[PATCH 3.16.y-ckt 191/216] audit: use supplied gfp_mask from audit_buffer in kauditd_send_multicast_skb

Luis Henriques
2015-01-12T18:38:56Z

From: Richard Guy Briggs <rgb@redhat.com>

commit 54dc77d974a50147d6639dac6f59cb2c29207161 upstream.

Eric Paris explains: Since kauditd_send_multicast_skb() gets called in
audit_log_end(), which can come from any context (aka even a sleeping context)
GFP_KERNEL can't be used. Since the audit_buffer knows what context it should
use, pass that down and use that.

See: https://lkml.org/lkml/2014/12/16/542

BUG: sleeping function called from invalid context at mm/slab.c:2849
in_atomic(): 1, irqs_disabled(): 0, pid: 885, name: sulogin
2 locks held by sulogin/885:
#0: (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff91152e30>] prepare_bprm_creds+0x28/0x8b
#1: (tty_files_lock){+.+.+.}, at: [<ffffffff9123e787>] selinux_bprm_committing_creds+0x55/0x22b
CPU: 1 PID: 885 Comm: sulogin Not tainted 3.18.0-next-20141216 #30
Hardware name: Dell Inc. Latitude E6530/07Y85M, BIOS A15 06/20/2014
ffff880223744f10 ffff88022410f9b8 ffffffff916ba529 0000000000000375
ffff880223744f10 ffff88022410f9e8 ffffffff91063185 0000000000000006
0000000000000000 0000000000000000 0000000000000000 ffff88022410fa38
Call Trace:
[<ffffffff916ba529>] dump_stack+0x50/0xa8
[<ffffffff91063185>] ___might_sleep+0x1b6/0x1be
[<ffffffff910632a6>] __might_sleep+0x119/0x128
[<ffffffff91140720>] cache_alloc_debugcheck_before.isra.45+0x1d/0x1f
[<ffffffff91141d81>] kmem_cache_alloc+0x43/0x1c9
[<ffffffff914e148d>] __alloc_skb+0x42/0x1a3
[<ffffffff914e2b62>] skb_copy+0x3e/0xa3
[<ffffffff910c263e>] audit_log_end+0x83/0x100
[<ffffffff9123b8d3>] ? avc_audit_pre_callback+0x103/0x103
[<ffffffff91252a73>] common_lsm_audit+0x441/0x450
[<ffffffff9123c163>] slow_avc_audit+0x63/0x67
[<ffffffff9123c42c>] avc_has_perm+0xca/0xe3
[<ffffffff9123dc2d>] inode_has_perm+0x5a/0x65
[<ffffffff9123e7ca>] selinux_bprm_committing_creds+0x98/0x22b
[<ffffffff91239e64>] security_bprm_committing_creds+0xe/0x10
[<ffffffff911515e6>] install_exec_creds+0xe/0x79
[<ffffffff911974cf>] load_elf_binary+0xe36/0x10d7
[<ffffffff9115198e>] search_binary_handler+0x81/0x18c
[<ffffffff91153376>] do_execveat_common.isra.31+0x4e3/0x7b7
[<ffffffff91153669>] do_execve+0x1f/0x21
[<ffffffff91153967>] SyS_execve+0x25/0x29
[<ffffffff916c61a9>] stub_execve+0x69/0xa0

Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Tested-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Paul Moore <pmoore@redhat.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
kernel/audit.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 6726aa6f82be..a0918e23d647 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -429,7 +429,7 @@ static void kauditd_send_skb(struct sk_buff *skb)
* This function doesn't consume an skb as might be expected since it has to
* copy it anyways.
*/
-static void kauditd_send_multicast_skb(struct sk_buff *skb)
+static void kauditd_send_multicast_skb(struct sk_buff *skb, gfp_t gfp_mask)
{
struct sk_buff *copy;
struct audit_net *aunet = net_generic(&init_net, audit_net_id);
@@ -448,11 +448,11 @@ static void kauditd_send_multicast_skb(struct sk_buff *skb)
* no reason for new multicast clients to continue with this
* non-compliance.
*/
- copy = skb_copy(skb, GFP_KERNEL);
+ copy = skb_copy(skb, gfp_mask);
if (!copy)
return;

- nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
+ nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, gfp_mask);
}

/*
@@ -1959,7 +1959,7 @@ void audit_log_end(struct audit_buffer *ab)
} else {
struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);

- kauditd_send_multicast_skb(ab->skb);
+ kauditd_send_multicast_skb(ab->skb, ab->gfp_mask);

/*
* The original kaudit unicast socket sends up messages with
--
2.1.4