UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity
OpenCloudOS-Kernel/kernel
History
Gianluca Borello a5e8c07059 bpf: add bpf_probe_read_str helper 
Provide a simple helper with the same semantics of strncpy_from_unsafe():

int bpf_probe_read_str(void *dst, int size, const void *unsafe_addr)

This gives more flexibility to a bpf program. A typical use case is
intercepting a file name during sys_open(). The current approach is:

SEC("kprobe/sys_open")
void bpf_sys_open(struct pt_regs *ctx)
{
	char buf[PATHLEN]; // PATHLEN is defined to 256
	bpf_probe_read(buf, sizeof(buf), ctx->di);

	/* consume buf */
}

This is suboptimal because the size of the string needs to be estimated
at compile time, causing more memory to be copied than often necessary,
and can become more problematic if further processing on buf is done,
for example by pushing it to userspace via bpf_perf_event_output(),
since the real length of the string is unknown and the entire buffer
must be copied (and defining an unrolled strnlen() inside the bpf
program is a very inefficient and unfeasible approach).

With the new helper, the code can easily operate on the actual string
length rather than the buffer size:

SEC("kprobe/sys_open")
void bpf_sys_open(struct pt_regs *ctx)
{
	char buf[PATHLEN]; // PATHLEN is defined to 256
	int res = bpf_probe_read_str(buf, sizeof(buf), ctx->di);

	/* consume buf, for example push it to userspace via
	 * bpf_perf_event_output(), but this time we can use
	 * res (the string length) as event size, after checking
	 * its boundaries.
	 */
}

Another useful use case is when parsing individual process arguments or
individual environment variables navigating current->mm->arg_start and
current->mm->env_start: using this helper and the return value, one can
quickly iterate at the right offset of the memory area.

The code changes simply leverage the already existent
strncpy_from_unsafe() kernel function, which is safe to be called from a
bpf program as it is used in bpf_trace_printk().

Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
 		2017-01-20 12:08:43 -05:00
..
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-01-17 15:19:37 -05:00
configs config: android: enable CONFIG_SECCOMP 2016-10-11 15:06:32 -07:00
debug kdb: call vkdb_printf() from vprintk_default() only when wanted 2016-12-14 16:04:08 -08:00
events perf/x86/intel: Account interrupts for PEBS errors 2017-01-14 11:06:49 +01:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq genirq/affinity: Fix node generation from cpumask 2016-12-15 12:32:35 +01:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
power Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
printk Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
rcu rcu: Don't kick unless grace period or request 2016-11-14 10:46:31 -08:00
sched ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
time nohz: Fix collision between tick and other hrtimers 2017-01-11 10:41:33 +01:00
trace bpf: add bpf_probe_read_str helper 2017-01-20 12:08:43 -05:00
.gitignore
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.locks locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES 2016-10-25 11:31:51 +02:00
Kconfig.preempt
…
Makefile Merge branch 'akpm' (patches from Andrew) 2016-12-14 17:25:18 -08:00
acct.c
…
async.c
…
audit.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit.h audit_log_{name,link_denied}: constify struct path 2016-12-05 19:00:38 -05:00
audit_fsnotify.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit_tree.c Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2017-01-05 23:06:06 -08:00
audit_watch.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
auditfilter.c audit: add support for session ID user filter 2016-11-29 15:10:12 -05:00
auditsc.c Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2016-12-14 14:06:40 -08:00
backtracetest.c
…
bounds.c
…
capability.c capability: export has_capability 2017-01-12 07:01:56 -07:00
cgroup.c cgroup: add support for eBPF programs 2016-11-25 16:25:52 -05:00
cgroup_freezer.c
…
cgroup_pids.c cgroup: Use lld instead of ld when printing pids controller events_limit 2016-06-21 15:03:36 -04:00
compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
configs.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
context_tracking.c
…
cpu.c smp/hotplug: Undo tglxs brainfart 2016-12-26 17:30:24 -08:00
cpu_pm.c
…
cpuset.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
crash_dump.c
…
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-06-30 18:05:09 -05:00
delayacct.c
…
dma.c
…
elfcore.c
…
exec_domain.c
…
exit.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
extable.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
fork.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex.c ktime: Get rid of the union 2016-12-25 17:21:22 +01:00
futex_compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
groups.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hung_task.c hung_task: decrement sysctl_hung_task_warnings only if it is positive 2016-12-12 18:55:09 -08:00
irq_work.c
…
jump_label.c jump_labels: API for flushing deferred jump label updates 2017-01-12 14:33:16 +01:00
kallsyms.c kallsyms: add support for relative offsets in kallsyms address table 2016-03-15 16:55:16 -07:00
kcmp.c
…
kcov.c kcov: make kcov work properly with KASLR enabled 2016-12-20 09:48:47 -08:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kexec_core.c kexec: add cond_resched into kimage_alloc_crash_control_pages 2016-12-14 16:04:07 -08:00
kexec_file.c ima: on soft reboot, save the measurement list 2016-12-20 09:48:44 -08:00
kexec_internal.h kexec_file: Allow arch-specific memory walking for kexec_add_buffer 2016-11-30 23:14:57 +11:00
kmod.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
kprobes.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ksysfs.c kexec: add a kexec_crash_loaded() function 2016-08-02 19:35:30 -04:00
kthread.c kthread: add __printf attributes 2016-12-12 18:55:06 -08:00
latencytop.c
…
membarrier.c
…
memremap.c mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done} 2017-01-10 18:31:54 -08:00
module-internal.h
…
module.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
module_signing.c KEYS: Move the point of trust determination to __key_link() 2016-04-11 22:43:43 +01:00
notifier.c
…
nsproxy.c cgroup: introduce cgroup namespaces 2016-02-16 13:04:58 -05:00
padata.c padata: Remove unused but set variables 2016-10-25 11:08:10 +08:00
panic.c taint/module: Clean up global and module taint flags handling 2016-11-26 11:18:01 -08:00
params.c
…
pid.c remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
pid_namespace.c pid: fix lockdep deadlock warning due to ucount_lock 2017-01-10 13:34:56 +13:00
profile.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ptrace.c ptrace: Don't allow accessing an undumpable mm 2016-11-22 12:57:38 -06:00
range.c
…
reboot.c
…
relay.c relay: check array offset before using it 2016-12-14 16:04:08 -08:00
resource.c /proc/iomem: only expose physical resource addresses to privileged users 2016-04-14 12:56:09 -07:00
seccomp.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-12-14 13:57:44 -08:00
signal.c signal: protect SIGNAL_UNKILLABLE from unintentional clearing. 2017-01-10 18:31:55 -08:00
smp.c kernel/smp: Tell the user we're bringing up secondary CPUs 2016-10-26 12:02:35 +02:00
smpboot.c kthread/smpboot: do not park in kthread_create_on_cpu() 2016-10-11 15:06:33 -07:00
smpboot.h cpu/hotplug: Create hotplug threads 2016-03-01 20:36:56 +01:00
softirq.c softirq: Display IRQ_POLL for irq-poll statistics 2016-10-21 15:45:47 -06:00
stacktrace.c
…
stop_machine.c locking/core, stop_machine: Yield the CPU during stop machine() 2016-11-16 10:15:09 +01:00
sys.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sys_ni.c move aio compat to fs/aio.c 2016-12-22 22:58:37 -05:00
sysctl.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sysctl_binary.c sysctl: add KERN_CONT to deprecated_sysctl_warning() 2016-12-14 16:04:07 -08:00
task_work.c task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works 2016-08-02 19:35:02 -04:00
taskstats.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
test_kprobes.c
…
torture.c torture: Convert torture_shutdown() to hrtimer 2016-08-22 10:01:49 -07:00
tracepoint.c tracing: Have the reg function allow to fail 2016-12-09 09:13:30 -05:00
tsacct.c time, acct: Drop irq save & restore from __acct_update_integrals() 2016-02-29 09:53:09 +01:00
ucount.c mntns: Add a limit on the number of mount namespaces. 2016-08-31 07:28:35 -05:00
uid16.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user-return-notifier.c
…
user.c
…
user_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname_sysctl.c
…
watchdog.c kernel/watchdog.c: move hardlockup detector to separate file 2016-12-14 16:04:08 -08:00
watchdog_hld.c kernel/watchdog.c: move hardlockup detector to separate file 2016-12-14 16:04:08 -08:00
workqueue.c Merge branch 'for-4.9' into for-4.10 2016-10-19 12:12:40 -04:00
workqueue_internal.h sched/core: Get rid of 'cpu' argument in wq_worker_sleeping() 2016-03-02 10:28:47 -05:00