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fix(driver): fix bpf probe verifier on linux 5.14 and llvm 12.0.1 #81

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merged 6 commits into from
Sep 22, 2021
Merged

fix(driver): fix bpf probe verifier on linux 5.14 and llvm 12.0.1 #81

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32409be
fix(driver): fix bpf probe verifier for bpf_poll_parse_fds() and bpf_…
FedeDP Sep 13, 2021
6ac9d9d
Update driver/bpf/fillers.h
FedeDP Sep 14, 2021
0761f46
fix(driver/bpf): fix verifier issues in latest clang versions
jasondellaluce Sep 16, 2021
9edc706
fix(driver/bpf): fixing typos
jasondellaluce Sep 16, 2021
e7c194e
Trim some useless whitespaces
FedeDP Sep 16, 2021
1095bf3
fix(driver/bpf): enhance support to older kernels
jasondellaluce Sep 17, 2021
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39 changes: 21 additions & 18 deletions driver/bpf/filler_helpers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -719,17 +719,20 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
{
unsigned int len_dyn = 0;
unsigned int len;
unsigned long curoff_bounded;

curoff_bounded = data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF;
if (data->state->tail_ctx.curoff > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

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if (dyn_idx != (u8)-1) {
*((u8 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = dyn_idx;
*((u8 *)&data->buf[curoff_bounded]) = dyn_idx;
len_dyn = sizeof(u8);
data->state->tail_ctx.curoff += len_dyn;
data->state->tail_ctx.len += len_dyn;
}

curoff_bounded = data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF;
if (data->state->tail_ctx.curoff > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

Expand All @@ -740,7 +743,7 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
if (!data->curarg_already_on_frame) {
int res;

res = bpf_probe_read_str(&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF],
res = bpf_probe_read_str(&data->buf[curoff_bounded],
PPM_MAX_ARG_SIZE,
(const void *)val);
if (res == -EFAULT)
Expand All @@ -763,15 +766,15 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
dpi_lookahead_size = len;

if (!data->curarg_already_on_frame) {
volatile unsigned long read_size = dpi_lookahead_size;
volatile u16 read_size = dpi_lookahead_size;

#ifdef BPF_FORBIDS_ZERO_ACCESS
if (read_size)
if (bpf_probe_read(&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF],
if (bpf_probe_read(&data->buf[curoff_bounded],
((read_size - 1) & SCRATCH_SIZE_HALF) + 1,
(void *)val))
#else
if (bpf_probe_read(&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF],
if (bpf_probe_read(&data->buf[curoff_bounded],
read_size & SCRATCH_SIZE_HALF,
(void *)val))
#endif
Expand All @@ -787,15 +790,15 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
len = PPM_MAX_ARG_SIZE;

if (!data->curarg_already_on_frame) {
volatile unsigned long read_size = len;
volatile u16 read_size = len;

#ifdef BPF_FORBIDS_ZERO_ACCESS
if (read_size)
if (bpf_probe_read(&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF],
if (bpf_probe_read(&data->buf[curoff_bounded],
((read_size - 1) & SCRATCH_SIZE_HALF) + 1,
(void *)val))
#else
if (bpf_probe_read(&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF],
if (bpf_probe_read(&data->buf[curoff_bounded],
read_size & SCRATCH_SIZE_HALF,
(void *)val))
#endif
Expand All @@ -821,13 +824,13 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
case PT_FLAGS8:
case PT_UINT8:
case PT_SIGTYPE:
*((u8 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((u8 *)&data->buf[curoff_bounded]) = val;
len = sizeof(u8);
break;
case PT_FLAGS16:
case PT_UINT16:
case PT_SYSCALLID:
*((u16 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((u16 *)&data->buf[curoff_bounded]) = val;
len = sizeof(u16);
break;
case PT_FLAGS32:
Expand All @@ -836,32 +839,32 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
case PT_UID:
case PT_GID:
case PT_SIGSET:
*((u32 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((u32 *)&data->buf[curoff_bounded]) = val;
len = sizeof(u32);
break;
case PT_RELTIME:
case PT_ABSTIME:
case PT_UINT64:
*((u64 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((u64 *)&data->buf[curoff_bounded]) = val;
len = sizeof(u64);
break;
case PT_INT8:
*((s8 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((s8 *)&data->buf[curoff_bounded]) = val;
len = sizeof(s8);
break;
case PT_INT16:
*((s16 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((s16 *)&data->buf[curoff_bounded]) = val;
len = sizeof(s16);
break;
case PT_INT32:
*((s32 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((s32 *)&data->buf[curoff_bounded]) = val;
len = sizeof(s32);
break;
case PT_INT64:
case PT_ERRNO:
case PT_FD:
case PT_PID:
*((s64 *)&data->buf[data->state->tail_ctx.curoff & SCRATCH_SIZE_HALF]) = val;
*((s64 *)&data->buf[curoff_bounded]) = val;
len = sizeof(s64);
break;
default: {
Expand All @@ -871,7 +874,7 @@ static __always_inline int __bpf_val_to_ring(struct filler_data *data,
return PPM_FAILURE_BUG;
}
}

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if (len_dyn + len > PPM_MAX_ARG_SIZE)
return PPM_FAILURE_BUFFER_FULL;

Expand Down
33 changes: 20 additions & 13 deletions driver/bpf/fillers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -308,26 +308,21 @@ static __always_inline int bpf_poll_parse_fds(struct filler_data *data,

#pragma unroll
for (j = 0; j < POLL_MAXFDS; ++j) {
u16 flags;
if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

if (j == nfds)
break;

u16 flags;
if (enter_event) {
flags = poll_events_to_scap(fds[j].events);
} else {
if (!fds[j].revents)
continue;

flags = poll_events_to_scap(fds[j].revents);
}

if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

*(s64 *)&data->buf[off & SCRATCH_SIZE_HALF] = fds[j].fd;
off += sizeof(s64);

if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

Expand Down Expand Up @@ -415,10 +410,14 @@ static __always_inline int bpf_parse_readv_writev_bufs(struct filler_data *data,
#endif
return PPM_FAILURE_INVALID_USER_MEMORY;


#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)
break;

size += iov[j].iov_len;
}
Expand Down Expand Up @@ -1506,23 +1505,27 @@ static __always_inline int __bpf_append_cgroup(struct css_set *cgroups,
char *cgroup_path[MAX_CGROUP_PATHS];
bool prev_empty = false;
int off = *len;
unsigned int off_bounded;

off_bounded = off & SCRATCH_SIZE_HALF;
if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

int res = bpf_probe_read_str(&buf[off & SCRATCH_SIZE_HALF],
int res = bpf_probe_read_str(&buf[off_bounded],
SCRATCH_SIZE_HALF,
subsys_name);
if (res == -EFAULT)
return PPM_FAILURE_INVALID_USER_MEMORY;

off += res - 1;

off_bounded = off & SCRATCH_SIZE_HALF;
if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

buf[off & SCRATCH_SIZE_HALF] = '=';
buf[off_bounded] = '=';
++off;
off_bounded = off & SCRATCH_SIZE_HALF;

#pragma unroll MAX_CGROUP_PATHS
for (int k = 0; k < MAX_CGROUP_PATHS; ++k) {
Expand All @@ -1541,20 +1544,24 @@ static __always_inline int __bpf_append_cgroup(struct css_set *cgroups,
if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

buf[off & SCRATCH_SIZE_HALF] = '/';
buf[off_bounded] = '/';
++off;
off_bounded = off & SCRATCH_SIZE_HALF;
}

prev_empty = false;

if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

res = bpf_probe_read_str(&buf[off & SCRATCH_SIZE_HALF],
res = bpf_probe_read_str(&buf[off_bounded],
SCRATCH_SIZE_HALF,
cgroup_path[k]);
if (res > 1)
{
off += res - 1;
off_bounded = off & SCRATCH_SIZE_HALF;
}
else if (res == 1)
prev_empty = true;
else
Expand All @@ -1565,7 +1572,7 @@ static __always_inline int __bpf_append_cgroup(struct css_set *cgroups,
if (off > SCRATCH_SIZE_HALF)
return PPM_FAILURE_BUFFER_FULL;

buf[off & SCRATCH_SIZE_HALF] = 0;
buf[off_bounded] = 0;
++off;
*len = off;

Expand Down