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crypto: ccp: Reject SEV commands with mismatching command buffer

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WARN on and reject SEV commands that provide a valid data pointer, but do
not have a known, non-zero length.  And conversely, reject commands that
take a command buffer but none is provided (data is null).

Aside from sanity checking input, disallowing a non-null pointer without
a non-zero size will allow a future patch to cleanly handle vmalloc'd
data by copying the data to an internal __pa() friendly buffer.

Note, this also effectively prevents callers from using commands that
have a non-zero length and are not known to the kernel.  This is not an
explicit goal, but arguably the side effect is a good thing from the
kernel's perspective.

Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210406224952.4177376-4-seanjc@google.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-04-06 15:49:47 -07:00 committed by Paolo Bonzini
parent 74c1f1366e
commit d5760dee12
1 changed files with 7 additions and 2 deletions
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9
drivers/crypto/ccp/sev-dev.c
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@ -142,6 +142,7 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
struct sev_device *sev;
unsigned int phys_lsb, phys_msb;
unsigned int reg, ret = 0;
int buf_len;
if (!psp || !psp->sev_data)
return -ENODEV;
@ -151,6 +152,10 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
sev = psp->sev_data;
buf_len = sev_cmd_buffer_len(cmd);
if (WARN_ON_ONCE(!data != !buf_len))
return -EINVAL;
if (data && WARN_ON_ONCE(!virt_addr_valid(data)))
return -EINVAL;
@ -162,7 +167,7 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
cmd, phys_msb, phys_lsb, psp_timeout);
print_hex_dump_debug("(in): ", DUMP_PREFIX_OFFSET, 16, 2, data,
sev_cmd_buffer_len(cmd), false);
buf_len, false);
iowrite32(phys_lsb, sev->io_regs + sev->vdata->cmdbuff_addr_lo_reg);
iowrite32(phys_msb, sev->io_regs + sev->vdata->cmdbuff_addr_hi_reg);
@ -198,7 +203,7 @@ static int __sev_do_cmd_locked(int cmd, void *data, int *psp_ret)
}
print_hex_dump_debug("(out): ", DUMP_PREFIX_OFFSET, 16, 2, data,
sev_cmd_buffer_len(cmd), false);
buf_len, false);
return ret;
}