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Merge tag 'caps-pr-20251204' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux

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Pull capabilities update from Serge Hallyn:
 "Ryan Foster had sent a patch to add testing of the
  rootid_owns_currentns() function. That patch pointed out
  that this function was not as clear as it should be. Fix it:

   - Clarify the intent of the function in the name

   - Split the function so that the base functionality is easier to test
     from a kunit test"

* tag 'caps-pr-20251204' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux:
  Clarify the rootid_owns_currentns
This commit is contained in:
Linus Torvalds
2025-12-04 20:10:28 -08:00
parent deb879faa9 9891d2f79a
commit 2061f18ad7
1 changed files with 22 additions and 12 deletions
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34
security/commoncap.c
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@@ -358,17 +358,17 @@ int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry)
return error;
}
static bool rootid_owns_currentns(vfsuid_t rootvfsuid)
/**
* kuid_root_in_ns - check whether the given kuid is root in the given ns
* @kuid: the kuid to be tested
* @ns: the user namespace to test against
*
* Returns true if @kuid represents the root user in @ns, false otherwise.
*/
static bool kuid_root_in_ns(kuid_t kuid, struct user_namespace *ns)
{
struct user_namespace *ns;
kuid_t kroot;
if (!vfsuid_valid(rootvfsuid))
return false;
kroot = vfsuid_into_kuid(rootvfsuid);
for (ns = current_user_ns();; ns = ns->parent) {
if (from_kuid(ns, kroot) == 0)
for (;; ns = ns->parent) {
if (from_kuid(ns, kuid) == 0)
return true;
if (ns == &init_user_ns)
break;
@@ -377,6 +377,16 @@ static bool rootid_owns_currentns(vfsuid_t rootvfsuid)
return false;
}
static bool vfsuid_root_in_currentns(vfsuid_t vfsuid)
{
kuid_t kuid;
if (!vfsuid_valid(vfsuid))
return false;
kuid = vfsuid_into_kuid(vfsuid);
return kuid_root_in_ns(kuid, current_user_ns());
}
static __u32 sansflags(__u32 m)
{
return m & ~VFS_CAP_FLAGS_EFFECTIVE;
@@ -481,7 +491,7 @@ int cap_inode_getsecurity(struct mnt_idmap *idmap,
goto out_free;
}
if (!rootid_owns_currentns(vfsroot)) {
if (!vfsuid_root_in_currentns(vfsroot)) {
size = -EOVERFLOW;
goto out_free;
}
@@ -722,7 +732,7 @@ int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
/* Limit the caps to the mounter of the filesystem
* or the more limited uid specified in the xattr.
*/
if (!rootid_owns_currentns(rootvfsuid))
if (!vfsuid_root_in_currentns(rootvfsuid))
return -ENODATA;
cpu_caps->permitted.val = le32_to_cpu(caps->data[0].permitted);