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authorUlrich Drepper <drepper@redhat.com>1998-07-21 13:58:40 +0000
committerUlrich Drepper <drepper@redhat.com>1998-07-21 13:58:40 +0000
commitc13de8877bb60d2a7cc23e6c36e6ed1b25b3b624 (patch)
treec3ea38566facfffd85986f89060eb596fcc4ab5d /sysdeps
parent2b25f93f7ad09ec1c2b93e07ceae577b56b44a80 (diff)
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Update.
1998-07-21 16:08 -0400 Zack Weinberg <zack@rabi.phys.columbia.edu> * sysdeps/unix/sysv/linux/sendmsg.c: If passing a SCM_CREDS message, copy the buffer and resize it to what the kernel wants to see. Bug found and analyzed by Thorsten Kukuk <kukuk@weber-eb.uni-paderborn.de>
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/unix/sysv/linux/sendmsg.c100
1 files changed, 67 insertions, 33 deletions
diff --git a/sysdeps/unix/sysv/linux/sendmsg.c b/sysdeps/unix/sysv/linux/sendmsg.c
index 16774c4..c0f009d 100644
--- a/sysdeps/unix/sysv/linux/sendmsg.c
+++ b/sysdeps/unix/sysv/linux/sendmsg.c
@@ -18,6 +18,8 @@
#include <sys/socket.h>
#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
#include <unistd.h>
#include <asm/posix_types.h>
@@ -25,12 +27,24 @@
/* The kernel expects this structure in SCM_CREDS messages.
* Note: sizeof(struct __kernel_ucred) <= sizeof(struct cmsgcred) must hold.
*/
-struct __kernel_ucred
-{
- __kernel_pid_t pid;
- __kernel_uid_t uid;
- __kernel_gid_t gid;
-};
+struct kernel_ucred
+ {
+ __kernel_pid_t pid;
+ __kernel_uid_t uid;
+ __kernel_gid_t gid;
+ };
+
+struct credmsg
+ {
+ struct cmsghdr cm;
+ struct cmsgcred cc;
+ };
+
+struct kcredmsg
+ {
+ struct cmsghdr cm;
+ struct kernel_ucred cc;
+ };
extern int __syscall_sendmsg (int, const struct msghdr *, int);
@@ -39,51 +53,71 @@ extern int __syscall_sendmsg (int, const struct msghdr *, int);
int
__libc_sendmsg (int fd, const struct msghdr *message, int flags)
{
+ struct msghdr m;
+ char *buf, *a, *b;
+ struct credmsg *cred = 0;
+ struct kcredmsg *kcred;
struct cmsghdr *cm;
- struct cmsgcred *cc;
- struct __kernel_ucred *u;
+ long int offset = 0;
pid_t pid;
/* Preprocess the message control block for SCM_CREDS. */
- cm = CMSG_FIRSTHDR (message);
- while (cm)
+ if (message->msg_controllen)
{
- if (cm->cmsg_type == SCM_CREDS)
+ cm = CMSG_FIRSTHDR (message);
+ while (cm)
{
- if (cm->cmsg_len < CMSG_SPACE (sizeof (struct cmsgcred)))
+ if (cm->cmsg_type == SCM_CREDS)
{
- __set_errno (EINVAL);
- return -1;
+ if (cred ||
+ cm->cmsg_len < CMSG_LEN (sizeof (struct cmsgcred)))
+ {
+ __set_errno (EINVAL);
+ return -1;
+ }
+ else
+ {
+ cred = (struct credmsg *) cm;
+ offset = (char *) cm - (char *) message->msg_control;
+ }
}
+ cm = CMSG_NXTHDR ((struct msghdr *) message, cm);
+ }
+
+ if (cred)
+ {
+ buf = alloca (message->msg_controllen);
+ memcpy (buf, message->msg_control, message->msg_controllen);
+ kcred = (struct kcredmsg *) (buf + offset);
+ a = (char *) kcred + CMSG_LEN (sizeof (struct kernel_ucred));
+ b = (char *) kcred + CMSG_LEN (sizeof (struct cmsgcred));
+ memmove (a, b, message->msg_controllen - (b - buf));
+
+ kcred->cm.cmsg_len = CMSG_LEN (sizeof (struct kernel_ucred));
- u = (struct __kernel_ucred *) CMSG_DATA (cm);
- cc = (struct cmsgcred *) CMSG_DATA (cm);
/* Linux expects the calling process to pass in
its credentials, and sanity checks them.
You can send real, effective, or set- uid and gid.
If the user hasn't filled in the buffer, we default to
real uid and gid. */
pid = __getpid ();
- if (cc->cmcred_pid != pid)
- {
- u->pid = pid;
- u->uid = __getuid ();
- u->gid = __getgid ();
- }
+ if (cred->cc.cmcred_pid != pid)
+ {
+ kcred->cc.pid = pid;
+ kcred->cc.uid = __getuid ();
+ kcred->cc.gid = __getgid ();
+ }
else
- {
- struct __kernel_ucred v;
- v.pid = cc->cmcred_pid;
- v.uid = cc->cmcred_uid;
- v.gid = cc->cmcred_gid;
- u->pid = v.pid;
- u->uid = v.uid;
- u->gid = v.gid;
- }
+ {
+ kcred->cc.uid = cred->cc.cmcred_uid;
+ kcred->cc.gid = cred->cc.cmcred_gid;
+ }
+ memcpy (&m, message, sizeof (struct msghdr));
+ m.msg_control = buf;
+ m.msg_controllen -= b - a;
+ return __syscall_sendmsg (fd, &m, flags);
}
- cm = CMSG_NXTHDR ((struct msghdr *) message, cm);
}
-
return __syscall_sendmsg (fd, message, flags);
}