From a8574d00552dc9f3012a3f84ab2bcac5fb6d7e7b Mon Sep 17 00:00:00 2001 From: Ondrej Kozina Date: Wed, 19 Feb 2020 12:39:26 +0100 Subject: [PATCH] cryptsetup-generator: add detached LUKS header support Adds support for LUKS detached header device on kernel command line. It's introduced via extension to existing luks.options 'header=' argument beyond colon (see examples below). If LUKS header device is specified it's expected to contain filesystem with LUKS header image on a path specified in the first part of header specification. The second parameter 'luks.data' specifies LUKS data device supposed to be paired with detached LUKS header (note that encrypted LUKS data device with detached header is unrecognisable by standard blkid probe). This adds support for LUKS encrypted rootfs partition with detached header. It can also be used for initializing online LUKS2 encryption of data device. Examples: luks.data==/dev/sdz luks.data==/dev/vg/lv luks.data==/dev/mapper/lv luks.data==PARTUUID= luks.data==PARTLABEL= luks.options==header=/header/path:UUID= luks.options==header=/header/path:PARTUUID= luks.options==header=/header/path:PARTLABEL= luks.options==header=/header/path:LABEL= luks.options==header=/header/path:/dev/sdx luks.options==header=/header/path:/dev/vg/lv The '/header/path' is considered to be relative location within filesystem residing on the header device specified beyond colon character --- man/systemd-cryptsetup-generator.xml | 80 +++++++++++--- src/cryptsetup/cryptsetup-generator.c | 151 ++++++++++++++++++++++++-- 2 files changed, 207 insertions(+), 24 deletions(-) diff --git a/man/systemd-cryptsetup-generator.xml b/man/systemd-cryptsetup-generator.xml index e3c17d64d8..cb18db246b 100644 --- a/man/systemd-cryptsetup-generator.xml +++ b/man/systemd-cryptsetup-generator.xml @@ -105,6 +105,9 @@ LUKS device given by the UUID appear under the provided name. + This parameter is the analogue of the first crypttab + 5 field volume-name. + rd.luks.name= is honored only by initial RAM disk (initrd) while luks.name= is honored by both the main system and the initrd. @@ -112,20 +115,30 @@ - luks.options= - rd.luks.options= + luks.data= + rd.luks.data= - Takes a LUKS super block UUID followed by an - = and a string of options separated by - commas as argument. This will override the options for the - given UUID. - If only a list of options, without an UUID, is - specified, they apply to any UUIDs not specified elsewhere, - and without an entry in - /etc/crypttab. - rd.luks.options= is honored only by initial - RAM disk (initrd) while luks.options= is - honored by both the main system and the initrd. + Takes a LUKS super block UUID followed by a = and a block device + specification for device hosting encrypted data. + + For those entries specified with rd.luks.uuid= or + luks.uuid=, the data device will be set to the one specified by + rd.luks.data= or luks.data= of the corresponding UUID. + + LUKS data device parameter is usefull for specifying encrypted data devices with detached headers specified in + luks.options entry containing header= argument. For example, + rd.luks.uuid=b40f1abf-2a53-400a-889a-2eccc27eaa40 + rd.luks.options=b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/path/to/luks.hdr + rd.luks.data=b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx. + Hence, in this case, we will attempt to unlock LUKS device assembled from data device /dev/sdx + and LUKS header (metadata) put in /path/to/luks.hdr file. This syntax is for now + only supported on a per-device basis, i.e. you have to specify LUKS device UUID. + + This parameter is the analogue of the second crypttab + 5 field encrypted-device. + + rd.luks.data= is honored only by initial RAM disk (initrd) while + luks.data= is honored by both the main system and the initrd. @@ -157,6 +170,9 @@ This syntax is for now only supported on a per-device basis, i.e. you have to specify LUKS device UUID. + This parameter is the analogue of the third crypttab + 5 field key-file. + rd.luks.key= is honored only by initial RAM disk (initrd) while @@ -165,6 +181,44 @@ the initrd. + + + luks.options= + rd.luks.options= + + Takes a LUKS super block UUID followed by an + = and a string of options separated by + commas as argument. This will override the options for the + given UUID. + If only a list of options, without an UUID, is + specified, they apply to any UUIDs not specified elsewhere, + and without an entry in + /etc/crypttab. + + This parameter is the analogue of the fourth crypttab + 5 field options. + + It is possible to specify an external device which + should be mounted before we attempt to unlock the LUKS device. + systemd-cryptsetup will assemble LUKS device by combining + data device specified in luks.data with + detached LUKS header found in header= + argument. For example, + rd.luks.uuid=b40f1abf-2a53-400a-889a-2eccc27eaa40 + rd.luks.options=b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/luks.hdr:LABEL=hdrdev + rd.luks.data=b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx. + Hence, in this case, we will attempt to mount file system + residing on the block device with label hdrdev, and look + for luks.hdr on that file system. Said header will be used + to unlock (decrypt) encrypted data stored on /dev/sdx. + This syntax is for now only supported on a per-device basis, + i.e. you have to specify LUKS device UUID. + + rd.luks.options= is honored only by initial + RAM disk (initrd) while luks.options= is + honored by both the main system and the initrd. + + diff --git a/src/cryptsetup/cryptsetup-generator.c b/src/cryptsetup/cryptsetup-generator.c index 4857f8ae15..ea9965d6c4 100644 --- a/src/cryptsetup/cryptsetup-generator.c +++ b/src/cryptsetup/cryptsetup-generator.c @@ -29,6 +29,8 @@ typedef struct crypto_device { char *uuid; char *keyfile; char *keydev; + char *headerdev; + char *datadev; char *name; char *options; bool create; @@ -277,13 +279,14 @@ static int create_disk( const char *device, const char *password, const char *keydev, + const char *headerdev, const char *options, const char *source) { _cleanup_free_ char *n = NULL, *d = NULL, *u = NULL, *e = NULL, *keydev_mount = NULL, *keyfile_timeout_value = NULL, *filtered = NULL, *u_escaped = NULL, *name_escaped = NULL, *header_path = NULL, *password_buffer = NULL, - *tmp_fstype = NULL; + *tmp_fstype = NULL, *filtered_header = NULL, *headerdev_mount = NULL; _cleanup_fclose_ FILE *f = NULL; const char *dmname; bool noauto, nofail, swap, netdev, attach_in_initrd; @@ -302,7 +305,12 @@ static int create_disk( if (keyfile_can_timeout < 0) return log_error_errno(keyfile_can_timeout, "Failed to parse keyfile-timeout= option value: %m"); - detached_header = fstab_filter_options(options, "header\0", NULL, &header_path, NULL); + detached_header = fstab_filter_options( + options, + "header\0", + NULL, + &header_path, + headerdev ? &filtered_header : NULL); if (detached_header < 0) return log_error_errno(detached_header, "Failed to parse header= option value: %m"); @@ -399,6 +407,55 @@ static int create_disk( } } + if (headerdev) { + _cleanup_free_ char *unit = NULL, *umount_unit = NULL, *p = NULL; + + r = generate_device_mount( + name, + headerdev, + "headerdev", + NULL, + /* canfail= */ false, /* header is always necessary */ + /* readonly= */ false, /* LUKS2 recovery requires rw header access */ + &unit, + &headerdev_mount); + if (r < 0) + return log_error_errno(r, "Failed to generate header device mount unit: %m"); + + r = generate_device_umount(name, headerdev_mount, "headerdev", &umount_unit); + if (r < 0) + return log_error_errno(r, "Failed to generate header device umount unit: %m"); + + p = path_join(headerdev_mount, header_path); + if (!p) + return log_oom(); + + free_and_replace(header_path, p); + + if (isempty(filtered_header)) + p = strjoin("header=", header_path); + else + p = strjoin(filtered_header, ",header=", header_path); + + if (!p) + return log_oom(); + + free_and_replace(filtered_header, p); + options = filtered_header; + + fprintf(f, "After=%s\n" + "Requires=%s\n", unit, unit); + + if (umount_unit) { + fprintf(f, + "Wants=%s\n" + "Before=%s\n", + umount_unit, + umount_unit + ); + } + } + if (!nofail) fprintf(f, "Before=%s\n", @@ -411,7 +468,7 @@ static int create_disk( } /* Check if a header option was specified */ - if (detached_header > 0) { + if (detached_header > 0 && !headerdev) { r = print_dependencies(f, header_path); if (r < 0) return r; @@ -537,6 +594,41 @@ static bool warn_uuid_invalid(const char *uuid, const char *key) { return false; } +static int filter_header_device(const char *options, + char **ret_headerdev, + char **ret_filtered_headerdev_options) { + int r; + _cleanup_free_ char *headerfile = NULL, *headerdev = NULL, *headerspec = NULL, + *filtered_headerdev = NULL, *filtered_headerspec = NULL; + + assert(ret_headerdev); + assert(ret_filtered_headerdev_options); + + r = fstab_filter_options(options, "header\0", NULL, &headerspec, &filtered_headerspec); + if (r < 0) + return log_error_errno(r, "Failed to parse header= option value: %m"); + + if (r > 0) { + r = split_locationspec(headerspec, &headerfile, &headerdev); + if (r < 0) + return r; + + if (isempty(filtered_headerspec)) + filtered_headerdev = strjoin("header=", headerfile); + else + filtered_headerdev = strjoin(filtered_headerspec, ",header=", headerfile); + + if (!filtered_headerdev) + return log_oom(); + } else + filtered_headerdev = TAKE_PTR(filtered_headerspec); + + *ret_filtered_headerdev_options = TAKE_PTR(filtered_headerdev); + *ret_headerdev = TAKE_PTR(headerdev); + + return 0; +} + static int parse_proc_cmdline_item(const char *key, const char *value, void *data) { _cleanup_free_ char *uuid = NULL, *uuid_value = NULL; crypto_device *d; @@ -570,20 +662,28 @@ static int parse_proc_cmdline_item(const char *key, const char *value, void *dat d->create = arg_allow_list = true; } else if (streq(key, "luks.options")) { + _cleanup_free_ char *headerdev = NULL, *filtered_headerdev_options = NULL; if (proc_cmdline_value_missing(key, value)) return 0; r = sscanf(value, "%m[0-9a-fA-F-]=%ms", &uuid, &uuid_value); - if (r == 2) { - d = get_crypto_device(uuid); - if (!d) - return log_oom(); + if (r != 2) + return free_and_strdup(&arg_default_options, value) < 0 ? log_oom() : 0; - free_and_replace(d->options, uuid_value); - } else if (free_and_strdup(&arg_default_options, value) < 0) + if (warn_uuid_invalid(uuid, key)) + return 0; + + d = get_crypto_device(uuid); + if (!d) return log_oom(); + r = filter_header_device(uuid_value, &headerdev, &filtered_headerdev_options); + if (r < 0) + return r; + + free_and_replace(d->options, filtered_headerdev_options); + free_and_replace(d->headerdev, headerdev); } else if (streq(key, "luks.key")) { size_t n; _cleanup_free_ char *keyfile = NULL, *keydev = NULL; @@ -617,7 +717,35 @@ static int parse_proc_cmdline_item(const char *key, const char *value, void *dat free_and_replace(d->keyfile, keyfile); free_and_replace(d->keydev, keydev); + } else if (streq(key, "luks.data")) { + size_t n; + _cleanup_free_ char *datadev = NULL; + if (proc_cmdline_value_missing(key, value)) + return 0; + + n = strspn(value, ALPHANUMERICAL "-"); + if (value[n] != '=') { + log_warning("Failed to parse luks.data= kernel command line switch. UUID is invalid, ignoring."); + return 0; + } + + uuid = strndup(value, n); + if (!uuid) + return log_oom(); + + if (warn_uuid_invalid(uuid, key)) + return 0; + + d = get_crypto_device(uuid); + if (!d) + return log_oom(); + + datadev = fstab_node_to_udev_node(value + n + 1); + if (!datadev) + return log_oom(); + + free_and_replace(d->datadev, datadev); } else if (streq(key, "luks.name")) { if (proc_cmdline_value_missing(key, value)) @@ -701,7 +829,7 @@ static int add_crypttab_devices(void) { if (r < 0) return r; - r = create_disk(name, device, keyfile, keydev, (d && d->options) ? d->options : options, arg_crypttab); + r = create_disk(name, device, keyfile, keydev, d ? d->headerdev : NULL, (d && d->options) ? d->options : options, arg_crypttab); if (r < 0) return r; @@ -733,9 +861,10 @@ static int add_proc_cmdline_devices(void) { return log_oom(); r = create_disk(d->name, - device, + d->datadev ?: device, d->keyfile ?: arg_default_keyfile, d->keydev, + d->headerdev, d->options ?: arg_default_options, "/proc/cmdline"); if (r < 0)