Re: [PATCH] Enable splitting the logs to both auditd and kernel simultaneously

Allow the audit subsystem to send audit events to both the kernel message buffer and auditd at the same time. Signed-off-by: William Roberts <w.roberts(a)sta.samsung.com&gt; --- include/uapi/linux/audit.h | 11 ++++++++++ init/Kconfig | 8 +++++++ kernel/audit.c | 52 ++++++++++++++++++++++++++++++++++++++++------ kernel/audit.h | 6 ++++++ 4 files changed, 71 insertions(+), 6 deletions(-) diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 75cef3f..0af5d78 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -68,6 +68,8 @@ #define AUDIT_MAKE_EQUIV 1015 /* Append to watched tree */ #define AUDIT_TTY_GET 1016 /* Get TTY auditing status */ #define AUDIT_TTY_SET 1017 /* Set TTY auditing status */ +#define AUDIT_LOGSPLIT_GET 1018 /* Get logsplit status */ +#define AUDIT_LOGSPLIT_SET 1019 /* Set logsplit status */ #define AUDIT_FIRST_USER_MSG 1100 /* Userspace messages mostly uninteresting to kernel */ #define AUDIT_USER_AVC 1107 /* We filter this differently */ @@ -321,6 +323,10 @@ enum { #define AUDIT_FAIL_PRINTK 1 #define AUDIT_FAIL_PANIC 2 +/* Audit splitlog options */ +#define AUDIT_LOGSPLIT_OFF 0 +#define AUDIT_LOGSPLIT_ON 1 + /* distinguish syscall tables */ #define __AUDIT_ARCH_64BIT 0x80000000 #define __AUDIT_ARCH_LE 0x40000000 @@ -374,6 +380,11 @@ struct audit_tty_status { __u32 log_passwd; /* 1 = enabled, 0 = disabled */ }; +struct audit_logsplit_status { + __u32 enabled; /* AUDIT_LOGSPLIT_ON or + AUDIT_LOGSPLIT_OFF */ +}; + /* audit_rule_data supports filter rules with both integer and string * fields. It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and * AUDIT_LIST_RULES requests. diff --git a/init/Kconfig b/init/Kconfig index 9d3a788..52efca6 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -286,6 +286,14 @@ config AUDIT_LOGINUID_IMMUTABLE one to drop potentially dangerous capabilites from the login tasks, but may not be backwards compatible with older init systems. +config AUDIT_SPLITLOG + bool "Split audit messages to userspace and kernel by default" + depends on AUDIT + help + Setting this to true will cause the audit messages to be split + by default to both the kernel message log and a userspace audit + daemon if registered. + source "kernel/irq/Kconfig" source "kernel/time/Kconfig" diff --git a/kernel/audit.c b/kernel/audit.c index 21c7fa6..ccd2f60 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -88,6 +88,9 @@ static int audit_default; /* If auditing cannot proceed, audit_failure selects what happens. */ static int audit_failure = AUDIT_FAIL_PRINTK; +/* Whether or not logsplit is enabled */ +static int audit_logsplit = AUDIT_SPLITLOG_INIT; + /* * If audit records are to be written to the netlink socket, audit_pid * contains the pid of the auditd process and audit_nlk_portid contains @@ -343,6 +346,17 @@ static int audit_set_failure(int state) return audit_do_config_change("audit_failure", &audit_failure, state); } +static int audit_set_logsplit(int state) +{ + if (state != AUDIT_LOGSPLIT_OFF + && state != AUDIT_LOGSPLIT_ON) + return -EINVAL; + + return audit_do_config_change("audit_logsplit", &audit_logsplit, state); +} + + + /* * Queue skbs to be sent to auditd when/if it comes back. These skbs should * already have been sent via prink/syslog and so if these messages are dropped @@ -361,11 +375,8 @@ static void audit_hold_skb(struct sk_buff *skb) kfree_skb(skb); } -/* - * For one reason or another this nlh isn't getting delivered to the userspace - * audit daemon, just send it to printk. - */ -static void audit_printk_skb(struct sk_buff *skb) +/* Just printks the skb, no audit_hold or free of any kind */ +static void __audit_printk_skb(struct sk_buff *skb) { struct nlmsghdr *nlh = nlmsg_hdr(skb); char *data = nlmsg_data(nlh); @@ -376,7 +387,14 @@ static void audit_printk_skb(struct sk_buff *skb) else audit_log_lost("printk limit exceeded\n"); } - +} +/* + * For one reason or another this nlh isn't getting delivered to the userspace + * audit daemon, just send it to printk. + */ +static void audit_printk_skb(struct sk_buff *skb) +{ + __audit_printk_skb(skb); audit_hold_skb(skb); } @@ -590,6 +608,8 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) case AUDIT_SIGNAL_INFO: case AUDIT_TTY_GET: case AUDIT_TTY_SET: + case AUDIT_LOGSPLIT_GET: + case AUDIT_LOGSPLIT_SET: case AUDIT_TRIM: case AUDIT_MAKE_EQUIV: if (!capable(CAP_AUDIT_CONTROL)) @@ -843,7 +863,24 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) spin_unlock(&tsk->sighand->siglock); break; } + case AUDIT_LOGSPLIT_GET: { + struct audit_logsplit_status s; + s.enabled = audit_logsplit; + audit_send_reply(NETLINK_CB(skb).portid, seq, + AUDIT_LOGSPLIT_GET, 0, 0, &s, sizeof(s)); + break; + } + case AUDIT_LOGSPLIT_SET: { + struct audit_logsplit_status *s; + if (nlh->nlmsg_len < sizeof(struct audit_logsplit_status)) + return -EINVAL; + s = data; + err = audit_set_logsplit(s->enabled); + break; + } + default: + printk(KERN_ERR "Unkown audit command"); err = -EINVAL; break; } @@ -1670,6 +1707,9 @@ void audit_log_end(struct audit_buffer *ab) nlh->nlmsg_len = ab->skb->len - NLMSG_HDRLEN; if (audit_pid) { + if (audit_logsplit == AUDIT_LOGSPLIT_ON) + __audit_printk_skb(ab->skb); + skb_queue_tail(&audit_skb_queue, ab->skb); wake_up_interruptible(&kauditd_wait); } else { diff --git a/kernel/audit.h b/kernel/audit.h index 1c95131..ef43bb1 100644 --- a/kernel/audit.h +++ b/kernel/audit.h @@ -321,4 +321,10 @@ extern struct list_head *audit_killed_trees(void); #define audit_filter_inodes(t,c) AUDIT_DISABLED #endif +#ifdef CONFIG_AUDIT_SPLITLOG +#define AUDIT_SPLITLOG_INIT AUDIT_LOGSPLIT_ON +#else +#define AUDIT_SPLITLOG_INIT AUDIT_LOGSPLIT_OFF +#endif + extern struct mutex audit_cmd_mutex; -- 1.8.2.2