| Message ID | 20171012195331.bdzwqzyrjc6fi5lj@pd.tnic (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
On 10/12/17 2:53 PM, Borislav Petkov wrote: ... > Ok, a couple of things here: > > * Move the checks first and the allocations second so that you allocate > memory only after all checks have been passed and you don't allocate > pointlessly. I assume you mean performing the SEV state check before allocating the memory for the CSR blob, right ? In my patches, I typically perform all the SW specific checks and allocation before invoking the HW routines. Handling the PSP commands will take longer compare to kmalloc() or access_ok() etc. If its not a big deal then I would prefer to keep that way. > > * That: > > if (state == SEV_STATE_WORKING) { > ret = -EBUSY; > goto e_free_blob; > } else if (state == SEV_STATE_UNINIT) { > ret = sev_firmware_init(&argp->error); > if (ret) > goto e_free_blob; > do_shutdown = 1; > } > > is a repeating pattern. Perhaps it should be called > sev_firmware_reinit() and called by other functions. > * The rest is simplifications and streamlining. > > --- > diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c > index e3ee68afd068..d41f5448a25b 100644 > --- a/drivers/crypto/ccp/psp-dev.c > +++ b/drivers/crypto/ccp/psp-dev.c > @@ -302,33 +302,30 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp) > int ret, state; > void *blob; > > - if (copy_from_user(&input, (void __user *)(uintptr_t)argp->data, > - sizeof(struct sev_user_data_pek_csr))) > + if (copy_from_user(&input, (void __user *)argp->data, sizeof(input))) > + return -EFAULT; > + > + if (!input.address) > + return -EINVAL; > + > + /* allocate a physically contiguous buffer to store the CSR blob */ > + if (!access_ok(VERIFY_WRITE, input.address, input.length) || > + input.length > SEV_FW_BLOB_MAX_SIZE) > return -EFAULT; > > data = kzalloc(sizeof(*data), GFP_KERNEL); > if (!data) > return -ENOMEM; > > - /* allocate a temporary physical contigous buffer to store the CSR blob */ > - blob = NULL; > - if (input.address) { > - if (!access_ok(VERIFY_WRITE, input.address, input.length) || > - input.length > SEV_FW_BLOB_MAX_SIZE) { > - ret = -EFAULT; > - goto e_free; > - } > - > - blob = kmalloc(input.length, GFP_KERNEL); > - if (!blob) { > - ret = -ENOMEM; > - goto e_free; > - } > - > - data->address = __psp_pa(blob); > - data->len = input.length; > + blob = kmalloc(input.length, GFP_KERNEL); > + if (!blob) { > + ret = -ENOMEM; > + goto e_free; > } > > + data->address = __psp_pa(blob); > + data->len = input.length; > + > ret = sev_platform_get_state(&state, &argp->error); > if (ret) > goto e_free_blob; > @@ -349,25 +346,23 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp) > do_shutdown = 1; > } > > - ret = sev_handle_cmd(SEV_CMD_PEK_CSR, data, &argp->error); > + ret = sev_do_cmd(SEV_CMD_PEK_CSR, data, &argp->error); > > input.length = data->len; > > /* copy blob to userspace */ > - if (blob && > - copy_to_user((void __user *)(uintptr_t)input.address, > - blob, input.length)) { > + if (copy_to_user((void __user *)input.address, blob, input.length)) { > ret = -EFAULT; > goto e_shutdown; > } > > - if (copy_to_user((void __user *)(uintptr_t)argp->data, &input, > - sizeof(struct sev_user_data_pek_csr))) > + if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) > ret = -EFAULT; > > e_shutdown: > if (do_shutdown) > - sev_handle_cmd(SEV_CMD_SHUTDOWN, 0, NULL); > + ret = sev_do_cmd(SEV_CMD_SHUTDOWN, 0, NULL); > + > e_free_blob: > kfree(blob); > e_free: > @@ -408,10 +403,10 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) > ret = sev_ioctl_pdh_gen(&input); > break; > > - case SEV_PEK_CSR: { > + case SEV_PEK_CSR: > ret = sev_ioctl_pek_csr(&input); > break; > - } > + > default: > ret = -EINVAL; > goto out; >
On 10/12/17 9:24 PM, Brijesh Singh wrote: > > On 10/12/17 2:53 PM, Borislav Petkov wrote: > ... > >> Ok, a couple of things here: >> >> * Move the checks first and the allocations second so that you allocate >> memory only after all checks have been passed and you don't allocate >> pointlessly. > > I assume you mean performing the SEV state check before allocating the > memory for the CSR blob, right ? In my patches, I typically perform all > the SW specific checks and allocation before invoking the HW routines. > Handling the PSP commands will take longer compare to kmalloc() or > access_ok() etc. If its not a big deal then I would prefer to keep that > way. > > >> * That: >> >> if (state == SEV_STATE_WORKING) { >> ret = -EBUSY; >> goto e_free_blob; >> } else if (state == SEV_STATE_UNINIT) { >> ret = sev_firmware_init(&argp->error); >> if (ret) >> goto e_free_blob; >> do_shutdown = 1; >> } >> >> is a repeating pattern. Perhaps it should be called >> sev_firmware_reinit() and called by other functions. > >> * The rest is simplifications and streamlining. >> >> --- >> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c >> index e3ee68afd068..d41f5448a25b 100644 >> --- a/drivers/crypto/ccp/psp-dev.c >> +++ b/drivers/crypto/ccp/psp-dev.c >> @@ -302,33 +302,30 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp) >> int ret, state; >> void *blob; >> >> - if (copy_from_user(&input, (void __user *)(uintptr_t)argp->data, >> - sizeof(struct sev_user_data_pek_csr))) >> + if (copy_from_user(&input, (void __user *)argp->data, sizeof(input))) >> + return -EFAULT; >> + >> + if (!input.address) >> + return -EINVAL; >> + As per the spec, its perfectly legal to pass input.address = 0x0 and input.length = 0x0. If userspace wants to query CSR length then it will fill all the fields with. In response, FW will return error (LENGTH_TO_SMALL) and input.length will be filled with the expected length. Several command work very similar (e.g PEK_CSR, PEK_CERT_EXPORT). A typical usage from userspace will be: - query the length of the blob (call command with all fields set to zero) - SEV FW will response with expected length - userspace allocate the blob and retries the command. >> + /* allocate a physically contiguous buffer to store the CSR blob */ >> + if (!access_ok(VERIFY_WRITE, input.address, input.length) || >> + input.length > SEV_FW_BLOB_MAX_SIZE) >> return -EFAULT; >> >> data = kzalloc(sizeof(*data), GFP_KERNEL); >> if (!data) >> return -ENOMEM; >> >> - /* allocate a temporary physical contigous buffer to store the CSR blob */ >> - blob = NULL; >> - if (input.address) { >> - if (!access_ok(VERIFY_WRITE, input.address, input.length) || >> - input.length > SEV_FW_BLOB_MAX_SIZE) { >> - ret = -EFAULT; >> - goto e_free; >> - } >> - >> - blob = kmalloc(input.length, GFP_KERNEL); >> - if (!blob) { >> - ret = -ENOMEM; >> - goto e_free; >> - } >> - >> - data->address = __psp_pa(blob); >> - data->len = input.length; >> + blob = kmalloc(input.length, GFP_KERNEL); >> + if (!blob) { >> + ret = -ENOMEM; >> + goto e_free; >> } >> >> + data->address = __psp_pa(blob); >> + data->len = input.length; >> + >> ret = sev_platform_get_state(&state, &argp->error); >> if (ret) >> goto e_free_blob; >> @@ -349,25 +346,23 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp) >> do_shutdown = 1; >> } >> >> - ret = sev_handle_cmd(SEV_CMD_PEK_CSR, data, &argp->error); >> + ret = sev_do_cmd(SEV_CMD_PEK_CSR, data, &argp->error); >> >> input.length = data->len; >> >> /* copy blob to userspace */ >> - if (blob && >> - copy_to_user((void __user *)(uintptr_t)input.address, >> - blob, input.length)) { >> + if (copy_to_user((void __user *)input.address, blob, input.length)) { >> ret = -EFAULT; >> goto e_shutdown; >> } >> >> - if (copy_to_user((void __user *)(uintptr_t)argp->data, &input, >> - sizeof(struct sev_user_data_pek_csr))) >> + if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) >> ret = -EFAULT; >> >> e_shutdown: >> if (do_shutdown) >> - sev_handle_cmd(SEV_CMD_SHUTDOWN, 0, NULL); >> + ret = sev_do_cmd(SEV_CMD_SHUTDOWN, 0, NULL); >> + >> e_free_blob: >> kfree(blob); >> e_free: >> @@ -408,10 +403,10 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) >> ret = sev_ioctl_pdh_gen(&input); >> break; >> >> - case SEV_PEK_CSR: { >> + case SEV_PEK_CSR: >> ret = sev_ioctl_pek_csr(&input); >> break; >> - } >> + >> default: >> ret = -EINVAL; >> goto out; >>
On Thu, Oct 12, 2017 at 09:24:01PM -0500, Brijesh Singh wrote: > I assume you mean performing the SEV state check before allocating the > memory for the CSR blob, right ? I mean, do those first: if (copy_from_user(&input, (void __user *)argp->data, sizeof(input))) return -EFAULT; if (!input.address) return -EINVAL; /* allocate a physically contiguous buffer to store the CSR blob */ if (!access_ok(VERIFY_WRITE, input.address, input.length) || input.length > SEV_FW_BLOB_MAX_SIZE) return -EFAULT; Because if you allocate the memory first and some of those checks fail, you allocate in vain to free it immediately after. And you can save yourself all that.
diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c index e3ee68afd068..d41f5448a25b 100644 --- a/drivers/crypto/ccp/psp-dev.c +++ b/drivers/crypto/ccp/psp-dev.c @@ -302,33 +302,30 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp) int ret, state; void *blob; - if (copy_from_user(&input, (void __user *)(uintptr_t)argp->data, - sizeof(struct sev_user_data_pek_csr))) + if (copy_from_user(&input, (void __user *)argp->data, sizeof(input))) + return -EFAULT; + + if (!input.address) + return -EINVAL; + + /* allocate a physically contiguous buffer to store the CSR blob */ + if (!access_ok(VERIFY_WRITE, input.address, input.length) || + input.length > SEV_FW_BLOB_MAX_SIZE) return -EFAULT; data = kzalloc(sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; - /* allocate a temporary physical contigous buffer to store the CSR blob */ - blob = NULL; - if (input.address) { - if (!access_ok(VERIFY_WRITE, input.address, input.length) || - input.length > SEV_FW_BLOB_MAX_SIZE) { - ret = -EFAULT; - goto e_free; - } - - blob = kmalloc(input.length, GFP_KERNEL); - if (!blob) { - ret = -ENOMEM; - goto e_free; - } - - data->address = __psp_pa(blob); - data->len = input.length; + blob = kmalloc(input.length, GFP_KERNEL); + if (!blob) { + ret = -ENOMEM; + goto e_free; } + data->address = __psp_pa(blob); + data->len = input.length; + ret = sev_platform_get_state(&state, &argp->error); if (ret) goto e_free_blob; @@ -349,25 +346,23 @@ static int sev_ioctl_pek_csr(struct sev_issue_cmd *argp) do_shutdown = 1; } - ret = sev_handle_cmd(SEV_CMD_PEK_CSR, data, &argp->error); + ret = sev_do_cmd(SEV_CMD_PEK_CSR, data, &argp->error); input.length = data->len; /* copy blob to userspace */ - if (blob && - copy_to_user((void __user *)(uintptr_t)input.address, - blob, input.length)) { + if (copy_to_user((void __user *)input.address, blob, input.length)) { ret = -EFAULT; goto e_shutdown; } - if (copy_to_user((void __user *)(uintptr_t)argp->data, &input, - sizeof(struct sev_user_data_pek_csr))) + if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) ret = -EFAULT; e_shutdown: if (do_shutdown) - sev_handle_cmd(SEV_CMD_SHUTDOWN, 0, NULL); + ret = sev_do_cmd(SEV_CMD_SHUTDOWN, 0, NULL); + e_free_blob: kfree(blob); e_free: @@ -408,10 +403,10 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) ret = sev_ioctl_pdh_gen(&input); break; - case SEV_PEK_CSR: { + case SEV_PEK_CSR: ret = sev_ioctl_pek_csr(&input); break; - } + default: ret = -EINVAL; goto out;