Re: [PATCH v4 2/4] seccomp: Add sysctl to configure actions that should be logged

diff --git a/kernel/seccomp.c b/kernel/seccomp.c index e36dfe9..270a227 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -509,6 +509,22 @@ static void seccomp_send_sigsys(int syscall, int reason) } #endif /* CONFIG_SECCOMP_FILTER */ +static u32 seccomp_log_max_action = SECCOMP_RET_KILL; + +static inline void seccomp_log(unsigned long syscall, long signr, u32 action) +{ + /* Force an audit message to be emitted when the action is not greater + * than the configured maximum action. + */ + if (action <= seccomp_log_max_action) + return __audit_seccomp(syscall, signr, action); + + /* Let the audit subsystem decide if the action should be audited based + * on whether the current task itself is being audited. + */

+ return audit_seccomp(syscall, signr, action); +} + /* * Secure computing mode 1 allows only read/write/exit/sigreturn. * To be fully secure this must be combined with rlimit @@ -534,7 +550,7 @@ static void __secure_computing_strict(int this_syscall) #ifdef SECCOMP_DEBUG dump_stack(); #endif - audit_seccomp(this_syscall, SIGKILL, SECCOMP_RET_KILL); + seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL); do_exit(SIGKILL); } @@ -633,18 +649,30 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd, return 0; case SECCOMP_RET_ALLOW: + /* Open-coded seccomp_log(), optimized for the RET_ALLOW hot + * path. + * + * We only want to log RET_ALLOW actions when the admin has + * configured them to be logged via the log_max_action sysctl. + * Therefore, call __audit_seccomp() directly so that RET_ALLOW + * actions are not audited simply because the task is being + * audited. + */ + if (unlikely(seccomp_log_max_action == SECCOMP_RET_ALLOW)) + __audit_seccomp(this_syscall, 0, action); + return 0; case SECCOMP_RET_KILL: default: - audit_seccomp(this_syscall, SIGSYS, action); + seccomp_log(this_syscall, SIGSYS, action); do_exit(SIGSYS); } unreachable(); skip: - audit_seccomp(this_syscall, 0, action); + seccomp_log(this_syscall, 0, action); return -1; } #else @@ -917,12 +945,96 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, #define SECCOMP_RET_TRACE_NAME "trace" #define SECCOMP_RET_ALLOW_NAME "allow" +/* Largest strlen() of all action names */ +#define SECCOMP_RET_MAX_NAME_LEN 5 + static char seccomp_actions_avail[] = SECCOMP_RET_KILL_NAME " " SECCOMP_RET_TRAP_NAME " " SECCOMP_RET_ERRNO_NAME " " SECCOMP_RET_TRACE_NAME " " SECCOMP_RET_ALLOW_NAME; +struct seccomp_action_name { + u32 action; + const char *name; +}; + +static struct seccomp_action_name seccomp_action_names[] = {