Bug#327416: CAN-2005-2490/CAN-2005-2492: Two sendmsg() related vulnerabilites
Package: linux-2.6
Severity: important
Tags: security
[Severity important only, as amd64 is not yet officially in the archive]
These patches were posted as part of the stable review cycle on linux-kernel,
they're probably available in git already.
CAN-2005-2490: (local privilege escalation on amd64)
When we copy 32bit ->msg_control contents to kernel, we walk the same
userland data twice without sanity checks on the second pass.
Second version of this patch: the original broke with 64-bit arches
running 32-bit-compat-mode executables doing sendmsg() syscalls with
unaligned CMSG data areas
Another thing is that we use kmalloc() to allocate and sock_kfree_s()
to free afterwards; less serious, but also needs fixing.
Patch by Al Viro, David Miller, David Woodhouse
Signed-off-by: Chris Wright <chrisw@osdl.org>
---
include/net/compat.h | 2 +-
net/compat.c | 44 ++++++++++++++++++++++++++------------------
net/socket.c | 3 ++-
3 files changed, 29 insertions(+), 20 deletions(-)
Index: linux-2.6.13.y/include/net/compat.h
===================================================================
--- linux-2.6.13.y.orig/include/net/compat.h
+++ linux-2.6.13.y/include/net/compat.h
@@ -33,7 +33,7 @@ extern asmlinkage long compat_sys_sendms
extern asmlinkage long compat_sys_recvmsg(int,struct compat_msghdr __user *,unsigned);
extern asmlinkage long compat_sys_getsockopt(int, int, int, char __user *, int __user *);
extern int put_cmsg_compat(struct msghdr*, int, int, int, void *);
-extern int cmsghdr_from_user_compat_to_kern(struct msghdr *, unsigned char *,
+extern int cmsghdr_from_user_compat_to_kern(struct msghdr *, struct sock *, unsigned char *,
int);
#endif /* NET_COMPAT_H */
Index: linux-2.6.13.y/net/compat.c
===================================================================
--- linux-2.6.13.y.orig/net/compat.c
+++ linux-2.6.13.y/net/compat.c
@@ -135,13 +135,14 @@ static inline struct compat_cmsghdr __us
* thus placement) of cmsg headers and length are different for
* 32-bit apps. -DaveM
*/
-int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg,
+int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
unsigned char *stackbuf, int stackbuf_size)
{
struct compat_cmsghdr __user *ucmsg;
struct cmsghdr *kcmsg, *kcmsg_base;
compat_size_t ucmlen;
__kernel_size_t kcmlen, tmp;
+ int err = -EFAULT;
kcmlen = 0;
kcmsg_base = kcmsg = (struct cmsghdr *)stackbuf;
@@ -156,6 +157,7 @@ int cmsghdr_from_user_compat_to_kern(str
tmp = ((ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg))) +
CMSG_ALIGN(sizeof(struct cmsghdr)));
+ tmp = CMSG_ALIGN(tmp);
kcmlen += tmp;
ucmsg = cmsg_compat_nxthdr(kmsg, ucmsg, ucmlen);
}
@@ -167,30 +169,34 @@ int cmsghdr_from_user_compat_to_kern(str
* until we have successfully copied over all of the data
* from the user.
*/
- if(kcmlen > stackbuf_size)
- kcmsg_base = kcmsg = kmalloc(kcmlen, GFP_KERNEL);
- if(kcmsg == NULL)
+ if (kcmlen > stackbuf_size)
+ kcmsg_base = kcmsg = sock_kmalloc(sk, kcmlen, GFP_KERNEL);
+ if (kcmsg == NULL)
return -ENOBUFS;
/* Now copy them over neatly. */
memset(kcmsg, 0, kcmlen);
ucmsg = CMSG_COMPAT_FIRSTHDR(kmsg);
while(ucmsg != NULL) {
- __get_user(ucmlen, &ucmsg->cmsg_len);
+ if (__get_user(ucmlen, &ucmsg->cmsg_len))
+ goto Efault;
+ if (!CMSG_COMPAT_OK(ucmlen, ucmsg, kmsg))
+ goto Einval;
tmp = ((ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg))) +
CMSG_ALIGN(sizeof(struct cmsghdr)));
+ if ((char *)kcmsg_base + kcmlen - (char *)kcmsg < CMSG_ALIGN(tmp))
+ goto Einval;
kcmsg->cmsg_len = tmp;
- __get_user(kcmsg->cmsg_level, &ucmsg->cmsg_level);
- __get_user(kcmsg->cmsg_type, &ucmsg->cmsg_type);
-
- /* Copy over the data. */
- if(copy_from_user(CMSG_DATA(kcmsg),
- CMSG_COMPAT_DATA(ucmsg),
- (ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg)))))
- goto out_free_efault;
+ tmp = CMSG_ALIGN(tmp);
+ if (__get_user(kcmsg->cmsg_level, &ucmsg->cmsg_level) ||
+ __get_user(kcmsg->cmsg_type, &ucmsg->cmsg_type) ||
+ copy_from_user(CMSG_DATA(kcmsg),
+ CMSG_COMPAT_DATA(ucmsg),
+ (ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg)))))
+ goto Efault;
/* Advance. */
- kcmsg = (struct cmsghdr *)((char *)kcmsg + CMSG_ALIGN(tmp));
+ kcmsg = (struct cmsghdr *)((char *)kcmsg + tmp);
ucmsg = cmsg_compat_nxthdr(kmsg, ucmsg, ucmlen);
}
@@ -199,10 +205,12 @@ int cmsghdr_from_user_compat_to_kern(str
kmsg->msg_controllen = kcmlen;
return 0;
-out_free_efault:
- if(kcmsg_base != (struct cmsghdr *)stackbuf)
- kfree(kcmsg_base);
- return -EFAULT;
+Einval:
+ err = -EINVAL;
+Efault:
+ if (kcmsg_base != (struct cmsghdr *)stackbuf)
+ sock_kfree_s(sk, kcmsg_base, kcmlen);
+ return err;
}
int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *data)
Index: linux-2.6.13.y/net/socket.c
===================================================================
--- linux-2.6.13.y.orig/net/socket.c
+++ linux-2.6.13.y/net/socket.c
@@ -1739,10 +1739,11 @@ asmlinkage long sys_sendmsg(int fd, stru
goto out_freeiov;
ctl_len = msg_sys.msg_controllen;
if ((MSG_CMSG_COMPAT & flags) && ctl_len) {
- err = cmsghdr_from_user_compat_to_kern(&msg_sys, ctl, sizeof(ctl));
+ err = cmsghdr_from_user_compat_to_kern(&msg_sys, sock->sk, ctl, sizeof(ctl));
if (err)
goto out_freeiov;
ctl_buf = msg_sys.msg_control;
+ ctl_len = msg_sys.msg_controllen;
} else if (ctl_len) {
if (ctl_len > sizeof(ctl))
{
Minor update from David Miller for clean sparc64 build.
diff --git a/include/net/compat.h b/include/net/compat.h
--- a/include/net/compat.h
+++ b/include/net/compat.h
@@ -33,7 +33,8 @@ extern asmlinkage long compat_sys_sendms
extern asmlinkage long compat_sys_recvmsg(int,struct compat_msghdr __user *,unsigned);
extern asmlinkage long compat_sys_getsockopt(int, int, int, char __user *, int __user *);
extern int put_cmsg_compat(struct msghdr*, int, int, int, void *);
-extern int cmsghdr_from_user_compat_to_kern(struct msghdr *, struct sock *, unsigned char *,
- int);
+
+struct sock;
+extern int cmsghdr_from_user_compat_to_kern(struct msghdr *, struct sock *, unsigned char *, int);
#endif /* NET_COMPAT_H */
CAN-2005-2492 (information leakage / DoS)
From: Al Viro <aviro@redhat.com>
Fix unchecked __get_user that could be tricked into generating a
memory read on an arbitrary address. The result of the read is not
returned directly but you may be able to divine some information about
it, or use the read to cause a crash on some architectures by reading
hardware state. CAN-2005-2492.
Fix from Al Viro, ack from Dave Miller.
Signed-off-by: Chris Wright <chrisw@osdl.org>
---
net/ipv4/raw.c | 2 +-
net/ipv6/raw.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6.13.y/net/ipv4/raw.c
===================================================================
--- linux-2.6.13.y.orig/net/ipv4/raw.c
+++ linux-2.6.13.y/net/ipv4/raw.c
@@ -358,7 +358,7 @@ static void raw_probe_proto_opt(struct f
if (type && code) {
get_user(fl->fl_icmp_type, type);
- __get_user(fl->fl_icmp_code, code);
+ get_user(fl->fl_icmp_code, code);
probed = 1;
}
break;
Index: linux-2.6.13.y/net/ipv6/raw.c
===================================================================
--- linux-2.6.13.y.orig/net/ipv6/raw.c
+++ linux-2.6.13.y/net/ipv6/raw.c
@@ -619,7 +619,7 @@ static void rawv6_probe_proto_opt(struct
if (type && code) {
get_user(fl->fl_icmp_type, type);
- __get_user(fl->fl_icmp_code, code);
+ get_user(fl->fl_icmp_code, code);
probed = 1;
}
break;
Cheers,
Moritz
-- System Information:
Debian Release: testing/unstable
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: i386 (i686)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.13
Locale: LANG=C, LC_CTYPE=de_DE.ISO-8859-15@euro (charmap=ISO-8859-15)
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