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QoL improvements for inject #1682

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merged 2 commits into from
Apr 16, 2018
Merged

QoL improvements for inject #1682

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fb3c0a7
Make parsing more strict
Apr 13, 2018
45bcfb7
More helpful help message
Apr 13, 2018
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More helpful help message
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Howard McLauchlan committed Apr 13, 2018
commit 45bcfb7ca13f37b8e51117364b025d47550dec3c
22 changes: 19 additions & 3 deletions tools/inject.py
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Original file line number Diff line number Diff line change
Expand Up @@ -295,6 +295,21 @@ def attach(self, bpf):


class Tool:

examples ="""
EXAMPLES:
# ./inject.py kmalloc -v 'SyS_mount()'
Fails all calls to syscall mount
# ./inject.py kmalloc -v '(true) => SyS_mount()(true)'
Explicit rewriting of above
# ./inject.py kmalloc -v 'mount_subtree() => btrfs_mount()'
Fails btrfs mounts only
# ./inject.py kmalloc -v 'd_alloc_parallel(struct dentry *parent, const struct \\
qstr *name)(STRCMP(name->name, 'bananas'))'
Fails dentry allocations of files named 'bananas'
# ./inject.py kmalloc -v -P 0.01 'SyS_mount()'
Fails calls to syscall mount with 1% probability
"""
# add cases as necessary
error_injection_mapping = {
"kmalloc": "should_failslab(struct kmem_cache *s, gfp_t gfpflags)",
Expand All @@ -304,8 +319,9 @@ class Tool:
def __init__(self):
parser = argparse.ArgumentParser(description="Fail specified kernel" +
" functionality when call chain and predicates are met",
formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument(metavar="mode", dest="mode",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=Tool.examples)
parser.add_argument(dest="mode", choices=['kmalloc','bio'],
help="indicate which base kernel function to fail")
parser.add_argument(metavar="spec", dest="spec",
help="specify call chain")
Expand All @@ -316,7 +332,7 @@ def __init__(self):
metavar="probability", type=float,
help="probability that this call chain will fail")
parser.add_argument("-v", "--verbose", action="store_true",
help="print BPF program")
help="print BPF program")
self.args = parser.parse_args()

self.program = ""
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17 changes: 15 additions & 2 deletions tools/inject_example.txt
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Expand Up @@ -115,12 +115,12 @@ fail our mounts half the time:
# ./inject.py kmalloc -v -P 0.01 'SyS_mount()'

USAGE message:
usage: inject.py [-h] [-I header] [-P probability] [-v] mode spec
usage: inject.py [-h] [-I header] [-P probability] [-v] {kmalloc,bio} spec

Fail specified kernel functionality when call chain and predicates are met

positional arguments:
mode indicate which base kernel function to fail
{kmalloc,bio} indicate which base kernel function to fail
spec specify call chain

optional arguments:
Expand All @@ -130,3 +130,16 @@ optional arguments:
-P probability, --probability probability
probability that this call chain will fail
-v, --verbose print BPF program

EXAMPLES:
# ./inject.py kmalloc -v 'SyS_mount()'
Fails all calls to syscall mount
# ./inject.py kmalloc -v '(true) => SyS_mount()(true)'
Explicit rewriting of above
# ./inject.py kmalloc -v 'mount_subtree() => btrfs_mount()'
Fails btrfs mounts only
# ./inject.py kmalloc -v 'd_alloc_parallel(struct dentry *parent, const struct \
qstr *name)(STRCMP(name->name, 'bananas'))'
Fails dentry allocations of files named 'bananas'
# ./inject.py kmalloc -v -P 0.01 'SyS_mount()'
Fails calls to syscall mount with 1% probability