[PATCH 2/3] uml: Create a private mount of proc for mconsole
From: Eric W. Biederman <hidden>
Date: 2020-02-28 20:20:59
Also in:
linux-fsdevel, linux-security-module, lkml
Subsystem:
the rest, user-mode linux (uml) · Maintainers:
Linus Torvalds, Richard Weinberger, Anton Ivanov, Johannes Berg
Possibly related (same subject, not in this thread)
- 2020-02-28 · Re: [PATCH 2/3] uml: Create a private mount of proc for mconsole · Christian Brauner <hidden>
- 2020-02-28 · Re: [PATCH 2/3] uml: Create a private mount of proc for mconsole · Eric W. Biederman <hidden>
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 <redacted> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Signed-off-by: Eric W. Biederman <redacted> --- arch/um/drivers/mconsole_kern.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-)
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 <os.h> +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);
--
2.25.0