Re: [PATCH] audit: use current whenever possible

There are many places, notably audit_log_task_info() and audit_log_exit(), that take task_struct pointers but in reality they are always working on the current task. This patch eliminates the task_struct arguments and uses current directly which allows a number of cleanups as well. Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt;

--- drivers/tty/tty_audit.c | 13 ++-- include/linux/audit.h | 6 +- kernel/audit.c | 34 +++++----- kernel/audit.h | 2 - kernel/auditsc.c | 131 ++++++++++++++++++-------------------- security/integrity/ima/ima_api.c | 2 - 6 files changed, 90 insertions(+), 98 deletions(-) diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c index 50f567b6a66e..28f87fd6a28e 100644 --- a/drivers/tty/tty_audit.c +++ b/drivers/tty/tty_audit.c @@ -61,20 +61,19 @@ static void tty_audit_log(const char *description, dev_t dev, unsigned char *data, size_t size) { struct audit_buffer *ab; - struct task_struct *tsk = current; - pid_t pid = task_pid_nr(tsk); - uid_t uid = from_kuid(&init_user_ns, task_uid(tsk)); - uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk)); - unsigned int sessionid = audit_get_sessionid(tsk); + pid_t pid = task_pid_nr(current); + uid_t uid = from_kuid(&init_user_ns, task_uid(current)); + uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current)); + unsigned int sessionid = audit_get_sessionid(current); ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY); if (ab) { - char name[sizeof(tsk->comm)]; + char name[sizeof(current->comm)]; audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d" " minor=%d comm=", description, pid, uid, loginuid, sessionid, MAJOR(dev), MINOR(dev)); - get_task_comm(name, tsk); + get_task_comm(name, current); audit_log_untrustedstring(ab, name); audit_log_format(ab, " data="); audit_log_n_hex(ab, data, size); diff --git a/include/linux/audit.h b/include/linux/audit.h index 58cf665f597e..a625c29a2ea2 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -151,8 +151,7 @@ extern void audit_log_link_denied(const char *operation); extern void audit_log_lost(const char *message); extern int audit_log_task_context(struct audit_buffer *ab); -extern void audit_log_task_info(struct audit_buffer *ab, - struct task_struct *tsk); +extern void audit_log_task_info(struct audit_buffer *ab); extern int audit_update_lsm_rules(void); @@ -200,8 +199,7 @@ static inline int audit_log_task_context(struct audit_buffer *ab) { return 0; } -static inline void audit_log_task_info(struct audit_buffer *ab, - struct task_struct *tsk) +static inline void audit_log_task_info(struct audit_buffer *ab) { } #define audit_enabled AUDIT_OFF #endif /* CONFIG_AUDIT */ diff --git a/kernel/audit.c b/kernel/audit.c index d09298d3c2d2..779671883349 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1096,10 +1096,11 @@ static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature if (audit_enabled == AUDIT_OFF) return; + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE); if (!ab) return; - audit_log_task_info(ab, current); + audit_log_task_info(ab); audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d", audit_feature_names[which], !!old_feature, !!new_feature, !!old_lock, !!new_lock, res); @@ -2246,15 +2247,15 @@ void audit_log_d_path_exe(struct audit_buffer *ab, audit_log_format(ab, " exe=(null)"); } -struct tty_struct *audit_get_tty(struct task_struct *tsk) +struct tty_struct *audit_get_tty(void) { struct tty_struct *tty = NULL; unsigned long flags; - spin_lock_irqsave(&tsk->sighand->siglock, flags); - if (tsk->signal) - tty = tty_kref_get(tsk->signal->tty); - spin_unlock_irqrestore(&tsk->sighand->siglock, flags); + spin_lock_irqsave(&current->sighand->siglock, flags); + if (current->signal) + tty = tty_kref_get(current->signal->tty); + spin_unlock_irqrestore(&current->sighand->siglock, flags); return tty; } @@ -2263,25 +2264,24 @@ void audit_put_tty(struct tty_struct *tty) tty_kref_put(tty); } -void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk) +void audit_log_task_info(struct audit_buffer *ab) { const struct cred *cred; - char comm[sizeof(tsk->comm)]; + char comm[sizeof(current->comm)]; struct tty_struct *tty; if (!ab) return; - /* tsk == current */ cred = current_cred(); - tty = audit_get_tty(tsk); + tty = audit_get_tty(); audit_log_format(ab, " ppid=%d pid=%d auid=%u uid=%u gid=%u" " euid=%u suid=%u fsuid=%u" " egid=%u sgid=%u fsgid=%u tty=%s ses=%u", - task_ppid_nr(tsk), - task_tgid_nr(tsk), - from_kuid(&init_user_ns, audit_get_loginuid(tsk)), + task_ppid_nr(current), + task_tgid_nr(current), + from_kuid(&init_user_ns, audit_get_loginuid(current)), from_kuid(&init_user_ns, cred->uid), from_kgid(&init_user_ns, cred->gid), from_kuid(&init_user_ns, cred->euid), @@ -2291,11 +2291,11 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk) from_kgid(&init_user_ns, cred->sgid), from_kgid(&init_user_ns, cred->fsgid), tty ? tty_name(tty) : "(none)", - audit_get_sessionid(tsk)); + audit_get_sessionid(current)); audit_put_tty(tty); audit_log_format(ab, " comm="); - audit_log_untrustedstring(ab, get_task_comm(comm, tsk)); - audit_log_d_path_exe(ab, tsk->mm); + audit_log_untrustedstring(ab, get_task_comm(comm, current)); + audit_log_d_path_exe(ab, current->mm); audit_log_task_context(ab); } EXPORT_SYMBOL(audit_log_task_info); @@ -2316,7 +2316,7 @@ void audit_log_link_denied(const char *operation) if (!ab) return; audit_log_format(ab, "op=%s", operation); - audit_log_task_info(ab, current); + audit_log_task_info(ab); audit_log_format(ab, " res=0"); audit_log_end(ab); } diff --git a/kernel/audit.h b/kernel/audit.h index 0b5295aeaebb..91421679a168 100644 --- a/kernel/audit.h +++ b/kernel/audit.h @@ -264,7 +264,7 @@ extern struct audit_entry *audit_dupe_rule(struct audit_krule *old); extern void audit_log_d_path_exe(struct audit_buffer *ab, struct mm_struct *mm); -extern struct tty_struct *audit_get_tty(struct task_struct *tsk); +extern struct tty_struct *audit_get_tty(void); extern void audit_put_tty(struct tty_struct *tty); /* audit watch functions */ diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 51e735aedf58..6593a5207fb0 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -830,44 +830,6 @@ void audit_filter_inodes(struct task_struct *tsk, struct audit_context *ctx) rcu_read_unlock(); } -/* Transfer the audit context pointer to the caller, clearing it in the tsk's struct */ -static inline struct audit_context *audit_take_context(struct task_struct *tsk, - int return_valid, - long return_code) -{ - struct audit_context *context = tsk->audit_context; - - if (!context) - return NULL; - context->return_valid = return_valid; - - /* - * we need to fix up the return code in the audit logs if the actual - * return codes are later going to be fixed up by the arch specific - * signal handlers - * - * This is actually a test for: - * (rc == ERESTARTSYS ) || (rc == ERESTARTNOINTR) || - * (rc == ERESTARTNOHAND) || (rc == ERESTART_RESTARTBLOCK) - * - * but is faster than a bunch of || - */ - if (unlikely(return_code <= -ERESTARTSYS) && - (return_code >= -ERESTART_RESTARTBLOCK) && - (return_code != -ENOIOCTLCMD)) - context->return_code = -EINTR; - else - context->return_code = return_code; - - if (context->in_syscall && !context->dummy) { - audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_EXIT]); - audit_filter_inodes(tsk, context); - } - - audit_set_context(tsk, NULL); - return context; -} - static inline void audit_proctitle_free(struct audit_context *context) { kfree(context->proctitle.value); @@ -1296,15 +1258,18 @@ static inline int audit_proctitle_rtrim(char *proctitle, int len) return len; } -static void audit_log_proctitle(struct task_struct *tsk, - struct audit_context *context) +static void audit_log_proctitle(void) { int res; char *buf; char *msg = "(null)"; int len = strlen(msg); + struct audit_context *context = audit_context(); struct audit_buffer *ab; + if (!context || context->dummy) + return; + ab = audit_log_start(context, GFP_KERNEL, AUDIT_PROCTITLE); if (!ab) return; /* audit_panic or being filtered */ @@ -1317,7 +1282,7 @@ static void audit_log_proctitle(struct task_struct *tsk, if (!buf) goto out; /* Historically called this from procfs naming */ - res = get_cmdline(tsk, buf, MAX_PROCTITLE_AUDIT_LEN); + res = get_cmdline(current, buf, MAX_PROCTITLE_AUDIT_LEN); if (res == 0) { kfree(buf); goto out; @@ -1337,15 +1302,15 @@ static void audit_log_proctitle(struct task_struct *tsk, audit_log_end(ab); } -static void audit_log_exit(struct audit_context *context, struct task_struct *tsk) +static void audit_log_exit(void) { int i, call_panic = 0; + struct audit_context *context = audit_context(); struct audit_buffer *ab; struct audit_aux_data *aux; struct audit_names *n; - /* tsk == current */ - context->personality = tsk->personality; + context->personality = current->personality; ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL); if (!ab) @@ -1367,7 +1332,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts context->argv[3], context->name_count); - audit_log_task_info(ab, tsk); + audit_log_task_info(ab); audit_log_key(ab, context->filterkey); audit_log_end(ab); @@ -1456,7 +1421,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts audit_log_name(context, n, NULL, i++, &call_panic); } - audit_log_proctitle(tsk, context); + audit_log_proctitle(); /* Send end of event record to help user space know we are finished */ ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE); @@ -1474,22 +1439,31 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts */ void __audit_free(struct task_struct *tsk) { - struct audit_context *context; + struct audit_context *context = tsk->audit_context; - context = audit_take_context(tsk, 0, 0); if (!context) return; - /* Check for system calls that do not go through the exit - * function (e.g., exit_group), then free context block. - * We use GFP_ATOMIC here because we might be doing this - * in the context of the idle thread */ - /* that can happen only if we are called from do_exit() */ - if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT) - audit_log_exit(context, tsk); + /* We are called either by do_exit() or the fork() error handling code; + * in the former case tsk == current and in the latter tsk is a + * random task_struct that doesn't doesn't have any meaningful data we + * need to log via audit_log_exit(). + */ + if (tsk == current && !context->dummy && context->in_syscall) { + context->return_valid = 0; + context->return_code = 0; + + audit_filter_syscall(tsk, context, + &audit_filter_list[AUDIT_FILTER_EXIT]); + audit_filter_inodes(tsk, context);

+ if (context->current_state == AUDIT_RECORD_CONTEXT) + audit_log_exit(); + } + if (!list_empty(&context->killed_trees)) audit_kill_trees(&context->killed_trees); + audit_set_context(tsk, NULL); audit_free_context(context); } @@ -1559,17 +1533,40 @@ void __audit_syscall_exit(int success, long return_code) { struct audit_context *context; - if (success) - success = AUDITSC_SUCCESS; - else - success = AUDITSC_FAILURE; - - context = audit_take_context(current, success, return_code); + context = audit_context(); if (!context) return; - if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT) - audit_log_exit(context, current); + if (!context->dummy && context->in_syscall) { + if (success) + context->return_valid = AUDITSC_SUCCESS; + else + context->return_valid = AUDITSC_FAILURE; + + /* + * we need to fix up the return code in the audit logs if the + * actual return codes are later going to be fixed up by the + * arch specific signal handlers + * + * This is actually a test for: + * (rc == ERESTARTSYS ) || (rc == ERESTARTNOINTR) || + * (rc == ERESTARTNOHAND) || (rc == ERESTART_RESTARTBLOCK) + * + * but is faster than a bunch of || + */ + if (unlikely(return_code <= -ERESTARTSYS) && + (return_code >= -ERESTART_RESTARTBLOCK) && + (return_code != -ENOIOCTLCMD)) + context->return_code = -EINTR; + else + context->return_code = return_code; + + audit_filter_syscall(current, context, + &audit_filter_list[AUDIT_FILTER_EXIT]); + audit_filter_inodes(current, context); + if (context->current_state == AUDIT_RECORD_CONTEXT) + audit_log_exit(); + } context->in_syscall = 0; context->prio = context->state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0; @@ -1591,7 +1588,6 @@ void __audit_syscall_exit(int success, long return_code) kfree(context->filterkey); context->filterkey = NULL; } - audit_set_context(current, context); } static inline void handle_one(const struct inode *inode) @@ -2025,7 +2021,7 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid, uid = from_kuid(&init_user_ns, task_uid(current)); oldloginuid = from_kuid(&init_user_ns, koldloginuid); loginuid = from_kuid(&init_user_ns, kloginuid), - tty = audit_get_tty(current); + tty = audit_get_tty(); audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid); audit_log_task_context(ab); @@ -2046,7 +2042,6 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid, */ int audit_set_loginuid(kuid_t loginuid) { - struct task_struct *task = current; unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET; kuid_t oldloginuid; int rc; @@ -2065,8 +2060,8 @@ int audit_set_loginuid(kuid_t loginuid) sessionid = (unsigned int)atomic_inc_return(&session_id); } - task->sessionid = sessionid; - task->loginuid = loginuid; + current->sessionid = sessionid; + current->loginuid = loginuid; out: audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc); return rc; diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 99dd1d53fc35..af134588ab4e 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -336,7 +336,7 @@ void ima_audit_measurement(struct integrity_iint_cache *iint, audit_log_untrustedstring(ab, filename); audit_log_format(ab, " hash=\"%s:%s\"", algo_name, hash); - audit_log_task_info(ab, current); + audit_log_task_info(ab); audit_log_end(ab); iint->flags |= IMA_AUDITED;