| Message ID | 20231030063652.68675-6-nikunj@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add Secure TSC support for SNP guests | expand |
On Sun, Oct 29, 2023 at 11:38 PM Nikunj A Dadhania <nikunj@amd.com> wrote: > > Drop vmpck and os_area_msg_seqno pointers so that secret page layout > does not need to be exposed to the sev-guest driver after the rework. > Instead, add helper APIs to access vmpck and os_area_msg_seqno when > needed. > > Also, change function is_vmpck_empty() to snp_is_vmpck_empty() in > preparation for moving to sev.c. > > Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> > --- > drivers/virt/coco/sev-guest/sev-guest.c | 85 ++++++++++++------------- > 1 file changed, 42 insertions(+), 43 deletions(-) > > diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c > index 5801dd52ffdf..4dd094c73e2f 100644 > --- a/drivers/virt/coco/sev-guest/sev-guest.c > +++ b/drivers/virt/coco/sev-guest/sev-guest.c > @@ -50,8 +50,7 @@ struct snp_guest_dev { > > struct snp_secrets_page_layout *layout; > struct snp_req_data input; > - u32 *os_area_msg_seqno; > - u8 *vmpck; > + unsigned int vmpck_id; > }; > > static u32 vmpck_id; > @@ -61,14 +60,22 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. > /* Mutex to serialize the shared buffer access and command handling. */ > static DEFINE_MUTEX(snp_cmd_mutex); > > -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) > +static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev) > { > - char zero_key[VMPCK_KEY_LEN] = {0}; > + return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN; > +} > > - if (snp_dev->vmpck) > - return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN); > +static inline u32 *snp_get_os_area_msg_seqno(struct snp_guest_dev *snp_dev) > +{ > + return &snp_dev->layout->os_area.msg_seqno_0 + snp_dev->vmpck_id; > +} > > - return true; > +static bool snp_is_vmpck_empty(struct snp_guest_dev *snp_dev) > +{ > + char zero_key[VMPCK_KEY_LEN] = {0}; > + u8 *key = snp_get_vmpck(snp_dev); > + > + return !memcmp(key, zero_key, VMPCK_KEY_LEN); > } > > /* > @@ -90,20 +97,22 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) > */ > static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) > { > + u8 *key = snp_get_vmpck(snp_dev); > + > dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", > - vmpck_id); > - memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); > - snp_dev->vmpck = NULL; > + snp_dev->vmpck_id); > + memzero_explicit(key, VMPCK_KEY_LEN); > } We disable the VMPCK because we believe the guest to be under attack, but this only clears a single key. Shouldn't we clear all VMPCK keys in the secrets page for good measure? If at VMPCK > 0, most likely the 0..VMPCK-1 keys have been zeroed by whatever was prior in the boot stack, but still better to be safe. > > static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) > { > + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); > u64 count; > > lockdep_assert_held(&snp_dev->cmd_mutex); > > /* Read the current message sequence counter from secrets pages */ > - count = *snp_dev->os_area_msg_seqno; > + count = *os_area_msg_seqno; > > return count + 1; > } > @@ -131,11 +140,13 @@ static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) > > static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) > { > + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); > + > /* > * The counter is also incremented by the PSP, so increment it by 2 > * and save in secrets page. > */ > - *snp_dev->os_area_msg_seqno += 2; > + *os_area_msg_seqno += 2; > } > > static inline struct snp_guest_dev *to_snp_dev(struct file *file) > @@ -145,15 +156,22 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) > return container_of(dev, struct snp_guest_dev, misc); > } > > -static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) > +static struct aesgcm_ctx *snp_init_crypto(struct snp_guest_dev *snp_dev) > { > struct aesgcm_ctx *ctx; > + u8 *key; > + > + if (snp_is_vmpck_empty(snp_dev)) { > + pr_err("SNP: vmpck id %d is null\n", snp_dev->vmpck_id); > + return NULL; > + } > > ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); > if (!ctx) > return NULL; > > - if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { > + key = snp_get_vmpck(snp_dev); > + if (aesgcm_expandkey(ctx, key, VMPCK_KEY_LEN, AUTHTAG_LEN)) { > pr_err("SNP: crypto init failed\n"); > kfree(ctx); > return NULL; > @@ -586,7 +604,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long > mutex_lock(&snp_dev->cmd_mutex); > > /* Check if the VMPCK is not empty */ > - if (is_vmpck_empty(snp_dev)) { > + if (snp_is_vmpck_empty(snp_dev)) { > dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); > mutex_unlock(&snp_dev->cmd_mutex); > return -ENOTTY; > @@ -656,32 +674,14 @@ static const struct file_operations snp_guest_fops = { > .unlocked_ioctl = snp_guest_ioctl, > }; > > -static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) > +bool snp_assign_vmpck(struct snp_guest_dev *dev, int vmpck_id) > { > - u8 *key = NULL; > + if (WARN_ON(vmpck_id > 3)) > + return false; The vmpck_id is an int for some reason, so < 0 is also a problem. Can we not use unsigned int? > > - switch (id) { > - case 0: > - *seqno = &layout->os_area.msg_seqno_0; > - key = layout->vmpck0; > - break; > - case 1: > - *seqno = &layout->os_area.msg_seqno_1; > - key = layout->vmpck1; > - break; > - case 2: > - *seqno = &layout->os_area.msg_seqno_2; > - key = layout->vmpck2; > - break; > - case 3: > - *seqno = &layout->os_area.msg_seqno_3; > - key = layout->vmpck3; > - break; > - default: > - break; > - } > + dev->vmpck_id = vmpck_id; > > - return key; > + return true; > } > > static int __init sev_guest_probe(struct platform_device *pdev) > @@ -713,14 +713,14 @@ static int __init sev_guest_probe(struct platform_device *pdev) > goto e_unmap; > > ret = -EINVAL; > - snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno); > - if (!snp_dev->vmpck) { > + snp_dev->layout = layout; > + if (!snp_assign_vmpck(snp_dev, vmpck_id)) { > dev_err(dev, "invalid vmpck id %d\n", vmpck_id); > goto e_unmap; > } > > /* Verify that VMPCK is not zero. */ > - if (is_vmpck_empty(snp_dev)) { > + if (snp_is_vmpck_empty(snp_dev)) { > dev_err(dev, "vmpck id %d is null\n", vmpck_id); > goto e_unmap; > } > @@ -728,7 +728,6 @@ static int __init sev_guest_probe(struct platform_device *pdev) > mutex_init(&snp_dev->cmd_mutex); > platform_set_drvdata(pdev, snp_dev); > snp_dev->dev = dev; > - snp_dev->layout = layout; > > /* Allocate the shared page used for the request and response message. */ > snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); > @@ -744,7 +743,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) > goto e_free_response; > > ret = -EIO; > - snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN); > + snp_dev->ctx = snp_init_crypto(snp_dev); > if (!snp_dev->ctx) > goto e_free_cert_data; > > -- > 2.34.1 >
On 10/30/23 11:16, Dionna Amalie Glaze wrote: > On Sun, Oct 29, 2023 at 11:38 PM Nikunj A Dadhania <nikunj@amd.com> wrote: >> >> Drop vmpck and os_area_msg_seqno pointers so that secret page layout >> does not need to be exposed to the sev-guest driver after the rework. >> Instead, add helper APIs to access vmpck and os_area_msg_seqno when >> needed. >> >> Also, change function is_vmpck_empty() to snp_is_vmpck_empty() in >> preparation for moving to sev.c. >> >> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> >> --- >> drivers/virt/coco/sev-guest/sev-guest.c | 85 ++++++++++++------------- >> 1 file changed, 42 insertions(+), 43 deletions(-) >> >> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c >> index 5801dd52ffdf..4dd094c73e2f 100644 >> --- a/drivers/virt/coco/sev-guest/sev-guest.c >> +++ b/drivers/virt/coco/sev-guest/sev-guest.c >> @@ -50,8 +50,7 @@ struct snp_guest_dev { >> >> struct snp_secrets_page_layout *layout; >> struct snp_req_data input; >> - u32 *os_area_msg_seqno; >> - u8 *vmpck; >> + unsigned int vmpck_id; >> }; >> >> static u32 vmpck_id; >> @@ -61,14 +60,22 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. >> /* Mutex to serialize the shared buffer access and command handling. */ >> static DEFINE_MUTEX(snp_cmd_mutex); >> >> -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) >> +static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev) >> { >> - char zero_key[VMPCK_KEY_LEN] = {0}; >> + return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN; >> +} >> >> - if (snp_dev->vmpck) >> - return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN); >> +static inline u32 *snp_get_os_area_msg_seqno(struct snp_guest_dev *snp_dev) >> +{ >> + return &snp_dev->layout->os_area.msg_seqno_0 + snp_dev->vmpck_id; >> +} >> >> - return true; >> +static bool snp_is_vmpck_empty(struct snp_guest_dev *snp_dev) >> +{ >> + char zero_key[VMPCK_KEY_LEN] = {0}; >> + u8 *key = snp_get_vmpck(snp_dev); >> + >> + return !memcmp(key, zero_key, VMPCK_KEY_LEN); >> } >> >> /* >> @@ -90,20 +97,22 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) >> */ >> static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) >> { >> + u8 *key = snp_get_vmpck(snp_dev); >> + >> dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", >> - vmpck_id); >> - memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); >> - snp_dev->vmpck = NULL; >> + snp_dev->vmpck_id); >> + memzero_explicit(key, VMPCK_KEY_LEN); >> } > > We disable the VMPCK because we believe the guest to be under attack, > but this only clears a single key. Shouldn't we clear all VMPCK keys > in the secrets page for good measure? If at VMPCK > 0, most likely the > 0..VMPCK-1 keys have been zeroed by whatever was prior in the boot > stack, but still better to be safe. Doing that would be a separate patch series and isn't appropriate here. Thanks, Tom > >> >> static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) >> { >> + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); >> u64 count; >> >> lockdep_assert_held(&snp_dev->cmd_mutex); >> >> /* Read the current message sequence counter from secrets pages */ >> - count = *snp_dev->os_area_msg_seqno; >> + count = *os_area_msg_seqno; >> >> return count + 1; >> } >> @@ -131,11 +140,13 @@ static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) >> >> static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) >> { >> + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); >> + >> /* >> * The counter is also incremented by the PSP, so increment it by 2 >> * and save in secrets page. >> */ >> - *snp_dev->os_area_msg_seqno += 2; >> + *os_area_msg_seqno += 2; >> } >> >> static inline struct snp_guest_dev *to_snp_dev(struct file *file) >> @@ -145,15 +156,22 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) >> return container_of(dev, struct snp_guest_dev, misc); >> } >> >> -static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) >> +static struct aesgcm_ctx *snp_init_crypto(struct snp_guest_dev *snp_dev) >> { >> struct aesgcm_ctx *ctx; >> + u8 *key; >> + >> + if (snp_is_vmpck_empty(snp_dev)) { >> + pr_err("SNP: vmpck id %d is null\n", snp_dev->vmpck_id); >> + return NULL; >> + } >> >> ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); >> if (!ctx) >> return NULL; >> >> - if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { >> + key = snp_get_vmpck(snp_dev); >> + if (aesgcm_expandkey(ctx, key, VMPCK_KEY_LEN, AUTHTAG_LEN)) { >> pr_err("SNP: crypto init failed\n"); >> kfree(ctx); >> return NULL; >> @@ -586,7 +604,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long >> mutex_lock(&snp_dev->cmd_mutex); >> >> /* Check if the VMPCK is not empty */ >> - if (is_vmpck_empty(snp_dev)) { >> + if (snp_is_vmpck_empty(snp_dev)) { >> dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); >> mutex_unlock(&snp_dev->cmd_mutex); >> return -ENOTTY; >> @@ -656,32 +674,14 @@ static const struct file_operations snp_guest_fops = { >> .unlocked_ioctl = snp_guest_ioctl, >> }; >> >> -static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) >> +bool snp_assign_vmpck(struct snp_guest_dev *dev, int vmpck_id) >> { >> - u8 *key = NULL; >> + if (WARN_ON(vmpck_id > 3)) >> + return false; > > The vmpck_id is an int for some reason, so < 0 is also a problem. Can > we not use unsigned int? > >> >> - switch (id) { >> - case 0: >> - *seqno = &layout->os_area.msg_seqno_0; >> - key = layout->vmpck0; >> - break; >> - case 1: >> - *seqno = &layout->os_area.msg_seqno_1; >> - key = layout->vmpck1; >> - break; >> - case 2: >> - *seqno = &layout->os_area.msg_seqno_2; >> - key = layout->vmpck2; >> - break; >> - case 3: >> - *seqno = &layout->os_area.msg_seqno_3; >> - key = layout->vmpck3; >> - break; >> - default: >> - break; >> - } >> + dev->vmpck_id = vmpck_id; >> >> - return key; >> + return true; >> } >> >> static int __init sev_guest_probe(struct platform_device *pdev) >> @@ -713,14 +713,14 @@ static int __init sev_guest_probe(struct platform_device *pdev) >> goto e_unmap; >> >> ret = -EINVAL; >> - snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno); >> - if (!snp_dev->vmpck) { >> + snp_dev->layout = layout; >> + if (!snp_assign_vmpck(snp_dev, vmpck_id)) { >> dev_err(dev, "invalid vmpck id %d\n", vmpck_id); >> goto e_unmap; >> } >> >> /* Verify that VMPCK is not zero. */ >> - if (is_vmpck_empty(snp_dev)) { >> + if (snp_is_vmpck_empty(snp_dev)) { >> dev_err(dev, "vmpck id %d is null\n", vmpck_id); >> goto e_unmap; >> } >> @@ -728,7 +728,6 @@ static int __init sev_guest_probe(struct platform_device *pdev) >> mutex_init(&snp_dev->cmd_mutex); >> platform_set_drvdata(pdev, snp_dev); >> snp_dev->dev = dev; >> - snp_dev->layout = layout; >> >> /* Allocate the shared page used for the request and response message. */ >> snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); >> @@ -744,7 +743,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) >> goto e_free_response; >> >> ret = -EIO; >> - snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN); >> + snp_dev->ctx = snp_init_crypto(snp_dev); >> if (!snp_dev->ctx) >> goto e_free_cert_data; >> >> -- >> 2.34.1 >> > >
On 10/30/23 01:36, Nikunj A Dadhania wrote: > Drop vmpck and os_area_msg_seqno pointers so that secret page layout > does not need to be exposed to the sev-guest driver after the rework. > Instead, add helper APIs to access vmpck and os_area_msg_seqno when > needed. > > Also, change function is_vmpck_empty() to snp_is_vmpck_empty() in > preparation for moving to sev.c. > > Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> With the fix to the snp_assign_vmpck() to change the int to an unsigned int as requested by Dionna... Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> > --- > drivers/virt/coco/sev-guest/sev-guest.c | 85 ++++++++++++------------- > 1 file changed, 42 insertions(+), 43 deletions(-) > > diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c > index 5801dd52ffdf..4dd094c73e2f 100644 > --- a/drivers/virt/coco/sev-guest/sev-guest.c > +++ b/drivers/virt/coco/sev-guest/sev-guest.c > @@ -50,8 +50,7 @@ struct snp_guest_dev { > > struct snp_secrets_page_layout *layout; > struct snp_req_data input; > - u32 *os_area_msg_seqno; > - u8 *vmpck; > + unsigned int vmpck_id; > }; > > static u32 vmpck_id; > @@ -61,14 +60,22 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. > /* Mutex to serialize the shared buffer access and command handling. */ > static DEFINE_MUTEX(snp_cmd_mutex); > > -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) > +static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev) > { > - char zero_key[VMPCK_KEY_LEN] = {0}; > + return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN; > +} > > - if (snp_dev->vmpck) > - return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN); > +static inline u32 *snp_get_os_area_msg_seqno(struct snp_guest_dev *snp_dev) > +{ > + return &snp_dev->layout->os_area.msg_seqno_0 + snp_dev->vmpck_id; > +} > > - return true; > +static bool snp_is_vmpck_empty(struct snp_guest_dev *snp_dev) > +{ > + char zero_key[VMPCK_KEY_LEN] = {0}; > + u8 *key = snp_get_vmpck(snp_dev); > + > + return !memcmp(key, zero_key, VMPCK_KEY_LEN); > } > > /* > @@ -90,20 +97,22 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) > */ > static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) > { > + u8 *key = snp_get_vmpck(snp_dev); > + > dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", > - vmpck_id); > - memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); > - snp_dev->vmpck = NULL; > + snp_dev->vmpck_id); > + memzero_explicit(key, VMPCK_KEY_LEN); > } > > static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) > { > + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); > u64 count; > > lockdep_assert_held(&snp_dev->cmd_mutex); > > /* Read the current message sequence counter from secrets pages */ > - count = *snp_dev->os_area_msg_seqno; > + count = *os_area_msg_seqno; > > return count + 1; > } > @@ -131,11 +140,13 @@ static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) > > static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) > { > + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); > + > /* > * The counter is also incremented by the PSP, so increment it by 2 > * and save in secrets page. > */ > - *snp_dev->os_area_msg_seqno += 2; > + *os_area_msg_seqno += 2; > } > > static inline struct snp_guest_dev *to_snp_dev(struct file *file) > @@ -145,15 +156,22 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) > return container_of(dev, struct snp_guest_dev, misc); > } > > -static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) > +static struct aesgcm_ctx *snp_init_crypto(struct snp_guest_dev *snp_dev) > { > struct aesgcm_ctx *ctx; > + u8 *key; > + > + if (snp_is_vmpck_empty(snp_dev)) { > + pr_err("SNP: vmpck id %d is null\n", snp_dev->vmpck_id); > + return NULL; > + } > > ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); > if (!ctx) > return NULL; > > - if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { > + key = snp_get_vmpck(snp_dev); > + if (aesgcm_expandkey(ctx, key, VMPCK_KEY_LEN, AUTHTAG_LEN)) { > pr_err("SNP: crypto init failed\n"); > kfree(ctx); > return NULL; > @@ -586,7 +604,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long > mutex_lock(&snp_dev->cmd_mutex); > > /* Check if the VMPCK is not empty */ > - if (is_vmpck_empty(snp_dev)) { > + if (snp_is_vmpck_empty(snp_dev)) { > dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); > mutex_unlock(&snp_dev->cmd_mutex); > return -ENOTTY; > @@ -656,32 +674,14 @@ static const struct file_operations snp_guest_fops = { > .unlocked_ioctl = snp_guest_ioctl, > }; > > -static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) > +bool snp_assign_vmpck(struct snp_guest_dev *dev, int vmpck_id) > { > - u8 *key = NULL; > + if (WARN_ON(vmpck_id > 3)) > + return false; > > - switch (id) { > - case 0: > - *seqno = &layout->os_area.msg_seqno_0; > - key = layout->vmpck0; > - break; > - case 1: > - *seqno = &layout->os_area.msg_seqno_1; > - key = layout->vmpck1; > - break; > - case 2: > - *seqno = &layout->os_area.msg_seqno_2; > - key = layout->vmpck2; > - break; > - case 3: > - *seqno = &layout->os_area.msg_seqno_3; > - key = layout->vmpck3; > - break; > - default: > - break; > - } > + dev->vmpck_id = vmpck_id; > > - return key; > + return true; > } > > static int __init sev_guest_probe(struct platform_device *pdev) > @@ -713,14 +713,14 @@ static int __init sev_guest_probe(struct platform_device *pdev) > goto e_unmap; > > ret = -EINVAL; > - snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno); > - if (!snp_dev->vmpck) { > + snp_dev->layout = layout; > + if (!snp_assign_vmpck(snp_dev, vmpck_id)) { > dev_err(dev, "invalid vmpck id %d\n", vmpck_id); > goto e_unmap; > } > > /* Verify that VMPCK is not zero. */ > - if (is_vmpck_empty(snp_dev)) { > + if (snp_is_vmpck_empty(snp_dev)) { > dev_err(dev, "vmpck id %d is null\n", vmpck_id); > goto e_unmap; > } > @@ -728,7 +728,6 @@ static int __init sev_guest_probe(struct platform_device *pdev) > mutex_init(&snp_dev->cmd_mutex); > platform_set_drvdata(pdev, snp_dev); > snp_dev->dev = dev; > - snp_dev->layout = layout; > > /* Allocate the shared page used for the request and response message. */ > snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); > @@ -744,7 +743,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) > goto e_free_response; > > ret = -EIO; > - snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN); > + snp_dev->ctx = snp_init_crypto(snp_dev); > if (!snp_dev->ctx) > goto e_free_cert_data; >
On 10/30/2023 10:42 PM, Tom Lendacky wrote: > On 10/30/23 11:16, Dionna Amalie Glaze wrote: >> On Sun, Oct 29, 2023 at 11:38 PM Nikunj A Dadhania <nikunj@amd.com> wrote: >>> @@ -656,32 +674,14 @@ static const struct file_operations snp_guest_fops = { >>> .unlocked_ioctl = snp_guest_ioctl, >>> }; >>> >>> -static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) >>> +bool snp_assign_vmpck(struct snp_guest_dev *dev, int vmpck_id) >>> { >>> - u8 *key = NULL; >>> + if (WARN_ON(vmpck_id > 3)) >>> + return false; >> >> The vmpck_id is an int for some reason, so < 0 is also a problem. Can >> we not use unsigned int? Yes, I will update that in my next revision, Thanks Nikunj
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 5801dd52ffdf..4dd094c73e2f 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -50,8 +50,7 @@ struct snp_guest_dev { struct snp_secrets_page_layout *layout; struct snp_req_data input; - u32 *os_area_msg_seqno; - u8 *vmpck; + unsigned int vmpck_id; }; static u32 vmpck_id; @@ -61,14 +60,22 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. /* Mutex to serialize the shared buffer access and command handling. */ static DEFINE_MUTEX(snp_cmd_mutex); -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) +static inline u8 *snp_get_vmpck(struct snp_guest_dev *snp_dev) { - char zero_key[VMPCK_KEY_LEN] = {0}; + return snp_dev->layout->vmpck0 + snp_dev->vmpck_id * VMPCK_KEY_LEN; +} - if (snp_dev->vmpck) - return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN); +static inline u32 *snp_get_os_area_msg_seqno(struct snp_guest_dev *snp_dev) +{ + return &snp_dev->layout->os_area.msg_seqno_0 + snp_dev->vmpck_id; +} - return true; +static bool snp_is_vmpck_empty(struct snp_guest_dev *snp_dev) +{ + char zero_key[VMPCK_KEY_LEN] = {0}; + u8 *key = snp_get_vmpck(snp_dev); + + return !memcmp(key, zero_key, VMPCK_KEY_LEN); } /* @@ -90,20 +97,22 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) */ static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) { + u8 *key = snp_get_vmpck(snp_dev); + dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", - vmpck_id); - memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); - snp_dev->vmpck = NULL; + snp_dev->vmpck_id); + memzero_explicit(key, VMPCK_KEY_LEN); } static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) { + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); u64 count; lockdep_assert_held(&snp_dev->cmd_mutex); /* Read the current message sequence counter from secrets pages */ - count = *snp_dev->os_area_msg_seqno; + count = *os_area_msg_seqno; return count + 1; } @@ -131,11 +140,13 @@ static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) { + u32 *os_area_msg_seqno = snp_get_os_area_msg_seqno(snp_dev); + /* * The counter is also incremented by the PSP, so increment it by 2 * and save in secrets page. */ - *snp_dev->os_area_msg_seqno += 2; + *os_area_msg_seqno += 2; } static inline struct snp_guest_dev *to_snp_dev(struct file *file) @@ -145,15 +156,22 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) return container_of(dev, struct snp_guest_dev, misc); } -static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) +static struct aesgcm_ctx *snp_init_crypto(struct snp_guest_dev *snp_dev) { struct aesgcm_ctx *ctx; + u8 *key; + + if (snp_is_vmpck_empty(snp_dev)) { + pr_err("SNP: vmpck id %d is null\n", snp_dev->vmpck_id); + return NULL; + } ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); if (!ctx) return NULL; - if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { + key = snp_get_vmpck(snp_dev); + if (aesgcm_expandkey(ctx, key, VMPCK_KEY_LEN, AUTHTAG_LEN)) { pr_err("SNP: crypto init failed\n"); kfree(ctx); return NULL; @@ -586,7 +604,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long mutex_lock(&snp_dev->cmd_mutex); /* Check if the VMPCK is not empty */ - if (is_vmpck_empty(snp_dev)) { + if (snp_is_vmpck_empty(snp_dev)) { dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); mutex_unlock(&snp_dev->cmd_mutex); return -ENOTTY; @@ -656,32 +674,14 @@ static const struct file_operations snp_guest_fops = { .unlocked_ioctl = snp_guest_ioctl, }; -static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno) +bool snp_assign_vmpck(struct snp_guest_dev *dev, int vmpck_id) { - u8 *key = NULL; + if (WARN_ON(vmpck_id > 3)) + return false; - switch (id) { - case 0: - *seqno = &layout->os_area.msg_seqno_0; - key = layout->vmpck0; - break; - case 1: - *seqno = &layout->os_area.msg_seqno_1; - key = layout->vmpck1; - break; - case 2: - *seqno = &layout->os_area.msg_seqno_2; - key = layout->vmpck2; - break; - case 3: - *seqno = &layout->os_area.msg_seqno_3; - key = layout->vmpck3; - break; - default: - break; - } + dev->vmpck_id = vmpck_id; - return key; + return true; } static int __init sev_guest_probe(struct platform_device *pdev) @@ -713,14 +713,14 @@ static int __init sev_guest_probe(struct platform_device *pdev) goto e_unmap; ret = -EINVAL; - snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno); - if (!snp_dev->vmpck) { + snp_dev->layout = layout; + if (!snp_assign_vmpck(snp_dev, vmpck_id)) { dev_err(dev, "invalid vmpck id %d\n", vmpck_id); goto e_unmap; } /* Verify that VMPCK is not zero. */ - if (is_vmpck_empty(snp_dev)) { + if (snp_is_vmpck_empty(snp_dev)) { dev_err(dev, "vmpck id %d is null\n", vmpck_id); goto e_unmap; } @@ -728,7 +728,6 @@ static int __init sev_guest_probe(struct platform_device *pdev) mutex_init(&snp_dev->cmd_mutex); platform_set_drvdata(pdev, snp_dev); snp_dev->dev = dev; - snp_dev->layout = layout; /* Allocate the shared page used for the request and response message. */ snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); @@ -744,7 +743,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) goto e_free_response; ret = -EIO; - snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN); + snp_dev->ctx = snp_init_crypto(snp_dev); if (!snp_dev->ctx) goto e_free_cert_data;
Drop vmpck and os_area_msg_seqno pointers so that secret page layout does not need to be exposed to the sev-guest driver after the rework. Instead, add helper APIs to access vmpck and os_area_msg_seqno when needed. Also, change function is_vmpck_empty() to snp_is_vmpck_empty() in preparation for moving to sev.c. Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> --- drivers/virt/coco/sev-guest/sev-guest.c | 85 ++++++++++++------------- 1 file changed, 42 insertions(+), 43 deletions(-)