On Sun, 2021-06-20 at 21:03 -0400, Mimi Zohar wrote:
> Output the data used in calculating the EVM digest and the resulting
> digest as ascii hexadecimal strings.
>
> Suggested-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
> (CONFIG_DYNAMIC_DEBUG)
> Reviewed-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx> (Use %zu for size_t)
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> ---
> Changelog v1:
> - Use %zu for size_t
Reviewed-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
-lakshmi
>
> security/integrity/evm/evm_crypto.c | 43
> +++++++++++++++++++++++++++++
> security/integrity/evm/evm_main.c | 4 +++
> 2 files changed, 47 insertions(+)
>
> diff --git a/security/integrity/evm/evm_crypto.c
> b/security/integrity/evm/evm_crypto.c
> index 1628e2ca9862..bebe160c57b9 100644
> --- a/security/integrity/evm/evm_crypto.c
> +++ b/security/integrity/evm/evm_crypto.c
> @@ -10,6 +10,8 @@
> * Using root's kernel master key (kmk), calculate the HMAC
> */
>
> +#define pr_fmt(fmt) "EVM: "fmt
> +
> #include <linux/export.h>
> #include <linux/crypto.h>
> #include <linux/xattr.h>
> @@ -175,6 +177,30 @@ static void hmac_add_misc(struct shash_desc
> *desc, struct inode *inode,
> type != EVM_XATTR_PORTABLE_DIGSIG)
> crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid,
> UUID_SIZE);
> crypto_shash_final(desc, digest);
> +
> + pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
> + (int)sizeof(struct h_misc), &hmac_misc);
> +}
> +
> +/*
> + * Dump large security xattr values as a continuous ascii
> hexademical string.
> + * (pr_debug is limited to 64 bytes.)
> + */
> +static void dump_security_xattr(const char *prefix, const void *src,
> + size_t count)
> +{
> +#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
> + char *asciihex, *p;
> +
> + p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
> + if (!asciihex)
> + return;
> +
> + p = bin2hex(p, src, count);
> + *p = 0;
> + pr_debug("%s: (%zu) %.*s\n", prefix, count, (int)count * 2,
> asciihex);
> + kfree(asciihex);
> +#endif
> }
>
> /*
> @@ -230,6 +256,16 @@ static int evm_calc_hmac_or_hash(struct dentry
> *dentry,
> req_xattr_value_len);
> if (is_ima)
> ima_present = true;
> +
> + if (req_xattr_value_len < 64)
> + pr_debug("%s: (%zu) [%*phN]\n",
> req_xattr_name,
> + req_xattr_value_len,
> + (int)req_xattr_value_len,
> + req_xattr_value);
> + else
> + dump_security_xattr(req_xattr_name,
> + req_xattr_value,
> + req_xattr_value_len
> );
> continue;
> }
> size = vfs_getxattr_alloc(&init_user_ns, dentry, xattr-
> >name,
> @@ -246,6 +282,13 @@ static int evm_calc_hmac_or_hash(struct dentry
> *dentry,
> crypto_shash_update(desc, (const u8 *)xattr_value,
> xattr_size);
> if (is_ima)
> ima_present = true;
> +
> + if (xattr_size < 64)
> + pr_debug("%s: (%zu) [%*phN]", xattr->name,
> xattr_size,
> + (int)xattr_size, xattr_value);
> + else
> + dump_security_xattr(xattr->name, xattr_value,
> + xattr_size);
> }
> hmac_add_misc(desc, inode, type, data->digest);
>
> diff --git a/security/integrity/evm/evm_main.c
> b/security/integrity/evm/evm_main.c
> index 977208aecd06..1c8435dfabee 100644
> --- a/security/integrity/evm/evm_main.c
> +++ b/security/integrity/evm/evm_main.c
> @@ -11,6 +11,8 @@
> * evm_inode_removexattr, and evm_verifyxattr
> */
>
> +#define pr_fmt(fmt) "EVM: "fmt
> +
> #include <linux/init.h>
> #include <linux/crypto.h>
> #include <linux/audit.h>
> @@ -272,6 +274,8 @@ static enum integrity_status
> evm_verify_hmac(struct dentry *dentry,
> else
> evm_status = INTEGRITY_FAIL;
> }
> + pr_debug("digest: (%d) [%*phN]\n", digest.hdr.length,
> digest.hdr.length,
> + digest.digest);
> out:
> if (iint)
> iint->evm_status = evm_status;
