diff options
| -rw-r--r-- | arch/x86/entry/syscalls/syscall_32.tbl | 3 | ||||
| -rw-r--r-- | arch/x86/entry/syscalls/syscall_64.tbl | 1 | ||||
| -rw-r--r-- | fs/fs_context.c | 51 | ||||
| -rw-r--r-- | fs/fsopen.c | 265 | ||||
| -rw-r--r-- | fs/internal.h | 3 | ||||
| -rw-r--r-- | include/linux/syscalls.h | 2 | ||||
| -rw-r--r-- | include/uapi/linux/mount.h | 14 |
7 files changed, 338 insertions, 1 deletions
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 37fd1fc5396e..786728143205 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -401,7 +401,8 @@ 387 i386 open_tree sys_open_tree __ia32_sys_open_tree 388 i386 move_mount sys_move_mount __ia32_sys_move_mount 389 i386 fsopen sys_fsopen __ia32_sys_fsopen -# don't use numbers 390 through 392, add new calls at the end +390 i386 fsconfig sys_fsconfig __ia32_sys_fsconfig +# don't use numbers 391 through 392, add new calls at the end 393 i386 semget sys_semget __ia32_sys_semget 394 i386 semctl sys_semctl __ia32_compat_sys_semctl 395 i386 shmget sys_shmget __ia32_sys_shmget diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index 511608a21611..7039a809d37d 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -346,6 +346,7 @@ 335 common open_tree __x64_sys_open_tree 336 common move_mount __x64_sys_move_mount 337 common fsopen __x64_sys_fsopen +338 common fsconfig __x64_sys_fsconfig # don't use numbers 387 through 423, add new calls after the last # 'common' entry 424 common pidfd_send_signal __x64_sys_pidfd_send_signal diff --git a/fs/fs_context.c b/fs/fs_context.c index dcf3786f90f9..a47ccd5a4a78 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -721,3 +721,54 @@ int parse_monolithic_mount_data(struct fs_context *fc, void *data) return monolithic_mount_data(fc, data); } + +/* + * Clean up a context after performing an action on it and put it into a state + * from where it can be used to reconfigure a superblock. + * + * Note that here we do only the parts that can't fail; the rest is in + * finish_clean_context() below and in between those fs_context is marked + * FS_CONTEXT_AWAITING_RECONF. The reason for splitup is that after + * successful mount or remount we need to report success to userland. + * Trying to do full reinit (for the sake of possible subsequent remount) + * and failing to allocate memory would've put us into a nasty situation. + * So here we only discard the old state and reinitialization is left + * until we actually try to reconfigure. + */ +void vfs_clean_context(struct fs_context *fc) +{ + if (fc->need_free && fc->ops && fc->ops->free) + fc->ops->free(fc); + fc->need_free = false; + fc->fs_private = NULL; + fc->s_fs_info = NULL; + fc->sb_flags = 0; + security_free_mnt_opts(&fc->security); + kfree(fc->subtype); + fc->subtype = NULL; + kfree(fc->source); + fc->source = NULL; + + fc->purpose = FS_CONTEXT_FOR_RECONFIGURE; + fc->phase = FS_CONTEXT_AWAITING_RECONF; +} + +int finish_clean_context(struct fs_context *fc) +{ + int error; + + if (fc->phase != FS_CONTEXT_AWAITING_RECONF) + return 0; + + if (fc->fs_type->init_fs_context) + error = fc->fs_type->init_fs_context(fc); + else + error = legacy_init_fs_context(fc); + if (unlikely(error)) { + fc->phase = FS_CONTEXT_FAILED; + return error; + } + fc->need_free = true; + fc->phase = FS_CONTEXT_RECONF_PARAMS; + return 0; +} diff --git a/fs/fsopen.c b/fs/fsopen.c index 5fce6347de7a..65cc2f68f994 100644 --- a/fs/fsopen.c +++ b/fs/fsopen.c @@ -10,6 +10,7 @@ */ #include <linux/fs_context.h> +#include <linux/fs_parser.h> #include <linux/slab.h> #include <linux/uaccess.h> #include <linux/syscalls.h> @@ -18,6 +19,7 @@ #include <linux/namei.h> #include <linux/file.h> #include <uapi/linux/mount.h> +#include "internal.h" #include "mount.h" /* @@ -153,3 +155,266 @@ err_fc: put_fs_context(fc); return ret; } + +/* + * Check the state and apply the configuration. Note that this function is + * allowed to 'steal' the value by setting param->xxx to NULL before returning. + */ +static int vfs_fsconfig_locked(struct fs_context *fc, int cmd, + struct fs_parameter *param) +{ + struct super_block *sb; + int ret; + + ret = finish_clean_context(fc); + if (ret) + return ret; + switch (cmd) { + case FSCONFIG_CMD_CREATE: + if (fc->phase != FS_CONTEXT_CREATE_PARAMS) + return -EBUSY; + fc->phase = FS_CONTEXT_CREATING; + ret = vfs_get_tree(fc); + if (ret) + break; + sb = fc->root->d_sb; + ret = security_sb_kern_mount(sb); + if (unlikely(ret)) { + fc_drop_locked(fc); + break; + } + up_write(&sb->s_umount); + fc->phase = FS_CONTEXT_AWAITING_MOUNT; + return 0; + case FSCONFIG_CMD_RECONFIGURE: + if (fc->phase != FS_CONTEXT_RECONF_PARAMS) + return -EBUSY; + fc->phase = FS_CONTEXT_RECONFIGURING; + sb = fc->root->d_sb; + if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) { + ret = -EPERM; + break; + } + down_write(&sb->s_umount); + ret = reconfigure_super(fc); + up_write(&sb->s_umount); + if (ret) + break; + vfs_clean_context(fc); + return 0; + default: + if (fc->phase != FS_CONTEXT_CREATE_PARAMS && + fc->phase != FS_CONTEXT_RECONF_PARAMS) + return -EBUSY; + + return vfs_parse_fs_param(fc, param); + } + fc->phase = FS_CONTEXT_FAILED; + return ret; +} + +/** + * sys_fsconfig - Set parameters and trigger actions on a context + * @fd: The filesystem context to act upon + * @cmd: The action to take + * @_key: Where appropriate, the parameter key to set + * @_value: Where appropriate, the parameter value to set + * @aux: Additional information for the value + * + * This system call is used to set parameters on a context, including + * superblock settings, data source and security labelling. + * + * Actions include triggering the creation of a superblock and the + * reconfiguration of the superblock attached to the specified context. + * + * When setting a parameter, @cmd indicates the type of value being proposed + * and @_key indicates the parameter to be altered. + * + * @_value and @aux are used to specify the value, should a value be required: + * + * (*) fsconfig_set_flag: No value is specified. The parameter must be boolean + * in nature. The key may be prefixed with "no" to invert the + * setting. @_value must be NULL and @aux must be 0. + * + * (*) fsconfig_set_string: A string value is specified. The parameter can be + * expecting boolean, integer, string or take a path. A conversion to an + * appropriate type will be attempted (which may include looking up as a + * path). @_value points to a NUL-terminated string and @aux must be 0. + * + * (*) fsconfig_set_binary: A binary blob is specified. @_value points to the + * blob and @aux indicates its size. The parameter must be expecting a + * blob. + * + * (*) fsconfig_set_path: A non-empty path is specified. The parameter must be + * expecting a path object. @_value points to a NUL-terminated string that + * is the path and @aux is a file descriptor at which to start a relative + * lookup or AT_FDCWD. + * + * (*) fsconfig_set_path_empty: As fsconfig_set_path, but with AT_EMPTY_PATH + * implied. + * + * (*) fsconfig_set_fd: An open file descriptor is specified. @_value must be + * NULL and @aux indicates the file descriptor. + */ +SYSCALL_DEFINE5(fsconfig, + int, fd, + unsigned int, cmd, + const char __user *, _key, + const void __user *, _value, + int, aux) +{ + struct fs_context *fc; + struct fd f; + int ret; + + struct fs_parameter param = { + .type = fs_value_is_undefined, + }; + + if (fd < 0) + return -EINVAL; + + switch (cmd) { + case FSCONFIG_SET_FLAG: + if (!_key || _value || aux) + return -EINVAL; + break; + case FSCONFIG_SET_STRING: + if (!_key || !_value || aux) + return -EINVAL; + break; + case FSCONFIG_SET_BINARY: + if (!_key || !_value || aux <= 0 || aux > 1024 * 1024) + return -EINVAL; + break; + case FSCONFIG_SET_PATH: + case FSCONFIG_SET_PATH_EMPTY: + if (!_key || !_value || (aux != AT_FDCWD && aux < 0)) + return -EINVAL; + break; + case FSCONFIG_SET_FD: + if (!_key || _value || aux < 0) + return -EINVAL; + break; + case FSCONFIG_CMD_CREATE: + case FSCONFIG_CMD_RECONFIGURE: + if (_key || _value || aux) + return -EINVAL; + break; + default: + return -EOPNOTSUPP; + } + + f = fdget(fd); + if (!f.file) + return -EBADF; + ret = -EINVAL; + if (f.file->f_op != &fscontext_fops) + goto out_f; + + fc = f.file->private_data; + if (fc->ops == &legacy_fs_context_ops) { + switch (cmd) { + case FSCONFIG_SET_BINARY: + case FSCONFIG_SET_PATH: + case FSCONFIG_SET_PATH_EMPTY: + case FSCONFIG_SET_FD: + ret = -EOPNOTSUPP; + goto out_f; + } + } + + if (_key) { + param.key = strndup_user(_key, 256); + if (IS_ERR(param.key)) { + ret = PTR_ERR(param.key); + goto out_f; + } + } + + switch (cmd) { + case FSCONFIG_SET_FLAG: + param.type = fs_value_is_flag; + break; + case FSCONFIG_SET_STRING: + param.type = fs_value_is_string; + param.string = strndup_user(_value, 256); + if (IS_ERR(param.string)) { + ret = PTR_ERR(param.string); + goto out_key; + } + param.size = strlen(param.string); + break; + case FSCONFIG_SET_BINARY: + param.type = fs_value_is_blob; + param.size = aux; + param.blob = memdup_user_nul(_value, aux); + if (IS_ERR(param.blob)) { + ret = PTR_ERR(param.blob); + goto out_key; + } + break; + case FSCONFIG_SET_PATH: + param.type = fs_value_is_filename; + param.name = getname_flags(_value, 0, NULL); + if (IS_ERR(param.name)) { + ret = PTR_ERR(param.name); + goto out_key; + } + param.dirfd = aux; + param.size = strlen(param.name->name); + break; + case FSCONFIG_SET_PATH_EMPTY: + param.type = fs_value_is_filename_empty; + param.name = getname_flags(_value, LOOKUP_EMPTY, NULL); + if (IS_ERR(param.name)) { + ret = PTR_ERR(param.name); + goto out_key; + } + param.dirfd = aux; + param.size = strlen(param.name->name); + break; + case FSCONFIG_SET_FD: + param.type = fs_value_is_file; + ret = -EBADF; + param.file = fget(aux); + if (!param.file) + goto out_key; + break; + default: + break; + } + + ret = mutex_lock_interruptible(&fc->uapi_mutex); + if (ret == 0) { + ret = vfs_fsconfig_locked(fc, cmd, ¶m); + mutex_unlock(&fc->uapi_mutex); + } + + /* Clean up the our record of any value that we obtained from + * userspace. Note that the value may have been stolen by the LSM or + * filesystem, in which case the value pointer will have been cleared. + */ + switch (cmd) { + case FSCONFIG_SET_STRING: + case FSCONFIG_SET_BINARY: + kfree(param.string); + break; + case FSCONFIG_SET_PATH: + case FSCONFIG_SET_PATH_EMPTY: + if (param.name) + putname(param.name); + break; + case FSCONFIG_SET_FD: + if (param.file) + fput(param.file); + break; + default: + break; + } +out_key: + kfree(param.key); +out_f: + fdput(f); + return ret; +} diff --git a/fs/internal.h b/fs/internal.h index f3a027c44758..95cf7b0af21f 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -55,8 +55,11 @@ extern void __init chrdev_init(void); /* * fs_context.c */ +extern const struct fs_context_operations legacy_fs_context_ops; extern int parse_monolithic_mount_data(struct fs_context *, void *); extern void fc_drop_locked(struct fs_context *); +extern void vfs_clean_context(struct fs_context *fc); +extern int finish_clean_context(struct fs_context *fc); /* * namei.c diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 0c9bd5427e8f..925f9dfc356b 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -990,6 +990,8 @@ asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path, int to_dfd, const char __user *to_path, unsigned int ms_flags); asmlinkage long sys_fsopen(const char __user *fs_name, unsigned int flags); +asmlinkage long sys_fsconfig(int fs_fd, unsigned int cmd, const char __user *key, + const void __user *value, int aux); asmlinkage long sys_pidfd_send_signal(int pidfd, int sig, siginfo_t __user *info, unsigned int flags); diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 7570df43d08f..4b90ba9d1770 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -77,4 +77,18 @@ */ #define FSOPEN_CLOEXEC 0x00000001 +/* + * The type of fsconfig() call made. + */ +enum fsconfig_command { + FSCONFIG_SET_FLAG = 0, /* Set parameter, supplying no value */ + FSCONFIG_SET_STRING = 1, /* Set parameter, supplying a string value */ + FSCONFIG_SET_BINARY = 2, /* Set parameter, supplying a binary blob value */ + FSCONFIG_SET_PATH = 3, /* Set parameter, supplying an object by path */ + FSCONFIG_SET_PATH_EMPTY = 4, /* Set parameter, supplying an object by (empty) path */ + FSCONFIG_SET_FD = 5, /* Set parameter, supplying an object by fd */ + FSCONFIG_CMD_CREATE = 6, /* Invoke superblock creation */ + FSCONFIG_CMD_RECONFIGURE = 7, /* Invoke superblock reconfiguration */ +}; + #endif /* _UAPI_LINUX_MOUNT_H */ |