From 1376956c5e9e7871978153a483904dc3238e96fb Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 14 Aug 2025 19:17:32 -0700 Subject: integrity: Select CRYPTO from INTEGRITY_ASYMMETRIC_KEYS Select CRYPTO from INTEGRITY_ASYMMETRIC_KEYS, since INTEGRITY_ASYMMETRIC_KEYS selects several options that depend on CRYPTO. This unblocks the removal of the CRYPTO selection from SIGNATURE. SIGNATURE (lib/digsig.c) itself will no longer need CRYPTO, but INTEGRITY_ASYMMETRIC_KEYS was depending on it indirectly via the chain SIGNATURE => INTEGRITY_SIGNATURE => INTEGRITY_ASYMMETRIC_KEYS. Signed-off-by: Eric Biggers Reviewed-by: Paul Menzel Signed-off-by: Mimi Zohar --- security/integrity/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig index 3c45f4f3455f..916d4f2bfc44 100644 --- a/security/integrity/Kconfig +++ b/security/integrity/Kconfig @@ -36,6 +36,7 @@ config INTEGRITY_ASYMMETRIC_KEYS default n select ASYMMETRIC_KEY_TYPE select ASYMMETRIC_PUBLIC_KEY_SUBTYPE + select CRYPTO select CRYPTO_RSA select X509_CERTIFICATE_PARSER help -- cgit v1.2.3 From 191cac349c8eeeb6d64453b8db194d3ad42ca9dc Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 14 Aug 2025 19:17:33 -0700 Subject: lib/digsig: Use SHA-1 library instead of crypto_shash Now that a SHA-1 library API is available, use it instead of crypto_shash. This is simpler and faster. Signed-off-by: Eric Biggers Reviewed-by: Paul Menzel Signed-off-by: Mimi Zohar --- lib/Kconfig | 3 +-- lib/digsig.c | 46 ++++++---------------------------------------- 2 files changed, 7 insertions(+), 42 deletions(-) diff --git a/lib/Kconfig b/lib/Kconfig index c483951b624f..e629449dd2a3 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -477,8 +477,7 @@ config MPILIB config SIGNATURE tristate depends on KEYS - select CRYPTO - select CRYPTO_SHA1 + select CRYPTO_LIB_SHA1 select MPILIB help Digital signature verification. Currently only RSA is supported. diff --git a/lib/digsig.c b/lib/digsig.c index 04b5e55ed95f..5ddcc52f7686 100644 --- a/lib/digsig.c +++ b/lib/digsig.c @@ -18,15 +18,11 @@ #include #include #include -#include -#include #include #include #include #include -static struct crypto_shash *shash; - static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg, unsigned long msglen, unsigned long modulus_bitlen, @@ -199,12 +195,12 @@ err1: int digsig_verify(struct key *keyring, const char *sig, int siglen, const char *data, int datalen) { - int err = -ENOMEM; struct signature_hdr *sh = (struct signature_hdr *)sig; - struct shash_desc *desc = NULL; + struct sha1_ctx ctx; unsigned char hash[SHA1_DIGEST_SIZE]; struct key *key; char name[20]; + int err; if (siglen < sizeof(*sh) + 2) return -EINVAL; @@ -231,49 +227,19 @@ int digsig_verify(struct key *keyring, const char *sig, int siglen, return PTR_ERR(key); } - desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash), - GFP_KERNEL); - if (!desc) - goto err; - - desc->tfm = shash; - - crypto_shash_init(desc); - crypto_shash_update(desc, data, datalen); - crypto_shash_update(desc, sig, sizeof(*sh)); - crypto_shash_final(desc, hash); - - kfree(desc); + sha1_init(&ctx); + sha1_update(&ctx, data, datalen); + sha1_update(&ctx, sig, sizeof(*sh)); + sha1_final(&ctx, hash); /* pass signature mpis address */ err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh), hash, sizeof(hash)); -err: key_put(key); return err ? -EINVAL : 0; } EXPORT_SYMBOL_GPL(digsig_verify); -static int __init digsig_init(void) -{ - shash = crypto_alloc_shash("sha1", 0, 0); - if (IS_ERR(shash)) { - pr_err("shash allocation failed\n"); - return PTR_ERR(shash); - } - - return 0; - -} - -static void __exit digsig_cleanup(void) -{ - crypto_free_shash(shash); -} - -module_init(digsig_init); -module_exit(digsig_cleanup); - MODULE_LICENSE("GPL"); -- cgit v1.2.3 From 88b4cbcf6b041ae0f2fc8a34554a5b6a83a2b7cd Mon Sep 17 00:00:00 2001 From: Coiby Xu Date: Mon, 15 Sep 2025 13:55:23 +0800 Subject: ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr Currently when both IMA and EVM are in fix mode, the IMA signature will be reset to IMA hash if a program first stores IMA signature in security.ima and then writes/removes some other security xattr for the file. For example, on Fedora, after booting the kernel with "ima_appraise=fix evm=fix ima_policy=appraise_tcb" and installing rpm-plugin-ima, installing/reinstalling a package will not make good reference IMA signature generated. Instead IMA hash is generated, # getfattr -m - -d -e hex /usr/bin/bash # file: usr/bin/bash security.ima=0x0404... This happens because when setting security.selinux, the IMA_DIGSIG flag that had been set early was cleared. As a result, IMA hash is generated when the file is closed. Similarly, IMA signature can be cleared on file close after removing security xattr like security.evm or setting/removing ACL. Prevent replacing the IMA file signature with a file hash, by preventing the IMA_DIGSIG flag from being reset. Here's a minimal C reproducer which sets security.selinux as the last step which can also replaced by removing security.evm or setting ACL, #include #include #include #include #include #include int main() { const char* file_path = "/usr/sbin/test_binary"; const char* hex_string = "030204d33204490066306402304"; int length = strlen(hex_string); char* ima_attr_value; int fd; fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644); if (fd == -1) { perror("Error opening file"); return 1; } ima_attr_value = (char*)malloc(length / 2 ); for (int i = 0, j = 0; i < length; i += 2, j++) { sscanf(hex_string + i, "%2hhx", &ima_attr_value[j]); } if (fsetxattr(fd, "security.ima", ima_attr_value, length/2, 0) == -1) { perror("Error setting extended attribute"); close(fd); return 1; } const char* selinux_value= "system_u:object_r:bin_t:s0"; if (fsetxattr(fd, "security.selinux", selinux_value, strlen(selinux_value), 0) == -1) { perror("Error setting extended attribute"); close(fd); return 1; } close(fd); return 0; } Signed-off-by: Coiby Xu Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_appraise.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index f435eff4667f..5149ff4fd50d 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -694,6 +694,15 @@ static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, return 0; } +/* + * ima_reset_appraise_flags - reset ima_iint_cache flags + * + * @digsig: whether to clear/set IMA_DIGSIG flag, tristate values + * 0: clear IMA_DIGSIG + * 1: set IMA_DIGSIG + * -1: don't change IMA_DIGSIG + * + */ static void ima_reset_appraise_flags(struct inode *inode, int digsig) { struct ima_iint_cache *iint; @@ -706,9 +715,9 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig) return; iint->measured_pcrs = 0; set_bit(IMA_CHANGE_XATTR, &iint->atomic_flags); - if (digsig) + if (digsig == 1) set_bit(IMA_DIGSIG, &iint->atomic_flags); - else + else if (digsig == 0) clear_bit(IMA_DIGSIG, &iint->atomic_flags); } @@ -794,6 +803,8 @@ static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG); } else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) { digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG); + } else { + digsig = -1; } if (result == 1 || evm_revalidate_status(xattr_name)) { ima_reset_appraise_flags(d_backing_inode(dentry), digsig); @@ -807,7 +818,7 @@ static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) { if (evm_revalidate_status(acl_name)) - ima_reset_appraise_flags(d_backing_inode(dentry), 0); + ima_reset_appraise_flags(d_backing_inode(dentry), -1); return 0; } @@ -815,11 +826,13 @@ static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, static int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *xattr_name) { - int result; + int result, digsig = -1; result = ima_protect_xattr(dentry, xattr_name, NULL, 0); if (result == 1 || evm_revalidate_status(xattr_name)) { - ima_reset_appraise_flags(d_backing_inode(dentry), 0); + if (!strcmp(xattr_name, XATTR_NAME_IMA)) + digsig = 0; + ima_reset_appraise_flags(d_backing_inode(dentry), digsig); if (result == 1) result = 0; } -- cgit v1.2.3