From 3640dcfa4fd00cd91d88bb86250bdb496f7070c0 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Fri, 19 Dec 2014 18:35:53 -0500 Subject: audit: don't attempt to lookup PIDs when changing PID filtering audit rules Commit f1dc4867 ("audit: anchor all pid references in the initial pid namespace") introduced a find_vpid() call when adding/removing audit rules with PID/PPID filters; unfortunately this is problematic as find_vpid() only works if there is a task with the associated PID alive on the system. The following commands demonstrate a simple reproducer. # auditctl -D # auditctl -l # autrace /bin/true # auditctl -l This patch resolves the problem by simply using the PID provided by the user without any additional validation, e.g. no calls to check to see if the task/PID exists. Cc: stable@vger.kernel.org # 3.15 Cc: Richard Guy Briggs Signed-off-by: Paul Moore Acked-by: Eric Paris Reviewed-by: Richard Guy Briggs diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index d214cd0..c0d148b 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -444,19 +444,6 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, f->val = 0; } - if ((f->type == AUDIT_PID) || (f->type == AUDIT_PPID)) { - struct pid *pid; - rcu_read_lock(); - pid = find_vpid(f->val); - if (!pid) { - rcu_read_unlock(); - err = -ESRCH; - goto exit_free; - } - f->val = pid_nr(pid); - rcu_read_unlock(); - } - err = audit_field_valid(entry, f); if (err) goto exit_free; -- cgit v0.10.2 From 54dc77d974a50147d6639dac6f59cb2c29207161 Mon Sep 17 00:00:00 2001 From: Richard Guy Briggs Date: Thu, 18 Dec 2014 23:09:27 -0500 Subject: audit: use supplied gfp_mask from audit_buffer in kauditd_send_multicast_skb 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: [] prepare_bprm_creds+0x28/0x8b #1: (tty_files_lock){+.+.+.}, at: [] 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: [] dump_stack+0x50/0xa8 [] ___might_sleep+0x1b6/0x1be [] __might_sleep+0x119/0x128 [] cache_alloc_debugcheck_before.isra.45+0x1d/0x1f [] kmem_cache_alloc+0x43/0x1c9 [] __alloc_skb+0x42/0x1a3 [] skb_copy+0x3e/0xa3 [] audit_log_end+0x83/0x100 [] ? avc_audit_pre_callback+0x103/0x103 [] common_lsm_audit+0x441/0x450 [] slow_avc_audit+0x63/0x67 [] avc_has_perm+0xca/0xe3 [] inode_has_perm+0x5a/0x65 [] selinux_bprm_committing_creds+0x98/0x22b [] security_bprm_committing_creds+0xe/0x10 [] install_exec_creds+0xe/0x79 [] load_elf_binary+0xe36/0x10d7 [] search_binary_handler+0x81/0x18c [] do_execveat_common.isra.31+0x4e3/0x7b7 [] do_execve+0x1f/0x21 [] SyS_execve+0x25/0x29 [] stub_execve+0x69/0xa0 Cc: stable@vger.kernel.org #v3.16-rc1 Reported-by: Valdis Kletnieks Signed-off-by: Richard Guy Briggs Tested-by: Valdis Kletnieks Signed-off-by: Paul Moore diff --git a/kernel/audit.c b/kernel/audit.c index f3a981d..c7e097a 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); } /* @@ -1949,7 +1949,7 @@ void audit_log_end(struct audit_buffer *ab) struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); nlh->nlmsg_len = ab->skb->len; - kauditd_send_multicast_skb(ab->skb); + kauditd_send_multicast_skb(ab->skb, ab->gfp_mask); /* * The original kaudit unicast socket sends up messages with -- cgit v0.10.2 From 4a92843601ad0f5067f441d2f0dca55bbe18c076 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Mon, 22 Dec 2014 12:27:39 -0500 Subject: audit: correctly record file names with different path name types There is a problem with the audit system when multiple audit records are created for the same path, each with a different path name type. The root cause of the problem is in __audit_inode() when an exact match (both the path name and path name type) is not found for a path name record; the existing code creates a new path name record, but it never sets the path name in this record, leaving it NULL. This patch corrects this problem by assigning the path name to these newly created records. There are many ways to reproduce this problem, but one of the easiest is the following (assuming auditd is running): # mkdir /root/tmp/test # touch /root/tmp/test/567 # auditctl -a always,exit -F dir=/root/tmp/test # touch /root/tmp/test/567 Afterwards, or while the commands above are running, check the audit log and pay special attention to the PATH records. A faulty kernel will display something like the following for the file creation: type=SYSCALL msg=audit(1416957442.025:93): arch=c000003e syscall=2 success=yes exit=3 ... comm="touch" exe="/usr/bin/touch" type=CWD msg=audit(1416957442.025:93): cwd="/root/tmp" type=PATH msg=audit(1416957442.025:93): item=0 name="test/" inode=401409 ... nametype=PARENT type=PATH msg=audit(1416957442.025:93): item=1 name=(null) inode=393804 ... nametype=NORMAL type=PATH msg=audit(1416957442.025:93): item=2 name=(null) inode=393804 ... nametype=NORMAL While a patched kernel will show the following: type=SYSCALL msg=audit(1416955786.566:89): arch=c000003e syscall=2 success=yes exit=3 ... comm="touch" exe="/usr/bin/touch" type=CWD msg=audit(1416955786.566:89): cwd="/root/tmp" type=PATH msg=audit(1416955786.566:89): item=0 name="test/" inode=401409 ... nametype=PARENT type=PATH msg=audit(1416955786.566:89): item=1 name="test/567" inode=393804 ... nametype=NORMAL This issue was brought up by a number of people, but special credit should go to hujianyang@huawei.com for reporting the problem along with an explanation of the problem and a patch. While the original patch did have some problems (see the archive link below), it did demonstrate the problem and helped kickstart the fix presented here. * https://lkml.org/lkml/2014/9/5/66 Reported-by: hujianyang Signed-off-by: Paul Moore Acked-by: Richard Guy Briggs diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 8933572..287b3d3 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1877,12 +1877,18 @@ void __audit_inode(struct filename *name, const struct dentry *dentry, } out_alloc: - /* unable to find the name from a previous getname(). Allocate a new - * anonymous entry. - */ - n = audit_alloc_name(context, AUDIT_TYPE_NORMAL); + /* unable to find an entry with both a matching name and type */ + n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN); if (!n) return; + if (name) + /* since name is not NULL we know there is already a matching + * name record, see audit_getname(), so there must be a type + * mismatch; reuse the string path since the original name + * record will keep the string valid until we free it in + * audit_free_names() */ + n->name = name; + out: if (parent) { n->name_len = n->name ? parent_len(n->name->name) : AUDIT_NAME_FULL; -- cgit v0.10.2 From 041d7b98ffe59c59fdd639931dea7d74f9aa9a59 Mon Sep 17 00:00:00 2001 From: Richard Guy Briggs Date: Tue, 23 Dec 2014 13:02:04 -0500 Subject: audit: restore AUDIT_LOGINUID unset ABI A regression was caused by commit 780a7654cee8: audit: Make testing for a valid loginuid explicit. (which in turn attempted to fix a regression caused by e1760bd) When audit_krule_to_data() fills in the rules to get a listing, there was a missing clause to convert back from AUDIT_LOGINUID_SET to AUDIT_LOGINUID. This broke userspace by not returning the same information that was sent and expected. The rule: auditctl -a exit,never -F auid=-1 gives: auditctl -l LIST_RULES: exit,never f24=0 syscall=all when it should give: LIST_RULES: exit,never auid=-1 (0xffffffff) syscall=all Tag it so that it is reported the same way it was set. Create a new private flags audit_krule field (pflags) to store it that won't interact with the public one from the API. Cc: stable@vger.kernel.org # v3.10-rc1+ Signed-off-by: Richard Guy Briggs Signed-off-by: Paul Moore diff --git a/include/linux/audit.h b/include/linux/audit.h index 36dffec..9333192 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -47,6 +47,7 @@ struct sk_buff; struct audit_krule { int vers_ops; + u32 pflags; u32 flags; u32 listnr; u32 action; @@ -64,6 +65,9 @@ struct audit_krule { u64 prio; }; +/* Flag to indicate legacy AUDIT_LOGINUID unset usage */ +#define AUDIT_LOGINUID_LEGACY 0x1 + struct audit_field { u32 type; union { diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index c0d148b..103586e 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -442,6 +442,7 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, if ((f->type == AUDIT_LOGINUID) && (f->val == AUDIT_UID_UNSET)) { f->type = AUDIT_LOGINUID_SET; f->val = 0; + entry->rule.pflags |= AUDIT_LOGINUID_LEGACY; } err = audit_field_valid(entry, f); @@ -617,6 +618,13 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule) data->buflen += data->values[i] = audit_pack_string(&bufp, krule->filterkey); break; + case AUDIT_LOGINUID_SET: + if (krule->pflags & AUDIT_LOGINUID_LEGACY && !f->val) { + data->fields[i] = AUDIT_LOGINUID; + data->values[i] = AUDIT_UID_UNSET; + break; + } + /* fallthrough if set */ default: data->values[i] = f->val; } @@ -633,6 +641,7 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b) int i; if (a->flags != b->flags || + a->pflags != b->pflags || a->listnr != b->listnr || a->action != b->action || a->field_count != b->field_count) @@ -751,6 +760,7 @@ struct audit_entry *audit_dupe_rule(struct audit_krule *old) new = &entry->rule; new->vers_ops = old->vers_ops; new->flags = old->flags; + new->pflags = old->pflags; new->listnr = old->listnr; new->action = old->action; for (i = 0; i < AUDIT_BITMASK_SIZE; i++) -- cgit v0.10.2