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authorDavid Howells <dhowells@redhat.com>2018-11-01 23:07:25 +0000
committerDavid Howells <dhowells@redhat.com>2018-12-20 16:32:56 +0000
commit43f5e655eff7e124d4e484515689cba374ab698e (patch)
tree40e0581b86f123bb4aaa540ff672d575fdcfa83d /include/linux/mount.h
parente262e32d6bde0f77fb0c95d977482fc872c51996 (diff)
vfs: Separate changing mount flags full remount
Separate just the changing of mount flags (MS_REMOUNT|MS_BIND) from full remount because the mount data will get parsed with the new fs_context stuff prior to doing a remount - and this causes the syscall to fail under some circumstances. To quote Eric's explanation: [...] mount(..., MS_REMOUNT|MS_BIND, ...) now validates the mount options string, which breaks systemd unit files with ProtectControlGroups=yes (e.g. systemd-networkd.service) when systemd does the following to change a cgroup (v1) mount to read-only: mount(NULL, "/run/systemd/unit-root/sys/fs/cgroup/systemd", NULL, MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_REMOUNT|MS_BIND, NULL) ... when the kernel has CONFIG_CGROUPS=y but no cgroup subsystems enabled, since in that case the error "cgroup1: Need name or subsystem set" is hit when the mount options string is empty. Probably it doesn't make sense to validate the mount options string at all in the MS_REMOUNT|MS_BIND case, though maybe you had something else in mind. This is also worthwhile doing because we will need to add a mount_setattr() syscall to take over the remount-bind function. Reported-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'include/linux/mount.h')
-rw-r--r--include/linux/mount.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 45b1f56c6c2f..037eed52164b 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -81,7 +81,7 @@ extern void mnt_drop_write_file(struct file *file);
extern void mntput(struct vfsmount *mnt);
extern struct vfsmount *mntget(struct vfsmount *mnt);
extern struct vfsmount *mnt_clone_internal(const struct path *path);
-extern int __mnt_is_readonly(struct vfsmount *mnt);
+extern bool __mnt_is_readonly(struct vfsmount *mnt);
extern bool mnt_may_suid(struct vfsmount *mnt);
struct path;