Messages in this thread Patch in this message | | | Subject | [PATCH] Allow either tid or pid in SCM_CREDENTIALS struct ucred | From | Jeremy Fitzhardinge <> | Date | Thu, 21 Aug 2003 00:39:19 -0700 |
| |
Andrew,
Could you stick this in -mm and see if anyone complains? It fixes an apparent bug in the validation of the SCM_CREDENTIALS structure in a unix-domain socket sendmsg().
I found this because with Valgrind, the sendmsg call is being done in a different thread from the one which did a getpid() to fill out the SCM_CREDENTIALS structure, which causes the kernel to fail the sendmsg with EPERM. In the general case, this would cause a multithreaded program sending messages with SCM_CREDENTIALS to appear schizophrenic to a recipient, because every message would have a different pid depending on which thread happened to send it.
If you use SCM_CREDENTIALS with a unix domain socket, and you're non-root, then the kernel double-checks the values you supply for pid, uid and gid in struct ucred. In the case of uid or gid, it allows any of effective, saved or real uid/gid. In the case of pid, it only allows current->pid, which is actually the tid.
This patch also makes it accept tgid in the SCM_CREDENTIALS pid field. That is, a threaded program can either supply the ID of the whole process (tgid) or a particular thread (pid).
Thanks, J
net/core/scm.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletion(-)
diff -puN net/core/scm.c~scm_allow_tgid net/core/scm.c --- local-2.6/net/core/scm.c~scm_allow_tgid 2003-08-20 19:52:40.000000000 -0700 +++ local-2.6-jeremy/net/core/scm.c 2003-08-21 00:28:10.295629745 -0700 @@ -41,7 +41,8 @@ static __inline__ int scm_check_creds(struct ucred *creds) { - if ((creds->pid == current->pid || capable(CAP_SYS_ADMIN)) && + if (((creds->pid == current->pid || creds->pid == current->tgid) || + capable(CAP_SYS_ADMIN)) && ((creds->uid == current->uid || creds->uid == current->euid || creds->uid == current->suid) || capable(CAP_SETUID)) && ((creds->gid == current->gid || creds->gid == current->egid || _
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |