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fix: Validate TA-supplied pointers in secure-kernel syscalls #252

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Merged
tdrozdovsky merged 2 commits into from
Aug 5, 2026
Merged

fix: Validate TA-supplied pointers in secure-kernel syscalls #252

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f05cfb7
tee: validate TA-supplied pointers in secure-kernel syscalls
bmolodan Aug 3, 2026
db36183
test: remove temporary TA-pointer access-rights negative test
bmolodan Aug 5, 2026
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5 changes: 5 additions & 0 deletions tee/include/tee/tee_svc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,11 @@ TEE_Result syscall_invoke_ta_command(unsigned long sess,
TEE_Result syscall_check_access_rights(unsigned long flags, const void *buf,
size_t len);

struct user_ta_ctx;

TEE_Result tee_mmu_check_access_rights(struct user_ta_ctx *utc, uint32_t flags,
uaddr_t uaddr, size_t len);

TEE_Result tee_svc_copy_from_user(void *kaddr, const void *uaddr, size_t len);
TEE_Result tee_svc_copy_to_user(void *uaddr, const void *kaddr, size_t len);

Expand Down
87 changes: 60 additions & 27 deletions tee/tee/tee_svc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -926,41 +926,74 @@ vaddr_t tee_svc_uref_base = 0;
// (uaddr_t)buf, len);
//}
//
/*
* tee_mmu_check_access_rights - validate a TA-supplied pointer range.
*
* In this ARMv8-M port TAs are statically linked into the secure image and run
* privileged in a single flat address space: there is no per-TA MMU/MPU context
* or region table (utc->mmu is not populated), so the OP-TEE-style ownership and
* secure/non-secure attribution this signature was designed for have no backing
* state. Every live caller requests TEE_MEMORY_ACCESS_ANY_OWNER, i.e. "do not
* enforce per-TA ownership, just accessibility", so this validates the property
* that is actually meaningful here: the range is a real, non-wrapping range. This
* mirrors the wrap/overflow guard cmse_check_address_range() performs on the
* non-secure boundary and rejects the dangerous primitive of an attacker- or
* bug-supplied length that would drive an out-of-bounds copy.
*/
TEE_Result tee_mmu_check_access_rights(struct user_ta_ctx *utc, uint32_t flags,
uaddr_t uaddr, size_t len)
{
(void)utc; /* unused: no per-TA region data here; callers pass NULL */
(void)flags; /* ANY_OWNER: ownership is not (and can not be) enforced */

if (!len)
return TEE_SUCCESS; /* zero-length range is trivially OK */
if (!uaddr)
return TEE_ERROR_ACCESS_DENIED;
/*
* Reject a range that wraps the address space. len is non-zero here, so
* the last byte is at uaddr + len - 1; if that is below uaddr the range
* overflowed. Matches cmse_check_address_range()'s end-of-range test and
* still accepts a range whose last byte sits at the top of memory.
*/
if (uaddr + len - 1 < uaddr)
return TEE_ERROR_ACCESS_DENIED;

return TEE_SUCCESS;
}

TEE_Result tee_svc_copy_from_user(void *kaddr, const void *uaddr, size_t len)
{
// TEE_Result res;
// struct tee_ta_session *s;
//
// res = tee_ta_get_current_session(&s);
// if (res != TEE_SUCCESS)
// return res;
//
// res = tee_mmu_check_access_rights(to_user_ta_ctx(s->ctx),
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)uaddr, len);
// if (res != TEE_SUCCESS)
// return res;
//
TEE_Result res;

/*
* No session lookup here: tee_mmu_check_access_rights() ignores the utc
* in this port, and tee_ta_get_current_session() returns TEE_SUCCESS with
* a NULL current_session when no TA session is active, so dereferencing
* it (to_user_ta_ctx(s->ctx)) would fault instead of failing gracefully.
*/
res = tee_mmu_check_access_rights(NULL,
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)uaddr, len);
if (res != TEE_SUCCESS)
return res;

memcpy(kaddr, uaddr, len);
return TEE_SUCCESS;
}

TEE_Result tee_svc_copy_to_user(void *uaddr, const void *kaddr, size_t len)
{
// TEE_Result res;
// struct tee_ta_session *s;
//
// res = tee_ta_get_current_session(&s);
// if (res != TEE_SUCCESS)
// return res;
//
// res = tee_mmu_check_access_rights(to_user_ta_ctx(s->ctx),
// TEE_MEMORY_ACCESS_WRITE |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)uaddr, len);
// if (res != TEE_SUCCESS)
// return res;
TEE_Result res;

/* See tee_svc_copy_from_user() on why no session is looked up here. */
res = tee_mmu_check_access_rights(NULL,
TEE_MEMORY_ACCESS_WRITE |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)uaddr, len);
if (res != TEE_SUCCESS)
return res;

memcpy(uaddr, kaddr, len);
return TEE_SUCCESS;
Expand Down
108 changes: 56 additions & 52 deletions tee/tee/tee_svc_cryp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1337,15 +1337,19 @@ static TEE_Result copy_in_attrs(struct user_ta_ctx *utc,
const struct utee_attribute *usr_attrs,
uint32_t attr_count, TEE_Attribute *attrs)
{
// TEE_Result res;
TEE_Result res;
uint32_t n;
(void) utc;
// res = tee_mmu_check_access_rights(utc,
// TEE_MEMORY_ACCESS_READ | TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)usr_attrs,
// attr_count * sizeof(struct utee_attribute));
// if (res != TEE_SUCCESS)
// return res;
size_t attrs_size;

/* Guard the range length against a 32-bit multiply wrap. */
if (MUL_OVERFLOW(attr_count, sizeof(struct utee_attribute), &attrs_size))
return TEE_ERROR_OVERFLOW;

res = tee_mmu_check_access_rights(utc,
TEE_MEMORY_ACCESS_READ | TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)usr_attrs, attrs_size);
if (res != TEE_SUCCESS)
return res;

for (n = 0; n < attr_count; n++) {
attrs[n].attributeID = usr_attrs[n].attribute_id;
Expand All @@ -1356,11 +1360,11 @@ static TEE_Result copy_in_attrs(struct user_ta_ctx *utc,
uintptr_t buf = usr_attrs[n].a;
size_t len = usr_attrs[n].b;

// res = tee_mmu_check_access_rights(utc,
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_ANY_OWNER, buf, len);
// if (res != TEE_SUCCESS)
// return res;
res = tee_mmu_check_access_rights(utc,
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_ANY_OWNER, buf, len);
if (res != TEE_SUCCESS)
return res;
attrs[n].content.ref.buffer = (void *)buf;
attrs[n].content.ref.length = len;
}
Expand Down Expand Up @@ -2231,12 +2235,12 @@ TEE_Result utee_hash_update(unsigned long state, const void *chunk,
if (res != TEE_SUCCESS)
return res;

// res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)chunk, chunk_size);
// if (res != TEE_SUCCESS)
// return res;
res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)chunk, chunk_size);
if (res != TEE_SUCCESS)
return res;

res = tee_svc_cryp_get_state(sess, tee_svc_uref_to_vaddr(state), &cs);
if (res != TEE_SUCCESS)
Expand Down Expand Up @@ -2277,24 +2281,24 @@ TEE_Result utee_hash_final(unsigned long state, const void *chunk,
if (res != TEE_SUCCESS)
return res;

// res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)chunk, chunk_size);
// if (res != TEE_SUCCESS)
// return res;
res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)chunk, chunk_size);
if (res != TEE_SUCCESS)
return res;

res = tee_svc_copy_from_user(&hlen, hash_len, sizeof(hlen));
if (res != TEE_SUCCESS)
return res;

// res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_WRITE |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)hash, hlen);
// if (res != TEE_SUCCESS)
// return res;
res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_WRITE |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)hash, hlen);
if (res != TEE_SUCCESS)
return res;

res = tee_svc_cryp_get_state(sess, tee_svc_uref_to_vaddr(state), &cs);
if (res != TEE_SUCCESS)
Expand Down Expand Up @@ -2373,13 +2377,13 @@ TEE_Result utee_cipher_init(unsigned long state, const void *iv,
if (res != TEE_SUCCESS)
return res;

// res = tee_mmu_check_access_rights(utc,
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t) iv, iv_len);
// if (res != TEE_SUCCESS)
// return res;
//
res = tee_mmu_check_access_rights(utc,
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t) iv, iv_len);
if (res != TEE_SUCCESS)
return res;

res = tee_obj_get(utc, cs->key1, &o);
if (res != TEE_SUCCESS)
return res;
Expand Down Expand Up @@ -2427,12 +2431,12 @@ static TEE_Result tee_svc_cipher_update_helper(unsigned long state,
if (res != TEE_SUCCESS)
return res;

// res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)src, src_len);
// if (res != TEE_SUCCESS)
// return res;
res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)src, src_len);
if (res != TEE_SUCCESS)
return res;

if (!dst_len) {
dlen = 0;
Expand All @@ -2441,13 +2445,13 @@ static TEE_Result tee_svc_cipher_update_helper(unsigned long state,
if (res != TEE_SUCCESS)
return res;

// res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
// TEE_MEMORY_ACCESS_READ |
// TEE_MEMORY_ACCESS_WRITE |
// TEE_MEMORY_ACCESS_ANY_OWNER,
// (uaddr_t)dst, dlen);
// if (res != TEE_SUCCESS)
// return res;
res = tee_mmu_check_access_rights(to_user_ta_ctx(sess->ctx),
TEE_MEMORY_ACCESS_READ |
TEE_MEMORY_ACCESS_WRITE |
TEE_MEMORY_ACCESS_ANY_OWNER,
(uaddr_t)dst, dlen);
if (res != TEE_SUCCESS)
return res;
}

if (dlen < src_len) {
Expand Down
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