From 79af75f7776fc20b0d7eb6afe1e27c00fdb4b9b4 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Mon, 15 Feb 2021 17:08:06 -0700 Subject: [PATCH] fit: Don't allow verification of images with @ nodes When searching for a node called 'fred', any unit address appended to the name is ignored by libfdt, meaning that 'fred' can match 'fred@1'. This means that we cannot be sure that the node originally intended is the one that is used. Disallow use of nodes with unit addresses. Update the forge test also, since it uses @ addresses. CVE-2021-27138 Signed-off-by: Simon Glass Reported-by: Bruce Monroe Reported-by: Arie Haenel Reported-by: Julien Lenoir --- common/image-fit-sig.c | 22 ++++++++++++++++++++-- common/image-fit.c | 20 +++++++++++++++----- test/py/tests/test_fit.py | 24 ++++++++++++------------ test/py/tests/vboot_forge.py | 12 ++++++------ 4 files changed, 53 insertions(+), 25 deletions(-) diff --git a/common/image-fit-sig.c b/common/image-fit-sig.c index 897e04c7a3..34ebb8edfe 100644 --- a/common/image-fit-sig.c +++ b/common/image-fit-sig.c @@ -149,6 +149,14 @@ static int fit_image_verify_sig(const void *fit, int image_noffset, fdt_for_each_subnode(noffset, fit, image_noffset) { const char *name = fit_get_name(fit, noffset, NULL); + /* + * We don't support this since libfdt considers names with the + * name root but different @ suffix to be equal + */ + if (strchr(name, '@')) { + err_msg = "Node name contains @"; + goto error; + } if (!strncmp(name, FIT_SIG_NODENAME, strlen(FIT_SIG_NODENAME))) { ret = fit_image_check_sig(fit, noffset, data, @@ -398,9 +406,10 @@ error: return -EPERM; } -int fit_config_verify_required_sigs(const void *fit, int conf_noffset, - const void *sig_blob) +static int fit_config_verify_required_sigs(const void *fit, int conf_noffset, + const void *sig_blob) { + const char *name = fit_get_name(fit, conf_noffset, NULL); int noffset; int sig_node; int verified = 0; @@ -408,6 +417,15 @@ int fit_config_verify_required_sigs(const void *fit, int conf_noffset, bool reqd_policy_all = true; const char *reqd_mode; + /* + * We don't support this since libfdt considers names with the + * name root but different @ suffix to be equal + */ + if (strchr(name, '@')) { + printf("Configuration node '%s' contains '@'\n", name); + return -EPERM; + } + /* Work out what we need to verify */ sig_node = fdt_subnode_offset(sig_blob, 0, FIT_SIG_NODENAME); if (sig_node < 0) { diff --git a/common/image-fit.c b/common/image-fit.c index adc3e551de..c3dc814115 100644 --- a/common/image-fit.c +++ b/common/image-fit.c @@ -1369,21 +1369,31 @@ error: */ int fit_image_verify(const void *fit, int image_noffset) { + const char *name = fit_get_name(fit, image_noffset, NULL); const void *data; size_t size; - int noffset = 0; char *err_msg = ""; + if (strchr(name, '@')) { + /* + * We don't support this since libfdt considers names with the + * name root but different @ suffix to be equal + */ + err_msg = "Node name contains @"; + goto err; + } /* Get image data and data length */ if (fit_image_get_data_and_size(fit, image_noffset, &data, &size)) { err_msg = "Can't get image data/size"; - printf("error!\n%s for '%s' hash node in '%s' image node\n", - err_msg, fit_get_name(fit, noffset, NULL), - fit_get_name(fit, image_noffset, NULL)); - return 0; + goto err; } return fit_image_verify_with_data(fit, image_noffset, data, size); + +err: + printf("error!\n%s in '%s' image node\n", err_msg, + fit_get_name(fit, image_noffset, NULL)); + return 0; } /** diff --git a/test/py/tests/test_fit.py b/test/py/tests/test_fit.py index 84b3f95850..6d5b43c3ba 100755 --- a/test/py/tests/test_fit.py +++ b/test/py/tests/test_fit.py @@ -17,7 +17,7 @@ base_its = ''' #address-cells = <1>; images { - kernel@1 { + kernel-1 { data = /incbin/("%(kernel)s"); type = "kernel"; arch = "sandbox"; @@ -26,7 +26,7 @@ base_its = ''' load = <0x40000>; entry = <0x8>; }; - kernel@2 { + kernel-2 { data = /incbin/("%(loadables1)s"); type = "kernel"; arch = "sandbox"; @@ -35,19 +35,19 @@ base_its = ''' %(loadables1_load)s entry = <0x0>; }; - fdt@1 { + fdt-1 { description = "snow"; data = /incbin/("%(fdt)s"); type = "flat_dt"; arch = "sandbox"; %(fdt_load)s compression = "%(compression)s"; - signature@1 { + signature-1 { algo = "sha1,rsa2048"; key-name-hint = "dev"; }; }; - ramdisk@1 { + ramdisk-1 { description = "snow"; data = /incbin/("%(ramdisk)s"); type = "ramdisk"; @@ -56,7 +56,7 @@ base_its = ''' %(ramdisk_load)s compression = "%(compression)s"; }; - ramdisk@2 { + ramdisk-2 { description = "snow"; data = /incbin/("%(loadables2)s"); type = "ramdisk"; @@ -67,10 +67,10 @@ base_its = ''' }; }; configurations { - default = "conf@1"; - conf@1 { - kernel = "kernel@1"; - fdt = "fdt@1"; + default = "conf-1"; + conf-1 { + kernel = "kernel-1"; + fdt = "fdt-1"; %(ramdisk_config)s %(loadables_config)s }; @@ -410,7 +410,7 @@ def test_fit(u_boot_console): # Try a ramdisk with cons.log.section('Kernel + FDT + Ramdisk load'): - params['ramdisk_config'] = 'ramdisk = "ramdisk@1";' + params['ramdisk_config'] = 'ramdisk = "ramdisk-1";' params['ramdisk_load'] = 'load = <%#x>;' % params['ramdisk_addr'] fit = make_fit(mkimage, params) cons.restart_uboot() @@ -419,7 +419,7 @@ def test_fit(u_boot_console): # Configuration with some Loadables with cons.log.section('Kernel + FDT + Ramdisk load + Loadables'): - params['loadables_config'] = 'loadables = "kernel@2", "ramdisk@2";' + params['loadables_config'] = 'loadables = "kernel-2", "ramdisk-2";' params['loadables1_load'] = ('load = <%#x>;' % params['loadables1_addr']) params['loadables2_load'] = ('load = <%#x>;' % diff --git a/test/py/tests/vboot_forge.py b/test/py/tests/vboot_forge.py index 0fb7ef4024..b41105bd0e 100644 --- a/test/py/tests/vboot_forge.py +++ b/test/py/tests/vboot_forge.py @@ -376,12 +376,12 @@ def manipulate(root, strblock): """ Maliciously manipulates the structure to create a crafted FIT file """ - # locate /images/kernel@1 (frankly, it just expects it to be the first one) + # locate /images/kernel-1 (frankly, it just expects it to be the first one) kernel_node = root[0][0] # clone it to save time filling all the properties fake_kernel = kernel_node.clone() # rename the node - fake_kernel.name = b'kernel@2' + fake_kernel.name = b'kernel-2' # get rid of signatures/hashes fake_kernel.children = [] # NOTE: this simply replaces the first prop... either description or data @@ -391,13 +391,13 @@ def manipulate(root, strblock): root[0].children.append(fake_kernel) # modify the default configuration - root[1].props[0].value = b'conf@2\x00' + root[1].props[0].value = b'conf-2\x00' # clone the first (only?) configuration fake_conf = root[1][0].clone() # rename and change kernel and fdt properties to select the crafted kernel - fake_conf.name = b'conf@2' - fake_conf.props[0].value = b'kernel@2\x00' - fake_conf.props[1].value = b'fdt@1\x00' + fake_conf.name = b'conf-2' + fake_conf.props[0].value = b'kernel-2\x00' + fake_conf.props[1].value = b'fdt-1\x00' # insert the new configuration under /configurations root[1].children.append(fake_conf) -- 2.39.5