Bug #623 ยป fix-sigbus-race.patch
| src/bin/lttng-sessiond/shm.c | ||
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/* Default permissions */
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mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
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/* Change owner of the shm path */
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/*
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* Change owner of the shm path.
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*/
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if (global) {
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ret = chown(shm_path, 0, 0);
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if (ret < 0) {
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if (errno != ENOENT) {
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PERROR("chown wait shm");
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goto error;
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}
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}
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/*
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* If global session daemon, any application can register so the shm
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* needs to be set in read-only mode for others.
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* If global session daemon, any application can
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* register. Make it initially writeable so applications
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* registering concurrently can do ftruncate() by
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* themselves.
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*/
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mode |= S_IROTH;
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} else {
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ret = chown(shm_path, getuid(), getgid());
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if (ret < 0) {
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if (errno != ENOENT) {
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PERROR("chown wait shm");
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goto error;
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}
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}
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}
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/*
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* Set permissions to the shm even if we did not create the shm.
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*/
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ret = chmod(shm_path, mode);
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if (ret < 0) {
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if (errno != ENOENT) {
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PERROR("chmod wait shm");
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goto error;
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}
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mode |= S_IROTH | S_IWOTH;
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}
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/*
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| ... | ... | |
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}
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#ifndef __FreeBSD__
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ret = fchmod(wait_shm_fd, mode);
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if (ret < 0) {
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PERROR("fchmod");
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exit(EXIT_FAILURE);
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if (global) {
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ret = fchown(wait_shm_fd, 0, 0);
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if (ret < 0) {
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PERROR("fchown");
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exit(EXIT_FAILURE);
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}
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/*
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* If global session daemon, any application can
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* register so the shm needs to be set in read-only mode
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* for others.
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*/
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mode &= ~S_IWOTH;
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ret = fchmod(wait_shm_fd, mode);
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if (ret < 0) {
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PERROR("fchmod");
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exit(EXIT_FAILURE);
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}
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} else {
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ret = fchown(wait_shm_fd, getuid(), getgid());
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if (ret < 0) {
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PERROR("fchown");
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exit(EXIT_FAILURE);
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}
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}
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#else
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#warning "FreeBSD does not support setting file mode on shm FD. Remember that for secure use, lttng-sessiond should be started before applications linked on lttng-ust."
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#warning "FreeBSD does not support setting file mode on shm FD."
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#endif
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DBG("Got the wait shm fd %d", wait_shm_fd);
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