From c7fd0d48bde943e228e9c28ce971a22d6a1744c4 Mon Sep 17 00:00:00 2001 From: Matthew Daley Date: Fri, 14 Oct 2011 18:45:03 +0000 Subject: x25: Validate incoming call user data lengths X.25 call user data is being copied in its entirety from incoming messages without consideration to the size of the destination buffers, leading to possible buffer overflows. Validate incoming call user data lengths before these copies are performed. It appears this issue was noticed some time ago, however nothing seemed to come of it: see http://www.spinics.net/lists/linux-x25/msg00043.html and commit 8db09f26f912f7c90c764806e804b558da520d4f. Signed-off-by: Matthew Daley Acked-by: Eric Dumazet Tested-by: Andrew Hendry Cc: stable Signed-off-by: David S. Miller --- net/x25/af_x25.c | 6 ++++++ net/x25/x25_in.c | 3 +++ 2 files changed, 9 insertions(+) (limited to 'net/x25') diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index d30615419b4d..a4bd1720e39b 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -958,6 +958,12 @@ int x25_rx_call_request(struct sk_buff *skb, struct x25_neigh *nb, goto out_clear_request; skb_pull(skb,len); + /* + * Ensure that the amount of call user data is valid. + */ + if (skb->len > X25_MAX_CUD_LEN) + goto out_clear_request; + /* * Find a listener for the particular address/cud pair. */ diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c index 0b073b51b183..63488fd4885a 100644 --- a/net/x25/x25_in.c +++ b/net/x25/x25_in.c @@ -127,6 +127,9 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp * Copy any Call User Data. */ if (skb->len > 0) { + if (skb->len > X25_MAX_CUD_LEN) + goto out_clear; + skb_copy_from_linear_data(skb, x25->calluserdata.cuddata, skb->len); -- cgit v1.2.1 From cb101ed2c3c7c0224d16953fe77bfb9d6c2cb9df Mon Sep 17 00:00:00 2001 From: Matthew Daley Date: Fri, 14 Oct 2011 18:45:04 +0000 Subject: x25: Handle undersized/fragmented skbs There are multiple locations in the X.25 packet layer where a skb is assumed to be of at least a certain size and that all its data is currently available at skb->data. These assumptions are not checked, hence buffer overreads may occur. Use pskb_may_pull to check these minimal size assumptions and ensure that data is available at skb->data when necessary, as well as use skb_copy_bits where needed. Signed-off-by: Matthew Daley Cc: Eric Dumazet Cc: Andrew Hendry Cc: stable Acked-by: Andrew Hendry Signed-off-by: David S. Miller --- net/x25/af_x25.c | 31 ++++++++++++++++++++++++------- net/x25/x25_dev.c | 6 ++++++ net/x25/x25_facilities.c | 10 ++++++---- net/x25/x25_in.c | 40 +++++++++++++++++++++++++++++++++++----- net/x25/x25_link.c | 3 +++ net/x25/x25_subr.c | 14 +++++++++++++- 6 files changed, 87 insertions(+), 17 deletions(-) (limited to 'net/x25') diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index a4bd1720e39b..aa567b09ea9a 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -91,7 +91,7 @@ int x25_parse_address_block(struct sk_buff *skb, int needed; int rc; - if (skb->len < 1) { + if (!pskb_may_pull(skb, 1)) { /* packet has no address block */ rc = 0; goto empty; @@ -100,7 +100,7 @@ int x25_parse_address_block(struct sk_buff *skb, len = *skb->data; needed = 1 + (len >> 4) + (len & 0x0f); - if (skb->len < needed) { + if (!pskb_may_pull(skb, needed)) { /* packet is too short to hold the addresses it claims to hold */ rc = -1; @@ -951,10 +951,10 @@ int x25_rx_call_request(struct sk_buff *skb, struct x25_neigh *nb, * * Facilities length is mandatory in call request packets */ - if (skb->len < 1) + if (!pskb_may_pull(skb, 1)) goto out_clear_request; len = skb->data[0] + 1; - if (skb->len < len) + if (!pskb_may_pull(skb, len)) goto out_clear_request; skb_pull(skb,len); @@ -964,6 +964,13 @@ int x25_rx_call_request(struct sk_buff *skb, struct x25_neigh *nb, if (skb->len > X25_MAX_CUD_LEN) goto out_clear_request; + /* + * Get all the call user data so it can be used in + * x25_find_listener and skb_copy_from_linear_data up ahead. + */ + if (!pskb_may_pull(skb, skb->len)) + goto out_clear_request; + /* * Find a listener for the particular address/cud pair. */ @@ -1172,6 +1179,9 @@ static int x25_sendmsg(struct kiocb *iocb, struct socket *sock, * byte of the user data is the logical value of the Q Bit. */ if (test_bit(X25_Q_BIT_FLAG, &x25->flags)) { + if (!pskb_may_pull(skb, 1)) + goto out_kfree_skb; + qbit = skb->data[0]; skb_pull(skb, 1); } @@ -1250,7 +1260,9 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock, struct x25_sock *x25 = x25_sk(sk); struct sockaddr_x25 *sx25 = (struct sockaddr_x25 *)msg->msg_name; size_t copied; - int qbit; + int qbit, header_len = x25->neighbour->extended ? + X25_EXT_MIN_LEN : X25_STD_MIN_LEN; + struct sk_buff *skb; unsigned char *asmptr; int rc = -ENOTCONN; @@ -1271,6 +1283,9 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock, skb = skb_dequeue(&x25->interrupt_in_queue); + if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) + goto out_free_dgram; + skb_pull(skb, X25_STD_MIN_LEN); /* @@ -1291,10 +1306,12 @@ static int x25_recvmsg(struct kiocb *iocb, struct socket *sock, if (!skb) goto out; + if (!pskb_may_pull(skb, header_len)) + goto out_free_dgram; + qbit = (skb->data[0] & X25_Q_BIT) == X25_Q_BIT; - skb_pull(skb, x25->neighbour->extended ? - X25_EXT_MIN_LEN : X25_STD_MIN_LEN); + skb_pull(skb, header_len); if (test_bit(X25_Q_BIT_FLAG, &x25->flags)) { asmptr = skb_push(skb, 1); diff --git a/net/x25/x25_dev.c b/net/x25/x25_dev.c index e547ca1578c3..fa2b41888bd9 100644 --- a/net/x25/x25_dev.c +++ b/net/x25/x25_dev.c @@ -32,6 +32,9 @@ static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb) unsigned short frametype; unsigned int lci; + if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) + return 0; + frametype = skb->data[2]; lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF); @@ -115,6 +118,9 @@ int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev, goto drop; } + if (!pskb_may_pull(skb, 1)) + return 0; + switch (skb->data[0]) { case X25_IFACE_DATA: diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c index f77e4e75f914..36384a1fa9f2 100644 --- a/net/x25/x25_facilities.c +++ b/net/x25/x25_facilities.c @@ -44,7 +44,7 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask) { - unsigned char *p = skb->data; + unsigned char *p; unsigned int len; *vc_fac_mask = 0; @@ -60,14 +60,16 @@ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae)); memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae)); - if (skb->len < 1) + if (!pskb_may_pull(skb, 1)) return 0; - len = *p++; + len = skb->data[0]; - if (len >= skb->len) + if (!pskb_may_pull(skb, 1 + len)) return -1; + p = skb->data + 1; + while (len > 0) { switch (*p & X25_FAC_CLASS_MASK) { case X25_FAC_CLASS_A: diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c index 63488fd4885a..a49cd4ec551a 100644 --- a/net/x25/x25_in.c +++ b/net/x25/x25_in.c @@ -107,6 +107,8 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp /* * Parse the data in the frame. */ + if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) + goto out_clear; skb_pull(skb, X25_STD_MIN_LEN); len = x25_parse_address_block(skb, &source_addr, @@ -130,9 +132,8 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp if (skb->len > X25_MAX_CUD_LEN) goto out_clear; - skb_copy_from_linear_data(skb, - x25->calluserdata.cuddata, - skb->len); + skb_copy_bits(skb, 0, x25->calluserdata.cuddata, + skb->len); x25->calluserdata.cudlength = skb->len; } if (!sock_flag(sk, SOCK_DEAD)) @@ -140,6 +141,9 @@ static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametyp break; } case X25_CLEAR_REQUEST: + if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) + goto out_clear; + x25_write_internal(sk, X25_CLEAR_CONFIRMATION); x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); break; @@ -167,6 +171,9 @@ static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametyp switch (frametype) { case X25_CLEAR_REQUEST: + if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) + goto out_clear; + x25_write_internal(sk, X25_CLEAR_CONFIRMATION); x25_disconnect(sk, 0, skb->data[3], skb->data[4]); break; @@ -180,6 +187,11 @@ static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametyp } return 0; + +out_clear: + x25_write_internal(sk, X25_CLEAR_REQUEST); + x25_start_t23timer(sk); + return 0; } /* @@ -209,6 +221,9 @@ static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametyp break; case X25_CLEAR_REQUEST: + if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) + goto out_clear; + x25_write_internal(sk, X25_CLEAR_CONFIRMATION); x25_disconnect(sk, 0, skb->data[3], skb->data[4]); break; @@ -307,6 +322,12 @@ static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametyp } return queued; + +out_clear: + x25_write_internal(sk, X25_CLEAR_REQUEST); + x25->state = X25_STATE_2; + x25_start_t23timer(sk); + return 0; } /* @@ -316,13 +337,13 @@ static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametyp */ static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) { + struct x25_sock *x25 = x25_sk(sk); + switch (frametype) { case X25_RESET_REQUEST: x25_write_internal(sk, X25_RESET_CONFIRMATION); case X25_RESET_CONFIRMATION: { - struct x25_sock *x25 = x25_sk(sk); - x25_stop_timer(sk); x25->condition = 0x00; x25->va = 0; @@ -334,6 +355,9 @@ static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametyp break; } case X25_CLEAR_REQUEST: + if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) + goto out_clear; + x25_write_internal(sk, X25_CLEAR_CONFIRMATION); x25_disconnect(sk, 0, skb->data[3], skb->data[4]); break; @@ -343,6 +367,12 @@ static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametyp } return 0; + +out_clear: + x25_write_internal(sk, X25_CLEAR_REQUEST); + x25->state = X25_STATE_2; + x25_start_t23timer(sk); + return 0; } /* Higher level upcall for a LAPB frame */ diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c index 037958ff8eed..4acacf3c6617 100644 --- a/net/x25/x25_link.c +++ b/net/x25/x25_link.c @@ -90,6 +90,9 @@ void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb, break; case X25_DIAGNOSTIC: + if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4)) + break; + printk(KERN_WARNING "x25: diagnostic #%d - %02X %02X %02X\n", skb->data[3], skb->data[4], skb->data[5], skb->data[6]); diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c index 24a342ebc7f5..5170d52bfd96 100644 --- a/net/x25/x25_subr.c +++ b/net/x25/x25_subr.c @@ -269,7 +269,11 @@ int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, int *d, int *m) { struct x25_sock *x25 = x25_sk(sk); - unsigned char *frame = skb->data; + unsigned char *frame; + + if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) + return X25_ILLEGAL; + frame = skb->data; *ns = *nr = *q = *d = *m = 0; @@ -294,6 +298,10 @@ int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, if (frame[2] == X25_RR || frame[2] == X25_RNR || frame[2] == X25_REJ) { + if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) + return X25_ILLEGAL; + frame = skb->data; + *nr = (frame[3] >> 1) & 0x7F; return frame[2]; } @@ -308,6 +316,10 @@ int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, if (x25->neighbour->extended) { if ((frame[2] & 0x01) == X25_DATA) { + if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) + return X25_ILLEGAL; + frame = skb->data; + *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; *d = (frame[0] & X25_D_BIT) == X25_D_BIT; *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT; -- cgit v1.2.1 From 7f81e25befdfb3272345a2e775f520e1d515fa20 Mon Sep 17 00:00:00 2001 From: Matthew Daley Date: Fri, 14 Oct 2011 18:45:05 +0000 Subject: x25: Prevent skb overreads when checking call user data x25_find_listener does not check that the amount of call user data given in the skb is big enough in per-socket comparisons, hence buffer overreads may occur. Fix this by adding a check. Signed-off-by: Matthew Daley Cc: Eric Dumazet Cc: Andrew Hendry Cc: stable Acked-by: Andrew Hendry Signed-off-by: David S. Miller --- net/x25/af_x25.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/x25') diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c index aa567b09ea9a..5f03e4ea65bf 100644 --- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -295,7 +295,8 @@ static struct sock *x25_find_listener(struct x25_address *addr, * Found a listening socket, now check the incoming * call user data vs this sockets call user data */ - if(skb->len > 0 && x25_sk(s)->cudmatchlength > 0) { + if (x25_sk(s)->cudmatchlength > 0 && + skb->len >= x25_sk(s)->cudmatchlength) { if((memcmp(x25_sk(s)->calluserdata.cuddata, skb->data, x25_sk(s)->cudmatchlength)) == 0) { -- cgit v1.2.1