[kernel/stabilization] CVE-2014-4014 possible priv escalation in userns (rhbz 1107966 1109836)
Josh Boyer
jwboyer at fedoraproject.org
Mon Jun 16 13:16:31 UTC 2014
commit 7c02a3a60c04e7332b43570873544a0f7c8da94e
Author: Josh Boyer <jwboyer at fedoraproject.org>
Date: Mon Jun 16 09:12:50 2014 -0400
CVE-2014-4014 possible priv escalation in userns (rhbz 1107966 1109836)
...hange-inode_capable-to-capable_wrt_inode_.patch | 209 ++++++++++++++++++++
kernel.spec | 9 +
2 files changed, 218 insertions(+), 0 deletions(-)
---
diff --git a/fs-userns-Change-inode_capable-to-capable_wrt_inode_.patch b/fs-userns-Change-inode_capable-to-capable_wrt_inode_.patch
new file mode 100644
index 0000000..b56e717
--- /dev/null
+++ b/fs-userns-Change-inode_capable-to-capable_wrt_inode_.patch
@@ -0,0 +1,209 @@
+Bugzilla: 1109836
+Upstream-status: 3.16-rc1 and CC'd to stable
+
+From 23adbe12ef7d3d4195e80800ab36b37bee28cd03 Mon Sep 17 00:00:00 2001
+From: Andy Lutomirski <luto at amacapital.net>
+Date: Tue, 10 Jun 2014 12:45:42 -0700
+Subject: [PATCH] fs,userns: Change inode_capable to capable_wrt_inode_uidgid
+
+The kernel has no concept of capabilities with respect to inodes; inodes
+exist independently of namespaces. For example, inode_capable(inode,
+CAP_LINUX_IMMUTABLE) would be nonsense.
+
+This patch changes inode_capable to check for uid and gid mappings and
+renames it to capable_wrt_inode_uidgid, which should make it more
+obvious what it does.
+
+Fixes CVE-2014-4014.
+
+Cc: Theodore Ts'o <tytso at mit.edu>
+Cc: Serge Hallyn <serge.hallyn at ubuntu.com>
+Cc: "Eric W. Biederman" <ebiederm at xmission.com>
+Cc: Dave Chinner <david at fromorbit.com>
+Cc: stable at vger.kernel.org
+Signed-off-by: Andy Lutomirski <luto at amacapital.net>
+Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
+---
+ fs/attr.c | 8 ++++----
+ fs/inode.c | 10 +++++++---
+ fs/namei.c | 11 ++++++-----
+ fs/xfs/xfs_ioctl.c | 2 +-
+ include/linux/capability.h | 2 +-
+ kernel/capability.c | 20 ++++++++------------
+ 6 files changed, 27 insertions(+), 26 deletions(-)
+
+diff --git a/fs/attr.c b/fs/attr.c
+index 5d4e59d..6530ced 100644
+--- a/fs/attr.c
++++ b/fs/attr.c
+@@ -50,14 +50,14 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr)
+ if ((ia_valid & ATTR_UID) &&
+ (!uid_eq(current_fsuid(), inode->i_uid) ||
+ !uid_eq(attr->ia_uid, inode->i_uid)) &&
+- !inode_capable(inode, CAP_CHOWN))
++ !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
+ return -EPERM;
+
+ /* Make sure caller can chgrp. */
+ if ((ia_valid & ATTR_GID) &&
+ (!uid_eq(current_fsuid(), inode->i_uid) ||
+ (!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) &&
+- !inode_capable(inode, CAP_CHOWN))
++ !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
+ return -EPERM;
+
+ /* Make sure a caller can chmod. */
+@@ -67,7 +67,7 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr)
+ /* Also check the setgid bit! */
+ if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
+ inode->i_gid) &&
+- !inode_capable(inode, CAP_FSETID))
++ !capable_wrt_inode_uidgid(inode, CAP_FSETID))
+ attr->ia_mode &= ~S_ISGID;
+ }
+
+@@ -160,7 +160,7 @@ void setattr_copy(struct inode *inode, const struct iattr *attr)
+ umode_t mode = attr->ia_mode;
+
+ if (!in_group_p(inode->i_gid) &&
+- !inode_capable(inode, CAP_FSETID))
++ !capable_wrt_inode_uidgid(inode, CAP_FSETID))
+ mode &= ~S_ISGID;
+ inode->i_mode = mode;
+ }
+diff --git a/fs/inode.c b/fs/inode.c
+index 2feb9b6..6eecb7f 100644
+--- a/fs/inode.c
++++ b/fs/inode.c
+@@ -1839,14 +1839,18 @@ EXPORT_SYMBOL(inode_init_owner);
+ * inode_owner_or_capable - check current task permissions to inode
+ * @inode: inode being checked
+ *
+- * Return true if current either has CAP_FOWNER to the inode, or
+- * owns the file.
++ * Return true if current either has CAP_FOWNER in a namespace with the
++ * inode owner uid mapped, or owns the file.
+ */
+ bool inode_owner_or_capable(const struct inode *inode)
+ {
++ struct user_namespace *ns;
++
+ if (uid_eq(current_fsuid(), inode->i_uid))
+ return true;
+- if (inode_capable(inode, CAP_FOWNER))
++
++ ns = current_user_ns();
++ if (ns_capable(ns, CAP_FOWNER) && kuid_has_mapping(ns, inode->i_uid))
+ return true;
+ return false;
+ }
+diff --git a/fs/namei.c b/fs/namei.c
+index 8016827..985c6f3 100644
+--- a/fs/namei.c
++++ b/fs/namei.c
+@@ -332,10 +332,11 @@ int generic_permission(struct inode *inode, int mask)
+
+ if (S_ISDIR(inode->i_mode)) {
+ /* DACs are overridable for directories */
+- if (inode_capable(inode, CAP_DAC_OVERRIDE))
++ if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
+ return 0;
+ if (!(mask & MAY_WRITE))
+- if (inode_capable(inode, CAP_DAC_READ_SEARCH))
++ if (capable_wrt_inode_uidgid(inode,
++ CAP_DAC_READ_SEARCH))
+ return 0;
+ return -EACCES;
+ }
+@@ -345,7 +346,7 @@ int generic_permission(struct inode *inode, int mask)
+ * at least one exec bit set.
+ */
+ if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
+- if (inode_capable(inode, CAP_DAC_OVERRIDE))
++ if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
+ return 0;
+
+ /*
+@@ -353,7 +354,7 @@ int generic_permission(struct inode *inode, int mask)
+ */
+ mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
+ if (mask == MAY_READ)
+- if (inode_capable(inode, CAP_DAC_READ_SEARCH))
++ if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
+ return 0;
+
+ return -EACCES;
+@@ -2379,7 +2380,7 @@ static inline int check_sticky(struct inode *dir, struct inode *inode)
+ return 0;
+ if (uid_eq(dir->i_uid, fsuid))
+ return 0;
+- return !inode_capable(inode, CAP_FOWNER);
++ return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
+ }
+
+ /*
+diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
+index 0b18776..6152cbe 100644
+--- a/fs/xfs/xfs_ioctl.c
++++ b/fs/xfs/xfs_ioctl.c
+@@ -1215,7 +1215,7 @@ xfs_ioctl_setattr(
+ * cleared upon successful return from chown()
+ */
+ if ((ip->i_d.di_mode & (S_ISUID|S_ISGID)) &&
+- !inode_capable(VFS_I(ip), CAP_FSETID))
++ !capable_wrt_inode_uidgid(VFS_I(ip), CAP_FSETID))
+ ip->i_d.di_mode &= ~(S_ISUID|S_ISGID);
+
+ /*
+diff --git a/include/linux/capability.h b/include/linux/capability.h
+index a6ee1f9..84b13ad 100644
+--- a/include/linux/capability.h
++++ b/include/linux/capability.h
+@@ -210,7 +210,7 @@ extern bool has_ns_capability_noaudit(struct task_struct *t,
+ struct user_namespace *ns, int cap);
+ extern bool capable(int cap);
+ extern bool ns_capable(struct user_namespace *ns, int cap);
+-extern bool inode_capable(const struct inode *inode, int cap);
++extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
+ extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
+
+ /* audit system wants to get cap info from files as well */
+diff --git a/kernel/capability.c b/kernel/capability.c
+index 84b2bbf..a5cf13c 100644
+--- a/kernel/capability.c
++++ b/kernel/capability.c
+@@ -424,23 +424,19 @@ bool capable(int cap)
+ EXPORT_SYMBOL(capable);
+
+ /**
+- * inode_capable - Check superior capability over inode
++ * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
+ * @inode: The inode in question
+ * @cap: The capability in question
+ *
+- * Return true if the current task has the given superior capability
+- * targeted at it's own user namespace and that the given inode is owned
+- * by the current user namespace or a child namespace.
+- *
+- * Currently we check to see if an inode is owned by the current
+- * user namespace by seeing if the inode's owner maps into the
+- * current user namespace.
+- *
++ * Return true if the current task has the given capability targeted at
++ * its own user namespace and that the given inode's uid and gid are
++ * mapped into the current user namespace.
+ */
+-bool inode_capable(const struct inode *inode, int cap)
++bool capable_wrt_inode_uidgid(const struct inode *inode, int cap)
+ {
+ struct user_namespace *ns = current_user_ns();
+
+- return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid);
++ return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid) &&
++ kgid_has_mapping(ns, inode->i_gid);
+ }
+-EXPORT_SYMBOL(inode_capable);
++EXPORT_SYMBOL(capable_wrt_inode_uidgid);
+--
+1.9.3
+
diff --git a/kernel.spec b/kernel.spec
index 7f304fa..6b007f1 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -737,6 +737,9 @@ Patch25100: dm-thin-update-discard_granularity-to-reflect-the-thin-pool-blocksiz
#rhbz 1103528
Patch25101: elantech-Deal-with-clickpads-reporting-right-button-.patch
+#CVE-2014-4014 rhbz 1107966 1109836
+Patch25102: fs-userns-Change-inode_capable-to-capable_wrt_inode_.patch
+
# END OF PATCH DEFINITIONS
%endif
@@ -1442,6 +1445,9 @@ ApplyPatch dm-thin-update-discard_granularity-to-reflect-the-thin-pool-blocksize
#rhbz 1103528
ApplyPatch elantech-Deal-with-clickpads-reporting-right-button-.patch
+#CVE-2014-4014 rhbz 1107966 1109836
+ApplyPatch fs-userns-Change-inode_capable-to-capable_wrt_inode_.patch
+
# END OF PATCH APPLICATIONS
%endif
@@ -2254,6 +2260,9 @@ fi
# ||----w |
# || ||
%changelog
+* Mon Jun 16 2014 Josh Boyer <jwboyer at fedoraproject.org>
+- CVE-2014-4014 possible priv escalation in userns (rhbz 1107966 1109836)
+
* Wed Jun 11 2014 Josh Boyer <jwboyer at fedoraproject.org>
- Fix elantech right click on Dell vostro 5470 (rhbz 1103528)
- Fix fstrim on dm-thin volume data (rhbz 1106856)
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