From: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> To: Linux Containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org> Cc: Miklos Szeredi <miklos-sUDqSbJrdHQHWmgEVkV9KA@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, James Bottomley <James.Bottomley-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>, Seth Forshee <seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Djalal Harouni <tixxdz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Subject: [PATCH review 11/13] mnt: Simplify mount_too_revealing Date: Mon, 20 Jun 2016 12:21:28 -0500 [thread overview] Message-ID: <20160620172130.15712-11-ebiederm@xmission.com> (raw) In-Reply-To: <20160620172130.15712-1-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> Verify all filesystems that we check in mount_too_revealing set SB_I_NOEXEC and SB_I_NODEV in sb->s_iflags. That is true for today and it should remain true in the future. Remove the now unnecessary checks from mnt_already_visibile that ensure MNT_LOCK_NOSUID, MNT_LOCK_NOEXEC, and MNT_LOCK_NODEV are preserved. Making the code shorter and easier to read. Relying on SB_I_NOEXEC and SB_I_NODEV instead of the user visible MNT_NOSUID, MNT_NOEXEC, and MNT_NODEV ensures the many current systems where proc and sysfs are mounted with "nosuid, nodev, noexec" and several slightly buggy container applications don't bother to set those flags continue to work. Signed-off-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> --- fs/namespace.c | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 2e13f6cfe5df..b1da7f8182c4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3232,12 +3232,8 @@ static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) continue; - /* Read the mount flags and filter out flags that - * may safely be ignored. - */ + /* A local view of the mount flags */ mnt_flags = mnt->mnt.mnt_flags; - if (mnt->mnt.mnt_sb->s_iflags & SB_I_NOEXEC) - mnt_flags &= ~(MNT_LOCK_NOSUID | MNT_LOCK_NOEXEC); /* Don't miss readonly hidden in the superblock flags */ if (mnt->mnt.mnt_sb->s_flags & MS_RDONLY) @@ -3249,15 +3245,6 @@ static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, if ((mnt_flags & MNT_LOCK_READONLY) && !(new_flags & MNT_READONLY)) continue; - if ((mnt_flags & MNT_LOCK_NODEV) && - !(new_flags & MNT_NODEV)) - continue; - if ((mnt_flags & MNT_LOCK_NOSUID) && - !(new_flags & MNT_NOSUID)) - continue; - if ((mnt_flags & MNT_LOCK_NOEXEC) && - !(new_flags & MNT_NOEXEC)) - continue; if ((mnt_flags & MNT_LOCK_ATIME) && ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) continue; @@ -3277,9 +3264,6 @@ static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, } /* Preserve the locked attributes */ *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ - MNT_LOCK_NODEV | \ - MNT_LOCK_NOSUID | \ - MNT_LOCK_NOEXEC | \ MNT_LOCK_ATIME); visible = true; goto found; @@ -3292,6 +3276,7 @@ found: static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags) { + const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; struct mnt_namespace *ns = current->nsproxy->mnt_ns; unsigned long s_iflags; @@ -3303,6 +3288,12 @@ static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags) if (!(s_iflags & SB_I_USERNS_VISIBLE)) return false; + if ((s_iflags & required_iflags) != required_iflags) { + WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", + required_iflags); + return true; + } + return !mnt_already_visible(ns, mnt, new_mnt_flags); } -- 2.8.3
WARNING: multiple messages have this Message-ID (diff)
From: "Eric W. Biederman" <ebiederm@xmission.com> To: Linux Containers <containers@lists.linux-foundation.org> Cc: linux-fsdevel@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>, James Bottomley <James.Bottomley@HansenPartnership.com>, Djalal Harouni <tixxdz@gmail.com>, Seth Forshee <seth.forshee@canonical.com>, "Serge E. Hallyn" <serge@hallyn.com>, Andy Lutomirski <luto@amacapital.net> Subject: [PATCH review 11/13] mnt: Simplify mount_too_revealing Date: Mon, 20 Jun 2016 12:21:28 -0500 [thread overview] Message-ID: <20160620172130.15712-11-ebiederm@xmission.com> (raw) In-Reply-To: <20160620172130.15712-1-ebiederm@xmission.com> Verify all filesystems that we check in mount_too_revealing set SB_I_NOEXEC and SB_I_NODEV in sb->s_iflags. That is true for today and it should remain true in the future. Remove the now unnecessary checks from mnt_already_visibile that ensure MNT_LOCK_NOSUID, MNT_LOCK_NOEXEC, and MNT_LOCK_NODEV are preserved. Making the code shorter and easier to read. Relying on SB_I_NOEXEC and SB_I_NODEV instead of the user visible MNT_NOSUID, MNT_NOEXEC, and MNT_NODEV ensures the many current systems where proc and sysfs are mounted with "nosuid, nodev, noexec" and several slightly buggy container applications don't bother to set those flags continue to work. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- fs/namespace.c | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 2e13f6cfe5df..b1da7f8182c4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3232,12 +3232,8 @@ static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) continue; - /* Read the mount flags and filter out flags that - * may safely be ignored. - */ + /* A local view of the mount flags */ mnt_flags = mnt->mnt.mnt_flags; - if (mnt->mnt.mnt_sb->s_iflags & SB_I_NOEXEC) - mnt_flags &= ~(MNT_LOCK_NOSUID | MNT_LOCK_NOEXEC); /* Don't miss readonly hidden in the superblock flags */ if (mnt->mnt.mnt_sb->s_flags & MS_RDONLY) @@ -3249,15 +3245,6 @@ static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, if ((mnt_flags & MNT_LOCK_READONLY) && !(new_flags & MNT_READONLY)) continue; - if ((mnt_flags & MNT_LOCK_NODEV) && - !(new_flags & MNT_NODEV)) - continue; - if ((mnt_flags & MNT_LOCK_NOSUID) && - !(new_flags & MNT_NOSUID)) - continue; - if ((mnt_flags & MNT_LOCK_NOEXEC) && - !(new_flags & MNT_NOEXEC)) - continue; if ((mnt_flags & MNT_LOCK_ATIME) && ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) continue; @@ -3277,9 +3264,6 @@ static bool mnt_already_visible(struct mnt_namespace *ns, struct vfsmount *new, } /* Preserve the locked attributes */ *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ - MNT_LOCK_NODEV | \ - MNT_LOCK_NOSUID | \ - MNT_LOCK_NOEXEC | \ MNT_LOCK_ATIME); visible = true; goto found; @@ -3292,6 +3276,7 @@ found: static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags) { + const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; struct mnt_namespace *ns = current->nsproxy->mnt_ns; unsigned long s_iflags; @@ -3303,6 +3288,12 @@ static bool mount_too_revealing(struct vfsmount *mnt, int *new_mnt_flags) if (!(s_iflags & SB_I_USERNS_VISIBLE)) return false; + if ((s_iflags & required_iflags) != required_iflags) { + WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", + required_iflags); + return true; + } + return !mnt_already_visible(ns, mnt, new_mnt_flags); } -- 2.8.3
next prev parent reply other threads:[~2016-06-20 17:21 UTC|newest] Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-20 17:09 [PATCH review 0/13] Adding a userns owner to struct super_block Eric W. Biederman 2016-06-20 17:09 ` Eric W. Biederman [not found] ` <87fus77pns.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org> 2016-06-20 17:21 ` [PATCH review 01/13] mnt: Account for MS_RDONLY in fs_fully_visible Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [not found] ` <20160620172130.15712-1-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-20 17:21 ` [PATCH review 02/13] mnt: Refactor fs_fully_visible into mount_too_revealing Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [not found] ` <20160620172130.15712-2-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-20 22:53 ` Andy Lutomirski 2016-06-20 22:53 ` Andy Lutomirski [not found] ` <CALCETrXv2aeP38AmUaRVMC+O-oeWKwDcy8fPfsOCu1f8mncZEA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2016-06-21 18:54 ` Eric W. Biederman 2016-06-21 18:54 ` Eric W. Biederman [not found] ` <874m8m4bky.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org> 2016-06-23 21:23 ` Djalal Harouni 2016-06-23 21:23 ` Djalal Harouni 2016-06-24 6:56 ` Serge E. Hallyn 2016-06-24 6:56 ` Serge E. Hallyn 2016-06-22 19:40 ` Seth Forshee 2016-06-22 19:40 ` Seth Forshee 2016-06-20 17:21 ` [PATCH review 03/13] ipc: Initialize ipc_namespace->user_ns early Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [not found] ` <20160620172130.15712-3-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-24 14:34 ` Djalal Harouni 2016-06-24 14:34 ` Djalal Harouni 2016-06-20 17:21 ` [PATCH review 04/13] vfs: Pass data, ns, and ns->userns to mount_ns Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman 2016-06-20 17:21 ` [PATCH review 05/13] proc: Convert proc_mount to use mount_ns Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [not found] ` <20160620172130.15712-5-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-23 11:50 ` Djalal Harouni 2016-06-23 11:50 ` Djalal Harouni 2016-06-20 17:21 ` [PATCH review 06/13] fs: Add user namespace member to struct super_block Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman 2016-06-20 17:21 ` [PATCH review 07/13] mnt: Move the FS_USERNS_MOUNT check into sget_userns Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [not found] ` <20160620172130.15712-7-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-22 19:43 ` Seth Forshee 2016-06-22 19:43 ` Seth Forshee 2016-06-20 17:21 ` [PATCH review 08/13] kernfs: The cgroup filesystem also benefits from SB_I_NOEXEC Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman 2016-06-20 17:21 ` [PATCH review 09/13] ipc/mqueue: The mqueue filesystem should never contain executables Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman 2016-06-20 17:21 ` [PATCH review 10/13] vfs: Generalize filesystem nodev handling Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [not found] ` <20160620172130.15712-10-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-20 22:57 ` Andy Lutomirski 2016-06-20 22:57 ` Andy Lutomirski [not found] ` <CALCETrUWsnRgjyRyb+_0u0PYubx9gg=hUAso=073yjJY+m205g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2016-06-21 19:09 ` Eric W. Biederman 2016-06-21 19:09 ` Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman [this message] 2016-06-20 17:21 ` [PATCH review 11/13] mnt: Simplify mount_too_revealing Eric W. Biederman [not found] ` <20160620172130.15712-11-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-22 19:48 ` Seth Forshee 2016-06-22 19:48 ` Seth Forshee 2016-06-20 17:21 ` [PATCH review 12/13] userns: Remove implicit MNT_NODEV fragility Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman 2016-06-22 19:49 ` Seth Forshee [not found] ` <20160620172130.15712-12-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-20 22:58 ` Andy Lutomirski 2016-06-20 22:58 ` Andy Lutomirski 2016-06-22 19:49 ` Seth Forshee 2016-06-20 17:21 ` [PATCH review 13/13] userns: Remove the now unnecessary FS_USERNS_DEV_MOUNT flag Eric W. Biederman 2016-06-20 17:21 ` Eric W. Biederman 2016-06-22 19:50 ` Seth Forshee [not found] ` <20160620172130.15712-13-ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 2016-06-22 19:50 ` Seth Forshee
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