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From: Christian Brauner <christian.brauner@ubuntu.com>
To: "Stéphane Graber" <stgraber@ubuntu.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Aleksa Sarai" <cyphar@cyphar.com>,
	"Jann Horn" <jannh@google.com>
Cc: smbarber@chromium.org, Seth Forshee <seth.forshee@canonical.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Serge Hallyn <serge@hallyn.com>, James Morris <jmorris@namei.org>,
	Kees Cook <keescook@chromium.org>,
	Jonathan Corbet <corbet@lwn.net>, Phil Estes <estesp@gmail.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	containers@lists.linux-foundation.org,
	linux-security-module@vger.kernel.org, linux-api@vger.kernel.org,
	Christian Brauner <christian.brauner@ubuntu.com>
Subject: [PATCH v3 13/25] stat: handle fsid mappings
Date: Tue, 18 Feb 2020 15:33:59 +0100	[thread overview]
Message-ID: <20200218143411.2389182-14-christian.brauner@ubuntu.com> (raw)
In-Reply-To: <20200218143411.2389182-1-christian.brauner@ubuntu.com>

Switch attribute functions looking up fsids to them up in the fsid mappings. If
no fsid mappings are setup the behavior is unchanged, i.e. fsids are looked up
in the id mappings.

Filesystems that share a superblock in all user namespaces they are mounted in
will retain their old semantics even with the introduction of fsid mappings.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
unchanged

/* v3 */
- Tycho Andersen <tycho@tycho.ws>:
  - Replace , with = when converting to uid and gid in cp_new_stat64().
---
 fs/stat.c            | 48 +++++++++++++++++++++++++++++++++++---------
 include/linux/stat.h |  1 +
 2 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/fs/stat.c b/fs/stat.c
index 030008796479..612714ebacb4 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -10,6 +10,7 @@
 #include <linux/errno.h>
 #include <linux/file.h>
 #include <linux/highuid.h>
+#include <linux/fsuidgid.h>
 #include <linux/fs.h>
 #include <linux/namei.h>
 #include <linux/security.h>
@@ -79,6 +80,8 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
 	if (IS_AUTOMOUNT(inode))
 		stat->attributes |= STATX_ATTR_AUTOMOUNT;
 
+	stat->userns_visible = is_userns_visible(inode->i_sb->s_iflags);
+
 	if (inode->i_op->getattr)
 		return inode->i_op->getattr(path, stat, request_mask,
 					    query_flags);
@@ -239,8 +242,13 @@ static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * sta
 	tmp.st_nlink = stat->nlink;
 	if (tmp.st_nlink != stat->nlink)
 		return -EOVERFLOW;
-	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
-	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
+	if (stat->userns_visible) {
+		SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
+		SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
+	} else {
+		SET_UID(tmp.st_uid, from_kfsuid_munged(current_user_ns(), stat->uid));
+		SET_GID(tmp.st_gid, from_kfsgid_munged(current_user_ns(), stat->gid));
+	}
 	tmp.st_rdev = old_encode_dev(stat->rdev);
 #if BITS_PER_LONG == 32
 	if (stat->size > MAX_NON_LFS)
@@ -327,8 +335,13 @@ static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 	tmp.st_nlink = stat->nlink;
 	if (tmp.st_nlink != stat->nlink)
 		return -EOVERFLOW;
-	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
-	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
+	if (stat->userns_visible) {
+		SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
+		SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
+	} else {
+		SET_UID(tmp.st_uid, from_kfsuid_munged(current_user_ns(), stat->uid));
+		SET_GID(tmp.st_gid, from_kfsgid_munged(current_user_ns(), stat->gid));
+	}
 	tmp.st_rdev = encode_dev(stat->rdev);
 	tmp.st_size = stat->size;
 	tmp.st_atime = stat->atime.tv_sec;
@@ -471,8 +484,13 @@ static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
 #endif
 	tmp.st_mode = stat->mode;
 	tmp.st_nlink = stat->nlink;
-	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
-	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
+	if (stat->userns_visible) {
+		tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
+		tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
+	} else {
+		tmp.st_uid = from_kfsuid_munged(current_user_ns(), stat->uid);
+		tmp.st_gid = from_kfsgid_munged(current_user_ns(), stat->gid);
+	}
 	tmp.st_atime = stat->atime.tv_sec;
 	tmp.st_atime_nsec = stat->atime.tv_nsec;
 	tmp.st_mtime = stat->mtime.tv_sec;
@@ -544,8 +562,13 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
 	tmp.stx_blksize = stat->blksize;
 	tmp.stx_attributes = stat->attributes;
 	tmp.stx_nlink = stat->nlink;
-	tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid);
-	tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid);
+	if (stat->userns_visible) {
+		tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid);
+		tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid);
+	} else {
+		tmp.stx_uid = from_kfsuid_munged(current_user_ns(), stat->uid);
+		tmp.stx_gid = from_kfsgid_munged(current_user_ns(), stat->gid);
+	}
 	tmp.stx_mode = stat->mode;
 	tmp.stx_ino = stat->ino;
 	tmp.stx_size = stat->size;
@@ -615,8 +638,13 @@ static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
 	tmp.st_nlink = stat->nlink;
 	if (tmp.st_nlink != stat->nlink)
 		return -EOVERFLOW;
-	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
-	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
+	if (stat->userns_visible) {
+		SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
+		SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
+	} else {
+		SET_UID(tmp.st_uid, from_kfsuid_munged(current_user_ns(), stat->uid));
+		SET_GID(tmp.st_gid, from_kfsgid_munged(current_user_ns(), stat->gid));
+	}
 	tmp.st_rdev = old_encode_dev(stat->rdev);
 	if ((u64) stat->size > MAX_NON_LFS)
 		return -EOVERFLOW;
diff --git a/include/linux/stat.h b/include/linux/stat.h
index 528c4baad091..e6d4ba73a970 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h
@@ -47,6 +47,7 @@ struct kstat {
 	struct timespec64 ctime;
 	struct timespec64 btime;			/* File creation time */
 	u64		blocks;
+	bool		userns_visible;
 };
 
 #endif
-- 
2.25.0


  parent reply	other threads:[~2020-02-18 14:36 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 14:33 [PATCH v3 00/25] user_namespace: introduce fsid mappings Christian Brauner
2020-02-18 14:33 ` [PATCH v3 01/25] user_namespace: introduce fsid mappings infrastructure Christian Brauner
2020-02-19  2:33   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 02/25] proc: add /proc/<pid>/fsuid_map Christian Brauner
2020-02-19  2:33   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 03/25] proc: add /proc/<pid>/fsgid_map Christian Brauner
2020-02-19  2:33   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 04/25] fsuidgid: add fsid mapping helpers Christian Brauner
2020-02-18 14:33 ` [PATCH v3 05/25] user_namespace: refactor map_write() Christian Brauner
2020-02-19  2:35   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 06/25] user_namespace: make map_write() support fsid mappings Christian Brauner
2020-02-19 16:18   ` Jann Horn
2020-02-18 14:33 ` [PATCH v3 07/25] proc: task_state(): use from_kfs{g,u}id_munged Christian Brauner
2020-02-19  2:36   ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 08/25] cred: add kfs{g,u}id Christian Brauner
2020-02-18 14:33 ` [PATCH v3 09/25] fs: add is_userns_visible() helper Christian Brauner
2020-02-19  2:42   ` Serge E. Hallyn
2020-02-19 12:06     ` Christian Brauner
2020-02-19 17:18       ` Andy Lutomirski
2020-02-20 14:26         ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 10/25] namei: may_{o_}create(): handle fsid mappings Christian Brauner
2020-02-18 14:33 ` [PATCH v3 11/25] inode: inode_owner_or_capable(): " Christian Brauner
2020-02-18 22:25   ` Christoph Hellwig
2020-02-19 12:29     ` Christian Brauner
2020-02-18 14:33 ` [PATCH v3 12/25] capability: privileged_wrt_inode_uidgid(): " Christian Brauner
2020-02-18 14:33 ` Christian Brauner [this message]
2020-02-18 14:34 ` [PATCH v3 14/25] open: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 15/25] posix_acl: " Christian Brauner
2020-02-18 22:26   ` Christoph Hellwig
2020-02-19 12:56     ` Christian Brauner
2020-02-18 14:34 ` [PATCH v3 16/25] attr: notify_change(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 17/25] commoncap: cap_bprm_set_creds(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 18/25] commoncap: cap_task_fix_setuid(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 19/25] commoncap: handle fsid mappings with vfs caps Christian Brauner
2020-02-19 15:53   ` Jann Horn
2020-02-18 14:34 ` [PATCH v3 20/25] exec: bprm_fill_uid(): handle fsid mappings Christian Brauner
2020-02-18 14:34 ` [PATCH v3 21/25] ptrace: adapt ptrace_may_access() to always uses unmapped fsids Christian Brauner
2020-02-18 14:34 ` [PATCH v3 22/25] devpts: handle fsid mappings Christian Brauner
2020-02-18 14:34 ` [PATCH v3 23/25] keys: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 24/25] sys: handle fsid mappings in set*id() calls Christian Brauner
2020-02-19 15:42   ` Jann Horn
2020-02-18 14:34 ` [PATCH v3 25/25] selftests: add simple fsid mapping selftests Christian Brauner
2020-02-18 23:50 ` [PATCH v3 00/25] user_namespace: introduce fsid mappings James Bottomley
2020-02-19 12:27   ` Christian Brauner
2020-02-19 15:36     ` James Bottomley
2020-02-19 15:33 ` Jann Horn
2020-02-19 19:35 ` Serge E. Hallyn
2020-02-19 21:48   ` Serge E. Hallyn
2020-02-19 21:56     ` Tycho Andersen
2020-02-27 19:33 ` Josef Bacik
2020-03-02 14:34   ` Serge E. Hallyn

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