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[seccomp] allow fcntl F_SETFD 

musl does a F_SETFD in its fdopendir
This commit is contained in:
Omar Polo 2021-01-24 19:12:32 +00:00
parent 252908e6bb
commit f88311e534
1 changed files with 6 additions and 1 deletions
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7
sandbox.c
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@ -179,17 +179,22 @@ sandbox()
/* alpine on amd64 does a clock_gettime(2) */
SC_ALLOW(clock_gettime),
/* for directory listing */
SC_ALLOW(getdents64),
SC_ALLOW(exit),
SC_ALLOW(exit_group),
/* allow only F_GETFL and F_SETFL fcntl */
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_fcntl, 0, 6),
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_fcntl, 0, 8),
BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
(offsetof(struct seccomp_data, args[1]))),
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, F_GETFL, 0, 1),
BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, F_SETFL, 0, 1),
BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, F_SETFD, 0, 1),
BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
BPF_STMT(BPF_RET | BPF_K, SC_FAIL),
/* re-load the syscall number */