diff options
Diffstat (limited to 'fs/fsopen.c')
| -rw-r--r-- | fs/fsopen.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/fs/fsopen.c b/fs/fsopen.c index d256f1ac9ff1..5fce6347de7a 100644 --- a/fs/fsopen.c +++ b/fs/fsopen.c @@ -20,6 +20,52 @@ #include <uapi/linux/mount.h> #include "mount.h" +/* + * Allow the user to read back any error, warning or informational messages. + */ +static ssize_t fscontext_read(struct file *file, + char __user *_buf, size_t len, loff_t *pos) +{ + struct fs_context *fc = file->private_data; + struct fc_log *log = fc->log; + unsigned int logsize = ARRAY_SIZE(log->buffer); + ssize_t ret; + char *p; + bool need_free; + int index, n; + + ret = mutex_lock_interruptible(&fc->uapi_mutex); + if (ret < 0) + return ret; + + if (log->head == log->tail) { + mutex_unlock(&fc->uapi_mutex); + return -ENODATA; + } + + index = log->tail & (logsize - 1); + p = log->buffer[index]; + need_free = log->need_free & (1 << index); + log->buffer[index] = NULL; + log->need_free &= ~(1 << index); + log->tail++; + mutex_unlock(&fc->uapi_mutex); + + ret = -EMSGSIZE; + n = strlen(p); + if (n > len) + goto err_free; + ret = -EFAULT; + if (copy_to_user(_buf, p, n) != 0) + goto err_free; + ret = n; + +err_free: + if (need_free) + kfree(p); + return ret; +} + static int fscontext_release(struct inode *inode, struct file *file) { struct fs_context *fc = file->private_data; @@ -32,6 +78,7 @@ static int fscontext_release(struct inode *inode, struct file *file) } const struct file_operations fscontext_fops = { + .read = fscontext_read, .release = fscontext_release, .llseek = no_llseek, }; @@ -50,6 +97,16 @@ static int fscontext_create_fd(struct fs_context *fc, unsigned int o_flags) return fd; } +static int fscontext_alloc_log(struct fs_context *fc) +{ + fc->log = kzalloc(sizeof(*fc->log), GFP_KERNEL); + if (!fc->log) + return -ENOMEM; + refcount_set(&fc->log->usage, 1); + fc->log->owner = fc->fs_type->owner; + return 0; +} + /* * Open a filesystem by name so that it can be configured for mounting. * @@ -62,6 +119,7 @@ SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags) struct file_system_type *fs_type; struct fs_context *fc; const char *fs_name; + int ret; if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN)) return -EPERM; @@ -84,5 +142,14 @@ SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags) return PTR_ERR(fc); fc->phase = FS_CONTEXT_CREATE_PARAMS; + + ret = fscontext_alloc_log(fc); + if (ret < 0) + goto err_fc; + return fscontext_create_fd(fc, flags & FSOPEN_CLOEXEC ? O_CLOEXEC : 0); + +err_fc: + put_fs_context(fc); + return ret; } |