From: Christian Brauner <christian.brauner@ubuntu.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
linux-fsdevel@vger.kernel.org
Cc: "John Johansen" <john.johansen@canonical.com>,
"James Morris" <jmorris@namei.org>,
"Mimi Zohar" <zohar@linux.ibm.com>,
"Dmitry Kasatkin" <dmitry.kasatkin@gmail.com>,
"Stephen Smalley" <stephen.smalley.work@gmail.com>,
"Casey Schaufler" <casey@schaufler-ca.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Andreas Dilger" <adilger.kernel@dilger.ca>,
"OGAWA Hirofumi" <hirofumi@mail.parknet.co.jp>,
"Geoffrey Thomas" <geofft@ldpreload.com>,
"Mrunal Patel" <mpatel@redhat.com>,
"Josh Triplett" <josh@joshtriplett.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Theodore Tso" <tytso@mit.edu>, "Alban Crequy" <alban@kinvolk.io>,
"Tycho Andersen" <tycho@tycho.ws>,
"David Howells" <dhowells@redhat.com>,
"James Bottomley" <James.Bottomley@hansenpartnership.com>,
"Seth Forshee" <seth.forshee@canonical.com>,
"Stéphane Graber" <stgraber@ubuntu.com>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Lennart Poettering" <lennart@poettering.net>,
"Eric W. Biederman" <ebiederm@xmission.com>,
smbarber@chromium.org, "Phil Estes" <estesp@gmail.com>,
"Serge Hallyn" <serge@hallyn.com>,
"Kees Cook" <keescook@chromium.org>,
"Todd Kjos" <tkjos@google.com>,
"Paul Moore" <paul@paul-moore.com>,
"Jonathan Corbet" <corbet@lwn.net>,
containers@lists.linux-foundation.org,
linux-security-module@vger.kernel.org, linux-api@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-integrity@vger.kernel.org,
selinux@vger.kernel.org,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Christoph Hellwig" <hch@lst.de>
Subject: [PATCH v4 34/40] fat: handle idmapped mounts
Date: Fri, 4 Dec 2020 00:57:30 +0100 [thread overview]
Message-ID: <20201203235736.3528991-35-christian.brauner@ubuntu.com> (raw)
In-Reply-To: <20201203235736.3528991-1-christian.brauner@ubuntu.com>
Let fat handle idmapped mounts. This allows to have the same fat mount
appear in multiple locations with different id mappings. This allows to
expose a vfat formatted USB stick to multiple user with different ids on
the host or in user namespaces allowing for dac permissions:
mount -o uid=1000,gid=1000 /dev/sdb /mnt
u1001@f2-vm:/lower1$ ls -ln /mnt/
total 4
-rwxr-xr-x 1 1000 1000 4 Oct 28 03:44 aaa
-rwxr-xr-x 1 1000 1000 0 Oct 28 01:09 bbb
-rwxr-xr-x 1 1000 1000 0 Oct 28 01:10 ccc
-rwxr-xr-x 1 1000 1000 0 Oct 28 03:46 ddd
-rwxr-xr-x 1 1000 1000 0 Oct 28 04:01 eee
mount-idmapped --map-mount b:1000:1001:1
u1001@f2-vm:/lower1$ ls -ln /lower1/
total 4
-rwxr-xr-x 1 1001 1001 4 Oct 28 03:44 aaa
-rwxr-xr-x 1 1001 1001 0 Oct 28 01:09 bbb
-rwxr-xr-x 1 1001 1001 0 Oct 28 01:10 ccc
-rwxr-xr-x 1 1001 1001 0 Oct 28 03:46 ddd
-rwxr-xr-x 1 1001 1001 0 Oct 28 04:01 eee
u1001@f2-vm:/lower1$ touch /lower1/fff
u1001@f2-vm:/lower1$ ls -ln /lower1/fff
-rwxr-xr-x 1 1001 1001 0 Oct 28 04:03 /lower1/fff
u1001@f2-vm:/lower1$ ls -ln /mnt/fff
-rwxr-xr-x 1 1000 1000 0 Oct 28 04:03 /mnt/fff
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
unchanged
/* v3 */
unchanged
/* v4 */
- Mauricio Vásquez Bernal <mauricio@kinvolk.io>:
- Fix mount example in commit message.
- Serge Hallyn <serge@hallyn.com>:
- Use "mnt_userns" to refer to a vfsmount's userns everywhere to make
terminology consistent.
---
fs/fat/file.c | 15 ++++++++-------
fs/fat/namei_msdos.c | 2 +-
fs/fat/namei_vfat.c | 2 +-
3 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 73acd0843d92..6a618e9450c8 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -398,7 +398,7 @@ int fat_getattr(struct user_namespace *mnt_userns, const struct path *path,
struct kstat *stat, u32 request_mask, unsigned int flags)
{
struct inode *inode = d_inode(path->dentry);
- generic_fillattr(&init_user_ns, inode, stat);
+ generic_fillattr(mnt_userns, inode, stat);
stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
@@ -447,12 +447,13 @@ static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
return 0;
}
-static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
+static int fat_allow_set_time(struct user_namespace *mnt_userns,
+ struct msdos_sb_info *sbi, struct inode *inode)
{
umode_t allow_utime = sbi->options.allow_utime;
- if (!uid_eq(current_fsuid(), inode->i_uid)) {
- if (in_group_p(inode->i_gid))
+ if (!uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode))) {
+ if (in_group_p(i_gid_into_mnt(mnt_userns, inode)))
allow_utime >>= 3;
if (allow_utime & MAY_WRITE)
return 1;
@@ -477,11 +478,11 @@ int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
/* Check for setting the inode time. */
ia_valid = attr->ia_valid;
if (ia_valid & TIMES_SET_FLAGS) {
- if (fat_allow_set_time(sbi, inode))
+ if (fat_allow_set_time(mnt_userns, sbi, inode))
attr->ia_valid &= ~TIMES_SET_FLAGS;
}
- error = setattr_prepare(&init_user_ns, dentry, attr);
+ error = setattr_prepare(mnt_userns, dentry, attr);
attr->ia_valid = ia_valid;
if (error) {
if (sbi->options.quiet)
@@ -551,7 +552,7 @@ int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
fat_truncate_time(inode, &attr->ia_mtime, S_MTIME);
attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
- setattr_copy(&init_user_ns, inode, attr);
+ setattr_copy(mnt_userns, inode, attr);
mark_inode_dirty(inode);
out:
return error;
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index a8f3375d9d10..efba301d68ae 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -667,7 +667,7 @@ static struct file_system_type msdos_fs_type = {
.name = "msdos",
.mount = msdos_mount,
.kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV,
+ .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
};
MODULE_ALIAS_FS("msdos");
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index 23936ecf79a5..5369d82e0bfb 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -1063,7 +1063,7 @@ static struct file_system_type vfat_fs_type = {
.name = "vfat",
.mount = vfat_mount,
.kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV,
+ .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
};
MODULE_ALIAS_FS("vfat");
--
2.29.2
next prev parent reply other threads:[~2020-12-04 0:13 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 23:56 [PATCH v4 00/40] idmapped mounts Christian Brauner
2020-12-03 23:56 ` [PATCH v4 01/40] namespace: take lock_mount_hash() directly when changing flags Christian Brauner
2020-12-03 23:56 ` [PATCH v4 02/40] mount: make {lock,unlock}_mount_hash() static Christian Brauner
2020-12-03 23:56 ` [PATCH v4 03/40] namespace: only take read lock in do_reconfigure_mnt() Christian Brauner
2020-12-03 23:57 ` [PATCH v4 04/40] fs: split out functions to hold writers Christian Brauner
2020-12-07 17:08 ` Christoph Hellwig
2020-12-03 23:57 ` [PATCH v4 05/40] fs: add attr_flags_to_mnt_flags helper Christian Brauner
2020-12-07 17:10 ` Christoph Hellwig
2020-12-08 10:07 ` Christian Brauner
2020-12-03 23:57 ` [PATCH v4 06/40] fs: add mount_setattr() Christian Brauner
2020-12-07 17:14 ` Christoph Hellwig
2020-12-08 10:37 ` Christian Brauner
2020-12-08 15:05 ` Christoph Hellwig
2020-12-08 15:22 ` Christian Brauner
2020-12-08 15:26 ` Christian Brauner
2020-12-03 23:57 ` [PATCH v4 07/40] tests: add mount_setattr() selftests Christian Brauner
2020-12-03 23:57 ` [PATCH v4 08/40] fs: add id translation helpers Christian Brauner
2020-12-03 23:57 ` [PATCH v4 09/40] mount: attach mappings to mounts Christian Brauner
2020-12-03 23:57 ` [PATCH v4 10/40] capability: handle idmapped mounts Christian Brauner
2020-12-03 23:57 ` [PATCH v4 11/40] namei: make permission helpers idmapped mount aware Christian Brauner
2020-12-03 23:57 ` [PATCH v4 12/40] inode: make init and " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 13/40] attr: handle idmapped mounts Christian Brauner
2020-12-03 23:57 ` [PATCH v4 14/40] acl: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 15/40] xattr: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 16/40] commoncap: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 17/40] stat: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 18/40] namei: handle idmapped mounts in may_*() helpers Christian Brauner
2020-12-03 23:57 ` [PATCH v4 19/40] namei: introduce struct renamedata Christian Brauner
2020-12-03 23:57 ` [PATCH v4 20/40] namei: prepare for idmapped mounts Christian Brauner
2020-12-03 23:57 ` [PATCH v4 21/40] open: handle idmapped mounts in do_truncate() Christian Brauner
2020-12-03 23:57 ` [PATCH v4 22/40] open: handle idmapped mounts Christian Brauner
2020-12-03 23:57 ` [PATCH v4 23/40] af_unix: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 24/40] utimes: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 25/40] fcntl: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 26/40] notify: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 27/40] init: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 28/40] ioctl: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 29/40] would_dump: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 30/40] exec: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 32/40] apparmor: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 33/40] ima: " Christian Brauner
2020-12-03 23:57 ` Christian Brauner [this message]
2020-12-03 23:57 ` [PATCH v4 35/40] ext4: support " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 36/40] ecryptfs: do not mount on top of " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 37/40] overlayfs: " Christian Brauner
2020-12-03 23:57 ` [PATCH v4 38/40] fs: introduce MOUNT_ATTR_IDMAP Christian Brauner
2020-12-03 23:57 ` [PATCH v4 39/40] tests: extend mount_setattr tests Christian Brauner
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