Re: [PATCH] TaskTracker : Simplified thread information tracker.

Richard Guy Briggs wrote: Me too. I added it. Steve Grubb wrote: What about printing uptime than current system clock for this record? Since system clock changes during boot upon applying timezone setting, time stamp within this record goes backwards. On the other hand, uptime does not go backwards and can serve for knowing when the past execve() had been called. Steve Grubb wrote: Steve Grubb wrote: Excuse me, but Richard Guy Briggs wrote: what does Richard's comment mean? We are using argc=$argc a0=$argv[0] a1=$argv[1] a2=$argv[2] ... format for type=EXECVE record. Are the userspace tools really looking for a constant number of fields per record type? If the userspace tools are not looking for a constant number of fields per record type, does Steve's comment suggest something like history_name[0]="swapper/0" history_pid[0]=1 history_start[0]=1.10 history_name[1]="init" history_pid[1]=1 history_start[1]=1.50 history_name[2]="systemd" history_pid[2]=1 history_start[2]=2.68 history_name[3]="sshd" history_pid[3]=1210 history_start[3]=29.28 history_name[4]="sshd" history_pid[4]=9185 history_start[4]=1609.00 history_name[5]="bash" history_pid[5]=9187 history_start[5]=1611.63 history_name[6]="tail" history_pid[6]=9230 history_start[6]=1616.51 than history="name=swapper/0;pid=1;start=1.10=>name=init;pid=1;start=1.50=> name=systemd;pid=1;start=2.68=>name=sshd;pid=1210;start=29.28=>name=sshd; pid=9185;start=1609.00=>name=bash;pid=9187;start=1611.63=>name=tail; pid=9230;start=1616.51" for this record? This would indeed avoid => in the $value field, but does this space-consuming format better than using => ? Steve Grubb wrote: Richard Guy Briggs wrote: OK. I changed to use audit_log_untrustedstring(), though audit_string_contains_control() is always false for this record because I already escaped user-influenced comm name in order to keep the $value field parsable. Patch follows. ------------------------------------------------------------ From: Tetsuo Handa <penguin-kernel(a)I-love.SAKURA.ne.jp&gt; Date: Tue, 20 Jan 2015 13:13:39 +0900 Subject: [PATCH v2] audit: Emit history of thread's comm name. When an unexpected system event (e.g. reboot) occurs, the administrator may want to identify which application triggered the event. System call auditing could be used for recording such event. However, the audit log may not be able to provide sufficient information for identifying the application because the audit log does not reflect how the program was executed. This patch adds ability to trace how the program was executed and emit it as an auxiliary record in the form of comm name, pid and uptime pairs as of execve(). type=UNKNOWN[1329] msg=audit(1421727157.228:5757): history="name=swapper/0; pid=1;start=1.10=>name=init;pid=1;start=1.50=>name=systemd;pid=1;start=2.68=> name=sshd;pid=1210;start=29.28=>name=sshd;pid=9185;start=1609.00=>name=bash; pid=9187;start=1611.63=>name=tail;pid=9230;start=1616.51" Signed-off-by: Tetsuo Handa <penguin-kernel(a)I-love.SAKURA.ne.jp&gt; --- fs/exec.c | 1 + include/linux/audit.h | 4 +++ include/linux/init_task.h | 5 +++ include/linux/sched.h | 3 ++ include/uapi/linux/audit.h | 1 + kernel/audit.c | 1 + kernel/auditsc.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++ 7 files changed, 104 insertions(+) diff --git a/fs/exec.c b/fs/exec.c index ad8798e..5e92651 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1200,6 +1200,7 @@ void install_exec_creds(struct linux_binprm *bprm) commit_creds(bprm->cred); bprm->cred = NULL; + audit_update_history(); /* * Disable monitoring for regular users * when executing setuid binaries. Must diff --git a/include/linux/audit.h b/include/linux/audit.h index af84234..74310a7 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -221,6 +221,8 @@ static inline void audit_ptrace(struct task_struct *t) __audit_ptrace(t); } +extern void audit_update_history(void); + /* Private API (for audit.c only) */ extern unsigned int audit_serial(void); extern int auditsc_get_stamp(struct audit_context *ctx, @@ -437,6 +439,8 @@ static inline void audit_mmap_fd(int fd, int flags) { } static inline void audit_ptrace(struct task_struct *t) { } +static inline void audit_update_history(void) +{ } #define audit_n_rules 0 #define audit_signals 0 #endif /* CONFIG_AUDITSYSCALL */ diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 3037fc0..078823a 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -98,8 +98,12 @@ extern struct group_info init_groups; #define INIT_IDS \ .loginuid = INVALID_UID, \ .sessionid = (unsigned int)-1, +extern char init_task_history[]; +#define INIT_THREAD_HISTORY \ + .comm_history = init_task_history, #else #define INIT_IDS +#define INIT_THREAD_HISTORY #endif #ifdef CONFIG_PREEMPT_RCU @@ -247,6 +251,7 @@ extern struct task_group root_task_group; INIT_RT_MUTEXES(tsk) \ INIT_VTIME(tsk) \ INIT_NUMA_BALANCING(tsk) \ + INIT_THREAD_HISTORY \ } diff --git a/include/linux/sched.h b/include/linux/sched.h index 8db31ef..77539e4 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1701,6 +1701,9 @@ struct task_struct { #ifdef CONFIG_DEBUG_ATOMIC_SLEEP unsigned long task_state_change; #endif +#ifdef CONFIG_AUDITSYSCALL + char *comm_history; +#endif }; /* Future-safe accessor for struct task_struct's cpus_allowed. */ diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index d3475e1..93ad58c 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -110,6 +110,7 @@ #define AUDIT_SECCOMP 1326 /* Secure Computing event */ #define AUDIT_PROCTITLE 1327 /* Proctitle emit event */ #define AUDIT_FEATURE_CHANGE 1328 /* audit log listing feature changes */ +#define AUDIT_PROCHISTORY 1329 /* Commname history emit event */ #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ diff --git a/kernel/audit.c b/kernel/audit.c index 72ab759..d45397e 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1154,6 +1154,7 @@ static int __init audit_init(void) { int i; + audit_update_history(); if (audit_initialized == AUDIT_DISABLED) return 0; diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 072566d..7a3d8f4 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -88,6 +88,9 @@ /* max length to print of cmdline/proctitle value during audit */ #define MAX_PROCTITLE_AUDIT_LEN 128 +/* thread's comm name history length */ +#define COMM_HISTORY_SIZE 1024 + /* number of audit rules */ int audit_n_rules; @@ -945,6 +948,11 @@ int audit_alloc(struct task_struct *tsk) enum audit_state state; char *key = NULL; + tsk->comm_history = kmemdup(current->comm_history, COMM_HISTORY_SIZE, + GFP_KERNEL); + if (!tsk->comm_history) + return -ENOMEM; + if (likely(!audit_ever_enabled)) return 0; /* Return if not auditing. */ @@ -955,6 +963,8 @@ int audit_alloc(struct task_struct *tsk) } if (!(context = audit_alloc_context(state))) { + kfree(tsk->comm_history); + tsk->comm_history = NULL; kfree(key); audit_log_lost("out of memory in audit_alloc"); return -ENOMEM; @@ -1344,6 +1354,18 @@ out: audit_log_end(ab); } +static void audit_log_history(struct audit_context *context) +{ + struct audit_buffer *ab; + + ab = audit_log_start(context, GFP_KERNEL, AUDIT_PROCHISTORY); + if (!ab) + return; /* audit_panic or being filtered */ + audit_log_format(ab, "history="); + audit_log_untrustedstring(ab, current->comm_history); + audit_log_end(ab); +} + static void audit_log_exit(struct audit_context *context, struct task_struct *tsk) { int i, call_panic = 0; @@ -1462,6 +1484,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts } audit_log_proctitle(tsk, context); + audit_log_history(context); /* Send end of event record to help user space know we are finished */ ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE); @@ -1481,6 +1504,8 @@ void __audit_free(struct task_struct *tsk) { struct audit_context *context; + kfree(tsk->comm_history); + tsk->comm_history = NULL; context = audit_take_context(tsk, 0, 0); if (!context) return; @@ -2535,3 +2560,67 @@ struct list_head *audit_killed_trees(void) return NULL; return &ctx->killed_trees; } + +char init_task_history[COMM_HISTORY_SIZE]; + +/** + * audit_update_history - Update current->comm_history field. + * + * Returns nothing. + * + * Update is done locklessly because current thread's history is updated by + * only current thread upon boot up and successful execve() operation, and + * we don't read other thread's history. + */ +void audit_update_history(void) +{ + char *cp; + int pos; + int required; + char buf[256]; + const unsigned long long now = nsec_to_clock_t(ktime_get_boot_ns()); + + /* + * Lockless read because this is current thread and being unexpectedly + * modified by other thread is not a fatal problem. + */ + cp = buf; + cp += snprintf(buf, sizeof(buf) - 1, "name="); + for (pos = 0; pos < TASK_COMM_LEN; pos++) { + const unsigned char c = current->comm[pos]; + + if (!c) + break; + if (isalnum(c) || c == '.' || c == '_' || c == '-' || c == '/') + cp += snprintf(cp, buf - cp + sizeof(buf) - 1, "%c", + c); + else + cp += snprintf(cp, buf - cp + sizeof(buf) - 1, + "\\%03o", c); + } + /* Append PID of init namespace. */ + cp += snprintf(cp, buf - cp + sizeof(buf) - 1, ";pid=%u", + current->pid); + /* Append uptime. */ + cp += snprintf(cp, buf - cp + sizeof(buf) - 1, ";start=%llu.%02llu", + now / 100, now % 100); + /* Terminate the buffer. */ + if (cp >= buf + sizeof(buf)) + cp = buf + sizeof(buf) - 1; + *cp = '\0'; + required = cp - buf; + /* Make some room by truncating old history. */ + cp = current->comm_history; + pos = strlen(cp); + while (pos + required >= COMM_HISTORY_SIZE - 10) { + char *cp2 = memchr(cp, '>', pos) + 1; + + pos -= cp2 - cp; + memmove(cp, cp2, pos + 1); + } + /* Emit the buffer. */ + if (pos) + sprintf(cp + pos, "=>%s", buf); + else + sprintf(cp, "%s", buf); +} -- 1.8.3.1