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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2023-10-09 13:52:45 -0600 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2023-10-20 10:52:41 -0700 |
| commit | 68a8f644575bde6b35c5fa8a3e6f024aa580e071 (patch) | |
| tree | e79efbc1dcf7d421f18b3534aacc00944974cad0 /security | |
| parent | 8d7af820310cb547c4cb7bdc321c161833eba57f (diff) | |
| download | lwn-68a8f644575bde6b35c5fa8a3e6f024aa580e071.tar.gz lwn-68a8f644575bde6b35c5fa8a3e6f024aa580e071.zip | |
ima: Add __counted_by for struct modsig and use struct_size()
Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).
Also, relocate `hdr->raw_pkcs7_len = sig_len;` so that the __counted_by
annotation has effect, and flex-array member `raw_pkcs7` can be properly
bounds-checked at run-time.
While there, use struct_size() helper, instead of the open-coded
version, to calculate the size for the allocation of the whole
flexible structure, including of course, the flexible-array member.
This code was found with the help of Coccinelle, and audited and
fixed manually.
Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/ZSRaDcJNARUUWUwS@work
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/integrity/ima/ima_modsig.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c index 3e7bee30080f..3265d744d5ce 100644 --- a/security/integrity/ima/ima_modsig.c +++ b/security/integrity/ima/ima_modsig.c @@ -29,7 +29,7 @@ struct modsig { * storing the signature. */ int raw_pkcs7_len; - u8 raw_pkcs7[]; + u8 raw_pkcs7[] __counted_by(raw_pkcs7_len); }; /* @@ -65,10 +65,11 @@ int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, buf_len -= sig_len + sizeof(*sig); /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ - hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); + hdr = kzalloc(struct_size(hdr, raw_pkcs7, sig_len), GFP_KERNEL); if (!hdr) return -ENOMEM; + hdr->raw_pkcs7_len = sig_len; hdr->pkcs7_msg = pkcs7_parse_message(buf + buf_len, sig_len); if (IS_ERR(hdr->pkcs7_msg)) { rc = PTR_ERR(hdr->pkcs7_msg); @@ -77,7 +78,6 @@ int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, } memcpy(hdr->raw_pkcs7, buf + buf_len, sig_len); - hdr->raw_pkcs7_len = sig_len; /* We don't know the hash algorithm yet. */ hdr->hash_algo = HASH_ALGO__LAST; |