lwn.git/net/sctp/sysctl.c, branch v4.1.9

sctp: avoid to repeatedly declare external variables

2015-03-25T15:40:16+00:00

Move the declaration for external variables to sctp.h file avoiding to repeatedly declare them with extern keyword. Signed-off-by: Ying Xue Signed-off-by: David S. Miller

net: sctp: only warn in proc_sctp_do_alpha_beta if write

2014-07-03T01:44:07+00:00

Only warn if the value is written to alpha or beta. We don't care emitting a one-time warning when only reading it. Reported-by: Jiri Pirko Signed-off-by: Daniel Borkmann Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller

net: sctp: check proc_dointvec result in proc_sctp_do_auth

2014-06-20T04:30:19+00:00

When writing to the sysctl field net.sctp.auth_enable, it can well be that the user buffer we handed over to proc_dointvec() via proc_sctp_do_auth() handler contains something other than integers. In that case, we would set an uninitialized 4-byte value from the stack to net->sctp.auth_enable that can be leaked back when reading the sysctl variable, and it can unintentionally turn auth_enable on/off based on the stack content since auth_enable is interpreted as a boolean. Fix it up by making sure proc_dointvec() returned sucessfully. Fixes: b14878ccb7fa ("net: sctp: cache auth_enable per endpoint") Reported-by: Florian Westphal Signed-off-by: Daniel Borkmann Acked-by: Neil Horman Acked-by: Vlad Yasevich Signed-off-by: David S. Miller

net: sctp: propagate sysctl errors from proc_do* properly

2014-06-19T00:03:07+00:00

sysctl handler proc_sctp_do_hmac_alg(), proc_sctp_do_rto_min() and proc_sctp_do_rto_max() do not properly reflect some error cases when writing values via sysctl from internal proc functions such as proc_dointvec() and proc_dostring(). In all these cases we pass the test for write != 0 and partially do additional work just to notice that additional sanity checks fail and we return with hard-coded -EINVAL while proc_do* functions might also return different errors. So fix this up by simply testing a successful return of proc_do* right after calling it. This also allows to propagate its return value onwards to the user. While touching this, also fix up some minor style issues. Fixes: 4f3fdf3bc59c ("sctp: add check rto_min and rto_max in sysctl") Fixes: 3c68198e7511 ("sctp: Make hmac algorithm selection for cookie generation dynamic") Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

net: sctp: fix permissions for rto_alpha and rto_beta knobs

2014-06-15T08:17:32+00:00

Commit 3fd091e73b81 ("[SCTP]: Remove multiple levels of msecs to jiffies conversions.") has silently changed permissions for rto_alpha and rto_beta knobs from 0644 to 0444. The purpose of this was to discourage users from tweaking rto_alpha and rto_beta knobs in production environments since they are key to correctly compute rtt/srtt. RFC4960 under section 6.3.1. RTO Calculation says regarding rto_alpha and rto_beta under rule C3 and C4: [...] C3) When a new RTT measurement R' is made, set RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'| and SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R' Note: The value of SRTT used in the update to RTTVAR is its value before updating SRTT itself using the second assignment. After the computation, update RTO <- SRTT + 4 * RTTVAR. C4) When data is in flight and when allowed by rule C5 below, a new RTT measurement MUST be made each round trip. Furthermore, new RTT measurements SHOULD be made no more than once per round trip for a given destination transport address. There are two reasons for this recommendation: First, it appears that measuring more frequently often does not in practice yield any significant benefit [ALLMAN99]; second, if measurements are made more often, then the values of RTO.Alpha and RTO.Beta in rule C3 above should be adjusted so that SRTT and RTTVAR still adjust to changes at roughly the same rate (in terms of how many round trips it takes them to reflect new values) as they would if making only one measurement per round-trip and using RTO.Alpha and RTO.Beta as given in rule C3. However, the exact nature of these adjustments remains a research issue. [...] While it is discouraged to adjust rto_alpha and rto_beta and not further specified how to adjust them, the RFC also doesn't explicitly forbid it, but rather gives a RECOMMENDED default value (rto_alpha=3, rto_beta=2). We have a couple of users relying on the old permissions before they got changed. That said, if someone really has the urge to adjust them, we could allow it with a warning in the log. Fixes: 3fd091e73b81 ("[SCTP]: Remove multiple levels of msecs to jiffies conversions.") Signed-off-by: Daniel Borkmann Cc: Vlad Yasevich Signed-off-by: David S. Miller

sctp: add a checking for sctp_sysctl_net_register

2014-05-09T20:41:09+00:00

When register_net_sysctl failed, we should free the sysctl_table. Signed-off-by: Wang Weidong Signed-off-by: David S. Miller

Revert "sctp: optimize the sctp_sysctl_net_register"

2014-05-09T20:41:08+00:00

This revert commit efb842c45("sctp: optimize the sctp_sysctl_net_register"), Since it doesn't kmemdup a sysctl_table for init_net, so the init_net->sctp.sysctl_header->ctl_table_arg points to sctp_net_table which is a static array pointer. So when doing sctp_sysctl_net_unregister, it will free sctp_net_table, then we will get a NULL pointer dereference like that: [ 262.948220] BUG: unable to handle kernel NULL pointer dereference at 000000000000006c [ 262.948232] IP: [] kfree+0x80/0x420 [ 262.948260] PGD db80a067 PUD dae12067 PMD 0 [ 262.948268] Oops: 0000 [#1] SMP [ 262.948273] Modules linked in: sctp(-) crc32c_generic libcrc32c ... [ 262.948338] task: ffff8800db830190 ti: ffff8800dad00000 task.ti: ffff8800dad00000 [ 262.948344] RIP: 0010:[] [] kfree+0x80/0x420 [ 262.948353] RSP: 0018:ffff8800dad01d88 EFLAGS: 00010046 [ 262.948358] RAX: 0100000000000000 RBX: ffffffffa0227940 RCX: ffffea0000707888 [ 262.948363] RDX: ffffea0000707888 RSI: 0000000000000001 RDI: ffffffffa0227940 [ 262.948369] RBP: ffff8800dad01de8 R08: 0000000000000000 R09: ffff8800d9e983a9 [ 262.948374] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa0227940 [ 262.948380] R13: ffffffff8187cfc0 R14: 0000000000000000 R15: ffffffff8187da10 [ 262.948386] FS: 00007fa2a2658700(0000) GS:ffff880112800000(0000) knlGS:0000000000000000 [ 262.948394] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 262.948400] CR2: 000000000000006c CR3: 00000000cddc0000 CR4: 00000000000006e0 [ 262.948410] Stack: [ 262.948413] ffff8800dad01da8 0000000000000286 0000000020227940 ffffffffa0227940 [ 262.948422] ffff8800dad01dd8 ffffffff811b7fa1 ffffffffa0227940 ffffffffa0227940 [ 262.948431] ffffffff8187d960 ffffffff8187cfc0 ffffffff8187d960 ffffffff8187da10 [ 262.948440] Call Trace: [ 262.948457] [] ? unregister_sysctl_table+0x51/0xa0 [ 262.948476] [] sctp_sysctl_net_unregister+0x21/0x30 [sctp] [ 262.948490] [] sctp_net_exit+0x12d/0x150 [sctp] [ 262.948512] [] ops_exit_list+0x39/0x60 [ 262.948522] [] unregister_pernet_operations+0x3d/0x70 [ 262.948530] [] unregister_pernet_subsys+0x22/0x40 [ 262.948544] [] sctp_exit+0x3c/0x12d [sctp] [ 262.948562] [] SyS_delete_module+0x194/0x210 [ 262.948577] [] ? trace_hardirqs_on_thunk+0x3a/0x3f [ 262.948587] [] system_call_fastpath+0x16/0x1b With this revert, it won't occur the Oops. Signed-off-by: Wang Weidong Signed-off-by: David S. Miller

net: sctp: cache auth_enable per endpoint

2014-04-18T22:32:00+00:00

Currently, it is possible to create an SCTP socket, then switch auth_enable via sysctl setting to 1 and crash the system on connect: Oops[#1]: CPU: 0 PID: 0 Comm: swapper Not tainted 3.14.1-mipsgit-20140415 #1 task: ffffffff8056ce80 ti: ffffffff8055c000 task.ti: ffffffff8055c000 [...] Call Trace: [] sctp_auth_asoc_set_default_hmac+0x68/0x80 [] sctp_process_init+0x5e0/0x8a4 [] sctp_sf_do_5_1B_init+0x234/0x34c [] sctp_do_sm+0xb4/0x1e8 [] sctp_endpoint_bh_rcv+0x1c4/0x214 [] sctp_rcv+0x588/0x630 [] sctp6_rcv+0x10/0x24 [] ip6_input+0x2c0/0x440 [] __netif_receive_skb_core+0x4a8/0x564 [] process_backlog+0xb4/0x18c [] net_rx_action+0x12c/0x210 [] __do_softirq+0x17c/0x2ac [] irq_exit+0x54/0xb0 [] ret_from_irq+0x0/0x4 [] rm7k_wait_irqoff+0x24/0x48 [] cpu_startup_entry+0xc0/0x148 [] start_kernel+0x37c/0x398 Code: dd0900b8 000330f8 0126302d 50c0fff1 0047182a a48306a0 03e00008 00000000 ---[ end trace b530b0551467f2fd ]--- Kernel panic - not syncing: Fatal exception in interrupt What happens while auth_enable=0 in that case is, that ep->auth_hmacs is initialized to NULL in sctp_auth_init_hmacs() when endpoint is being created. After that point, if an admin switches over to auth_enable=1, the machine can crash due to NULL pointer dereference during reception of an INIT chunk. When we enter sctp_process_init() via sctp_sf_do_5_1B_init() in order to respond to an INIT chunk, the INIT verification succeeds and while we walk and process all INIT params via sctp_process_param() we find that net->sctp.auth_enable is set, therefore do not fall through, but invoke sctp_auth_asoc_set_default_hmac() instead, and thus, dereference what we have set to NULL during endpoint initialization phase. The fix is to make auth_enable immutable by caching its value during endpoint initialization, so that its original value is being carried along until destruction. The bug seems to originate from the very first days. Fix in joint work with Daniel Borkmann. Reported-by: Joshua Kinard Signed-off-by: Vlad Yasevich Signed-off-by: Daniel Borkmann Acked-by: Neil Horman Tested-by: Joshua Kinard Signed-off-by: David S. Miller

sctp: optimize the sctp_sysctl_net_register

2014-02-13T22:08:29+00:00

Here, when the net is init_net, we needn't to kmemdup the ctl_table again. So add a check for net. Also we can save some memory. Signed-off-by: Wang Weidong Acked-by: Neil Horman Signed-off-by: David S. Miller

sctp: fix a missed .data initialization

2014-02-13T22:08:29+00:00

As commit 3c68198e75111a90("sctp: Make hmac algorithm selection for cookie generation dynamic"), we miss the .data initialization. If we don't use the net_namespace, the problem that parts of the sysctl configuration won't be isolation and won't occur. In sctp_sysctl_net_register(), we register the sysctl for each net, in the for(), we use the 'table[i].data' as check condition, so when the 'i' is the index of sctp_hmac_alg, the data is NULL, then break. So add the .data initialization. Acked-by: Neil Horman Signed-off-by: Wang Weidong Signed-off-by: David S. Miller