diff options
| author | Tom Lendacky <thomas.lendacky@amd.com> | 2023-02-22 17:39:39 +0100 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-03-01 10:17:46 +0100 |
| commit | dd093fb08e8f8a958fec4eef36f9f09eac047f60 (patch) | |
| tree | b048e4c4d88c70fa710ed9de09342be501f4bc7b /drivers/virt | |
| parent | Documentation/hw-vuln: Document the interaction between IBRS and STIBP (diff) | |
| download | linux-dd093fb08e8f8a958fec4eef36f9f09eac047f60.tar.xz linux-dd093fb08e8f8a958fec4eef36f9f09eac047f60.zip | |
virt/sev-guest: Return -EIO if certificate buffer is not large enough
Commit
47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver")
changed the behavior associated with the return value when the caller
does not supply a large enough certificate buffer. Prior to the commit a
value of -EIO was returned. Now, 0 is returned. This breaks the
established ABI with the user.
Change the code to detect the buffer size error and return -EIO.
Fixes: 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver")
Reported-by: Larry Dewey <larry.dewey@amd.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Larry Dewey <larry.dewey@amd.com>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee.1677083979.git.thomas.lendacky@amd.com
Diffstat (limited to 'drivers/virt')
| -rw-r--r-- | drivers/virt/coco/sev-guest/sev-guest.c | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 4ec4174e05a3..7b4e9009f335 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -377,9 +377,26 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in snp_dev->input.data_npages = certs_npages; } + /* + * Increment the message sequence number. There is no harm in doing + * this now because decryption uses the value stored in the response + * structure and any failure will wipe the VMPCK, preventing further + * use anyway. + */ + snp_inc_msg_seqno(snp_dev); + if (fw_err) *fw_err = err; + /* + * If an extended guest request was issued and the supplied certificate + * buffer was not large enough, a standard guest request was issued to + * prevent IV reuse. If the standard request was successful, return -EIO + * back to the caller as would have originally been returned. + */ + if (!rc && err == SNP_GUEST_REQ_INVALID_LEN) + return -EIO; + if (rc) { dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", @@ -395,9 +412,6 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in goto disable_vmpck; } - /* Increment to new message sequence after payload decryption was successful. */ - snp_inc_msg_seqno(snp_dev); - return 0; disable_vmpck: |