From 5fec25f2cb959cb5f189d7f6127bee3efc782530 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 24 Jun 2020 16:34:57 -0500 Subject: [PATCH 01/21] umh: Capture the pid in umh_pipe_setup The pid in struct subprocess_info is only used by umh_clean_and_save_pid to write the pid into umh_info. Instead always capture the pid on struct umh_info in umh_pipe_setup, removing code that is specific to user mode drivers from the common user path of user mode helpers. v1: https://lkml.kernel.org/r/87h7uygf9i.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/875zb97iix.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-1-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/umh.h | 1 - kernel/umh.c | 5 ++--- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/include/linux/umh.h b/include/linux/umh.h index 0c08de356d0d4..aae16a0ebd0f9 100644 --- a/include/linux/umh.h +++ b/include/linux/umh.h @@ -25,7 +25,6 @@ struct subprocess_info { struct file *file; int wait; int retval; - pid_t pid; int (*init)(struct subprocess_info *info, struct cred *new); void (*cleanup)(struct subprocess_info *info); void *data; diff --git a/kernel/umh.c b/kernel/umh.c index 79f139a7ca03c..c2a582b3a2bff 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -102,7 +102,6 @@ static int call_usermodehelper_exec_async(void *data) commit_creds(new); - sub_info->pid = task_pid_nr(current); if (sub_info->file) { retval = do_execve_file(sub_info->file, sub_info->argv, sub_info->envp); @@ -468,6 +467,7 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) umh_info->pipe_to_umh = to_umh[1]; umh_info->pipe_from_umh = from_umh[0]; + umh_info->pid = task_pid_nr(current); return 0; } @@ -476,13 +476,12 @@ static void umh_clean_and_save_pid(struct subprocess_info *info) struct umh_info *umh_info = info->data; /* cleanup if umh_pipe_setup() was successful but exec failed */ - if (info->pid && info->retval) { + if (info->retval) { fput(umh_info->pipe_to_umh); fput(umh_info->pipe_from_umh); } argv_free(info->argv); - umh_info->pid = info->pid; } /** From b044fa2ae50d52d8c9f9d130055c2aea032e7475 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 10:04:25 -0500 Subject: [PATCH 02/21] umh: Move setting PF_UMH into umh_pipe_setup I am separating the code specific to user mode drivers from the code for ordinary user space helpers. Move setting of PF_UMH from call_usermodehelper_exec_async which is core user mode helper code into umh_pipe_setup which is user mode driver code. The code is equally as easy to write in one location as the other and the movement minimizes the impact of the user mode driver code on the core of the user mode helper code. Setting PF_UMH unconditionally is harmless as an action will only happen if it is paired with an entry on umh_list. v1: https://lkml.kernel.org/r/87bll6gf8t.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87zh8l63xs.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-2-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- kernel/umh.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/umh.c b/kernel/umh.c index c2a582b3a2bff..e6b9d6636850e 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -102,12 +102,10 @@ static int call_usermodehelper_exec_async(void *data) commit_creds(new); - if (sub_info->file) { + if (sub_info->file) retval = do_execve_file(sub_info->file, sub_info->argv, sub_info->envp); - if (!retval) - current->flags |= PF_UMH; - } else + 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); @@ -468,6 +466,7 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) umh_info->pipe_to_umh = to_umh[1]; umh_info->pipe_from_umh = from_umh[0]; umh_info->pid = task_pid_nr(current); + current->flags |= PF_UMH; return 0; } From 3a171042aeab8702391c311d84633a6c267d566c Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 10:10:03 -0500 Subject: [PATCH 03/21] umh: Rename the user mode driver helpers for clarity Now that the functionality of umh_setup_pipe and umh_clean_and_save_pid has changed their names are too specific and don't make much sense. Instead name them umd_setup and umd_cleanup for the functional role in setting up user mode drivers. v1: https://lkml.kernel.org/r/875zbegf82.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87tuyt63x3.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-3-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- kernel/umh.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/umh.c b/kernel/umh.c index e6b9d6636850e..26c3d493f168a 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -429,7 +429,7 @@ struct subprocess_info *call_usermodehelper_setup_file(struct file *file, return sub_info; } -static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) +static int umd_setup(struct subprocess_info *info, struct cred *new) { struct umh_info *umh_info = info->data; struct file *from_umh[2]; @@ -470,11 +470,11 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) return 0; } -static void umh_clean_and_save_pid(struct subprocess_info *info) +static void umd_cleanup(struct subprocess_info *info) { struct umh_info *umh_info = info->data; - /* cleanup if umh_pipe_setup() was successful but exec failed */ + /* cleanup if umh_setup() was successful but exec failed */ if (info->retval) { fput(umh_info->pipe_to_umh); fput(umh_info->pipe_from_umh); @@ -520,8 +520,8 @@ int fork_usermode_blob(void *data, size_t len, struct umh_info *info) } err = -ENOMEM; - sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup, - umh_clean_and_save_pid, info); + sub_info = call_usermodehelper_setup_file(file, umd_setup, umd_cleanup, + info); if (!sub_info) goto out; From 21d598280675c463ea1b264fab06e9614aacd1e1 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 24 Jun 2020 17:01:18 -0500 Subject: [PATCH 04/21] umh: Remove call_usermodehelper_setup_file. The only caller of call_usermodehelper_setup_file is fork_usermode_blob. In fork_usermode_blob replace call_usermodehelper_setup_file with call_usermodehelper_setup and delete fork_usermodehelper_setup_file. For this to work the argv_free is moved from umh_clean_and_save_pid to fork_usermode_blob. v1: https://lkml.kernel.org/r/87zh8qf0mp.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87o8p163u1.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-4-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/umh.h | 3 --- kernel/umh.c | 42 +++++++++++------------------------------- 2 files changed, 11 insertions(+), 34 deletions(-) diff --git a/include/linux/umh.h b/include/linux/umh.h index aae16a0ebd0f9..de08af00c68a7 100644 --- a/include/linux/umh.h +++ b/include/linux/umh.h @@ -39,9 +39,6 @@ call_usermodehelper_setup(const char *path, char **argv, char **envp, int (*init)(struct subprocess_info *info, struct cred *new), void (*cleanup)(struct subprocess_info *), void *data); -struct subprocess_info *call_usermodehelper_setup_file(struct file *file, - int (*init)(struct subprocess_info *info, struct cred *new), - void (*cleanup)(struct subprocess_info *), void *data); struct umh_info { const char *cmdline; struct file *pipe_to_umh; diff --git a/kernel/umh.c b/kernel/umh.c index 26c3d493f168a..b8fa9b99b366d 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -402,33 +402,6 @@ struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, } EXPORT_SYMBOL(call_usermodehelper_setup); -struct subprocess_info *call_usermodehelper_setup_file(struct file *file, - int (*init)(struct subprocess_info *info, struct cred *new), - void (*cleanup)(struct subprocess_info *info), void *data) -{ - struct subprocess_info *sub_info; - struct umh_info *info = data; - const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; - - sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL); - if (!sub_info) - return NULL; - - sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL); - if (!sub_info->argv) { - kfree(sub_info); - return NULL; - } - - INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); - sub_info->path = "none"; - sub_info->file = file; - sub_info->init = init; - sub_info->cleanup = cleanup; - sub_info->data = data; - return sub_info; -} - static int umd_setup(struct subprocess_info *info, struct cred *new) { struct umh_info *umh_info = info->data; @@ -479,8 +452,6 @@ static void umd_cleanup(struct subprocess_info *info) fput(umh_info->pipe_to_umh); fput(umh_info->pipe_from_umh); } - - argv_free(info->argv); } /** @@ -501,7 +472,9 @@ static void umd_cleanup(struct subprocess_info *info) */ int fork_usermode_blob(void *data, size_t len, struct umh_info *info) { + const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; struct subprocess_info *sub_info; + char **argv = NULL; struct file *file; ssize_t written; loff_t pos = 0; @@ -520,11 +493,16 @@ int fork_usermode_blob(void *data, size_t len, struct umh_info *info) } err = -ENOMEM; - sub_info = call_usermodehelper_setup_file(file, umd_setup, umd_cleanup, - info); + argv = argv_split(GFP_KERNEL, cmdline, NULL); + if (!argv) + goto out; + + sub_info = call_usermodehelper_setup("none", argv, NULL, GFP_KERNEL, + umd_setup, umd_cleanup, info); if (!sub_info) goto out; + sub_info->file = file; err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); if (!err) { mutex_lock(&umh_list_lock); @@ -532,6 +510,8 @@ int fork_usermode_blob(void *data, size_t len, struct umh_info *info) mutex_unlock(&umh_list_lock); } out: + if (argv) + argv_free(argv); fput(file); return err; } From 884c5e683b67dbc52892e24c29eed864f330ec08 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 26 Jun 2020 12:23:00 -0500 Subject: [PATCH 05/21] umh: Separate the user mode driver and the user mode helper support This makes it clear which code is part of the core user mode helper support and which code is needed to implement user mode drivers. This makes the kernel smaller for everyone who does not use a usermode driver. v1: https://lkml.kernel.org/r/87tuyyf0ln.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87imf963s6.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-5-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/bpfilter.h | 2 +- include/linux/sched.h | 8 -- include/linux/umh.h | 10 --- include/linux/usermode_driver.h | 30 +++++++ kernel/Makefile | 1 + kernel/exit.c | 1 + kernel/umh.c | 139 ------------------------------ kernel/usermode_driver.c | 146 ++++++++++++++++++++++++++++++++ 8 files changed, 179 insertions(+), 158 deletions(-) create mode 100644 include/linux/usermode_driver.h create mode 100644 kernel/usermode_driver.c diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index d815622cd31e5..d6d6206052a62 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -3,7 +3,7 @@ #define _LINUX_BPFILTER_H #include -#include +#include struct sock; int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval, diff --git a/include/linux/sched.h b/include/linux/sched.h index b62e6aaf28f03..59d1e92bb88ea 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2020,14 +2020,6 @@ 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 de08af00c68a7..73173c4a07e5d 100644 --- a/include/linux/umh.h +++ b/include/linux/umh.h @@ -39,16 +39,6 @@ call_usermodehelper_setup(const char *path, char **argv, char **envp, int (*init)(struct subprocess_info *info, struct cred *new), void (*cleanup)(struct subprocess_info *), void *data); -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); - extern int call_usermodehelper_exec(struct subprocess_info *info, int wait); diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h new file mode 100644 index 0000000000000..c5f6dc9502275 --- /dev/null +++ b/include/linux/usermode_driver.h @@ -0,0 +1,30 @@ +#ifndef __LINUX_USERMODE_DRIVER_H__ +#define __LINUX_USERMODE_DRIVER_H__ + +#include + +#ifdef CONFIG_BPFILTER +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); +} +#else +static inline void exit_umh(struct task_struct *tsk) +{ +} +#endif + +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); + +#endif /* __LINUX_USERMODE_DRIVER_H__ */ diff --git a/kernel/Makefile b/kernel/Makefile index f3218bc5ec69f..43928759893a3 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -12,6 +12,7 @@ obj-y = fork.o exec_domain.o panic.o \ notifier.o ksysfs.o cred.o reboot.o \ async.o range.o smpboot.o ucount.o +obj-$(CONFIG_BPFILTER) += usermode_driver.o obj-$(CONFIG_MODULES) += kmod.o obj-$(CONFIG_MULTIUSER) += groups.o diff --git a/kernel/exit.c b/kernel/exit.c index 727150f281033..a081deea52ca3 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -63,6 +63,7 @@ #include #include #include +#include #include #include diff --git a/kernel/umh.c b/kernel/umh.c index b8fa9b99b366d..3e4e453d45c87 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -26,8 +26,6 @@ #include #include #include -#include -#include #include @@ -38,8 +36,6 @@ 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) { @@ -402,121 +398,6 @@ struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv, } EXPORT_SYMBOL(call_usermodehelper_setup); -static int umd_setup(struct subprocess_info *info, struct cred *new) -{ - struct umh_info *umh_info = info->data; - struct file *from_umh[2]; - struct file *to_umh[2]; - int err; - - /* create pipe to send data to umh */ - err = create_pipe_files(to_umh, 0); - if (err) - return err; - err = replace_fd(0, to_umh[0], 0); - fput(to_umh[0]); - if (err < 0) { - fput(to_umh[1]); - return err; - } - - /* create pipe to receive data from umh */ - err = create_pipe_files(from_umh, 0); - if (err) { - fput(to_umh[1]); - replace_fd(0, NULL, 0); - return err; - } - err = replace_fd(1, from_umh[1], 0); - fput(from_umh[1]); - if (err < 0) { - fput(to_umh[1]); - replace_fd(0, NULL, 0); - fput(from_umh[0]); - return err; - } - - umh_info->pipe_to_umh = to_umh[1]; - umh_info->pipe_from_umh = from_umh[0]; - umh_info->pid = task_pid_nr(current); - current->flags |= PF_UMH; - return 0; -} - -static void umd_cleanup(struct subprocess_info *info) -{ - struct umh_info *umh_info = info->data; - - /* cleanup if umh_setup() was successful but exec failed */ - if (info->retval) { - fput(umh_info->pipe_to_umh); - fput(umh_info->pipe_from_umh); - } -} - -/** - * fork_usermode_blob - fork a blob of bytes as a usermode process - * @data: a blob of bytes that can be do_execv-ed as a file - * @len: length of the blob - * @info: information about usermode process (shouldn't be NULL) - * - * If info->cmdline is set it will be used as command line for the - * user process, else "usermodehelper" is used. - * - * Returns either negative error or zero which indicates success - * in executing a blob of bytes as a usermode process. In such - * case 'struct umh_info *info' is populated with two pipes - * and a pid of the process. The caller is responsible for health - * check of the user process, killing it via pid, and closing the - * pipes when user process is no longer needed. - */ -int fork_usermode_blob(void *data, size_t len, struct umh_info *info) -{ - const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; - struct subprocess_info *sub_info; - char **argv = NULL; - struct file *file; - ssize_t written; - loff_t pos = 0; - int err; - - file = shmem_kernel_file_setup("", len, 0); - if (IS_ERR(file)) - return PTR_ERR(file); - - written = kernel_write(file, data, len, &pos); - if (written != len) { - err = written; - if (err >= 0) - err = -ENOMEM; - goto out; - } - - err = -ENOMEM; - argv = argv_split(GFP_KERNEL, cmdline, NULL); - if (!argv) - goto out; - - sub_info = call_usermodehelper_setup("none", argv, NULL, GFP_KERNEL, - umd_setup, umd_cleanup, info); - if (!sub_info) - goto out; - - sub_info->file = file; - 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: - if (argv) - argv_free(argv); - fput(file); - return err; -} -EXPORT_SYMBOL_GPL(fork_usermode_blob); - /** * call_usermodehelper_exec - start a usermode application * @sub_info: information about the subprocessa @@ -678,26 +559,6 @@ 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", diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c new file mode 100644 index 0000000000000..5b05863af8558 --- /dev/null +++ b/kernel/usermode_driver.c @@ -0,0 +1,146 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * umd - User mode driver support + */ +#include +#include +#include + +static LIST_HEAD(umh_list); +static DEFINE_MUTEX(umh_list_lock); + +static int umd_setup(struct subprocess_info *info, struct cred *new) +{ + struct umh_info *umh_info = info->data; + struct file *from_umh[2]; + struct file *to_umh[2]; + int err; + + /* create pipe to send data to umh */ + err = create_pipe_files(to_umh, 0); + if (err) + return err; + err = replace_fd(0, to_umh[0], 0); + fput(to_umh[0]); + if (err < 0) { + fput(to_umh[1]); + return err; + } + + /* create pipe to receive data from umh */ + err = create_pipe_files(from_umh, 0); + if (err) { + fput(to_umh[1]); + replace_fd(0, NULL, 0); + return err; + } + err = replace_fd(1, from_umh[1], 0); + fput(from_umh[1]); + if (err < 0) { + fput(to_umh[1]); + replace_fd(0, NULL, 0); + fput(from_umh[0]); + return err; + } + + umh_info->pipe_to_umh = to_umh[1]; + umh_info->pipe_from_umh = from_umh[0]; + umh_info->pid = task_pid_nr(current); + current->flags |= PF_UMH; + return 0; +} + +static void umd_cleanup(struct subprocess_info *info) +{ + struct umh_info *umh_info = info->data; + + /* cleanup if umh_setup() was successful but exec failed */ + if (info->retval) { + fput(umh_info->pipe_to_umh); + fput(umh_info->pipe_from_umh); + } +} + +/** + * fork_usermode_blob - fork a blob of bytes as a usermode process + * @data: a blob of bytes that can be do_execv-ed as a file + * @len: length of the blob + * @info: information about usermode process (shouldn't be NULL) + * + * If info->cmdline is set it will be used as command line for the + * user process, else "usermodehelper" is used. + * + * Returns either negative error or zero which indicates success + * in executing a blob of bytes as a usermode process. In such + * case 'struct umh_info *info' is populated with two pipes + * and a pid of the process. The caller is responsible for health + * check of the user process, killing it via pid, and closing the + * pipes when user process is no longer needed. + */ +int fork_usermode_blob(void *data, size_t len, struct umh_info *info) +{ + const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; + struct subprocess_info *sub_info; + char **argv = NULL; + struct file *file; + ssize_t written; + loff_t pos = 0; + int err; + + file = shmem_kernel_file_setup("", len, 0); + if (IS_ERR(file)) + return PTR_ERR(file); + + written = kernel_write(file, data, len, &pos); + if (written != len) { + err = written; + if (err >= 0) + err = -ENOMEM; + goto out; + } + + err = -ENOMEM; + argv = argv_split(GFP_KERNEL, cmdline, NULL); + if (!argv) + goto out; + + sub_info = call_usermodehelper_setup("none", argv, NULL, GFP_KERNEL, + umd_setup, umd_cleanup, info); + if (!sub_info) + goto out; + + sub_info->file = file; + 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: + if (argv) + argv_free(argv); + fput(file); + return err; +} +EXPORT_SYMBOL_GPL(fork_usermode_blob); + +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); +} + From 74be2d3b80af1bb264c3b9905b52c15efc03c0fe Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 26 Jun 2020 11:16:06 -0500 Subject: [PATCH 06/21] umd: For clarity rename umh_info umd_info This structure is only used for user mode drivers so change the prefix from umh to umd to make that clear. v1: https://lkml.kernel.org/r/87o8p6f0kw.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/878sg563po.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-6-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/bpfilter.h | 2 +- include/linux/usermode_driver.h | 6 +++--- kernel/usermode_driver.c | 20 ++++++++++---------- net/ipv4/bpfilter/sockopt.c | 2 +- 4 files changed, 15 insertions(+), 15 deletions(-) diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index d6d6206052a62..ec9972d822e09 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -11,7 +11,7 @@ int bpfilter_ip_set_sockopt(struct sock *sk, int optname, char __user *optval, int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval, int __user *optlen); struct bpfilter_umh_ops { - struct umh_info info; + struct umd_info info; /* since ip_getsockopt() can run in parallel, serialize access to umh */ struct mutex lock; int (*sockopt)(struct sock *sk, int optname, diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h index c5f6dc9502275..7131ea611bab8 100644 --- a/include/linux/usermode_driver.h +++ b/include/linux/usermode_driver.h @@ -17,14 +17,14 @@ static inline void exit_umh(struct task_struct *tsk) } #endif -struct umh_info { +struct umd_info { const char *cmdline; struct file *pipe_to_umh; struct file *pipe_from_umh; struct list_head list; - void (*cleanup)(struct umh_info *info); + void (*cleanup)(struct umd_info *info); pid_t pid; }; -int fork_usermode_blob(void *data, size_t len, struct umh_info *info); +int fork_usermode_blob(void *data, size_t len, struct umd_info *info); #endif /* __LINUX_USERMODE_DRIVER_H__ */ diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index 5b05863af8558..e73550e946d6a 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -11,7 +11,7 @@ static DEFINE_MUTEX(umh_list_lock); static int umd_setup(struct subprocess_info *info, struct cred *new) { - struct umh_info *umh_info = info->data; + struct umd_info *umd_info = info->data; struct file *from_umh[2]; struct file *to_umh[2]; int err; @@ -43,21 +43,21 @@ static int umd_setup(struct subprocess_info *info, struct cred *new) return err; } - umh_info->pipe_to_umh = to_umh[1]; - umh_info->pipe_from_umh = from_umh[0]; - umh_info->pid = task_pid_nr(current); + umd_info->pipe_to_umh = to_umh[1]; + umd_info->pipe_from_umh = from_umh[0]; + umd_info->pid = task_pid_nr(current); current->flags |= PF_UMH; return 0; } static void umd_cleanup(struct subprocess_info *info) { - struct umh_info *umh_info = info->data; + struct umd_info *umd_info = info->data; /* cleanup if umh_setup() was successful but exec failed */ if (info->retval) { - fput(umh_info->pipe_to_umh); - fput(umh_info->pipe_from_umh); + fput(umd_info->pipe_to_umh); + fput(umd_info->pipe_from_umh); } } @@ -72,12 +72,12 @@ static void umd_cleanup(struct subprocess_info *info) * * Returns either negative error or zero which indicates success * in executing a blob of bytes as a usermode process. In such - * case 'struct umh_info *info' is populated with two pipes + * case 'struct umd_info *info' is populated with two pipes * and a pid of the process. The caller is responsible for health * check of the user process, killing it via pid, and closing the * pipes when user process is no longer needed. */ -int fork_usermode_blob(void *data, size_t len, struct umh_info *info) +int fork_usermode_blob(void *data, size_t len, struct umd_info *info) { const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; struct subprocess_info *sub_info; @@ -126,7 +126,7 @@ EXPORT_SYMBOL_GPL(fork_usermode_blob); void __exit_umh(struct task_struct *tsk) { - struct umh_info *info; + struct umd_info *info; pid_t pid = tsk->pid; mutex_lock(&umh_list_lock); diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index 0480918bfc7cf..c0dbcc86fcdb5 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -12,7 +12,7 @@ struct bpfilter_umh_ops bpfilter_ops; EXPORT_SYMBOL_GPL(bpfilter_ops); -static void bpfilter_umh_cleanup(struct umh_info *info) +static void bpfilter_umh_cleanup(struct umd_info *info) { mutex_lock(&bpfilter_ops.lock); bpfilter_ops.stop = true; From 1199c6c3da5197e9924a906b9de71b8d0ac62a01 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 11:38:08 -0500 Subject: [PATCH 07/21] umd: Rename umd_info.cmdline umd_info.driver_name The only thing supplied in the cmdline today is the driver name so rename the field to clarify the code. As this value is always supplied stop trying to handle the case of a NULL cmdline. Additionally since we now have a name we can count on use the driver_name any place where the code is looking for a name of the binary. v1: https://lkml.kernel.org/r/87imfef0k3.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87366d63os.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-7-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/usermode_driver.h | 2 +- kernel/usermode_driver.c | 11 ++++------- net/ipv4/bpfilter/sockopt.c | 2 +- 3 files changed, 6 insertions(+), 9 deletions(-) diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h index 7131ea611bab8..48cf25e3145d8 100644 --- a/include/linux/usermode_driver.h +++ b/include/linux/usermode_driver.h @@ -18,7 +18,7 @@ static inline void exit_umh(struct task_struct *tsk) #endif struct umd_info { - const char *cmdline; + const char *driver_name; struct file *pipe_to_umh; struct file *pipe_from_umh; struct list_head list; diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index e73550e946d6a..46d60d855e93f 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -67,9 +67,6 @@ static void umd_cleanup(struct subprocess_info *info) * @len: length of the blob * @info: information about usermode process (shouldn't be NULL) * - * If info->cmdline is set it will be used as command line for the - * user process, else "usermodehelper" is used. - * * Returns either negative error or zero which indicates success * in executing a blob of bytes as a usermode process. In such * case 'struct umd_info *info' is populated with two pipes @@ -79,7 +76,6 @@ static void umd_cleanup(struct subprocess_info *info) */ int fork_usermode_blob(void *data, size_t len, struct umd_info *info) { - const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; struct subprocess_info *sub_info; char **argv = NULL; struct file *file; @@ -87,7 +83,7 @@ int fork_usermode_blob(void *data, size_t len, struct umd_info *info) loff_t pos = 0; int err; - file = shmem_kernel_file_setup("", len, 0); + file = shmem_kernel_file_setup(info->driver_name, len, 0); if (IS_ERR(file)) return PTR_ERR(file); @@ -100,11 +96,12 @@ int fork_usermode_blob(void *data, size_t len, struct umd_info *info) } err = -ENOMEM; - argv = argv_split(GFP_KERNEL, cmdline, NULL); + argv = argv_split(GFP_KERNEL, info->driver_name, NULL); if (!argv) goto out; - sub_info = call_usermodehelper_setup("none", argv, NULL, GFP_KERNEL, + sub_info = call_usermodehelper_setup(info->driver_name, argv, NULL, + GFP_KERNEL, umd_setup, umd_cleanup, info); if (!sub_info) goto out; diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index c0dbcc86fcdb5..5050de28333d1 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -70,7 +70,7 @@ 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.driver_name = "bpfilter_umh"; bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup; return 0; From e2dc9bf3f5275ca372001541e5f26af572976e65 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 13:12:59 -0500 Subject: [PATCH 08/21] umd: Transform fork_usermode_blob into fork_usermode_driver Instead of loading a binary blob into a temporary file with shmem_kernel_file_setup load a binary blob into a temporary tmpfs filesystem. This means that the blob can be stored in an init section and discared, and it means the binary blob will have a filename so can be executed normally. The only tricky thing about this code is that in the helper function blob_to_mnt __fput_sync is used. That is because a file can not be executed if it is still open for write, and the ordinary delayed close for kernel threads does not happen soon enough, which causes the following exec to fail. The function umd_load_blob is not called with any locks so this should be safe. Executing the blob normally winds up correcting several problems with the user mode driver code discovered by Tetsuo Handa[1]. By passing an ordinary filename into the exec, it is no longer necessary to figure out how to turn a O_RDWR file descriptor into a properly referende counted O_EXEC file descriptor that forbids all writes. For path based LSMs there are no new special cases. [1] https://lore.kernel.org/linux-fsdevel/2a8775b4-1dd5-9d5c-aa42-9872445e0942@i-love.sakura.ne.jp/ v1: https://lkml.kernel.org/r/87d05mf0j9.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87wo3p4p35.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-8-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/usermode_driver.h | 6 +- kernel/usermode_driver.c | 126 ++++++++++++++++++++++++-------- net/bpfilter/bpfilter_kern.c | 14 +++- 3 files changed, 113 insertions(+), 33 deletions(-) diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h index 48cf25e3145d8..97c919b7147cc 100644 --- a/include/linux/usermode_driver.h +++ b/include/linux/usermode_driver.h @@ -2,6 +2,7 @@ #define __LINUX_USERMODE_DRIVER_H__ #include +#include #ifdef CONFIG_BPFILTER void __exit_umh(struct task_struct *tsk); @@ -23,8 +24,11 @@ struct umd_info { struct file *pipe_from_umh; struct list_head list; void (*cleanup)(struct umd_info *info); + struct path wd; pid_t pid; }; -int fork_usermode_blob(void *data, size_t len, struct umd_info *info); +int umd_load_blob(struct umd_info *info, const void *data, size_t len); +int umd_unload_blob(struct umd_info *info); +int fork_usermode_driver(struct umd_info *info); #endif /* __LINUX_USERMODE_DRIVER_H__ */ diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index 46d60d855e93f..a86798759f836 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -4,11 +4,98 @@ */ #include #include +#include +#include +#include #include static LIST_HEAD(umh_list); static DEFINE_MUTEX(umh_list_lock); +static struct vfsmount *blob_to_mnt(const void *data, size_t len, const char *name) +{ + struct file_system_type *type; + struct vfsmount *mnt; + struct file *file; + ssize_t written; + loff_t pos = 0; + + type = get_fs_type("tmpfs"); + if (!type) + return ERR_PTR(-ENODEV); + + mnt = kern_mount(type); + put_filesystem(type); + if (IS_ERR(mnt)) + return mnt; + + file = file_open_root(mnt->mnt_root, mnt, name, O_CREAT | O_WRONLY, 0700); + if (IS_ERR(file)) { + mntput(mnt); + return ERR_CAST(file); + } + + written = kernel_write(file, data, len, &pos); + if (written != len) { + int err = written; + if (err >= 0) + err = -ENOMEM; + filp_close(file, NULL); + mntput(mnt); + return ERR_PTR(err); + } + + fput(file); + + /* Flush delayed fput so exec can open the file read-only */ + flush_delayed_fput(); + task_work_run(); + return mnt; +} + +/** + * umd_load_blob - Remember a blob of bytes for fork_usermode_driver + * @info: information about usermode driver + * @data: a blob of bytes that can be executed as a file + * @len: The lentgh of the blob + * + */ +int umd_load_blob(struct umd_info *info, const void *data, size_t len) +{ + struct vfsmount *mnt; + + if (WARN_ON_ONCE(info->wd.dentry || info->wd.mnt)) + return -EBUSY; + + mnt = blob_to_mnt(data, len, info->driver_name); + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + + info->wd.mnt = mnt; + info->wd.dentry = mnt->mnt_root; + return 0; +} +EXPORT_SYMBOL_GPL(umd_load_blob); + +/** + * umd_unload_blob - Disassociate @info from a previously loaded blob + * @info: information about usermode driver + * + */ +int umd_unload_blob(struct umd_info *info) +{ + if (WARN_ON_ONCE(!info->wd.mnt || + !info->wd.dentry || + info->wd.mnt->mnt_root != info->wd.dentry)) + return -EINVAL; + + kern_unmount(info->wd.mnt); + info->wd.mnt = NULL; + info->wd.dentry = NULL; + return 0; +} +EXPORT_SYMBOL_GPL(umd_unload_blob); + static int umd_setup(struct subprocess_info *info, struct cred *new) { struct umd_info *umd_info = info->data; @@ -43,6 +130,7 @@ static int umd_setup(struct subprocess_info *info, struct cred *new) return err; } + set_fs_pwd(current->fs, &umd_info->wd); umd_info->pipe_to_umh = to_umh[1]; umd_info->pipe_from_umh = from_umh[0]; umd_info->pid = task_pid_nr(current); @@ -62,39 +150,21 @@ static void umd_cleanup(struct subprocess_info *info) } /** - * fork_usermode_blob - fork a blob of bytes as a usermode process - * @data: a blob of bytes that can be do_execv-ed as a file - * @len: length of the blob - * @info: information about usermode process (shouldn't be NULL) + * fork_usermode_driver - fork a usermode driver + * @info: information about usermode driver (shouldn't be NULL) * - * Returns either negative error or zero which indicates success - * in executing a blob of bytes as a usermode process. In such - * case 'struct umd_info *info' is populated with two pipes - * and a pid of the process. The caller is responsible for health - * check of the user process, killing it via pid, and closing the - * pipes when user process is no longer needed. + * Returns either negative error or zero which indicates success in + * executing a usermode driver. In such case 'struct umd_info *info' + * is populated with two pipes and a pid of the process. The caller is + * responsible for health check of the user process, killing it via + * pid, and closing the pipes when user process is no longer needed. */ -int fork_usermode_blob(void *data, size_t len, struct umd_info *info) +int fork_usermode_driver(struct umd_info *info) { struct subprocess_info *sub_info; char **argv = NULL; - struct file *file; - ssize_t written; - loff_t pos = 0; int err; - file = shmem_kernel_file_setup(info->driver_name, len, 0); - if (IS_ERR(file)) - return PTR_ERR(file); - - written = kernel_write(file, data, len, &pos); - if (written != len) { - err = written; - if (err >= 0) - err = -ENOMEM; - goto out; - } - err = -ENOMEM; argv = argv_split(GFP_KERNEL, info->driver_name, NULL); if (!argv) @@ -106,7 +176,6 @@ int fork_usermode_blob(void *data, size_t len, struct umd_info *info) if (!sub_info) goto out; - sub_info->file = file; err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); if (!err) { mutex_lock(&umh_list_lock); @@ -116,10 +185,9 @@ int fork_usermode_blob(void *data, size_t len, struct umd_info *info) out: if (argv) argv_free(argv); - fput(file); return err; } -EXPORT_SYMBOL_GPL(fork_usermode_blob); +EXPORT_SYMBOL_GPL(fork_usermode_driver); void __exit_umh(struct task_struct *tsk) { diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index c0f0990f30b60..28883b00609db 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -77,9 +77,7 @@ static int start_umh(void) int err; /* fork usermode process */ - err = fork_usermode_blob(&bpfilter_umh_start, - &bpfilter_umh_end - &bpfilter_umh_start, - &bpfilter_ops.info); + err = fork_usermode_driver(&bpfilter_ops.info); if (err) return err; bpfilter_ops.stop = false; @@ -98,6 +96,12 @@ static int __init load_umh(void) { int err; + err = umd_load_blob(&bpfilter_ops.info, + &bpfilter_umh_start, + &bpfilter_umh_end - &bpfilter_umh_start); + if (err) + return err; + mutex_lock(&bpfilter_ops.lock); if (!bpfilter_ops.stop) { err = -EFAULT; @@ -110,6 +114,8 @@ static int __init load_umh(void) } out: mutex_unlock(&bpfilter_ops.lock); + if (err) + umd_unload_blob(&bpfilter_ops.info); return err; } @@ -122,6 +128,8 @@ static void __exit fini_umh(void) bpfilter_ops.sockopt = NULL; } mutex_unlock(&bpfilter_ops.lock); + + umd_unload_blob(&bpfilter_ops.info); } module_init(load_umh); module_exit(fini_umh); From 55e6074e3fa67e1fb9ec140904db7e6cae6eda4b Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 13:52:50 -0500 Subject: [PATCH 09/21] umh: Stop calling do_execve_file With the user mode driver code changed to not set subprocess_info.file there are no more users of subproces_info.file. Remove this field from struct subprocess_info and remove the only user in call_usermodehelper_exec_async that would call do_execve_file instead of do_execve if file was set. v1: https://lkml.kernel.org/r/877dvuf0i7.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87r1tx4p2a.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-9-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/umh.h | 1 - kernel/umh.c | 10 +++------- 2 files changed, 3 insertions(+), 8 deletions(-) diff --git a/include/linux/umh.h b/include/linux/umh.h index 73173c4a07e5d..244aff6382208 100644 --- a/include/linux/umh.h +++ b/include/linux/umh.h @@ -22,7 +22,6 @@ struct subprocess_info { const char *path; char **argv; char **envp; - struct file *file; int wait; int retval; int (*init)(struct subprocess_info *info, struct cred *new); diff --git a/kernel/umh.c b/kernel/umh.c index 3e4e453d45c87..6ca2096298b97 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -98,13 +98,9 @@ static int call_usermodehelper_exec_async(void *data) commit_creds(new); - if (sub_info->file) - retval = do_execve_file(sub_info->file, - sub_info->argv, sub_info->envp); - 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); + retval = do_execve(getname_kernel(sub_info->path), + (const char __user *const __user *)sub_info->argv, + (const char __user *const __user *)sub_info->envp); out: sub_info->retval = retval; /* From 25cf336de51b51a3e440e1893751f9532095eff0 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 13:56:40 -0500 Subject: [PATCH 10/21] exec: Remove do_execve_file Now that the last callser has been removed remove this code from exec. For anyone thinking of resurrecing do_execve_file please note that the code was buggy in several fundamental ways. - It did not ensure the file it was passed was read-only and that deny_write_access had been called on it. Which subtlely breaks invaniants in exec. - The caller of do_execve_file was expected to hold and put a reference to the file, but an extra reference for use by exec was not taken so that when exec put it's reference to the file an underflow occured on the file reference count. - The point of the interface was so that a pathname did not need to exist. Which breaks pathname based LSMs. Tetsuo Handa originally reported these issues[1]. While it was clear that deny_write_access was missing the fundamental incompatibility with the passed in O_RDWR filehandle was not immediately recognized. All of these issues were fixed by modifying the usermode driver code to have a path, so it did not need this hack. Reported-by: Tetsuo Handa [1] https://lore.kernel.org/linux-fsdevel/2a8775b4-1dd5-9d5c-aa42-9872445e0942@i-love.sakura.ne.jp/ v1: https://lkml.kernel.org/r/871rm2f0hi.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87lfk54p0m.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-10-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- fs/exec.c | 38 +++++++++----------------------------- include/linux/binfmts.h | 1 - 2 files changed, 9 insertions(+), 30 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index e6e8a9a703278..23dfbb8206264 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1818,13 +1818,14 @@ static int exec_binprm(struct linux_binprm *bprm) /* * sys_execve() executes a new program. */ -static int __do_execve_file(int fd, struct filename *filename, - struct user_arg_ptr argv, - struct user_arg_ptr envp, - int flags, struct file *file) +static int do_execveat_common(int fd, struct filename *filename, + struct user_arg_ptr argv, + struct user_arg_ptr envp, + int flags) { char *pathbuf = NULL; struct linux_binprm *bprm; + struct file *file; struct files_struct *displaced; int retval; @@ -1863,8 +1864,7 @@ static int __do_execve_file(int fd, struct filename *filename, check_unsafe_exec(bprm); current->in_execve = 1; - if (!file) - file = do_open_execat(fd, filename, flags); + file = do_open_execat(fd, filename, flags); retval = PTR_ERR(file); if (IS_ERR(file)) goto out_unmark; @@ -1872,9 +1872,7 @@ static int __do_execve_file(int fd, struct filename *filename, sched_exec(); bprm->file = file; - if (!filename) { - bprm->filename = "none"; - } else if (fd == AT_FDCWD || filename->name[0] == '/') { + if (fd == AT_FDCWD || filename->name[0] == '/') { bprm->filename = filename->name; } else { if (filename->name[0] == '\0') @@ -1935,8 +1933,7 @@ static int __do_execve_file(int fd, struct filename *filename, task_numa_free(current, false); free_bprm(bprm); kfree(pathbuf); - if (filename) - putname(filename); + putname(filename); if (displaced) put_files_struct(displaced); return retval; @@ -1967,27 +1964,10 @@ static int __do_execve_file(int fd, struct filename *filename, if (displaced) reset_files_struct(displaced); out_ret: - if (filename) - putname(filename); + putname(filename); return retval; } -static int do_execveat_common(int fd, struct filename *filename, - struct user_arg_ptr argv, - struct user_arg_ptr envp, - int flags) -{ - return __do_execve_file(fd, filename, argv, envp, flags, NULL); -} - -int do_execve_file(struct file *file, void *__argv, void *__envp) -{ - struct user_arg_ptr argv = { .ptr.native = __argv }; - struct user_arg_ptr envp = { .ptr.native = __envp }; - - return __do_execve_file(AT_FDCWD, NULL, argv, envp, 0, file); -} - int do_execve(struct filename *filename, const char __user *const __user *__argv, const char __user *const __user *__envp) diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index 4a20b7517dd03..7c27d7b578714 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -141,6 +141,5 @@ extern int do_execveat(int, struct filename *, const char __user * const __user *, const char __user * const __user *, int); -int do_execve_file(struct file *file, void *__argv, void *__envp); #endif /* _LINUX_BINFMTS_H */ From 0fe3c63148ef5df1b3cb067e4b4d45d45d0c0fdc Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 16:08:46 -0500 Subject: [PATCH 11/21] bpfilter: Move bpfilter_umh back into init data To allow for restarts 61fbf5933d42 ("net: bpfilter: restart bpfilter_umh when error occurred") moved the blob holding the userspace binary out of the init sections. Now that loading the blob into a filesystem is separate from executing the blob the blob no longer needs to live .rodata to allow for restarting. So move the blob back to .init.rodata. v1: https://lkml.kernel.org/r/87sgeidlvq.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87ftad4ozc.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-11-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- net/bpfilter/bpfilter_umh_blob.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/bpfilter/bpfilter_umh_blob.S b/net/bpfilter/bpfilter_umh_blob.S index 9ea6100dca875..40311d10d2f27 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 .rodata, "a" + .section .init.rodata, "a" .global bpfilter_umh_start bpfilter_umh_start: .incbin "net/bpfilter/bpfilter_umh" From 1c340ead18ee4b4a84357abdef6d4f39ee08328b Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 16:48:26 -0500 Subject: [PATCH 12/21] umd: Track user space drivers with struct pid Use struct pid instead of user space pid values that are prone to wrap araound. In addition track the entire thread group instead of just the first thread that is started by exec. There are no multi-threaded user mode drivers today but there is nothing preclucing user drivers from being multi-threaded, so it is just a good idea to track the entire process. Take a reference count on the tgid's in question to make it possible to remove exit_umh in a future change. As a struct pid is available directly use kill_pid_info. The prior process signalling code was iffy in using a userspace pid known to be in the initial pid namespace and then looking up it's task in whatever the current pid namespace is. It worked only because kernel threads always run in the initial pid namespace. As the tgid is now refcounted verify the tgid is NULL at the start of fork_usermode_driver to avoid the possibility of silent pid leaks. v1: https://lkml.kernel.org/r/87mu4qdlv2.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/a70l4oy8.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-12-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/usermode_driver.h | 2 +- kernel/exit.c | 3 ++- kernel/usermode_driver.c | 15 ++++++++++----- net/bpfilter/bpfilter_kern.c | 13 +++++-------- net/ipv4/bpfilter/sockopt.c | 3 ++- 5 files changed, 20 insertions(+), 16 deletions(-) diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h index 97c919b7147cc..45adbffb31d9c 100644 --- a/include/linux/usermode_driver.h +++ b/include/linux/usermode_driver.h @@ -25,7 +25,7 @@ struct umd_info { struct list_head list; void (*cleanup)(struct umd_info *info); struct path wd; - pid_t pid; + struct pid *tgid; }; int umd_load_blob(struct umd_info *info, const void *data, size_t len); int umd_unload_blob(struct umd_info *info); diff --git a/kernel/exit.c b/kernel/exit.c index a081deea52ca3..d3294b611df18 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -805,7 +805,8 @@ void __noreturn do_exit(long code) exit_task_namespaces(tsk); exit_task_work(tsk); exit_thread(tsk); - exit_umh(tsk); + if (group_dead) + exit_umh(tsk); /* * Flush inherited counters to the parent - before the parent diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index a86798759f836..f77f8d7ce9e32 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -133,7 +133,7 @@ static int umd_setup(struct subprocess_info *info, struct cred *new) set_fs_pwd(current->fs, &umd_info->wd); umd_info->pipe_to_umh = to_umh[1]; umd_info->pipe_from_umh = from_umh[0]; - umd_info->pid = task_pid_nr(current); + umd_info->tgid = get_pid(task_tgid(current)); current->flags |= PF_UMH; return 0; } @@ -146,6 +146,8 @@ static void umd_cleanup(struct subprocess_info *info) if (info->retval) { fput(umd_info->pipe_to_umh); fput(umd_info->pipe_from_umh); + put_pid(umd_info->tgid); + umd_info->tgid = NULL; } } @@ -155,9 +157,9 @@ static void umd_cleanup(struct subprocess_info *info) * * Returns either negative error or zero which indicates success in * executing a usermode driver. In such case 'struct umd_info *info' - * is populated with two pipes and a pid of the process. The caller is + * is populated with two pipes and a tgid of the process. The caller is * responsible for health check of the user process, killing it via - * pid, and closing the pipes when user process is no longer needed. + * tgid, and closing the pipes when user process is no longer needed. */ int fork_usermode_driver(struct umd_info *info) { @@ -165,6 +167,9 @@ int fork_usermode_driver(struct umd_info *info) char **argv = NULL; int err; + if (WARN_ON_ONCE(info->tgid)) + return -EBUSY; + err = -ENOMEM; argv = argv_split(GFP_KERNEL, info->driver_name, NULL); if (!argv) @@ -192,11 +197,11 @@ EXPORT_SYMBOL_GPL(fork_usermode_driver); void __exit_umh(struct task_struct *tsk) { struct umd_info *info; - pid_t pid = tsk->pid; + struct pid *tgid = task_tgid(tsk); mutex_lock(&umh_list_lock); list_for_each_entry(info, &umh_list, list) { - if (info->pid == pid) { + if (info->tgid == tgid) { list_del(&info->list); mutex_unlock(&umh_list_lock); goto out; diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index 28883b00609db..08ea77c2b1370 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -15,16 +15,13 @@ extern char bpfilter_umh_end; static void shutdown_umh(void) { - struct task_struct *tsk; + struct umd_info *info = &bpfilter_ops.info; + struct pid *tgid = info->tgid; if (bpfilter_ops.stop) return; - tsk = get_pid_task(find_vpid(bpfilter_ops.info.pid), PIDTYPE_PID); - if (tsk) { - send_sig(SIGKILL, tsk, 1); - put_task_struct(tsk); - } + kill_pid(tgid, SIGKILL, 1); } static void __stop_umh(void) @@ -48,7 +45,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, req.cmd = optname; req.addr = (long __force __user)optval; req.len = optlen; - if (!bpfilter_ops.info.pid) + if (!bpfilter_ops.info.tgid) goto out; n = __kernel_write(bpfilter_ops.info.pipe_to_umh, &req, sizeof(req), &pos); @@ -81,7 +78,7 @@ static int start_umh(void) if (err) return err; bpfilter_ops.stop = false; - pr_info("Loaded bpfilter_umh pid %d\n", bpfilter_ops.info.pid); + pr_info("Loaded bpfilter_umh pid %d\n", pid_nr(bpfilter_ops.info.tgid)); /* health check that usermode process started correctly */ if (__bpfilter_process_sockopt(NULL, 0, NULL, 0, 0) != 0) { diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index 5050de28333d1..56cbc43145f6d 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -18,7 +18,8 @@ static void bpfilter_umh_cleanup(struct umd_info *info) bpfilter_ops.stop = true; fput(info->pipe_to_umh); fput(info->pipe_from_umh); - info->pid = 0; + put_pid(info->tgid); + info->tgid = NULL; mutex_unlock(&bpfilter_ops.lock); } From 38fd525a4c61e7ecdc9ad4dcbf7b767d0a007962 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 1 Jul 2020 07:30:06 -0500 Subject: [PATCH 13/21] exit: Factor thread_group_exited out of pidfd_poll Create an independent helper thread_group_exited which returns true when all threads have passed exit_notify in do_exit. AKA all of the threads are at least zombies and might be dead or completely gone. Create this helper by taking the logic out of pidfd_poll where it is already tested, and adding a READ_ONCE on the read of task->exit_state. I will be changing the user mode driver code to use this same logic to know when a user mode driver needs to be restarted. Place the new helper thread_group_exited in kernel/exit.c and EXPORT it so it can be used by modules. Link: https://lkml.kernel.org/r/20200702164140.4468-13-ebiederm@xmission.com Acked-by: Christian Brauner Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/sched/signal.h | 2 ++ kernel/exit.c | 24 ++++++++++++++++++++++++ kernel/fork.c | 6 +----- 3 files changed, 27 insertions(+), 5 deletions(-) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 0ee5e696c5d8d..1bad18a1d8ba7 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -674,6 +674,8 @@ static inline int thread_group_empty(struct task_struct *p) #define delay_group_leader(p) \ (thread_group_leader(p) && !thread_group_empty(p)) +extern bool thread_group_exited(struct pid *pid); + extern struct sighand_struct *__lock_task_sighand(struct task_struct *task, unsigned long *flags); diff --git a/kernel/exit.c b/kernel/exit.c index d3294b611df18..dee246c0866f5 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1713,6 +1713,30 @@ COMPAT_SYSCALL_DEFINE5(waitid, } #endif +/** + * thread_group_exited - check that a thread group has exited + * @pid: tgid of thread group to be checked. + * + * Test if the thread group represented by tgid has exited (all + * threads are zombies, dead or completely gone). + * + * Return: true if the thread group has exited. false otherwise. + */ +bool thread_group_exited(struct pid *pid) +{ + struct task_struct *task; + bool exited; + + rcu_read_lock(); + task = pid_task(pid, PIDTYPE_PID); + exited = !task || + (READ_ONCE(task->exit_state) && thread_group_empty(task)); + rcu_read_unlock(); + + return exited; +} +EXPORT_SYMBOL(thread_group_exited); + __weak void abort(void) { BUG(); diff --git a/kernel/fork.c b/kernel/fork.c index 142b23645d82e..bf215af7a9040 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1787,22 +1787,18 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) */ static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts) { - struct task_struct *task; struct pid *pid = file->private_data; __poll_t poll_flags = 0; poll_wait(file, &pid->wait_pidfd, pts); - rcu_read_lock(); - task = pid_task(pid, PIDTYPE_PID); /* * Inform pollers only when the whole thread group exits. * If the thread group leader exits before all other threads in the * group, then poll(2) should block, similar to the wait(2) family. */ - if (!task || (task->exit_state && thread_group_empty(task))) + if (thread_group_exited(pid)) poll_flags = EPOLLIN | EPOLLRDNORM; - rcu_read_unlock(); return poll_flags; } From e80eb1dc868bc1ed93602389d54b27f170ca770c Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 17:23:22 -0500 Subject: [PATCH 14/21] bpfilter: Take advantage of the facilities of struct pid Instead of relying on the exit_umh cleanup callback use the fact a struct pid can be tested to see if a process still exists, and that struct pid has a wait queue that notifies when the process dies. v1: https://lkml.kernel.org/r/87h7uydlu9.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/874kqt4owu.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-14-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/bpfilter.h | 3 ++- net/bpfilter/bpfilter_kern.c | 15 +++++---------- net/ipv4/bpfilter/sockopt.c | 15 ++++++++------- 3 files changed, 15 insertions(+), 18 deletions(-) diff --git a/include/linux/bpfilter.h b/include/linux/bpfilter.h index ec9972d822e09..9b114c718a761 100644 --- a/include/linux/bpfilter.h +++ b/include/linux/bpfilter.h @@ -10,6 +10,8 @@ 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); +void bpfilter_umh_cleanup(struct umd_info *info); + struct bpfilter_umh_ops { struct umd_info info; /* since ip_getsockopt() can run in parallel, serialize access to umh */ @@ -18,7 +20,6 @@ struct bpfilter_umh_ops { 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 08ea77c2b1370..9616fb7defebe 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -18,10 +18,11 @@ static void shutdown_umh(void) struct umd_info *info = &bpfilter_ops.info; struct pid *tgid = info->tgid; - if (bpfilter_ops.stop) - return; - - kill_pid(tgid, SIGKILL, 1); + if (tgid) { + kill_pid(tgid, SIGKILL, 1); + wait_event(tgid->wait_pidfd, thread_group_exited(tgid)); + bpfilter_umh_cleanup(info); + } } static void __stop_umh(void) @@ -77,7 +78,6 @@ static int start_umh(void) err = fork_usermode_driver(&bpfilter_ops.info); if (err) return err; - bpfilter_ops.stop = false; pr_info("Loaded bpfilter_umh pid %d\n", pid_nr(bpfilter_ops.info.tgid)); /* health check that usermode process started correctly */ @@ -100,16 +100,11 @@ static int __init load_umh(void) return err; 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); if (err) umd_unload_blob(&bpfilter_ops.info); diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c index 56cbc43145f6d..9063c6767d341 100644 --- a/net/ipv4/bpfilter/sockopt.c +++ b/net/ipv4/bpfilter/sockopt.c @@ -12,16 +12,14 @@ struct bpfilter_umh_ops bpfilter_ops; EXPORT_SYMBOL_GPL(bpfilter_ops); -static void bpfilter_umh_cleanup(struct umd_info *info) +void bpfilter_umh_cleanup(struct umd_info *info) { - mutex_lock(&bpfilter_ops.lock); - bpfilter_ops.stop = true; fput(info->pipe_to_umh); fput(info->pipe_from_umh); put_pid(info->tgid); info->tgid = NULL; - mutex_unlock(&bpfilter_ops.lock); } +EXPORT_SYMBOL_GPL(bpfilter_umh_cleanup); static int bpfilter_mbox_request(struct sock *sk, int optname, char __user *optval, @@ -39,7 +37,11 @@ static int bpfilter_mbox_request(struct sock *sk, int optname, goto out; } } - if (bpfilter_ops.stop) { + if (bpfilter_ops.info.tgid && + thread_group_exited(bpfilter_ops.info.tgid)) + bpfilter_umh_cleanup(&bpfilter_ops.info); + + if (!bpfilter_ops.info.tgid) { err = bpfilter_ops.start(); if (err) goto out; @@ -70,9 +72,8 @@ 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.tgid = NULL; bpfilter_ops.info.driver_name = "bpfilter_umh"; - bpfilter_ops.info.cleanup = &bpfilter_umh_cleanup; return 0; } From 8c2f52663973e643c617663d826e2b0daa008b38 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 25 Jun 2020 17:40:40 -0500 Subject: [PATCH 15/21] umd: Remove exit_umh The bpfilter code no longer uses the umd_info.cleanup callback. This callback is what exit_umh exists to call. So remove exit_umh and all of it's associated booking. v1: https://lkml.kernel.org/r/87bll6dlte.fsf_-_@x220.int.ebiederm.org v2: https://lkml.kernel.org/r/87y2o53abg.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-15-ebiederm@xmission.com Reviewed-by: Greg Kroah-Hartman Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- include/linux/sched.h | 1 - include/linux/usermode_driver.h | 16 ---------------- kernel/exit.c | 3 --- kernel/usermode_driver.c | 28 ---------------------------- 4 files changed, 48 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 59d1e92bb88ea..edb2020875ad3 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1511,7 +1511,6 @@ extern struct pid *cad_pid; #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ #define PF_RANDOMIZE 0x00400000 /* Randomize virtual address space */ #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ -#define PF_UMH 0x02000000 /* I'm an Usermodehelper process */ #define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_mask */ #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ #define PF_MEMALLOC_NOCMA 0x10000000 /* All allocation request will have _GFP_MOVABLE cleared */ diff --git a/include/linux/usermode_driver.h b/include/linux/usermode_driver.h index 45adbffb31d9c..073a9e0ec07d0 100644 --- a/include/linux/usermode_driver.h +++ b/include/linux/usermode_driver.h @@ -4,26 +4,10 @@ #include #include -#ifdef CONFIG_BPFILTER -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); -} -#else -static inline void exit_umh(struct task_struct *tsk) -{ -} -#endif - struct umd_info { const char *driver_name; struct file *pipe_to_umh; struct file *pipe_from_umh; - struct list_head list; - void (*cleanup)(struct umd_info *info); struct path wd; struct pid *tgid; }; diff --git a/kernel/exit.c b/kernel/exit.c index dee246c0866f5..39226a018ed76 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -63,7 +63,6 @@ #include #include #include -#include #include #include @@ -805,8 +804,6 @@ void __noreturn do_exit(long code) exit_task_namespaces(tsk); exit_task_work(tsk); exit_thread(tsk); - if (group_dead) - exit_umh(tsk); /* * Flush inherited counters to the parent - before the parent diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index f77f8d7ce9e32..cd136f86f7997 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -9,9 +9,6 @@ #include #include -static LIST_HEAD(umh_list); -static DEFINE_MUTEX(umh_list_lock); - static struct vfsmount *blob_to_mnt(const void *data, size_t len, const char *name) { struct file_system_type *type; @@ -134,7 +131,6 @@ static int umd_setup(struct subprocess_info *info, struct cred *new) umd_info->pipe_to_umh = to_umh[1]; umd_info->pipe_from_umh = from_umh[0]; umd_info->tgid = get_pid(task_tgid(current)); - current->flags |= PF_UMH; return 0; } @@ -182,11 +178,6 @@ int fork_usermode_driver(struct umd_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: if (argv) argv_free(argv); @@ -194,23 +185,4 @@ int fork_usermode_driver(struct umd_info *info) } EXPORT_SYMBOL_GPL(fork_usermode_driver); -void __exit_umh(struct task_struct *tsk) -{ - struct umd_info *info; - struct pid *tgid = task_tgid(tsk); - - mutex_lock(&umh_list_lock); - list_for_each_entry(info, &umh_list, list) { - if (info->tgid == tgid) { - list_del(&info->list); - mutex_unlock(&umh_list_lock); - goto out; - } - } - mutex_unlock(&umh_list_lock); - return; -out: - if (info->cleanup) - info->cleanup(info); -} From 33c326014fe69304244868cc793c2c77be533125 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 29 Jun 2020 08:28:33 -0500 Subject: [PATCH 16/21] umd: Stop using split_argv There is exactly one argument so there is nothing to split. All split_argv does now is cause confusion and avoid the need for a cast when passing a "const char *" string to call_usermodehelper_setup. So avoid confusion and the possibility of an odd driver name causing problems by just using a fixed argv array with a cast in the call to call_usermodehelper_setup. v1: https://lkml.kernel.org/r/87sged3a9n.fsf_-_@x220.int.ebiederm.org Link: https://lkml.kernel.org/r/20200702164140.4468-16-ebiederm@xmission.com Acked-by: Alexei Starovoitov Tested-by: Alexei Starovoitov Signed-off-by: "Eric W. Biederman" --- kernel/usermode_driver.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/kernel/usermode_driver.c b/kernel/usermode_driver.c index cd136f86f7997..0b35212ffc3d0 100644 --- a/kernel/usermode_driver.c +++ b/kernel/usermode_driver.c @@ -160,27 +160,21 @@ static void umd_cleanup(struct subprocess_info *info) int fork_usermode_driver(struct umd_info *info) { struct subprocess_info *sub_info; - char **argv = NULL; + const char *argv[] = { info->driver_name, NULL }; int err; if (WARN_ON_ONCE(info->tgid)) return -EBUSY; err = -ENOMEM; - argv = argv_split(GFP_KERNEL, info->driver_name, NULL); - if (!argv) - goto out; - - sub_info = call_usermodehelper_setup(info->driver_name, argv, NULL, - GFP_KERNEL, + sub_info = call_usermodehelper_setup(info->driver_name, + (char **)argv, NULL, GFP_KERNEL, umd_setup, umd_cleanup, info); if (!sub_info) goto out; err = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); out: - if (argv) - argv_free(argv); return err; } EXPORT_SYMBOL_GPL(fork_usermode_driver); From f7d40ee7eff8fde2b0701b80c2aa3ba354f8f520 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 13 Jul 2020 20:55:48 -0700 Subject: [PATCH 17/21] selftests/bpf: Fix merge conflict resolution Remove double definition of structs. Fixes: 71930d61025e ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net") Signed-off-by: Alexei Starovoitov --- .../testing/selftests/bpf/progs/bpf_iter_netlink.c | 14 -------------- 1 file changed, 14 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_netlink.c b/tools/testing/selftests/bpf/progs/bpf_iter_netlink.c index b9c2756c5c97d..7de98a68599ab 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_netlink.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_netlink.c @@ -7,20 +7,6 @@ char _license[] SEC("license") = "GPL"; -#define sk_rmem_alloc sk_backlog.rmem_alloc -#define sk_refcnt __sk_common.skc_refcnt - -struct bpf_iter_meta { - struct seq_file *seq; - __u64 session_id; - __u64 seq_num; -} __attribute__((preserve_access_index)); - -struct bpf_iter__netlink { - struct bpf_iter_meta *meta; - struct netlink_sock *sk; -} __attribute__((preserve_access_index)); - static __attribute__((noinline)) struct inode *SOCK_INODE(struct socket *socket) { return &container_of(socket, struct socket_alloc, socket)->vfs_inode; From 079ef53673f2e3b3ee1728800311f20f28eed4f7 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 14 Jul 2020 12:25:33 +0200 Subject: [PATCH 18/21] bpf: Fix build for disabled CONFIG_DEBUG_INFO_BTF option Stephen reported following linker warnings on powerpc build: ld: warning: orphan section `.BTF_ids' from `kernel/trace/bpf_trace.o' being placed in section `.BTF_ids' ld: warning: orphan section `.BTF_ids' from `kernel/bpf/btf.o' being placed in section `.BTF_ids' ld: warning: orphan section `.BTF_ids' from `kernel/bpf/stackmap.o' being placed in section `.BTF_ids' ld: warning: orphan section `.BTF_ids' from `net/core/filter.o' being placed in section `.BTF_ids' ld: warning: orphan section `.BTF_ids' from `kernel/trace/bpf_trace.o' being placed in section `.BTF_ids' It's because we generated .BTF_ids section even when CONFIG_DEBUG_INFO_BTF is not enabled. Fixing this by generating empty btf_id arrays for this case. Reported-by: Stephen Rothwell Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Tested-by: Geert Uytterhoeven Link: https://lore.kernel.org/bpf/20200714102534.299280-1-jolsa@kernel.org --- include/linux/btf_ids.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index fe019774f8a72..b3c73db9587c5 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -3,6 +3,8 @@ #ifndef _LINUX_BTF_IDS_H #define _LINUX_BTF_IDS_H +#ifdef CONFIG_DEBUG_INFO_BTF + #include /* for __PASTE */ /* @@ -83,5 +85,12 @@ asm( \ ".zero 4 \n" \ ".popsection; \n"); +#else + +#define BTF_ID_LIST(name) static u32 name[5]; +#define BTF_ID(prefix, name) +#define BTF_ID_UNUSED + +#endif /* CONFIG_DEBUG_INFO_BTF */ #endif From 11bb2f7a45909f4f64afe471875672ae1b84a380 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 14 Jul 2020 12:25:34 +0200 Subject: [PATCH 19/21] bpf: Fix cross build for CONFIG_DEBUG_INFO_BTF option Stephen and 0-DAY CI Kernel Test Service reported broken cross build for arm (arm-linux-gnueabi-gcc (GCC) 9.3.0), with following output: /tmp/ccMS5uth.s: Assembler messages: /tmp/ccMS5uth.s:69: Error: unrecognized symbol type "" /tmp/ccMS5uth.s:82: Error: unrecognized symbol type "" Having '@object' for .type diretive is wrong because '@' is comment character for some architectures. Using STT_OBJECT instead that should work everywhere. Also using HOST* variables to build resolve_btfids so it's properly build in crossbuilds (stolen from objtool's Makefile). Reported-by: kernel test robot Reported-by: Stephen Rothwell Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Tested-by: Geert Uytterhoeven Link: https://lore.kernel.org/bpf/20200714102534.299280-2-jolsa@kernel.org --- include/linux/btf_ids.h | 2 +- tools/bpf/resolve_btfids/Makefile | 14 ++++++++++++++ 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index b3c73db9587c5..1cdb56950ffe6 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -23,7 +23,7 @@ asm( \ ".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \ ".local " #symbol " ; \n" \ -".type " #symbol ", @object; \n" \ +".type " #symbol ", STT_OBJECT; \n" \ ".size " #symbol ", 4; \n" \ #symbol ": \n" \ ".zero 4 \n" \ diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile index 948378ca73d4a..a88cd44263989 100644 --- a/tools/bpf/resolve_btfids/Makefile +++ b/tools/bpf/resolve_btfids/Makefile @@ -16,6 +16,20 @@ else MAKEFLAGS=--no-print-directory endif +# always use the host compiler +ifneq ($(LLVM),) +HOSTAR ?= llvm-ar +HOSTCC ?= clang +HOSTLD ?= ld.lld +else +HOSTAR ?= ar +HOSTCC ?= gcc +HOSTLD ?= ld +endif +AR = $(HOSTAR) +CC = $(HOSTCC) +LD = $(HOSTLD) + OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/ LIBBPF_SRC := $(srctree)/tools/lib/bpf/ From a4fa458950b40d3849946daa32466392811a3716 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 14 Jul 2020 12:31:45 -0700 Subject: [PATCH 20/21] bpfilter: Initialize pos variable Make sure 'pos' is initialized to zero before calling kernel_write(). Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Alexei Starovoitov --- net/bpfilter/bpfilter_kern.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c index 54f82c341e20b..2c31e82cb953a 100644 --- a/net/bpfilter/bpfilter_kern.c +++ b/net/bpfilter/bpfilter_kern.c @@ -48,6 +48,7 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname, req.len = optlen; if (!bpfilter_ops.info.tgid) goto out; + pos = 0; n = kernel_write(bpfilter_ops.info.pipe_to_umh, &req, sizeof(req), &pos); if (n != sizeof(req)) { From 9326e0f85bfaf0578d40f5357f8143ec857469f5 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 1 Jul 2020 18:26:44 +0900 Subject: [PATCH 21/21] bpfilter: Allow to build bpfilter_umh as a module without static library Originally, bpfilter_umh was linked with -static only when CONFIG_BPFILTER_UMH=y. Commit 8a2cc0505cc4 ("bpfilter: use 'userprogs' syntax to build bpfilter_umh") silently, accidentally dropped the CONFIG_BPFILTER_UMH=y test in the Makefile. Revive it in order to link it dynamically when CONFIG_BPFILTER_UMH=m. Since commit b1183b6dca3e ("bpfilter: check if $(CC) can link static libc in Kconfig"), the compiler must be capable of static linking to enable CONFIG_BPFILTER_UMH, but it requires more than needed. To loosen the compiler requirement, I changed the dependency as follows: depends on CC_CAN_LINK depends on m || CC_CAN_LINK_STATIC If CONFIG_CC_CAN_LINK_STATIC in unset, CONFIG_BPFILTER_UMH is restricted to 'm' or 'n'. In theory, CONFIG_CC_CAN_LINK is not required for CONFIG_BPFILTER_UMH=y, but I did not come up with a good way to describe it. Fixes: 8a2cc0505cc4 ("bpfilter: use 'userprogs' syntax to build bpfilter_umh") Reported-by: Michal Kubecek Signed-off-by: Masahiro Yamada Signed-off-by: Alexei Starovoitov Tested-by: Michal Kubecek Link: https://lore.kernel.org/bpf/20200701092644.762234-1-masahiroy@kernel.org --- net/bpfilter/Kconfig | 10 ++++++---- net/bpfilter/Makefile | 2 ++ 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/net/bpfilter/Kconfig b/net/bpfilter/Kconfig index 84015ef3ee27e..73d0b12789f1e 100644 --- a/net/bpfilter/Kconfig +++ b/net/bpfilter/Kconfig @@ -9,12 +9,14 @@ menuconfig BPFILTER if BPFILTER config BPFILTER_UMH tristate "bpfilter kernel module with user mode helper" - depends on CC_CAN_LINK_STATIC + depends on CC_CAN_LINK + depends on m || CC_CAN_LINK_STATIC default m help This builds bpfilter kernel module with embedded user mode helper - Note: your toolchain must support building static binaries, since - rootfs isn't mounted at the time when __init functions are called - and do_execv won't be able to find the elf interpreter. + Note: To compile this as built-in, your toolchain must support + building static binaries, since rootfs isn't mounted at the time + when __init functions are called and do_execv won't be able to find + the elf interpreter. endif diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile index f23b53294fbae..cdac82b8c53af 100644 --- a/net/bpfilter/Makefile +++ b/net/bpfilter/Makefile @@ -7,10 +7,12 @@ userprogs := bpfilter_umh bpfilter_umh-objs := main.o userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi +ifeq ($(CONFIG_BPFILTER_UMH), y) # builtin bpfilter_umh should be linked with -static # since rootfs isn't mounted at the time of __init # function is called and do_execv won't find elf interpreter userldflags += -static +endif $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh