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Subject[PATCH 04/15] user_ns: convert fs/attr.c to targeted capabilities
Date
From: "Serge E. Hallyn" <serge.hallyn@canonical.com>

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
---
fs/attr.c | 20 +++++++++++++-------
1 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/fs/attr.c b/fs/attr.c
index 538e279..e0cf46a 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -29,6 +29,7 @@
int inode_change_ok(const struct inode *inode, struct iattr *attr)
{
unsigned int ia_valid = attr->ia_valid;
+ struct user_namespace *ns;

/*
* First check size constraints. These can't be overriden using
@@ -44,26 +45,28 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr)
if (ia_valid & ATTR_FORCE)
return 0;

+ ns = inode_userns(inode);
/* Make sure a caller can chown. */
if ((ia_valid & ATTR_UID) &&
- (current_fsuid() != inode->i_uid ||
- attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
+ (ns != current_user_ns() || current_fsuid() != inode->i_uid ||
+ attr->ia_uid != inode->i_uid) && !ns_capable(ns, CAP_CHOWN))
return -EPERM;

/* Make sure caller can chgrp. */
if ((ia_valid & ATTR_GID) &&
- (current_fsuid() != inode->i_uid ||
+ (ns != current_user_ns() || current_fsuid() != inode->i_uid ||
(!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
- !capable(CAP_CHOWN))
+ !ns_capable(ns, CAP_CHOWN))
return -EPERM;

/* Make sure a caller can chmod. */
if (ia_valid & ATTR_MODE) {
+ gid_t gid = (ia_valid & ATTR_GID) ? attr->ia_gid : inode->i_gid;
if (!inode_owner_or_capable(inode))
return -EPERM;
/* Also check the setgid bit! */
- if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
- inode->i_gid) && !capable(CAP_FSETID))
+ if ((ns != current_user_ns() || !in_group_p(gid)) &&
+ !ns_capable(ns, CAP_FSETID))
attr->ia_mode &= ~S_ISGID;
}

@@ -154,9 +157,12 @@ void setattr_copy(struct inode *inode, const struct iattr *attr)
inode->i_sb->s_time_gran);
if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
+ struct user_namespace *ns = inode_userns(inode);

- if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+ if ((ns != current_user_ns() || !in_group_p(inode->i_gid)) &&
+ !ns_capable(ns, CAP_FSETID))
mode &= ~S_ISGID;
+
inode->i_mode = mode;
}
}
--
1.7.5.4


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