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authorLinus Torvalds <torvalds@linux-foundation.org>2012-12-18 10:55:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-18 10:55:28 -0800
commita2faf2fc534f57ba26bc4d613795236ed4f5fb1c (patch)
treed75c4daadb469c8f08c498532fbf1fff68879e69 /kernel/cred.c
parent4351654e3ddf86a04966163dce4def586303e5cc (diff)
parent5155040ed349950e16c093ba8e65ad534994df2a (diff)
downloadlinux-a2faf2fc534f57ba26bc4d613795236ed4f5fb1c.tar.gz
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull (again) user namespace infrastructure changes from Eric Biederman: "Those bugs, those darn embarrasing bugs just want don't want to get fixed. Linus I just updated my mirror of your kernel.org tree and it appears you successfully pulled everything except the last 4 commits that fix those embarrasing bugs. When you get a chance can you please repull my branch" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: userns: Fix typo in description of the limitation of userns_install userns: Add a more complete capability subset test to commit_creds userns: Require CAP_SYS_ADMIN for most uses of setns. Fix cap_capable to only allow owners in the parent user namespace to have caps.
Diffstat (limited to 'kernel/cred.c')
-rw-r--r--kernel/cred.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/kernel/cred.c b/kernel/cred.c
index 8888afb846e..e0573a43c7d 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -372,6 +372,31 @@ error_put:
return ret;
}
+static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
+{
+ const struct user_namespace *set_ns = set->user_ns;
+ const struct user_namespace *subset_ns = subset->user_ns;
+
+ /* If the two credentials are in the same user namespace see if
+ * the capabilities of subset are a subset of set.
+ */
+ if (set_ns == subset_ns)
+ return cap_issubset(subset->cap_permitted, set->cap_permitted);
+
+ /* The credentials are in a different user namespaces
+ * therefore one is a subset of the other only if a set is an
+ * ancestor of subset and set->euid is owner of subset or one
+ * of subsets ancestors.
+ */
+ for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
+ if ((set_ns == subset_ns->parent) &&
+ uid_eq(subset_ns->owner, set->euid))
+ return true;
+ }
+
+ return false;
+}
+
/**
* commit_creds - Install new credentials upon the current task
* @new: The credentials to be assigned
@@ -410,7 +435,7 @@ int commit_creds(struct cred *new)
!gid_eq(old->egid, new->egid) ||
!uid_eq(old->fsuid, new->fsuid) ||
!gid_eq(old->fsgid, new->fsgid) ||
- !cap_issubset(new->cap_permitted, old->cap_permitted)) {
+ !cred_cap_issubset(old, new)) {
if (task->mm)
set_dumpable(task->mm, suid_dumpable);
task->pdeath_signal = 0;