seccomp: Report number of loaded filters in /proc/$pid/status

A common question asked when debugging seccomp filters is "how many filters are attached to your process?" Provide a way to easily answer this question through /proc/$pid/status with a "Seccomp_filters" line.

Kees Cook committed 6 years ago

Commit c818c031 parent e4d05024 files · +10 −0Browse files

Unified · Split

4 files

fs/proc/array.c +2 −0
include/linux/seccomp.h +2 −0
init/init_task.c +3 −0
kernel/seccomp.c +3 −0

fs/proc/array.c+2−0

@@ -341,6 +341,8 @@ static inline void task_seccomp(struct seq_file m, struct task_struct p) · 340 unmodified lines
341	341	seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p));
342	342	#ifdef CONFIG_SECCOMP
343	343	seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
	344	+ seq_put_decimal_ull(m, "\nSeccomp_filters:\t",
	345	+ atomic_read(&p->seccomp.filter_count));
344	346	#endif
345	347	seq_puts(m, "\nSpeculation_Store_Bypass:\t");
346	348	switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_STORE_BYPASS)) {

include/linux/seccomp.h+2−0

@@ -13,6 +13,7 @@ · 12 unmodified lines
13	13	#ifdef CONFIG_SECCOMP
14	14
15	15	#include <linux/thread_info.h>
	16	+#include <linux/atomic.h>
16	17	#include <asm/seccomp.h>
17	18
18	19	struct seccomp_filter;
@@ -29,6 +30,7 @@ struct seccomp_filter; · 10 unmodified lines
29	30	*/
30	31	struct seccomp {
31	32	int mode;
	33	+ atomic_t filter_count;
32	34	struct seccomp_filter *filter;
33	35	};
34	36

init/init_task.c+3−0

@@ -204,6 +204,9 @@ struct task_struct init_task · 203 unmodified lines
204	204	#ifdef CONFIG_SECURITY
205	205	.security = NULL,
206	206	#endif
	207	+#ifdef CONFIG_SECCOMP
	208	+ .seccomp = { .filter_count = ATOMIC_INIT(0) },
	209	+#endif
207	210	};
208	211	EXPORT_SYMBOL(init_task);
209	212

kernel/seccomp.c+3−0

@@ -398,6 +398,8 @@ static inline void seccomp_sync_threads(unsigned long flags) · 397 unmodified lines
398	398	put_seccomp_filter(thread);
399	399	smp_store_release(&thread->seccomp.filter,
400	400	caller->seccomp.filter);
	401	+ atomic_set(&thread->seccomp.filter_count,
	402	+ atomic_read(&thread->seccomp.filter_count));
401	403
402	404	/*
403	405	* Don't let an unprivileged task work around
@@ -544,6 +546,7 @@ static long seccomp_attach_filter(unsigned int flags, · 140 unmodified lines
544	546	*/
545	547	filter->prev = current->seccomp.filter;
546	548	current->seccomp.filter = filter;
	549	+ atomic_inc(&current->seccomp.filter_count);
547	550
548	551	/* Now that the new filter is in place, synchronize to all threads. */
549	552	if (flags & SECCOMP_FILTER_FLAG_TSYNC)