diff options
| author | Rich Felker <dalias@aerifal.cx> | 2020-09-09 21:55:11 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2020-09-09 21:55:11 -0400 |
| commit | 55fb9a177316aa46c639d93dd0323d9a9a8c160c (patch) | |
| tree | e48ec6bc0079a981fe17ba9314b28378055a01c4 | |
| parent | f035c7b1e65b6566c979ed69bada82a466580ba2 (diff) | |
| download | musl-55fb9a177316aa46c639d93dd0323d9a9a8c160c.tar.gz | |
use new SYS_faccessat2 syscall to implement faccessat with flags
commit 0a05eace163cee9b08571d2ff9d90f5e82d9c228 implemented AT_EACCESS
for faccessat with a horrible hack, creating a child process to change
switch uid/gid and perform the access probe without making potentially
irreversible changes to the caller's credentials. this was due to the
syscall lacking a flags argument.
linux 5.8 introduced a new syscall, SYS_faccessat2, fixing this
deficiency. use it if any flags are passed, and fallback to the old
strategy on ENOSYS. continue using the old syscall when there are no
flags.
| -rw-r--r-- | src/unistd/faccessat.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/unistd/faccessat.c b/src/unistd/faccessat.c index 76bbd4c7..557503eb 100644 --- a/src/unistd/faccessat.c +++ b/src/unistd/faccessat.c @@ -25,12 +25,17 @@ static int checker(void *p) int faccessat(int fd, const char *filename, int amode, int flag) { - if (!flag || (flag==AT_EACCESS && getuid()==geteuid() && getgid()==getegid())) - return syscall(SYS_faccessat, fd, filename, amode, flag); + if (flag) { + int ret = __syscall(SYS_faccessat2, fd, filename, amode, flag); + if (ret != -ENOSYS) return __syscall_ret(ret); + } - if (flag != AT_EACCESS) + if (flag & ~AT_EACCESS) return __syscall_ret(-EINVAL); + if (!flag || (getuid()==geteuid() && getgid()==getegid())) + return syscall(SYS_faccessat, fd, filename, amode); + char stack[1024]; sigset_t set; pid_t pid; |