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{compat_,}verify_iovec(): switch to generic copying of iovecs
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use {compat_,}rw_copy_check_uvector().  As the result, we are
guaranteed that all iovecs seen in ->msg_iov by ->sendmsg()
and ->recvmsg() will pass access_ok().

Signed-off-by: Al Viro <[email protected]>
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Al Viro committed Nov 19, 2014
1 parent 666547f commit 0844932
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Showing 3 changed files with 37 additions and 89 deletions.
51 changes: 15 additions & 36 deletions net/compat.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,33 +31,6 @@
#include <asm/uaccess.h>
#include <net/compat.h>

static inline int iov_from_user_compat_to_kern(struct iovec *kiov,
struct compat_iovec __user *uiov32,
int niov)
{
int tot_len = 0;

while (niov > 0) {
compat_uptr_t buf;
compat_size_t len;

if (get_user(len, &uiov32->iov_len) ||
get_user(buf, &uiov32->iov_base))
return -EFAULT;

if (len > INT_MAX - tot_len)
len = INT_MAX - tot_len;

tot_len += len;
kiov->iov_base = compat_ptr(buf);
kiov->iov_len = (__kernel_size_t) len;
uiov32++;
kiov++;
niov--;
}
return tot_len;
}

int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
{
compat_uptr_t tmp1, tmp2, tmp3;
Expand All @@ -80,13 +53,15 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
}

/* I've named the args so it is easy to tell whose space the pointers are in. */
int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *iov,
struct sockaddr_storage *kern_address, int mode)
{
int tot_len;
struct compat_iovec __user *p;
struct iovec *res;
int err;

if (kern_msg->msg_name && kern_msg->msg_namelen) {
if (mode == VERIFY_READ) {
if (mode == WRITE) {
int err = move_addr_to_kernel(kern_msg->msg_name,
kern_msg->msg_namelen,
kern_address);
Expand All @@ -99,13 +74,17 @@ int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
kern_msg->msg_namelen = 0;
}

tot_len = iov_from_user_compat_to_kern(kern_iov,
(struct compat_iovec __user *)kern_msg->msg_iov,
kern_msg->msg_iovlen);
if (tot_len >= 0)
kern_msg->msg_iov = kern_iov;
if (kern_msg->msg_iovlen > UIO_MAXIOV)
return -EMSGSIZE;

return tot_len;
p = (struct compat_iovec __user *)kern_msg->msg_iov;
err = compat_rw_copy_check_uvector(mode, p, kern_msg->msg_iovlen,
UIO_FASTIOV, iov, &res);
if (err >= 0)
kern_msg->msg_iov = res;
else if (res != iov)
kfree(res);
return err;
}

/* Bleech... */
Expand Down
37 changes: 14 additions & 23 deletions net/core/iovec.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,13 @@

int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode)
{
int size, ct, err;
struct iovec *res;
int err;

if (m->msg_name && m->msg_namelen) {
if (mode == VERIFY_READ) {
void __user *namep;
namep = (void __user __force *) m->msg_name;
err = move_addr_to_kernel(namep, m->msg_namelen,
if (mode == WRITE) {
void __user *namep = (void __user __force *)m->msg_name;
int err = move_addr_to_kernel(namep, m->msg_namelen,
address);
if (err < 0)
return err;
Expand All @@ -53,24 +53,15 @@ int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *a
m->msg_name = NULL;
m->msg_namelen = 0;
}

size = m->msg_iovlen * sizeof(struct iovec);
if (copy_from_user(iov, (void __user __force *) m->msg_iov, size))
return -EFAULT;

m->msg_iov = iov;
err = 0;

for (ct = 0; ct < m->msg_iovlen; ct++) {
size_t len = iov[ct].iov_len;

if (len > INT_MAX - err) {
len = INT_MAX - err;
iov[ct].iov_len = len;
}
err += len;
}

if (m->msg_iovlen > UIO_MAXIOV)
return -EMSGSIZE;

err = rw_copy_check_uvector(mode, (void __user __force *)m->msg_iov,
m->msg_iovlen, UIO_FASTIOV, iov, &res);
if (err >= 0)
m->msg_iov = res;
else if (res != iov)
kfree(res);
return err;
}

Expand Down
38 changes: 8 additions & 30 deletions net/socket.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2032,24 +2032,14 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
return err;
}

if (msg_sys->msg_iovlen > UIO_FASTIOV) {
err = -EMSGSIZE;
if (msg_sys->msg_iovlen > UIO_MAXIOV)
goto out;
err = -ENOMEM;
iov = kmalloc(msg_sys->msg_iovlen * sizeof(struct iovec),
GFP_KERNEL);
if (!iov)
goto out;
}

/* This will also move the address data into kernel space */
if (MSG_CMSG_COMPAT & flags) {
err = verify_compat_iovec(msg_sys, iov, &address, VERIFY_READ);
} else
err = verify_iovec(msg_sys, iov, &address, VERIFY_READ);
if (MSG_CMSG_COMPAT & flags)
err = verify_compat_iovec(msg_sys, iovstack, &address, WRITE);
else
err = verify_iovec(msg_sys, iovstack, &address, WRITE);
if (err < 0)
goto out_freeiov;
iov = msg_sys->msg_iov;
total_len = err;

err = -ENOBUFS;
Expand Down Expand Up @@ -2118,7 +2108,6 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
out_freeiov:
if (iov != iovstack)
kfree(iov);
out:
return err;
}

Expand Down Expand Up @@ -2244,28 +2233,18 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
return err;
}

if (msg_sys->msg_iovlen > UIO_FASTIOV) {
err = -EMSGSIZE;
if (msg_sys->msg_iovlen > UIO_MAXIOV)
goto out;
err = -ENOMEM;
iov = kmalloc(msg_sys->msg_iovlen * sizeof(struct iovec),
GFP_KERNEL);
if (!iov)
goto out;
}

/* Save the user-mode address (verify_iovec will change the
* kernel msghdr to use the kernel address space)
*/
uaddr = (__force void __user *)msg_sys->msg_name;
uaddr_len = COMPAT_NAMELEN(msg);
if (MSG_CMSG_COMPAT & flags)
err = verify_compat_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
err = verify_compat_iovec(msg_sys, iovstack, &addr, READ);
else
err = verify_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
err = verify_iovec(msg_sys, iovstack, &addr, READ);
if (err < 0)
goto out_freeiov;
iov = msg_sys->msg_iov;
total_len = err;

cmsg_ptr = (unsigned long)msg_sys->msg_control;
Expand Down Expand Up @@ -2306,7 +2285,6 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
out_freeiov:
if (iov != iovstack)
kfree(iov);
out:
return err;
}

Expand Down

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