bionic: prevent root processes from calling __system_property_add
If a root process other than init calls __system_property_add, which
it should never do, it will break the design assumption that there is
only one mutator.
Pass O_EXCL to open() in map_prop_region_rw to ensure that only one
process ever has the property pages open for write.
(cherry picked from commit fb9b7b436f
)
Change-Id: I6df3afedbfb5d07891b095aa24b78278381a5aaf
This commit is contained in:
@@ -128,11 +128,13 @@ static int map_prop_area_rw()
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{
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prop_area *pa;
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int fd;
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int ret;
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/* dev is a tmpfs that we can use to carve a shared workspace
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* out of, so let's do that...
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*/
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fd = open(property_filename, O_RDWR | O_CREAT | O_NOFOLLOW, 0644);
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fd = open(property_filename, O_RDWR | O_CREAT | O_NOFOLLOW | O_CLOEXEC |
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O_EXCL, 0444);
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if (fd < 0) {
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if (errno == EACCES) {
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/* for consistency with the case where the process has already
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@@ -143,6 +145,10 @@ static int map_prop_area_rw()
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return -1;
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}
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ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
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if (ret < 0)
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goto out;
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if (ftruncate(fd, PA_SIZE) < 0)
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goto out;
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@@ -186,8 +192,16 @@ static int map_prop_area()
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{
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bool fromFile = true;
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int result = -1;
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int fd;
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int ret;
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int fd = open(property_filename, O_RDONLY | O_NOFOLLOW);
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fd = open(property_filename, O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
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if (fd >= 0) {
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/* For old kernels that don't support O_CLOEXEC */
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ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
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if (ret < 0)
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goto cleanup;
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}
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if ((fd < 0) && (errno == ENOENT)) {
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/*
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