diff options
Diffstat (limited to 'tools/perf/util/cap.c')
| -rw-r--r-- | tools/perf/util/cap.c | 63 |
1 files changed, 44 insertions, 19 deletions
diff --git a/tools/perf/util/cap.c b/tools/perf/util/cap.c index c3ba841bbf37..7574a67651bc 100644 --- a/tools/perf/util/cap.c +++ b/tools/perf/util/cap.c @@ -3,27 +3,52 @@ * Capability utilities */ -#ifdef HAVE_LIBCAP_SUPPORT - #include "cap.h" -#include <stdbool.h> -#include <sys/capability.h> - -bool perf_cap__capable(cap_value_t cap) -{ - cap_flag_value_t val; - cap_t caps = cap_get_proc(); +#include "debug.h" +#include <errno.h> +#include <string.h> +#include <unistd.h> +#include <linux/capability.h> +#include <sys/syscall.h> - if (!caps) - return false; +#ifndef SYS_capget +#define SYS_capget 90 +#endif - if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val) != 0) - val = CAP_CLEAR; +#define MAX_LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_3 - if (cap_free(caps) != 0) - return false; - - return val == CAP_SET; +bool perf_cap__capable(int cap, bool *used_root) +{ + struct __user_cap_header_struct header = { + .version = _LINUX_CAPABILITY_VERSION_3, + .pid = getpid(), + }; + struct __user_cap_data_struct data[MAX_LINUX_CAPABILITY_U32S]; + __u32 cap_val; + + *used_root = false; + while (syscall(SYS_capget, &header, &data[0]) == -1) { + /* Retry, first attempt has set the header.version correctly. */ + if (errno == EINVAL && header.version != _LINUX_CAPABILITY_VERSION_3 && + header.version == _LINUX_CAPABILITY_VERSION_1) + continue; + + pr_debug2("capget syscall failed (%s - %d) fall back on root check\n", + strerror(errno), errno); + *used_root = true; + return geteuid() == 0; + } + + /* Extract the relevant capability bit. */ + if (cap >= 32) { + if (header.version == _LINUX_CAPABILITY_VERSION_3) { + cap_val = data[1].effective; + } else { + /* Capability beyond 32 is requested but only 32 are supported. */ + return false; + } + } else { + cap_val = data[0].effective; + } + return (cap_val & (1 << (cap & 0x1f))) != 0; } - -#endif /* HAVE_LIBCAP_SUPPORT */ |