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bpf: Take return from set_memory_ro() into account with bpf_prog_lock_ro()

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set_memory_ro() can fail, leaving memory unprotected.

Check its return and take it into account as an error.

Link: https://github.com/KSPP/linux/issues/7
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linux-hardening@vger.kernel.org <linux-hardening@vger.kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Message-ID: <286def78955e04382b227cb3e4b6ba272a7442e3.1709850515.git.christophe.leroy@csgroup.eu>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Christophe Leroy 2024-03-08 06:38:07 +01:00 • committed by Alexei Starovoitov
parent 4d8926a040
commit 7d2cc63eca
3 changed files with 12 additions and 5 deletions
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5
include/linux/filter.h
View file

@ -887,14 +887,15 @@ bpf_ctx_narrow_access_offset(u32 off, u32 size, u32 size_default)
#define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0])) #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
static inline void bpf_prog_lock_ro(struct bpf_prog *fp) static inline int __must_check bpf_prog_lock_ro(struct bpf_prog *fp)
{ {
#ifndef CONFIG_BPF_JIT_ALWAYS_ON #ifndef CONFIG_BPF_JIT_ALWAYS_ON
if (!fp->jited) { if (!fp->jited) {
set_vm_flush_reset_perms(fp); set_vm_flush_reset_perms(fp);
set_memory_ro((unsigned long)fp, fp->pages); return set_memory_ro((unsigned long)fp, fp->pages);
} }
#endif #endif
return 0;
} }
static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr) static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)

4
kernel/bpf/core.c
View file

@ -2403,7 +2403,9 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
} }
finalize: finalize:
bpf_prog_lock_ro(fp); *err = bpf_prog_lock_ro(fp);
if (*err)
return fp;
/* The tail call compatibility check can only be done at /* The tail call compatibility check can only be done at
* this late stage as we need to determine, if we deal * this late stage as we need to determine, if we deal

8
kernel/bpf/verifier.c
View file

@ -19263,10 +19263,14 @@ static int jit_subprogs(struct bpf_verifier_env *env)
* bpf_prog_load will add the kallsyms for the main program. * bpf_prog_load will add the kallsyms for the main program.
*/ */
for (i = 1; i < env->subprog_cnt; i++) { for (i = 1; i < env->subprog_cnt; i++) {
bpf_prog_lock_ro(func[i]); err = bpf_prog_lock_ro(func[i]);
bpf_prog_kallsyms_add(func[i]); if (err)
goto out_free;
} }
for (i = 1; i < env->subprog_cnt; i++)
bpf_prog_kallsyms_add(func[i]);
/* Last step: make now unused interpreter insns from main /* Last step: make now unused interpreter insns from main
* prog consistent for later dump requests, so they can * prog consistent for later dump requests, so they can
* later look the same as if they were interpreted only. * later look the same as if they were interpreted only.