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authorEric W. Biederman <ebiederm@xmission.com>2011-11-22 04:40:54 +0400
committerEric W. Biederman <ebiederm@xmission.com>2012-11-19 17:59:23 +0400
commit3cdf5b45ffbac294bcdfac0393df72f7687c01e8 (patch)
tree8f6d5339dc7fc40107aecd11612617dbff63134e
parentae11e0f18482bfe0cd83b9b61434ea7e0bd94e25 (diff)
downloadlinux-3cdf5b45ffbac294bcdfac0393df72f7687c01e8.tar.xz
userns: Ignore suid and sgid on binaries if the uid or gid can not be mapped
When performing an exec where the binary lives in one user namespace and the execing process lives in another usre namespace there is the possibility that the target uids can not be represented. Instead of failing the exec simply ignore the suid/sgid bits and run the binary with lower privileges. We already do this in the case of MNT_NOSUID so this should be a well tested code path. As the user and group are not changed this should not introduce any security issues. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
-rw-r--r--fs/exec.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 0039055b1fc6..aef0c2f19750 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1266,14 +1266,13 @@ int prepare_binprm(struct linux_binprm *bprm)
bprm->cred->egid = current_egid();
if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
- !current->no_new_privs) {
+ !current->no_new_privs &&
+ kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
+ kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
/* Set-uid? */
if (mode & S_ISUID) {
- if (!kuid_has_mapping(bprm->cred->user_ns, inode->i_uid))
- return -EPERM;
bprm->per_clear |= PER_CLEAR_ON_SETID;
bprm->cred->euid = inode->i_uid;
-
}
/* Set-gid? */
@@ -1283,8 +1282,6 @@ int prepare_binprm(struct linux_binprm *bprm)
* executable.
*/
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
- if (!kgid_has_mapping(bprm->cred->user_ns, inode->i_gid))
- return -EPERM;
bprm->per_clear |= PER_CLEAR_ON_SETID;
bprm->cred->egid = inode->i_gid;
}