diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2014-06-10 12:45:42 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-16 13:42:52 -0700 |
| commit | 4f80c6c1825a91cecf3b3bd19c824e768d98fe48 (patch) | |
| tree | cdb4e44336c2a34d559d3a609784d74a37c7301a /fs | |
| parent | 853771148c5aa5998c423ed4dddd7605d4b4c949 (diff) | |
fs,userns: Change inode_capable to capable_wrt_inode_uidgid
commit 23adbe12ef7d3d4195e80800ab36b37bee28cd03 upstream.
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@mit.edu>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/attr.c | 8 | ||||
| -rw-r--r-- | fs/inode.c | 10 | ||||
| -rw-r--r-- | fs/namei.c | 11 |
3 files changed, 17 insertions, 12 deletions
diff --git a/fs/attr.c b/fs/attr.c index 8dd5825ec70..66fa6251c39 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 00d5fc3b86e..1b300a06b8b 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1837,14 +1837,18 @@ 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 1211ee5a1cb..6ac16a37ded 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -321,10 +321,11 @@ 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; } @@ -334,7 +335,7 @@ 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; /* @@ -342,7 +343,7 @@ 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; @@ -2199,7 +2200,7 @@ 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); } /* |