inode, int mask)
+{
+ int retval;
+
+ retval = sb_permission(inode->i_sb, inode, mask);
+ if (retval)
+ return retval;
+ return __inode_permission(inode, mask);
+}
+
+/**
* path_get - get a reference to a path
* @path: path to get the reference to
*
@@ -395,6 +427,18 @@ EXPORT_SYMBOL(path_put);
* to restart the path walk from the beginning in ref-walk mode.
*/
+static inline void lock_rcu_walk(void)
+{
+ br_read_lock(&vfsmount_lock);
+ rcu_read_lock();
+}
+
+static inline void unlock_rcu_walk(void)
+{
+ rcu_read_unlock();
+ br_read_unlock(&vfsmount_lock);
+}
+
/**
* unlazy_walk - try to switch to ref-walk mode.
* @nd: nameidata pathwalk data
@@ -448,8 +492,7 @@ static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
}
mntget(nd->path.mnt);
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
nd->flags &= ~LOOKUP_RCU;
return 0;
@@ -490,15 +533,13 @@ static int complete_walk(struct nameidata *nd)
spin_lock(&dentry->d_lock);
if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
spin_unlock(&dentry->d_lock);
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
return -ECHILD;
}
BUG_ON(nd->inode != dentry->d_inode);
spin_unlock(&dentry->d_lock);
mntget(nd->path.mnt);
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
}
if (likely(!(nd->flags & LOOKUP_JUMPED)))
@@ -690,7 +731,7 @@ int follow_up(struct path *path)
br_read_lock(&vfsmount_lock);
parent = mnt->mnt_parent;
- if (&parent->mnt == path->mnt) {
+ if (parent == mnt) {
br_read_unlock(&vfsmount_lock);
return 0;
}
@@ -953,8 +994,7 @@ failed:
nd->flags &= ~LOOKUP_RCU;
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
return -ECHILD;
}
@@ -1291,8 +1331,7 @@ static void terminate_walk(struct nameidata *nd)
nd->flags &= ~LOOKUP_RCU;
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
}
}
@@ -1659,8 +1698,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
nd->path = nd->root;
nd->inode = inode;
if (flags & LOOKUP_RCU) {
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
} else {
path_get(&nd->path);
@@ -1672,8 +1710,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
if (*name=='/') {
if (flags & LOOKUP_RCU) {
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
set_root_rcu(nd);
} else {
set_root(nd);
@@ -1685,8 +1722,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
struct fs_struct *fs = current->fs;
unsigned seq;
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
do {
seq = read_seqcount_begin(&fs->seq);
@@ -1721,8 +1757,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
if (fput_needed)
*fp = file;
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
} else {
path_get(&file->f_path);
fput_light(file, fput_needed);
@@ -1843,7 +1878,7 @@ struct dentry *kern_path_locked(const char *name, struct path *path)
return ERR_PTR(-EINVAL);
}
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
- d = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
+ d = __lookup_hash(&nd.last, nd.path.dentry, 0);
if (IS_ERR(d)) {
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
path_put(&nd.path);
generated by cgit v1.2.3 (git 2.39.0) at 2025-01-01 22:14:53 +0300