On Thu, 2026-02-19 at 10:26 +0100, Roberto Sassu wrote:
> On Thu, 2026-02-05 at 21:42 -0500, Daniel Hodges wrote:
> > The crypto_shash_update() and crypto_shash_final() functions can fail
> > and return error codes, but their return values were not being checked
> > in several places in security/integrity/evm/evm_crypto.c:
> >
> > - hmac_add_misc() ignored returns from crypto_shash_update() and
> > crypto_shash_final()
> > - evm_calc_hmac_or_hash() ignored returns from crypto_shash_update()
> > - evm_init_hmac() ignored returns from crypto_shash_update()
> >
> > If these hash operations fail silently, the resulting HMAC could be
> > invalid or incomplete, which could weaken the integrity verification
> > security that EVM provides.
> >
> > This patch converts hmac_add_misc() from void to int return type and
> > adds proper error checking and propagation for all crypto_shash_*
> > function calls. All callers are updated to handle the new return values.
> > Additionally, error messages are logged when cryptographic operations
> > fail to provide visibility into the failure rather than silently
> > returning error codes.
> >
> > Fixes: 66dbc325afce ("evm: re-release")
> > Signed-off-by: Daniel Hodges <[email protected]>
>
> After fixing the minor issue below:
Already did it. The patch is here (after fixing a conflict with
0496fc9cdc38 "evm: Use ordered xattrs list to calculate HMAC in
evm_init_hmac()"):
https://github.com/robertosassu/linux/commit/d5aba42198b602c6de002ef02a4e6cc1d75652d7
Roberto
> Reviewed-by: Roberto Sassu <[email protected]>
>
> > ---
> > security/integrity/evm/evm_crypto.c | 55 ++++++++++++++++++++++-------
> > 1 file changed, 42 insertions(+), 13 deletions(-)
> >
> > diff --git a/security/integrity/evm/evm_crypto.c
> > b/security/integrity/evm/evm_crypto.c
> > index a5e730ffda57..402eb1ca64ce 100644
> > --- a/security/integrity/evm/evm_crypto.c
> > +++ b/security/integrity/evm/evm_crypto.c
> > @@ -139,7 +139,7 @@ static struct shash_desc *init_desc(char type, uint8_t
> > hash_algo)
> > * (Additional directory/file metadata needs to be added for more complete
> > * protection.)
> > */
> > -static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
> > +static int hmac_add_misc(struct shash_desc *desc, struct inode *inode,
> > char type, char *digest)
> > {
> > struct h_misc {
> > @@ -149,6 +149,7 @@ static void hmac_add_misc(struct shash_desc *desc,
> > struct inode *inode,
> > gid_t gid;
> > umode_t mode;
> > } hmac_misc;
> > + int error;
> >
> > memset(&hmac_misc, 0, sizeof(hmac_misc));
> > /* Don't include the inode or generation number in portable
> > @@ -169,14 +170,28 @@ static void hmac_add_misc(struct shash_desc *desc,
> > struct inode *inode,
> > hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
> > hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
> > hmac_misc.mode = inode->i_mode;
> > - crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
> > + error = crypto_shash_update(desc, (const u8 *)&hmac_misc,
> > sizeof(hmac_misc));
> > + if (error) {
> > + pr_err("crypto_shash_update() failed: %d\n", error);
> > + return error;
> > + }
> > if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
> > - type != EVM_XATTR_PORTABLE_DIGSIG)
> > - crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid,
> > UUID_SIZE);
> > - crypto_shash_final(desc, digest);
> > + type != EVM_XATTR_PORTABLE_DIGSIG) {
> > + error = crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid,
> > UUID_SIZE);
> > + if (error) {
> > + pr_err("crypto_shash_update() failed: %d\n", error);
> > + return error;
> > + }
> > + }
> > + error = crypto_shash_final(desc, digest);
> > + if (error) {
> > + pr_err("crypto_shash_final() failed: %d\n", error);
> > + return error;
> > + }
> >
> > pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
> > (int)sizeof(struct h_misc), &hmac_misc);
> > + return 0;
> > }
> >
> > /*
> > @@ -260,9 +275,12 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
> >
> > if ((req_xattr_name && req_xattr_value)
> > && !strcmp(xattr->name, req_xattr_name)) {
> > - error = 0;
> > - crypto_shash_update(desc, (const u8 *)req_xattr_value,
> > + error = crypto_shash_update(desc, (const u8
> > *)req_xattr_value,
> > req_xattr_value_len);
>
> Please align this.
>
> Thanks
>
> Roberto
>
> > + if (error) {
> > + pr_err("crypto_shash_update() failed: %d\n",
> > error);
> > + goto out;
> > + }
> > if (is_ima)
> > ima_present = true;
> >
> > @@ -286,15 +304,20 @@ static int evm_calc_hmac_or_hash(struct dentry
> > *dentry,
> > pr_debug("file %s: xattr %s size mismatch (kernel: %d,
> > user: %d)\n",
> > dentry->d_name.name, xattr->name, size,
> > user_space_size);
> > - error = 0;
> > xattr_size = size;
> > - crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
> > + error = crypto_shash_update(desc, (const u8 *)xattr_value,
> > xattr_size);
> > + if (error) {
> > + pr_err("crypto_shash_update() failed: %d\n", error);
> > + goto out;
> > + }
> > if (is_ima)
> > ima_present = true;
> >
> > dump_security_xattr(xattr->name, xattr_value, xattr_size);
> > }
> > - hmac_add_misc(desc, inode, type, data->digest);
> > + error = hmac_add_misc(desc, inode, type, data->digest);
> > + if (error)
> > + goto out;
> >
> > if (inode != d_backing_inode(dentry) && iint) {
> > if (IS_I_VERSION(inode))
> > @@ -401,6 +424,7 @@ int evm_init_hmac(struct inode *inode, const struct
> > xattr *xattrs,
> > {
> > struct shash_desc *desc;
> > const struct xattr *xattr;
> > + int error;
> >
> > desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
> > if (IS_ERR(desc)) {
> > @@ -412,12 +436,17 @@ int evm_init_hmac(struct inode *inode, const struct
> > xattr *xattrs,
> > if (!evm_protected_xattr(xattr->name))
> > continue;
> >
> > - crypto_shash_update(desc, xattr->value, xattr->value_len);
> > + error = crypto_shash_update(desc, xattr->value,
> > xattr->value_len);
> > + if (error) {
> > + pr_err("crypto_shash_update() failed: %d\n", error);
> > + goto out;
> > + }
> > }
> >
> > - hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
> > + error = hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
> > +out:
> > kfree(desc);
> > - return 0;
> > + return error;
> > }
> >
> > /*
