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userns: Fail exec for suid and sgid binaries with ids outside our use…

…r namespace.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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1 parent a7c1938 commit 9e4a36ece652908276bc4abb4324ec56292453e1 @ebiederm ebiederm committed Nov 16, 2011
Showing with 5 additions and 0 deletions.
  1. +5 −0 fs/exec.c
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5 fs/exec.c
@@ -1291,8 +1291,11 @@ int prepare_binprm(struct linux_binprm *bprm)
if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
/* 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? */
@@ -1302,6 +1305,8 @@ 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;
}

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