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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>
This commit is contained in:
Ulrich Drepper 1998-07-21 13:58:40 +00:00
parent 2b25f93f7a
commit c13de8877b
2 changed files with 74 additions and 33 deletions
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7
ChangeLog
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@ -1,3 +1,10 @@
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>
1998-07-20 Jose M. Moya <josem@gnu.org>
* hurd/hurdmsg.c (_S_msg_get_env_variable): Copy getenv return

100
sysdeps/unix/sysv/linux/sendmsg.c
View File

@ -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);
}