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| author |   Daniel Borkmann <daniel@iogearbox.net> | 2017-03-11 16:55:49 +0100 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-03-12 23:51:34 -0700 |
| commit | 65869a47f3488253f5fd88cc4f14e0a4e2601a55 (patch) | |
| tree | e34da15943fbe50adc5aeaac96fce51b0cedf8bf /include | |
| parent | selftests/bpf: fix broken build (diff) | |
| download | linux-dev-65869a47f3488253f5fd88cc4f14e0a4e2601a55.tar.xz linux-dev-65869a47f3488253f5fd88cc4f14e0a4e2601a55.zip | |
bpf: improve read-only handling
Improve bpf_{prog,jit_binary}_{un,}lock_ro() by throwing a
one-time warning in case of an error when the image couldn't
be set read-only, and also mark struct bpf_prog as locked when
bpf_prog_lock_ro() was called.
Reason for the latter is that bpf_prog_unlock_ro() is called from
various places including error paths, and we shouldn't mess with
page attributes when really not needed.
For bpf_jit_binary_unlock_ro() this is not needed as jited flag
implicitly indicates this, thus for archs with ARCH_HAS_SET_MEMORY
we're guaranteed to have a previously locked image. Overall, this
should also help us to identify any further potential issues with
set_memory_*() helpers.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/filter.h | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index 0c167fdee5f7..fbf7b39e8103 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -409,6 +409,7 @@ struct bpf_prog { u16 pages; /* Number of allocated pages */ kmemcheck_bitfield_begin(meta); u16 jited:1, /* Is our filter JIT'ed? */ + locked:1, /* Program image locked? */ gpl_compatible:1, /* Is filter GPL compatible? */ cb_access:1, /* Is control block accessed? */ dst_needed:1, /* Do we need dst entry? */ @@ -554,22 +555,29 @@ static inline bool bpf_prog_was_classic(const struct bpf_prog *prog) #ifdef CONFIG_ARCH_HAS_SET_MEMORY static inline void bpf_prog_lock_ro(struct bpf_prog *fp) { - set_memory_ro((unsigned long)fp, fp->pages); + fp->locked = 1; + WARN_ON_ONCE(set_memory_ro((unsigned long)fp, fp->pages)); } static inline void bpf_prog_unlock_ro(struct bpf_prog *fp) { - set_memory_rw((unsigned long)fp, fp->pages); + if (fp->locked) { + WARN_ON_ONCE(set_memory_rw((unsigned long)fp, fp->pages)); + /* In case set_memory_rw() fails, we want to be the first + * to crash here instead of some random place later on. + */ + fp->locked = 0; + } } static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr) { - set_memory_ro((unsigned long)hdr, hdr->pages); + WARN_ON_ONCE(set_memory_ro((unsigned long)hdr, hdr->pages)); } static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr) { - set_memory_rw((unsigned long)hdr, hdr->pages); + WARN_ON_ONCE(set_memory_rw((unsigned long)hdr, hdr->pages)); } #else static inline void bpf_prog_lock_ro(struct bpf_prog *fp) |