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-rw-r--r--fs/inode.c124
1 files changed, 106 insertions, 18 deletions
diff --git a/fs/inode.c b/fs/inode.c
index c474c1d7062..c99163b1b31 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1487,10 +1487,30 @@ static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
return 0;
}
+/*
+ * This does the actual work of updating an inodes time or version. Must have
+ * had called mnt_want_write() before calling this.
+ */
+static int update_time(struct inode *inode, struct timespec *time, int flags)
+{
+ if (inode->i_op->update_time)
+ return inode->i_op->update_time(inode, time, flags);
+
+ if (flags & S_ATIME)
+ inode->i_atime = *time;
+ if (flags & S_VERSION)
+ inode_inc_iversion(inode);
+ if (flags & S_CTIME)
+ inode->i_ctime = *time;
+ if (flags & S_MTIME)
+ inode->i_mtime = *time;
+ mark_inode_dirty_sync(inode);
+ return 0;
+}
+
/**
* touch_atime - update the access time
- * @mnt: mount the inode is accessed on
- * @dentry: dentry accessed
+ * @path: the &struct path to update
*
* Update the accessed time on an inode and mark it for writeback.
* This function automatically handles read only file systems and media,
@@ -1525,12 +1545,83 @@ void touch_atime(struct path *path)
if (mnt_want_write(mnt))
return;
- inode->i_atime = now;
- mark_inode_dirty_sync(inode);
+ /*
+ * File systems can error out when updating inodes if they need to
+ * allocate new space to modify an inode (such is the case for
+ * Btrfs), but since we touch atime while walking down the path we
+ * really don't care if we failed to update the atime of the file,
+ * so just ignore the return value.
+ */
+ update_time(inode, &now, S_ATIME);
mnt_drop_write(mnt);
}
EXPORT_SYMBOL(touch_atime);
+/*
+ * The logic we want is
+ *
+ * if suid or (sgid and xgrp)
+ * remove privs
+ */
+int should_remove_suid(struct dentry *dentry)
+{
+ umode_t mode = dentry->d_inode->i_mode;
+ int kill = 0;
+
+ /* suid always must be killed */
+ if (unlikely(mode & S_ISUID))
+ kill = ATTR_KILL_SUID;
+
+ /*
+ * sgid without any exec bits is just a mandatory locking mark; leave
+ * it alone. If some exec bits are set, it's a real sgid; kill it.
+ */
+ if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
+ kill |= ATTR_KILL_SGID;
+
+ if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
+ return kill;
+
+ return 0;
+}
+EXPORT_SYMBOL(should_remove_suid);
+
+static int __remove_suid(struct dentry *dentry, int kill)
+{
+ struct iattr newattrs;
+
+ newattrs.ia_valid = ATTR_FORCE | kill;
+ return notify_change(dentry, &newattrs);
+}
+
+int file_remove_suid(struct file *file)
+{
+ struct dentry *dentry = file->f_path.dentry;
+ struct inode *inode = dentry->d_inode;
+ int killsuid;
+ int killpriv;
+ int error = 0;
+
+ /* Fast path for nothing security related */
+ if (IS_NOSEC(inode))
+ return 0;
+
+ killsuid = should_remove_suid(dentry);
+ killpriv = security_inode_need_killpriv(dentry);
+
+ if (killpriv < 0)
+ return killpriv;
+ if (killpriv)
+ error = security_inode_killpriv(dentry);
+ if (!error && killsuid)
+ error = __remove_suid(dentry, killsuid);
+ if (!error && (inode->i_sb->s_flags & MS_NOSEC))
+ inode->i_flags |= S_NOSEC;
+
+ return error;
+}
+EXPORT_SYMBOL(file_remove_suid);
+
/**
* file_update_time - update mtime and ctime time
* @file: file accessed
@@ -1540,18 +1631,20 @@ EXPORT_SYMBOL(touch_atime);
* usage in the file write path of filesystems, and filesystems may
* choose to explicitly ignore update via this function with the
* S_NOCMTIME inode flag, e.g. for network filesystem where these
- * timestamps are handled by the server.
+ * timestamps are handled by the server. This can return an error for
+ * file systems who need to allocate space in order to update an inode.
*/
-void file_update_time(struct file *file)
+int file_update_time(struct file *file)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct timespec now;
- enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
+ int sync_it = 0;
+ int ret;
/* First try to exhaust all avenues to not sync */
if (IS_NOCMTIME(inode))
- return;
+ return 0;
now = current_fs_time(inode->i_sb);
if (!timespec_equal(&inode->i_mtime, &now))
@@ -1564,21 +1657,16 @@ void file_update_time(struct file *file)
sync_it |= S_VERSION;
if (!sync_it)
- return;
+ return 0;
/* Finally allowed to write? Takes lock. */
if (mnt_want_write_file(file))
- return;
+ return 0;
- /* Only change inode inside the lock region */
- if (sync_it & S_VERSION)
- inode_inc_iversion(inode);
- if (sync_it & S_CTIME)
- inode->i_ctime = now;
- if (sync_it & S_MTIME)
- inode->i_mtime = now;
- mark_inode_dirty_sync(inode);
+ ret = update_time(inode, &now, sync_it);
mnt_drop_write_file(file);
+
+ return ret;
}
EXPORT_SYMBOL(file_update_time);