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Merge branch 'userns-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 

Pull user namespace update from Eric Biederman:
 "There are several pieces of active development, but only a single
  change made it through the gauntlet to be ready for v5.12. That change
  is tightening up the semantics of the v3 capabilities xattr. It is
  just short of being a bug-fix/security issue as no user space is known
  to even generate the problem case"

* 'userns-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  capabilities: Don't allow writing ambiguous v3 file capabilities
This commit is contained in:
Linus Torvalds 2021-02-22 17:13:33 -08:00
parent ac9e806c9c 95ebabde38
commit 7b0b78df9c
1 changed files with 11 additions and 1 deletions
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12
security/commoncap.c
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@ -500,7 +500,8 @@ int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size)
__u32 magic, nsmagic;
struct inode *inode = d_backing_inode(dentry);
struct user_namespace *task_ns = current_user_ns(),
*fs_ns = inode->i_sb->s_user_ns;
*fs_ns = inode->i_sb->s_user_ns,
*ancestor;
kuid_t rootid;
size_t newsize;
@ -523,6 +524,15 @@ int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size)
if (nsrootid == -1)
return -EINVAL;
/*
* Do not allow allow adding a v3 filesystem capability xattr
* if the rootid field is ambiguous.
*/
for (ancestor = task_ns->parent; ancestor; ancestor = ancestor->parent) {
if (from_kuid(ancestor, rootid) == 0)
return -EINVAL;
}
newsize = sizeof(struct vfs_ns_cap_data);
nscap = kmalloc(newsize, GFP_ATOMIC);
if (!nscap)