From af1abab986b85fdeb3e98c037988cfa4bf9d4018 Mon Sep 17 00:00:00 2001 From: Eric W. Biederman Date: Wed, 27 Jun 2018 14:39:54 -0500 Subject: uml: Don't consult current to find the proc_mnt in mconsole_proc Inspection of the control flow reveals that mconsole_proc is either called from mconsole_stop called from mc_work_proc or from mc_work_proc directly. The function mc_work_proc is dispatched to a kernel thread with schedule_work. All of the threads that run dispatched by schedule_work are in the init pid namespace. So make the code clearer and by using init_pid_ns instead of task_active_pid_ns(current). Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Signed-off-by: "Eric W. Biederman" --- arch/um/drivers/mconsole_kern.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/um') diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c index b80a1d616e4e..e8f5c81c2c6c 100644 --- a/arch/um/drivers/mconsole_kern.c +++ b/arch/um/drivers/mconsole_kern.c @@ -123,7 +123,7 @@ void mconsole_log(struct mc_request *req) void mconsole_proc(struct mc_request *req) { - struct vfsmount *mnt = task_active_pid_ns(current)->proc_mnt; + struct vfsmount *mnt = init_pid_ns.proc_mnt; char *buf; int len; struct file *file; -- cgit v1.2.3 From 76313c70c52f930af4afd21684509ca52297ea71 Mon Sep 17 00:00:00 2001 From: Eric W. Biederman Date: Wed, 19 Feb 2020 10:37:15 -0600 Subject: uml: Create a private mount of proc for mconsole The mconsole code only ever accesses proc for the initial pid namespace. Instead of depending upon the proc_mnt which is for proc_flush_task have uml create it's own mount of proc instead. This allows proc_flush_task to evolve and remove the need for having a proc_mnt to do it's job. Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Signed-off-by: Eric W. Biederman --- arch/um/drivers/mconsole_kern.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) (limited to 'arch/um') diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c index e8f5c81c2c6c..30575bd92975 100644 --- a/arch/um/drivers/mconsole_kern.c +++ b/arch/um/drivers/mconsole_kern.c @@ -36,6 +36,8 @@ #include "mconsole_kern.h" #include +static struct vfsmount *proc_mnt = NULL; + static int do_unlink_socket(struct notifier_block *notifier, unsigned long what, void *data) { @@ -123,7 +125,7 @@ void mconsole_log(struct mc_request *req) void mconsole_proc(struct mc_request *req) { - struct vfsmount *mnt = init_pid_ns.proc_mnt; + struct vfsmount *mnt = proc_mnt; char *buf; int len; struct file *file; @@ -134,6 +136,10 @@ void mconsole_proc(struct mc_request *req) ptr += strlen("proc"); ptr = skip_spaces(ptr); + if (!mnt) { + mconsole_reply(req, "Proc not available", 1, 0); + goto out; + } file = file_open_root(mnt->mnt_root, mnt, ptr, O_RDONLY, 0); if (IS_ERR(file)) { mconsole_reply(req, "Failed to open file", 1, 0); @@ -683,6 +689,24 @@ void mconsole_stack(struct mc_request *req) with_console(req, stack_proc, to); } +static int __init mount_proc(void) +{ + struct file_system_type *proc_fs_type; + struct vfsmount *mnt; + + proc_fs_type = get_fs_type("proc"); + if (!proc_fs_type) + return -ENODEV; + + mnt = kern_mount(proc_fs_type); + put_filesystem(proc_fs_type); + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + + proc_mnt = mnt; + return 0; +} + /* * Changed by mconsole_setup, which is __setup, and called before SMP is * active. @@ -696,6 +720,8 @@ static int __init mconsole_init(void) int err; char file[UNIX_PATH_MAX]; + mount_proc(); + if (umid_file_name("mconsole", file, sizeof(file))) return -1; snprintf(mconsole_socket_name, sizeof(file), "%s", file); -- cgit v1.2.3