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fix(driver/bpf): fixed a couple of verifier issues.
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Signed-off-by: Federico Di Pierro <[email protected]>
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@FedeDP
FedeDP committed Jun 5, 2024
1 parent c6ff3d0 commit ff2bbd6
Showing 1 changed file with 111 additions and 189 deletions.
300 changes: 111 additions & 189 deletions driver/bpf/fillers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -571,236 +571,158 @@ FILLER(sys_poll_x, true)
return bpf_poll_parse_fds(data, false);
}

#define MAX_IOVCNT 32
#define MAX_IOVCNT_COMPAT 8
#ifdef CONFIG_COMPAT
#define MAX_IOVCNT 8
#else
#define MAX_IOVCNT 32
#endif

static __always_inline int bpf_parse_readv_writev_bufs_64(struct filler_data *data,
static __always_inline int bpf_parse_readv_writev_bufs(struct filler_data *data,
const void __user *iovsrc,
unsigned long iovcnt,
long retval,
int flags,
unsigned long *size)
int flags)
{
const struct iovec *iov;
int res = PPM_SUCCESS;
unsigned long copylen;
long size = 0;
int j;
unsigned long iov_size = sizeof(struct iovec);
unsigned long len_off = offsetof(struct iovec, iov_len);
unsigned long base_off = offsetof(struct iovec, iov_base);
unsigned long ptr_size = sizeof(void *);

copylen = iovcnt * sizeof(struct iovec);
iov = (const struct iovec *)data->tmp_scratch;
#ifdef CONFIG_COMPAT
if (bpf_in_ia32_syscall())
{
iov_size = sizeof(struct compat_iovec);
len_off = offsetof(struct compat_iovec, iov_len);
base_off = offsetof(struct compat_iovec, iov_base);
ptr_size = 4;
}
#endif

copylen = iovcnt * iov_size;
if (copylen > SCRATCH_SIZE_MAX)
{
return PPM_FAILURE_FRAME_SCRATCH_MAP_FULL;
}

#ifdef BPF_FORBIDS_ZERO_ACCESS
if (copylen)
if (bpf_probe_read_user((void *)iov,
((copylen - 1) & SCRATCH_SIZE_MAX) + 1,
(void *)iovsrc))
if (copylen)
if (bpf_probe_read_user(data->tmp_scratch,
((copylen - 1) & SCRATCH_SIZE_MAX) + 1,
(void *)iovsrc))
#else
if (bpf_probe_read_user((void *)iov,
copylen & SCRATCH_SIZE_MAX,
(void *)iovsrc))
if (bpf_probe_read_user(data->tmp_scratch,
copylen & SCRATCH_SIZE_MAX,
(void *)iovsrc))
#endif
return PPM_FAILURE_INVALID_USER_MEMORY;

#pragma unroll

#pragma unroll
for (j = 0; j < MAX_IOVCNT; ++j) {
if (j == iovcnt)
break;
// BPF seems to require a hard limit to avoid overflows
if (*size == LONG_MAX)
if (size == LONG_MAX)
break;

*size += iov[j].iov_len;
volatile unsigned curr_shift = j * iov_size + len_off;
unsigned long shift_bounded = curr_shift & SCRATCH_SIZE_HALF;
if (curr_shift > SCRATCH_SIZE_HALF)
break;

long curr_len;
if (ptr_size == 4)
{
curr_len = *((int *)(((unsigned char *)data->tmp_scratch) + shift_bounded));
}
else
{
curr_len = *((long *)(((unsigned char *)data->tmp_scratch) + shift_bounded));
}
size += curr_len;
}

if ((flags & PRB_FLAG_IS_WRITE) == 0)
if (*size > retval)
*size = retval;
if (size > retval)
size = retval;

if (flags & PRB_FLAG_PUSH_SIZE && res == PPM_SUCCESS) {
res = bpf_push_u32_to_ring(data, (uint32_t)*size);
if (flags & PRB_FLAG_PUSH_SIZE) {
res = bpf_push_u32_to_ring(data, (uint32_t)size);
CHECK_RES(res);
}

if (flags & PRB_FLAG_PUSH_DATA) {
if (*size > 0) {
if (size > 0) {
unsigned long off = _READ(data->state->tail_ctx.curoff);
unsigned long remaining = *size;
int j;
unsigned long remaining = size;

#pragma unroll
#pragma unroll
for (j = 0; j < MAX_IOVCNT; ++j) {
volatile unsigned int to_read;

if (j == iovcnt)
break;

unsigned long off_bounded = off & SCRATCH_SIZE_HALF;
if (off > SCRATCH_SIZE_HALF)
break;

if (iov[j].iov_len <= remaining)
to_read = iov[j].iov_len;
volatile unsigned len_curr_shift = j * iov_size + len_off;
unsigned long len_shift_bounded = len_curr_shift & SCRATCH_SIZE_HALF;
if (len_curr_shift > SCRATCH_SIZE_HALF)
break;

long curr_len;
if (ptr_size == 4)
{
curr_len = *((int *)(((unsigned char *)data->tmp_scratch) + len_shift_bounded));
}
else
{
curr_len = *((long *)(((unsigned char *)data->tmp_scratch) + len_shift_bounded));
}
if (curr_len <= remaining)
to_read = curr_len;
else
to_read = remaining;

if (to_read > SCRATCH_SIZE_HALF)
to_read = SCRATCH_SIZE_HALF;

#ifdef BPF_FORBIDS_ZERO_ACCESS
if (to_read)
if (bpf_probe_read_user(&data->buf[off_bounded],
((to_read - 1) & SCRATCH_SIZE_HALF) + 1,
(void*)iov[j].iov_base))
#else
if (bpf_probe_read_user(&data->buf[off_bounded],
to_read & SCRATCH_SIZE_HALF,
(void*)iov[j].iov_base))
#endif
return PPM_FAILURE_INVALID_USER_MEMORY;

remaining -= to_read;
off += to_read;
}
} else {
*size = 0;
}
return PPM_SUCCESS;
}

return res;
}

#ifdef CONFIG_COMPAT
static __always_inline int bpf_parse_readv_writev_bufs_32(struct filler_data *data,
const void __user *iovsrc,
unsigned long iovcnt,
long retval,
int flags,
unsigned long *size)
{
const struct compat_iovec *compat_iov;
int res = PPM_SUCCESS;
unsigned long copylen;
int j;

copylen = iovcnt * sizeof(struct compat_iovec);
compat_iov = (const struct compat_iovec *)data->tmp_scratch;

if (copylen > SCRATCH_SIZE_MAX)
{
return PPM_FAILURE_FRAME_SCRATCH_MAP_FULL;
}

#ifdef BPF_FORBIDS_ZERO_ACCESS
if (copylen)
if (bpf_probe_read_user((void *)compat_iov,
((copylen - 1) & SCRATCH_SIZE_MAX) + 1,
(void *)iovsrc))
#else
if (bpf_probe_read_user((void *)compat_iov,
copylen & SCRATCH_SIZE_MAX,
(void *)iovsrc))
#endif
return PPM_FAILURE_INVALID_USER_MEMORY;

#pragma unroll
for (j = 0; j < MAX_IOVCNT_COMPAT; ++j) {
if (j == iovcnt)
break;
// BPF seems to require a hard limit to avoid overflows
if (*size == LONG_MAX)
break;

*size += compat_iov[j].iov_len;
}

if ((flags & PRB_FLAG_IS_WRITE) == 0)
if (*size > retval)
*size = retval;

if (flags & PRB_FLAG_PUSH_SIZE && res == PPM_SUCCESS) {
res = bpf_push_u32_to_ring(data, (uint32_t)*size);
CHECK_RES(res);
}

if (flags & PRB_FLAG_PUSH_DATA) {
if (*size > 0) {
unsigned long off = _READ(data->state->tail_ctx.curoff);
unsigned long remaining = *size;
int j;

// The 14 iovec count limit is due to old kernels verifiers
// complaining.
#pragma unroll
for (j = 0; j < MAX_IOVCNT_COMPAT; ++j) {
volatile unsigned int to_read;

if (j == iovcnt)
volatile unsigned base_curr_shift = j * iov_size + base_off;
unsigned long base_shift_bounded = base_curr_shift & SCRATCH_SIZE_HALF;
if (base_curr_shift > SCRATCH_SIZE_HALF)
break;

unsigned long off_bounded = off & SCRATCH_SIZE_HALF;
if (off > SCRATCH_SIZE_HALF)
break;

if (compat_iov[j].iov_len <= remaining)
to_read = compat_iov[j].iov_len;
unsigned long curr_base;
if (ptr_size == 4)
{
curr_base = *((unsigned int *)(((unsigned char *)data->tmp_scratch) + base_shift_bounded));
}
else
to_read = remaining;

if (to_read > SCRATCH_SIZE_HALF)
to_read = SCRATCH_SIZE_HALF;

#ifdef BPF_FORBIDS_ZERO_ACCESS
if (to_read)
if (bpf_probe_read_user(&data->buf[off_bounded],
((to_read - 1) & SCRATCH_SIZE_HALF) + 1,
(void*)compat_iov[j].iov_base))
#else
{
curr_base = *((unsigned long *)(((unsigned char *)data->tmp_scratch) + base_shift_bounded));
}
#ifdef BPF_FORBIDS_ZERO_ACCESS
if (to_read)
if (bpf_probe_read_user(&data->buf[off_bounded],
to_read & SCRATCH_SIZE_HALF,
(void*)compat_iov[j].iov_base))
#endif
((to_read - 1) & SCRATCH_SIZE_HALF) + 1,
(void *)curr_base))
#else
if (bpf_probe_read_user(&data->buf[off_bounded],
to_read & SCRATCH_SIZE_HALF,
(void *)curr_base))
#endif
return PPM_FAILURE_INVALID_USER_MEMORY;

remaining -= to_read;
off += to_read;
}
} else {
*size = 0;
size = 0;
}

return PPM_SUCCESS;
}
return res;
}
#endif

static __always_inline int bpf_parse_readv_writev_bufs(struct filler_data *data,
const void __user *iovsrc,
unsigned long iovcnt,
long retval,
int flags)
{
unsigned long size = 0;
int res = PPM_SUCCESS;
if (!bpf_in_ia32_syscall())
{
res = bpf_parse_readv_writev_bufs_64(data, iovsrc, iovcnt, retval, flags, &size);
}
else
{
#ifdef CONFIG_COMPAT
res = bpf_parse_readv_writev_bufs_32(data, iovsrc, iovcnt, retval, flags, &size);
#endif
}

if(flags & PRB_FLAG_PUSH_DATA && res == PPM_SUCCESS)
{
data->fd = bpf_syscall_get_argument(data, 0);
data->curarg_already_on_frame = true;
return __bpf_val_to_ring(data, 0, size, PT_BYTEBUF, -1, true, KERNEL);
Expand Down Expand Up @@ -4312,10 +4234,12 @@ FILLER(sys_recvfrom_x, true)
unsigned long val;
uint16_t size = 0;
long retval;
int addrlen;
int addrlen = 0;
int err = 0;
int res;
int fd;
bool push = true;
bool from_usr = false;

/*
* Push the common params to the ring
Expand All @@ -4324,6 +4248,7 @@ FILLER(sys_recvfrom_x, true)
res = f_sys_recv_x_common(data, retval);
CHECK_RES(res);


if (retval >= 0) {
/*
* Get the fd
Expand All @@ -4350,29 +4275,26 @@ FILLER(sys_recvfrom_x, true)
*/
err = bpf_addr_to_kernel(usrsockaddr, addrlen,
(struct sockaddr *)data->tmp_scratch);
if (err >= 0) {
if (err >= 0)
{
/*
* Convert the fd into socket endpoint information
* Convert the fd into socket endpoint information
*/
size = bpf_fd_to_socktuple(data,
fd,
(struct sockaddr *)data->tmp_scratch,
addrlen,
true,
true,
data->tmp_scratch + sizeof(struct sockaddr_storage));
from_usr = true;
}
} else {
else
{
// Do not send any socket endpoint info.
push = false;
}
}
if (push)
{
/*
* Get socket endpoint information from fd if the user-provided *sockaddr is NULL
*/
size = bpf_fd_to_socktuple(data,
fd,
NULL,
0,
false,
true,
data->tmp_scratch + sizeof(struct sockaddr_storage));
* Get socket endpoint information from fd if the user-provided *sockaddr is NULL
*/
size = bpf_fd_to_socktuple(data, fd, (struct sockaddr *)data->tmp_scratch, addrlen, from_usr,
true, data->tmp_scratch + sizeof(struct sockaddr_storage));
}
}

Expand Down

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