diff options
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 81 |
1 files changed, 68 insertions, 13 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 22cbfab..7c3c0f6 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -23,7 +23,6 @@ #include <linux/uaccess.h> #include <linux/proc_ns.h> #include <linux/magic.h> -#include <linux/delay.h> #include "pnode.h" #include "internal.h" @@ -316,11 +315,8 @@ int __mnt_want_write(struct vfsmount *m) * incremented count after it has set MNT_WRITE_HOLD. */ smp_mb(); - while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) { - preempt_enable(); - cpu_chill(); - preempt_disable(); - } + while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) + cpu_relax(); /* * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will * be set to match its requirements. So we must not load that until @@ -831,8 +827,21 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD; /* Don't allow unprivileged users to change mount flags */ - if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY)) - mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + if (flag & CL_UNPRIVILEGED) { + mnt->mnt.mnt_flags |= MNT_LOCK_ATIME; + + if (mnt->mnt.mnt_flags & MNT_READONLY) + mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + + if (mnt->mnt.mnt_flags & MNT_NODEV) + mnt->mnt.mnt_flags |= MNT_LOCK_NODEV; + + if (mnt->mnt.mnt_flags & MNT_NOSUID) + mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID; + + if (mnt->mnt.mnt_flags & MNT_NOEXEC) + mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC; + } /* Don't allow unprivileged users to reveal what is under a mount */ if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire)) @@ -1268,6 +1277,8 @@ static int do_umount(struct mount *mnt, int flags) * Special case for "unmounting" root ... * we just try to remount it readonly. */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; down_write(&sb->s_umount); if (!(sb->s_flags & MS_RDONLY)) retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); @@ -1336,6 +1347,9 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags) goto dput_and_out; if (mnt->mnt.mnt_flags & MNT_LOCKED) goto dput_and_out; + retval = -EPERM; + if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) + goto dput_and_out; retval = do_umount(mnt, flags); dput_and_out: @@ -1810,9 +1824,6 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags) if (readonly_request == __mnt_is_readonly(mnt)) return 0; - if (mnt->mnt_flags & MNT_LOCK_READONLY) - return -EPERM; - if (readonly_request) error = mnt_make_readonly(real_mount(mnt)); else @@ -1838,6 +1849,39 @@ static int do_remount(struct path *path, int flags, int mnt_flags, if (path->dentry != path->mnt->mnt_root) return -EINVAL; + /* Don't allow changing of locked mnt flags. + * + * No locks need to be held here while testing the various + * MNT_LOCK flags because those flags can never be cleared + * once they are set. + */ + if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && + !(mnt_flags & MNT_READONLY)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && + !(mnt_flags & MNT_NODEV)) { + /* Was the nodev implicitly added in mount? */ + if ((mnt->mnt_ns->user_ns != &init_user_ns) && + !(sb->s_type->fs_flags & FS_USERNS_DEV_MOUNT)) { + mnt_flags |= MNT_NODEV; + } else { + return -EPERM; + } + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) && + !(mnt_flags & MNT_NOSUID)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) && + !(mnt_flags & MNT_NOEXEC)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && + ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) { + return -EPERM; + } + err = security_sb_remount(sb, data); if (err) return err; @@ -1851,7 +1895,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags, err = do_remount_sb(sb, flags, data, 0); if (!err) { br_write_lock(&vfsmount_lock); - mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK; + mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; mnt->mnt.mnt_flags = mnt_flags; br_write_unlock(&vfsmount_lock); } @@ -2040,7 +2084,7 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, */ if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { flags |= MS_NODEV; - mnt_flags |= MNT_NODEV; + mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } } @@ -2358,6 +2402,14 @@ long do_mount(const char *dev_name, const char *dir_name, if (flags & MS_RDONLY) mnt_flags |= MNT_READONLY; + /* The default atime for remount is preservation */ + if ((flags & MS_REMOUNT) && + ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | + MS_STRICTATIME)) == 0)) { + mnt_flags &= ~MNT_ATIME_MASK; + mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK; + } + flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | MS_STRICTATIME); @@ -2704,6 +2756,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, /* make sure we can reach put_old from new_root */ if (!is_path_reachable(old_mnt, old.dentry, &new)) goto out4; + /* make certain new is below the root */ + if (!is_path_reachable(new_mnt, new.dentry, &root)) + goto out4; root_mp->m_count++; /* pin it so it won't go away */ br_write_lock(&vfsmount_lock); detach_mnt(new_mnt, &parent_path); |