From 73ab1cb2de9e3efe7f818d5453de271e5371df1d Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 9 Jan 2019 02:23:56 +0900 Subject: [PATCH 1/4] umh: add exit routine for UMH process A UMH process which is created by the fork_usermode_blob() such as bpfilter needs to release members of the umh_info when process is terminated. But the do_exit() does not release members of the umh_info. hence module which uses UMH needs own code to detect whether UMH process is terminated or not. But this implementation needs extra code for checking the status of UMH process. it eventually makes the code more complex. The new PF_UMH flag is added and it is used to identify UMH processes. The exit_umh() does not release members of the umh_info. Hence umh_info->cleanup callback should release both members of the umh_info and the private data. Suggested-by: David S. Miller Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller --- include/linux/sched.h | 9 +++++++++ include/linux/umh.h | 2 ++ kernel/exit.c | 1 + kernel/umh.c | 33 +++++++++++++++++++++++++++++++-- 4 files changed, 43 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 89541d248893e..e35e35b9fc48c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1406,6 +1406,7 @@ extern struct pid *cad_pid; #define PF_RANDOMIZE 0x00400000 /* Randomize virtual address space */ #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ #define PF_MEMSTALL 0x01000000 /* Stalled due to lack of memory */ +#define PF_UMH 0x02000000 /* I'm an Usermodehelper process */ #define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */ #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ #define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */ @@ -1904,6 +1905,14 @@ static inline void rseq_execve(struct task_struct *t) #endif +void __exit_umh(struct task_struct *tsk); + +static inline void exit_umh(struct task_struct *tsk) +{ + if (unlikely(tsk->flags & PF_UMH)) + __exit_umh(tsk); +} + #ifdef CONFIG_DEBUG_RSEQ void rseq_syscall(struct pt_regs *regs); diff --git a/include/linux/umh.h b/include/linux/umh.h index 235f51b62c71e..0c08de356d0d4 100644 --- a/include/linux/umh.h +++ b/include/linux/umh.h @@ -47,6 +47,8 @@ struct umh_info { const char *cmdline; struct file *pipe_to_umh; struct file *pipe_from_umh; + struct list_head list; + void (*cleanup)(struct umh_info *info); pid_t pid; }; int fork_usermode_blob(void *data, size_t len, struct umh_info *info); diff --git a/kernel/exit.c b/kernel/exit.c index 8a01b671dc1fb..dad70419195ce 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -866,6 +866,7 @@ void __noreturn do_exit(long code) exit_task_namespaces(tsk); exit_task_work(tsk); exit_thread(tsk); + exit_umh(tsk); /* * Flush inherited counters to the parent - before the parent diff --git a/kernel/umh.c b/kernel/umh.c index 0baa672e023cb..d937cbad903aa 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -37,6 +37,8 @@ static kernel_cap_t usermodehelper_bset = CAP_FULL_SET; static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET; static DEFINE_SPINLOCK(umh_sysctl_lock); static DECLARE_RWSEM(umhelper_sem); +static LIST_HEAD(umh_list); +static DEFINE_MUTEX(umh_list_lock); static void call_usermodehelper_freeinfo(struct subprocess_info *info) { @@ -100,10 +102,12 @@ static int call_usermodehelper_exec_async(void *data) commit_creds(new); sub_info->pid = task_pid_nr(current); - if (sub_info->file) + if (sub_info->file) { retval = do_execve_file(sub_info->file, sub_info->argv, sub_info->envp); - else + if (!retval) + current->flags |= PF_UMH; + } else retval = do_execve(getname_kernel(sub_info->path), (const char __user *const __user *)sub_info->argv, (const char __user *const __user *)sub_info->envp); @@ -517,6 +521,11 @@ int fork_usermode_blob(void *data, size_t len, struct umh_info *info) goto out; err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); + if (!err) { + mutex_lock(&umh_list_lock); + list_add(&info->list, &umh_list); + mutex_unlock(&umh_list_lock); + } out: fput(file); return err; @@ -679,6 +688,26 @@ static int proc_cap_handler(struct ctl_table *table, int write, return 0; } +void __exit_umh(struct task_struct *tsk) +{ + struct umh_info *info; + pid_t pid = tsk->pid; + + mutex_lock(&umh_list_lock); + list_for_each_entry(info, &umh_list, list) { + if (info->pid == pid) { + list_del(&info->list); + mutex_unlock(&umh_list_lock); + goto out; + } + } + mutex_unlock(&umh_list_lock); + return; +out: + if (info->cleanup) + info->cleanup(info); +} + struct ctl_table usermodehelper_table[] = { { .procname = "bset", From 5b4cb650e569db2e6a09d2fa0ef8eb789a0ac5d8 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 9 Jan 2019 02:24:34 +0900 Subject: [PATCH 2/4] net: bpfilter: use cleanup callback to release umh_info Now, UMH process is killed, do_exit() calls the umh_info->cleanup callback to release members of the umh_info. This patch makes bpfilter_umh's cleanup routine to use the umh_info->cleanup callback. Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller --- include/linux/bpfilter.h | 11 ++++++++--- net/bpfilter/bpfilter_kern.c | 23 ++++++++++------------- net/ipv4/bpfilter/sockopt.c | 33 ++++++++++++++++++++++++++------- 3 files changed, 44 insertions(+), 23 deletions(-) diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index f02cee0225d40..70ffeed280e9d 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -3,13 +3,18 @@ #define _LINUX_BPFILTER_H #include +#include struct sock; int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval, unsigned int optlen); int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, int __user *optlen); -extern int (*bpfilter_process_sockopt)(struct sock *sk, int optname, - char __user *optval, - unsigned int optlen, bool is_set); +struct bpfilter_umh_ops { + struct umh_info info; + int (*sockopt)(struct sock *sk, int optname, + char __user *optval, + unsigned int optlen, bool is_set); +}; +extern struct bpfilter_umh_ops bpfilter_ops; #endif diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index 7acfc83087d5c..a68940b74c015 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -13,7 +13,6 @@ extern char bpfilter_umh_start; extern char bpfilter_umh_end; -static struct umh_info info; /* since ip_getsockopt() can run in parallel, serialize access to umh */ static DEFINE_MUTEX(bpfilter_lock); @@ -28,16 +27,13 @@ static void shutdown_umh(struct umh_info *info) force_sig(SIGKILL, tsk); put_task_struct(tsk); } - fput(info->pipe_to_umh); - fput(info->pipe_from_umh); - info->pid = 0; } static void __stop_umh(void) { if (IS_ENABLED(CONFIG_INET)) { - bpfilter_process_sockopt = NULL; - shutdown_umh(&info); + bpfilter_ops.sockopt = NULL; + shutdown_umh(&bpfilter_ops.info); } } @@ -64,9 +60,10 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, req.addr = (long __force __user)optval; req.len = optlen; mutex_lock(&bpfilter_lock); - if (!info.pid) + if (!bpfilter_ops.info.pid) goto out; - n = __kernel_write(info.pipe_to_umh, &req, sizeof(req), &pos); + n = __kernel_write(bpfilter_ops.info.pipe_to_umh, &req, sizeof(req), + &pos); if (n != sizeof(req)) { pr_err("write fail %zd\n", n); __stop_umh(); @@ -74,7 +71,8 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, goto out; } pos = 0; - n = kernel_read(info.pipe_from_umh, &reply, sizeof(reply), &pos); + n = kernel_read(bpfilter_ops.info.pipe_from_umh, &reply, sizeof(reply), + &pos); if (n != sizeof(reply)) { pr_err("read fail %zd\n", n); __stop_umh(); @@ -92,13 +90,12 @@ static int __init load_umh(void) int err; /* fork usermode process */ - info.cmdline = "bpfilter_umh"; err = fork_usermode_blob(&bpfilter_umh_start, &bpfilter_umh_end - &bpfilter_umh_start, - &info); + &bpfilter_ops.info); if (err) return err; - pr_info("Loaded bpfilter_umh pid %d\n", info.pid); + pr_info("Loaded bpfilter_umh pid %d\n", bpfilter_ops.info.pid); /* health check that usermode process started correctly */ if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) { @@ -106,7 +103,7 @@ static int __init load_umh(void) return -EFAULT; } if (IS_ENABLED(CONFIG_INET)) - bpfilter_process_sockopt = &__bpfilter_process_sockopt; + bpfilter_ops.sockopt = &__bpfilter_process_sockopt; return 0; } diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index 5e04ed25bc0e9..c326cfbc0f621 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -1,28 +1,37 @@ // SPDX-License-Identifier: GPL-2.0 +#include +#include #include #include #include #include #include +#include +#include -int (*bpfilter_process_sockopt)(struct sock *sk, int optname, - char __user *optval, - unsigned int optlen, bool is_set); -EXPORT_SYMBOL_GPL(bpfilter_process_sockopt); +struct bpfilter_umh_ops bpfilter_ops; +EXPORT_SYMBOL_GPL(bpfilter_ops); + +static void bpfilter_umh_cleanup(struct umh_info *info) +{ + fput(info->pipe_to_umh); + fput(info->pipe_from_umh); + info->pid = 0; +} static int bpfilter_mbox_request(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set) { - if (!bpfilter_process_sockopt) { + if (!bpfilter_ops.sockopt) { int err = request_module("bpfilter"); if (err) return err; - if (!bpfilter_process_sockopt) + if (!bpfilter_ops.sockopt) return -ECHILD; } - return bpfilter_process_sockopt(sk, optname, optval, optlen, is_set); + return bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set); } int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval, @@ -41,3 +50,13 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, return bpfilter_mbox_request(sk, optname, optval, len, false); } + +static int __init bpfilter_sockopt_init(void) +{ + bpfilter_ops.info.cmdline = "bpfilter_umh"; + bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup; + + return 0; +} + +module_init(bpfilter_sockopt_init); From 61fbf5933d42b02f552123af5a87a06335a3b4db Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 9 Jan 2019 02:24:53 +0900 Subject: [PATCH 3/4] net: bpfilter: restart bpfilter_umh when error occurred The bpfilter_umh will be stopped via __stop_umh() when the bpfilter error occurred. The bpfilter_umh() couldn't start again because there is no restart routine. The section of the bpfilter_umh_{start/end} is no longer .init.rodata because these area should be reused in the restart routine. hence the section name is changed to .bpfilter_umh. The bpfilter_ops->start() is restart callback. it will be called when bpfilter_umh is stopped. The stop bit means bpfilter_umh is stopped. this bit is set by both start and stop routine. Before this patch, Test commands: $ iptables -vnL $ kill -9 $ iptables -vnL [ 480.045136] bpfilter: write fail -32 $ iptables -vnL All iptables commands will fail. After this patch, Test commands: $ iptables -vnL $ kill -9 $ iptables -vnL $ iptables -vnL Now, all iptables commands will work. Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller --- include/linux/bpfilter.h | 2 ++ net/bpfilter/bpfilter_kern.c | 37 +++++++++++++++++++++++--------- net/bpfilter/bpfilter_umh_blob.S | 2 +- net/ipv4/bpfilter/sockopt.c | 11 +++++++++- 4 files changed, 40 insertions(+), 12 deletions(-) diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index 70ffeed280e9d..8ebcbdd70bdc5 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -15,6 +15,8 @@ struct bpfilter_umh_ops { int (*sockopt)(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set); + int (*start)(void); + bool stop; }; extern struct bpfilter_umh_ops bpfilter_ops; #endif diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index a68940b74c015..c0fcde910a7ad 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -16,13 +16,14 @@ extern char bpfilter_umh_end; /* since ip_getsockopt() can run in parallel, serialize access to umh */ static DEFINE_MUTEX(bpfilter_lock); -static void shutdown_umh(struct umh_info *info) +static void shutdown_umh(void) { struct task_struct *tsk; - if (!info->pid) + if (bpfilter_ops.stop) return; - tsk = get_pid_task(find_vpid(info->pid), PIDTYPE_PID); + + tsk = get_pid_task(find_vpid(bpfilter_ops.info.pid), PIDTYPE_PID); if (tsk) { force_sig(SIGKILL, tsk); put_task_struct(tsk); @@ -31,10 +32,8 @@ static void shutdown_umh(struct umh_info *info) static void __stop_umh(void) { - if (IS_ENABLED(CONFIG_INET)) { - bpfilter_ops.sockopt = NULL; - shutdown_umh(&bpfilter_ops.info); - } + if (IS_ENABLED(CONFIG_INET)) + shutdown_umh(); } static void stop_umh(void) @@ -85,7 +84,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, return ret; } -static int __init load_umh(void) +static int start_umh(void) { int err; @@ -95,6 +94,7 @@ static int __init load_umh(void) &bpfilter_ops.info); if (err) return err; + bpfilter_ops.stop = false; pr_info("Loaded bpfilter_umh pid %d\n", bpfilter_ops.info.pid); /* health check that usermode process started correctly */ @@ -102,14 +102,31 @@ static int __init load_umh(void) stop_umh(); return -EFAULT; } - if (IS_ENABLED(CONFIG_INET)) - bpfilter_ops.sockopt = &__bpfilter_process_sockopt; return 0; } +static int __init load_umh(void) +{ + int err; + + if (!bpfilter_ops.stop) + return -EFAULT; + err = start_umh(); + if (!err && IS_ENABLED(CONFIG_INET)) { + bpfilter_ops.sockopt = &__bpfilter_process_sockopt; + bpfilter_ops.start = &start_umh; + } + + return err; +} + static void __exit fini_umh(void) { + if (IS_ENABLED(CONFIG_INET)) { + bpfilter_ops.start = NULL; + bpfilter_ops.sockopt = NULL; + } stop_umh(); } module_init(load_umh); diff --git a/net/bpfilter/bpfilter_umh_blob.S b/net/bpfilter/bpfilter_umh_blob.S index 40311d10d2f27..7f1c521dcc2f7 100644 --- a/net/bpfilter/bpfilter_umh_blob.S +++ b/net/bpfilter/bpfilter_umh_blob.S @@ -1,5 +1,5 @@ /* SPDX-License-Identifier: GPL-2.0 */ - .section .init.rodata, "a" + .section .bpfilter_umh, "a" .global bpfilter_umh_start bpfilter_umh_start: .incbin "net/bpfilter/bpfilter_umh" diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index c326cfbc0f621..de84ede4e7653 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -14,6 +14,7 @@ EXPORT_SYMBOL_GPL(bpfilter_ops); static void bpfilter_umh_cleanup(struct umh_info *info) { + bpfilter_ops.stop = true; fput(info->pipe_to_umh); fput(info->pipe_from_umh); info->pid = 0; @@ -23,14 +24,21 @@ static int bpfilter_mbox_request(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set) { + int err; + if (!bpfilter_ops.sockopt) { - int err = request_module("bpfilter"); + err = request_module("bpfilter"); if (err) return err; if (!bpfilter_ops.sockopt) return -ECHILD; } + if (bpfilter_ops.stop) { + err = bpfilter_ops.start(); + if (err) + return err; + } return bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set); } @@ -53,6 +61,7 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, static int __init bpfilter_sockopt_init(void) { + bpfilter_ops.stop = true; bpfilter_ops.info.cmdline = "bpfilter_umh"; bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup; From 71a8508402b570127d6500c1ad456bbd33ccf187 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 9 Jan 2019 02:25:10 +0900 Subject: [PATCH 4/4] net: bpfilter: disallow to remove bpfilter module while being used The bpfilter.ko module can be removed while functions of the bpfilter.ko are executing. so panic can occurred. in order to protect that, locks can be used. a bpfilter_lock protects routines in the __bpfilter_process_sockopt() but it's not enough because __exit routine can be executed concurrently. Now, the bpfilter_umh can not run in parallel. So, the module do not removed while it's being used and it do not double-create UMH process. The members of the umh_info and the bpfilter_umh_ops are protected by the bpfilter_umh_ops.lock. test commands: while : do iptables -I FORWARD -m string --string ap --algo kmp & modprobe -rv bpfilter & done splat looks like: [ 298.623435] BUG: unable to handle kernel paging request at fffffbfff807440b [ 298.628512] #PF error: [normal kernel read fault] [ 298.633018] PGD 124327067 P4D 124327067 PUD 11c1a3067 PMD 119eb2067 PTE 0 [ 298.638859] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 298.638859] CPU: 0 PID: 2997 Comm: iptables Not tainted 4.20.0+ #154 [ 298.638859] RIP: 0010:__mutex_lock+0x6b9/0x16a0 [ 298.638859] Code: c0 00 00 e8 89 82 ff ff 80 bd 8f fc ff ff 00 0f 85 d9 05 00 00 48 8b 85 80 fc ff ff 48 bf 00 00 00 00 00 fc ff df 48 c1 e8 03 <80> 3c 38 00 0f 85 1d 0e 00 00 48 8b 85 c8 fc ff ff 49 39 47 58 c6 [ 298.638859] RSP: 0018:ffff88810e7777a0 EFLAGS: 00010202 [ 298.638859] RAX: 1ffffffff807440b RBX: ffff888111bd4d80 RCX: 0000000000000000 [ 298.638859] RDX: 1ffff110235ff806 RSI: ffff888111bd5538 RDI: dffffc0000000000 [ 298.638859] RBP: ffff88810e777b30 R08: 0000000080000002 R09: 0000000000000000 [ 298.638859] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff168a42c [ 298.638859] R13: ffff888111bd4d80 R14: ffff8881040e9a05 R15: ffffffffc03a2000 [ 298.638859] FS: 00007f39e3758700(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000 [ 298.638859] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 298.638859] CR2: fffffbfff807440b CR3: 000000011243e000 CR4: 00000000001006f0 [ 298.638859] Call Trace: [ 298.638859] ? mutex_lock_io_nested+0x1560/0x1560 [ 298.638859] ? kasan_kmalloc+0xa0/0xd0 [ 298.638859] ? kmem_cache_alloc+0x1c2/0x260 [ 298.638859] ? __alloc_file+0x92/0x3c0 [ 298.638859] ? alloc_empty_file+0x43/0x120 [ 298.638859] ? alloc_file_pseudo+0x220/0x330 [ 298.638859] ? sock_alloc_file+0x39/0x160 [ 298.638859] ? __sys_socket+0x113/0x1d0 [ 298.638859] ? __x64_sys_socket+0x6f/0xb0 [ 298.638859] ? do_syscall_64+0x138/0x560 [ 298.638859] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 298.638859] ? __alloc_file+0x92/0x3c0 [ 298.638859] ? init_object+0x6b/0x80 [ 298.638859] ? cyc2ns_read_end+0x10/0x10 [ 298.638859] ? cyc2ns_read_end+0x10/0x10 [ 298.638859] ? hlock_class+0x140/0x140 [ 298.638859] ? sched_clock_local+0xd4/0x140 [ 298.638859] ? sched_clock_local+0xd4/0x140 [ 298.638859] ? check_flags.part.37+0x440/0x440 [ 298.638859] ? __lock_acquire+0x4f90/0x4f90 [ 298.638859] ? set_rq_offline.part.89+0x140/0x140 [ ... ] Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller --- include/linux/bpfilter.h | 2 ++ net/bpfilter/bpfilter_kern.c | 28 +++++++++++----------------- net/ipv4/bpfilter/sockopt.c | 22 ++++++++++++++++------ 3 files changed, 29 insertions(+), 23 deletions(-) diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index 8ebcbdd70bdc5..d815622cd31e5 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -12,6 +12,8 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, int __user *optlen); struct bpfilter_umh_ops { struct umh_info info; + /* since ip_getsockopt() can run in parallel, serialize access to umh */ + struct mutex lock; int (*sockopt)(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set); diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index c0fcde910a7ad..7ee4fea936375 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -13,9 +13,6 @@ extern char bpfilter_umh_start; extern char bpfilter_umh_end; -/* since ip_getsockopt() can run in parallel, serialize access to umh */ -static DEFINE_MUTEX(bpfilter_lock); - static void shutdown_umh(void) { struct task_struct *tsk; @@ -36,13 +33,6 @@ static void __stop_umh(void) shutdown_umh(); } -static void stop_umh(void) -{ - mutex_lock(&bpfilter_lock); - __stop_umh(); - mutex_unlock(&bpfilter_lock); -} - static int __bpfilter_process_sockopt(struct sock *sk, int optname, char __user *optval, unsigned int optlen, bool is_set) @@ -58,7 +48,6 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, req.cmd = optname; req.addr = (long __force __user)optval; req.len = optlen; - mutex_lock(&bpfilter_lock); if (!bpfilter_ops.info.pid) goto out; n = __kernel_write(bpfilter_ops.info.pipe_to_umh, &req, sizeof(req), @@ -80,7 +69,6 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, } ret = reply.status; out: - mutex_unlock(&bpfilter_lock); return ret; } @@ -99,7 +87,7 @@ static int start_umh(void) /* health check that usermode process started correctly */ if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) { - stop_umh(); + shutdown_umh(); return -EFAULT; } @@ -110,24 +98,30 @@ static int __init load_umh(void) { int err; - if (!bpfilter_ops.stop) - return -EFAULT; + mutex_lock(&bpfilter_ops.lock); + if (!bpfilter_ops.stop) { + err = -EFAULT; + goto out; + } err = start_umh(); if (!err && IS_ENABLED(CONFIG_INET)) { bpfilter_ops.sockopt = &__bpfilter_process_sockopt; bpfilter_ops.start = &start_umh; } - +out: + mutex_unlock(&bpfilter_ops.lock); return err; } static void __exit fini_umh(void) { + mutex_lock(&bpfilter_ops.lock); if (IS_ENABLED(CONFIG_INET)) { + shutdown_umh(); bpfilter_ops.start = NULL; bpfilter_ops.sockopt = NULL; } - stop_umh(); + mutex_unlock(&bpfilter_ops.lock); } module_init(load_umh); module_exit(fini_umh); diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index de84ede4e7653..1e976bb93d998 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -14,10 +14,12 @@ EXPORT_SYMBOL_GPL(bpfilter_ops); static void bpfilter_umh_cleanup(struct umh_info *info) { + mutex_lock(&bpfilter_ops.lock); bpfilter_ops.stop = true; fput(info->pipe_to_umh); fput(info->pipe_from_umh); info->pid = 0; + mutex_unlock(&bpfilter_ops.lock); } static int bpfilter_mbox_request(struct sock *sk, int optname, @@ -25,21 +27,28 @@ static int bpfilter_mbox_request(struct sock *sk, int optname, unsigned int optlen, bool is_set) { int err; - + mutex_lock(&bpfilter_ops.lock); if (!bpfilter_ops.sockopt) { + mutex_unlock(&bpfilter_ops.lock); err = request_module("bpfilter"); + mutex_lock(&bpfilter_ops.lock); if (err) - return err; - if (!bpfilter_ops.sockopt) - return -ECHILD; + goto out; + if (!bpfilter_ops.sockopt) { + err = -ECHILD; + goto out; + } } if (bpfilter_ops.stop) { err = bpfilter_ops.start(); if (err) - return err; + goto out; } - return bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set); + err = bpfilter_ops.sockopt(sk, optname, optval, optlen, is_set); +out: + mutex_unlock(&bpfilter_ops.lock); + return err; } int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval, @@ -61,6 +70,7 @@ int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, static int __init bpfilter_sockopt_init(void) { + mutex_init(&bpfilter_ops.lock); bpfilter_ops.stop = true; bpfilter_ops.info.cmdline = "bpfilter_umh"; bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup;