From 57eccb830f1cc93d4b506ba306d8dfa685e0c88f Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 22 Feb 2013 22:49:10 -0500 Subject: mount: consolidate permission checks ... and ask for global CAP_SYS_ADMIN only for superblock-level remounts Signed-off-by: Al Viro --- fs/namespace.c | 40 +++++++--------------------------------- 1 file changed, 7 insertions(+), 33 deletions(-) (limited to 'fs/namespace.c') diff --git a/fs/namespace.c b/fs/namespace.c index edac42c6eff..269919fa116 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1300,24 +1300,6 @@ SYSCALL_DEFINE1(oldumount, char __user *, name) #endif -static int mount_is_safe(struct path *path) -{ - if (may_mount()) - return 0; - return -EPERM; -#ifdef notyet - if (S_ISLNK(path->dentry->d_inode->i_mode)) - return -EPERM; - if (path->dentry->d_inode->i_mode & S_ISVTX) { - if (current_uid() != path->dentry->d_inode->i_uid) - return -EPERM; - } - if (inode_permission(path->dentry->d_inode, MAY_WRITE)) - return -EPERM; - return 0; -#endif -} - static bool mnt_ns_loop(struct path *path) { /* Could bind mounting the mount namespace inode cause a @@ -1640,9 +1622,6 @@ static int do_change_type(struct path *path, int flag) int type; int err = 0; - if (!may_mount()) - return -EPERM; - if (path->dentry != path->mnt->mnt_root) return -EINVAL; @@ -1676,9 +1655,7 @@ static int do_loopback(struct path *path, const char *old_name, LIST_HEAD(umount_list); struct path old_path; struct mount *mnt = NULL, *old; - int err = mount_is_safe(path); - if (err) - return err; + int err; if (!old_name || !*old_name) return -EINVAL; err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); @@ -1755,9 +1732,6 @@ static int do_remount(struct path *path, int flags, int mnt_flags, struct super_block *sb = path->mnt->mnt_sb; struct mount *mnt = real_mount(path->mnt); - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - if (!check_mnt(mnt)) return -EINVAL; @@ -1771,6 +1745,8 @@ static int do_remount(struct path *path, int flags, int mnt_flags, down_write(&sb->s_umount); if (flags & MS_BIND) err = change_mount_flags(path->mnt, flags); + else if (!capable(CAP_SYS_ADMIN)) + err = -EPERM; else err = do_remount_sb(sb, flags, data, 0); if (!err) { @@ -1803,9 +1779,7 @@ static int do_move_mount(struct path *path, const char *old_name) struct path old_path, parent_path; struct mount *p; struct mount *old; - int err = 0; - if (!may_mount()) - return -EPERM; + int err; if (!old_name || !*old_name) return -EINVAL; err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); @@ -1947,9 +1921,6 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, if (!fstype) return -EINVAL; - if (!may_mount()) - return -EPERM; - type = get_fs_type(fstype); if (!type) return -ENODEV; @@ -2263,6 +2234,9 @@ long do_mount(const char *dev_name, const char *dir_name, if (retval) goto dput_out; + if (!may_mount()) + return -EPERM; + /* Default to relatime unless overriden */ if (!(flags & MS_NOATIME)) mnt_flags |= MNT_RELATIME; -- cgit v1.2.3 From 496ad9aa8ef448058e36ca7a787c61f2e63f0f54 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 23 Jan 2013 17:07:38 -0500 Subject: new helper: file_inode(file) Signed-off-by: Al Viro --- fs/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/namespace.c') diff --git a/fs/namespace.c b/fs/namespace.c index 269919fa116..50ca17d3cb4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -384,7 +384,7 @@ EXPORT_SYMBOL_GPL(mnt_clone_write); */ int __mnt_want_write_file(struct file *file) { - struct inode *inode = file->f_dentry->d_inode; + struct inode *inode = file_inode(file); if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) return __mnt_want_write(file->f_path.mnt); -- cgit v1.2.3